MARAON BASIN

Technical Report

The Hydrocarbon Potential of NE Peru Huallaga, Santiago and Maraon

Basins Study

by

PARSEP

Proyecto de Asistencia para La Reglamentacin del Sector Energtico del Per

TEKNICA PERUPETRO S.A.

Gary Wine (Project Leader) Elmer Martnez (Senior Joe Arcuri (Senior Geophysicist) Geophysicist/Perupetro Coordinator)

Justo Fernandez (Senior Geologist) Ysabel Caldern (Geologist) Carlos Galdos (Geophysicist)

September 2002

On the cover: A 3D display of the Maraon Basin as seismically mapped on the Base of Cretaceous. View is from the north looking towards the south.

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TABLE OF CONTENTS TABLE OF CONTENTS.................................................................................................... 0 FIGURES............................................................................................................................ 4 TABLES ............................................................................................................................. 8 ENCLOSURES................................................................................................................... 9

Digital ........................................................................................................................... 10 APPENDIX....................................................................................................................... 10 EXECUTIVE SUMMARY .............................................................................................. 12

Interpretation................................................................................................................. 12 1.0 INTRODUCTION ..................................................................................................... 16 2.0 SCOPE OF PROJECT ............................................................................................... 18 3.0 PREVIOUS WORK IN THE STUDY AREA........................................................... 22 4.0 GEOLOGY OF THE MARANON AREA................................................................ 23

4.1 GENERAL BASIN DESCRIPTION..................................................................... 23 4.2 REGIONAL GEOLOGY....................................................................................... 24

4.2.1 Pre-Andean System......................................................................................... 24 4.2.2 Andean System ............................................................................................... 28

4.3 GEOLOGY MARAON PROJECT AREA........................................................ 32 4.3.1 Mapping Project Overview............................................................................. 32

4.3.1.1 Mapping Method...................................................................................... 32 4.3.1.2 Cretaceous Isopach Maps ........................................................................ 34

Cretaceous Isopach ........................................................................................... 34 Lower Cretaceous Isopach................................................................................ 34 Upper Cretaceous Isopach ................................................................................ 36 Vivian Formation Isopach................................................................................. 36

4.3.1.3 Tertiary Isopach Maps ............................................................................. 39 Lower Tertiary Isopach..................................................................................... 39 Lower Tertiary to Upper Cretaceous Isopach................................................... 39

4.3.1.4 Structure Maps ......................................................................................... 39 4.3.1.5 Cretaceous Sand/Shale Ratio Maps ......................................................... 40

Lower Cretaceous Sand/Shale Map ............................................................... 40 Upper Cretaceous Sand/Shale Map .................................................................. 42

4.3.2 Stratigraphy of the Maraon Area .................................................................. 42 4.3.2.1 Tertiary..................................................................................................... 44 4.3.2.2 Cretaceous................................................................................................ 45

Maraon Basin Hingeline Fault ........................................................................ 46 Maraon Basin Cretaceous Rifting................................................................... 47 Santiago Basin Cretaceous Rifting ................................................................... 47 Vivian/Chonta Contact...................................................................................... 50 Limonyacu 1X Well.......................................................................................... 50 Cretaceous aged Carbonate build-ups in the Maraon Basin ........................... 52

4.3.2.3 Jurassic (Sarayaquillo Fm) to Triassic (Mitu) ......................................... 52 Sarayaquillo Formation..................................................................................... 52 Pucar Group .................................................................................................... 55 Mitu................................................................................................................... 58

4.3.2.4 Paleozoic .................................................................................................. 58 4.3.1 Structural Analysis of Maraon Area ............................................................. 59

5.0 GEOPHYSICS........................................................................................................... 64

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5.1 INTRODUCTION ................................................................................................. 64 5.2 MARAON BASIN SEISMIC ACQUISTION HISTORY OF PARSEP DATA SET ............................................................................................................................... 65 5.3 SEISMIC INTERPRETATION............................................................................. 66

5.3.1 Data Quality .................................................................................................... 66 5.3.2 Well Data Seismic Ties................................................................................... 67 5.3.3 Maraon Basin Seismic Profiles..................................................................... 67

5.3.3.1 Profile 1 Orellana to Nahuapa (Enclosure 26a) ................................. 67 5.3.3.2 Profile 2 Samiria Sur to Bolognesi (Enclosure 26b)............................. 68 5.3.3.3 Profile 3 NW Ucayali to Tapiche (Enclosure 26c) ............................... 69 5.3.3.4 Profile 4 Shanusi to Zapote (Enclosure 26d) ........................................... 69 5.3.3.5 Profile 5 Huangana to Tangarana (Enclosure 26e) .............................. 69 5.3.3.6 Profile 6 Nanay to Nahuapa (Enclosure 26f)........................................ 70 5.3.3.7 Profile 7- Santiago Basin to Arabela (Enclosure 26g)............................. 70 5.3.3.8 Profile 8 Ungumayo to Otorongo (Enclosure 26h)............................... 70 5.3.3.9 Profile 9 Paiche to Piraa (Enclosure 26i)............................................ 71 5.3.3.10 Profile 10 Arabela to Corrientes (Enclosure 26j) .............................. 71

5.3.4 Maraon Basin Seismic Mapping................................................................... 71 6.0 SUMMARY OF WELLS DRILLED BETWEEN 1990 - 2000................................ 72

6.1 PUCACURO 1X.................................................................................................... 73 6.2 TIGRE 1X.............................................................................................................. 73 6.3 ARABELA 1X....................................................................................................... 73 6.4 DIANA MAE 1X................................................................................................... 74 6.5 TUCUNARE 1X.................................................................................................... 74 6.7 ZORRO 1X ............................................................................................................ 75 6.8 SANTA CATALINA 1X....................................................................................... 75 6. 9 SANTA MARTHA 1X......................................................................................... 76 6.10 ORELLANA 1X .................................................................................................. 76 6.11 SUNGAROYACU 1X......................................................................................... 76 6.12 LIMONYACU 1X ............................................................................................... 76 6.13 BLOCK 67 WELLS (Dorado 1X, Piraa 1X, Paiche 1X) .................................. 77 6.14 SUMMARY......................................................................................................... 78

7.0 PETROLEUM GEOLOGY ....................................................................................... 79 7.1 GEOCHEMISTRY ................................................................................................ 79

7.1.1 General............................................................................................................ 79 7.1.2 Source Rocks and Maturity............................................................................. 80

7.1.2.1 Tertiary..................................................................................................... 81 7.1.2.2 Cretaceous................................................................................................ 82 7.1.2.3 Triassic/Jurassic ....................................................................................... 83 7.1.2.4 Paleozoic .................................................................................................. 83

7.1.3 Oil Families..................................................................................................... 84 7.1.3.1 Maquia/Samiria oil Family (Family C).................................................... 86 7.1.3.2 The Tambo/Sungachi Oil Family (Families A and B)............................. 86 7.1.3.3 Other Oil Family Studies ......................................................................... 88

7.1.4 Oil/Oil and Oil Source Correlations ............................................................ 89 7.1.5 Migration of Hydrocarbons............................................................................. 89

7.2 THERMAL MATURITY AND HC GENERATION MODELING..................... 90 7.2.1 Introduction..................................................................................................... 90 7.2.2 Present-Day Maturity...................................................................................... 97 7.2.2 Thermal Maturity and HC Generation Modeling ........................................... 98

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7.2.2.1 Chambira Este 1X (123X) Well............................................................... 98 7.2.2.2 Chapuli 1X Well .................................................................................... 100 7.2.2.3 Corrientes 1X Well ................................................................................ 102 7.2.2.4 Forestal 1X (3X) Well ........................................................................... 103 7.2.2.5 Jibaro 1X Well ....................................................................................... 105 7.2.2.6 La Frontera 1X (3X) Well...................................................................... 107 7.2.2.7 Loreto 1X Well ...................................................................................... 109 7.2.2.8 Mahuaca 1X (3X) Well.......................................................................... 111 7.2.2.9 Maraon 110-1 Well .............................................................................. 112 7.2.2.10 Orellana 1X (3X) Well......................................................................... 114 7.2.2.11 Piraa 1X Well..................................................................................... 116 7.2.2.12 Santa Catalina 1X (2X) Well ............................................................... 118 7.2.2.13 Santa Lucia 1X (2X) Well ................................................................... 120 7.2.2.14 Shanusi 1X (2X) Well.......................................................................... 122 7.2.2.15 Tapiche 1X (2X) Well ......................................................................... 123 7.2.2.16 Tucunare 1X Well................................................................................ 125 7.2.2.17 Valencia 1X (25X) Well ...................................................................... 127 7.2.2.18 Yanayacu 1X (27X) Well .................................................................... 129 7.2.2.19 Yaez 1X (14X) Well .......................................................................... 130 7.2.2.20 Yarina 1X (2X) Well ........................................................................... 132

7.2.3 Temperature Gradient ................................................................................... 134 7.3 EXPLORATION CONCEPTS MARAON BASIN ......................................... 135

7.3.1 Historical Exploration Strategies for Oil Exploration in the Maraon Basin135 7.3.2 Revised Exploration Strategies for Oil Exploration in the Maraon Basin.. 139

7.3.2.1 Cretaceous............................................................................................... 139 Paleo-Stratigraphic Traps................................................................................ 140 Paleo-Structural Traps .................................................................................... 141 Conclusions..................................................................................................... 144

7.3.2.2 Pucar...................................................................................................... 145 7.3.2.3 Paleozoic ................................................................................................ 146

7.3.2 Other Exploration Issues............................................................................... 147 7.3.2.1 Data Issues ............................................................................................. 147 7.3.2.2 Hydrodynamics ...................................................................................... 148

7.4 NEW PROSPECTS AND LEADS IN THE MARAON BASIN .................... 149 7.4.1 Picuro Prospect ............................................................................................. 149 7.4.2 Pastococha/Samiria Area (Enclosure 31)...................................................... 152

7.4.2.1 Nutria Prospect (Figures 124 to 126)..................................................... 155 7.4.2.1 Other Lead Areas (Figures 124 and 125)............................................... 155

7.3.4 Majaz Prospect (Enclosure 32) ..................................................................... 155 7.3.4 Southwest Maraon Pucar Prospects .......................................................... 158

7.3.4.2 Shanusi 1X Offset .................................................................................. 158 7.3.4.2 Yurimaguas Structure ............................................................................ 159

8.0 CONCLUSIONS...................................................................................................... 160 9.0 SELECTED REFERENCES ................................................................................... 162

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FIGURES Figure 1: Areas of investigation of the PARSEP Group Huallaga, Santiago and Maraon Basins,

and intervening areas.................................................................................................... 16 Figure 2: Map showing location of 2D SEGY Seismic Data set and the new field wildcats utilized in

the Maraon Basin Evaluation....................................................................................... 18 Figure 3: Location of the Amerada and Oceanic data sets in the western Maraon Basin that were

interpreted off of paper copies. The results of this interpretation are included in montages (Enclosures 30a and 30b) outside of the digital data set interpretation. ............................... 19

Figure 4: Map of the Block 1AB area showing the lack of available SEGY seismic data ............... 20 Figure 5: Geology of the Maraon/Santiago/Huallaga Basin Area ............................................. 23 Figure 6: Magnetic Intensity Map of the Maraon Basin and surrounding area.......................... 25 Figure 7: Bouguer Gravity Map of the Maraon Basin and surrounding area ............................ 25 Figure 8: Stratigraphic Column of the NE Peruvian basins - highlighted in yellow is the

nomenclature used in this report .................................................................................... 26 Figure 9: Location of the Paleozoic penetrations in the Maraon Basin...................................... 28 Figure 10: Seismic line OR-95-08 in the southwestern most Maraon Basin showing the evolution of

a Late Permian to early Mesozoic extensional basin through the use of different datums (flattenings) (PARSEP, 2002) ......................................................................................... 29

Figure 11: (After Tankard, 2001) Late Jurassic Early Cretaceous paleogeography, showing two principal styles of basin formation, viz. strike-slip associated extensional basins in which the extensional normal faults are approximately northward oriented, and NW-oriented strike-slip basins. The locus of extensional subsidence was between the Contaya and Jambeli-Naranjal-Vuana shear zones. Ac, Acre basin; bsz, Biabo shear zone; C, Cutucu depocenter; co, Contaya high; csz, Contaya shear zone; H, Huallaga Basin; ia, Iquitos Arch; jnvsz, Jambeli-Naranjal-Vuana shear zone; jsz, Juru shear zone; lT ftb, late Tertiary fold thrust belt of the Madre de Dios range; N, Napo depocenter; pa, Paragua shear zone; psz, Pucalpa shear zone; S, Santiago Basin; sh, Shanusi fault (Chazuta Thrust-PARSEP); U, Ucayali Basin................................ 31

Figure 12: Structure Map on Top of Chonta Limestone showing the depositional edge of the unit. 33 Figure 13: Cretaceous Isopach Map....................................................................................... 33 Figure 14: Isopach of the Upper Cretaceous (Top Vivian to Chonta Limestone Marker).............. 35 Figure 15: Isopach of the Lower Cretaceous (Chonta Limestone Marker to Base Cretaceous) ...... 35 Figure 16: Isopach of the Vivian Formation............................................................................ 37 Figure 17: Isopach of the Lower Tertiary (Pozo Shale to the Top of Vivian) ............................... 37 Figure 18: Isopach of the Lower Tertiary (Pozo Shale) to the Chonta Limestone Marker............. 38 Figure 19: Structure Map Top of the Vivian Formation ........................................................... 38 Figure 20: Sand/Shale Ratio Map of the Lower Cretaceous (excluding the Cushabatay Formation)

................................................................................................................................... 41 Figure 21: Sand/Shale Ratio Map of the Upper Cretaceous....................................................... 41 Figure 22: West to east composite seismic line through the Maraon Basin showing several cycles of

Pozo deposition ............................................................................................................ 43 Figure 23: Seismic Line OXY-23 across the Maraon Basin Hingeline fault showing its influence on

Cretaceous deposition ................................................................................................... 46 Figure 24: Seismic line OXY 9 across the Situchi Graben showing evidence of transtensional

tectonics that were active in the northwest Maraon Basin during Cretaceous to Early Tertiary time. ........................................................................................................................... 48

Figure 25: A seismic example from the Santiago Basin demonstrating Cretaceous syn-depositional extensional tectonics. Note the dramatic thinning of the Cretaceous section from south to north........................................................................................................................... 49

Figure 26: Cross-Section from Capahuari Sur to the Tucunare well showing the prograding relationship of the Vivian and Upper Chonta Formations ................................................. 50

Figure 27: Location of Tambo 3D (southern Block 1AB area) ................................................... 51 Figure 28: Amplitude time slice through Tambo 3D survey 475ms below a flattened Pozo datum

showing location of composite seismic line ....................................................................... 51

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Figure 29: Composite 3D line through two buildups associated with the Chonta Limestone, with Pozo datum.................................................................................................................. 51

Figure 30: Carbonate anomalies detailed and datumed on near Base Chonta Limestone. ............. 51 Figure 31: As in Figure 30 above but displayed as an instantaneous amplitude section................. 51 Figure 32: Composite Seismic Line in the southern Maraon Basin showing the inter-Sarayaquillo

event separating the Upper and Lower Sarayaquillo Units. ............................................... 53 Figure 33: Isochron Map of the Lower Sarayaquillo Unit ......................................................... 54 Figure 34: Isochron Map of the Upper Sarayaquillo Unit ......................................................... 54 Figure 35: Coastal seismic line CP-739802 flattened on the Base Cretaceous Unconformity showing

westward progradational relationship between the Sarayaquillo and Pucar sequences. See Figure 33 for location.................................................................................................... 55

Figure 36: Isochron Map of the Pucar Group in the Maraon Basin ........................................ 56 Figure 37: Isochron map of Chonta to Paleozoic/Basement interval showing paleo-highs and lows in

the vicinity of Shanusi and Loreto wells that would have had an influence on the deposition of the Pucar Formation. .................................................................................................. 57

Figure 38: Series of flattenings across the Mitu graben located east of the Shanusi well (Figure 37).................................................................................................................................... 58

Figure 39: TWT Structure Map on the Contaya showing the distribution of Paleozoic rocks in the Southern Maraon Basin .............................................................................................. 59

Figure 40: Preserved Paleozoic section in the southern Maraon Basin showing the horst and graben system that developed at the beginning of the Andean Orogeny. Many of the normal faults cutting the Paleozoic section have undergone later minor compressional reactivation. The Paleozoic intervals noted on the seismic line are approximations only................................. 60

Figure 41: Deflection of the Shanusi fault around the Tiraco Dome (Modified from Ingemmet digital quadrangle maps). .............................................................................................. 60

Figure 42: Isochron of the Pozo to Base Cretaceous interval ..................................................... 61 Figure 43: Seismic example of the vertical uplift of the northern Campanquiz Mountains separating

the Santiago and Maraon Basins .................................................................................. 62 Figure 44: Seismic line MPH 23 across the southern plunge of the Tiraco Dome. This line is

orientated SW to NE and is located just south of the Tiraco Dome as shown in Figure 41...... 63 Figure 45: SW-NE seismic line through the northeast Maraon Basin (Block 67 Area) showing a

proliferation of faults with a very young origin that were formed during the Quechua III compressional tectonic event. ......................................................................................... 63

Figure 46: Map on left shows locations of the majority of seismic shot in the Maraon Basin since 1970. Map on right is a display of the SEGY Seismic data set that was used in this interpretation. Included in both are the available data sets in the Santiago and Huallaga Basins. ........................................................................................................................ 64

Figure 47: Map of the Maraon Basin showing the location of the ten Seismic Profiles ................ 68 Figure 48: Location of exploration wells drilled in the Maraon Basin between 1990 and 2000. .... 72 Figure 49: Distribution of Oil Families in the Maraon, Santiago and Huallaga Basins with the

Tambo/ Sungachi Family in the northern areas and the Maquia/Samiria Family in the south. Modified from CTI (2000) ............................................................................................. 85

Figure 50: Detail of Oil Families in the northern Maraon Basin, modified from Arco (1996)....... 85 Figure 51: Comparison of Sterane biomarker patterns of Sungachi and Tambo oils. Note close

correlation due to close genetic relationship. (Modified from CTI, 2000). ............................ 87 Figure 52: Distribution patterns of C25 and C26 Tricyclic Trepanes (T25 and T26) and C24-

Tetracyclic Terpane (Tet) in Sungachi 1,Samiria oils and Tiraco Dome Seep (Modified from CTI, 2000). .................................................................................................................. 87

Figure 53: Oil Families in the Maraon Basin Crude oils, from Arco (1996) ............................... 88 Figure 54: Migration pathways of Chonta and Pucar oils in the Maraon/Oriente Basin. Note

orientation of oil fields and Pucar subcrop. Modified from CTI (2000) .............................. 90 Figure 55: Index map of Maraon Basin wells which were modeled with BasinMod and cross

sections with present day maturity depths ....................................................................... 91 Figure 56: Present-Day Maturity in the Maraon Basin at Top Chonta level .............................. 92

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Figure 57: Present-Day Maturity in the Maraon Basin at bottom Chonta level. Maturity increases to the deep Western basin and to the NE where the Basement is at shallow depths ............... 92

Figure 58: Present-Day Maturity in the Maraon Basin at Top Pucar level............................... 93 Figure 59: Present-Day Maturity in the Maraon Basin at bottom Pucar level. Maturity increases

to the deep Western basin and to the NE where the Basement is at shallow depths ............... 93 Figure 60: Present day maturity in the northwestern and northern Maraon Basin .................... 94 Figure 61: Present day maturity in the southwestern and central Maraon Basin ....................... 95 Figure 62: Present day maturity in the southern and southeastern Maraon Basin. A pre-Cretaceous

maturity history is implied east of the Santa Lucia 2X well................................................ 96 Figure 63: Maturity burial in Chambira Este 123X Well shows the Pozo and Chonta in the early-

mature oil window and the Cretaceous Raya in the mid-mature oil window ........................ 99 Figure 64: Maturity versus Time plot in the Chambira Este 123X Well.................................... 100 Figure 65: Maturity burial in Chapuli 1X Well shows the Pozo in the early-mature oil window, all

Cretaceous in the mid-mature oil window and the Pucar mainly in the late-mature oil window.................................................................................................................................. 101

Figure 66: Maturity versus Time plot in the Chapuli 1X Well ................................................. 101 Figure 67: Maturity burial in Corrientes 1X Well shows the Pozo and Chonta Formations in the top

and middle of the early-mature oil window and the Raya the top of the mid-mature oil window................................................................................................................................. 102

Figure 68: Maturity versus Time plot in the Corrientes 1X Well ............................................. 103 Figure 69: Maturity burial in the Forestal 3X Well shows the Pozo in the early-mature oil window

and all the Cretaceous in the mid-mature oil windows .................................................... 104 Figure 70: Maturity versus Time plot in the Forestal 3X Well................................................. 105 Figure 71: Maturity burial in the Jibaro 1X Well shows the Pozo in the early-mature oil window and

all the Cretaceous in the mid-mature oil window............................................................ 106 Figure 72: Maturity versus Time plot in the Jibaro 1X Well ................................................... 106 Figure 73: Maturity burial in the La Frontera 3X Well shows the Cretaceous Chonta and Raya

Formations in the early-mature oil window and the Devonian Cabanillas in the main gas generation window ..................................................................................................... 108

Figure 74: Maturity versus Time plot in the La Frontera 3X Well ........................................... 108 Figure 75: Maturity versus Depth plot in the La Frontera 1X Well.......................................... 109 Figure 76: Maturity burial in the Loreto 1X Well shows the Pozo in the early-mature oil window, the

Cretaceous Chonta and Raya in the mid-mature oil window and the Pucar in the main gas generation window ..................................................................................................... 110

Figure 77: Maturity versus Depth plot in the Loreto 1X Well.................................................. 110 Figure 78: Maturity burial in the Mahuaca 3X Well shows the Pozo in the early-mature oil window,

the Cretaceous Chonta and Raya in the mid-mature oil window and the Pucar mainly in the top of the main gas generation window.......................................................................... 111

Figure 79: Maturity versus Time plot in the Mahuaca 3X Well ............................................... 112 Figure 80: Maturity burial in the Maraon 110 Well shows the Chonta and Raya Formations in the

early-mature oil window, and Devonian Cabanillas in the main gas generation window...... 113 Figure 81: Maturity versus Depth plot in the Maraon 110 Well ............................................. 114 Figure 82: Maturity burial in the Orellana 3X Well shows the Pozo Shale at the top of the early-

mature oil window, the Cretaceous Chonta and Raya Formations in the early-and mid-mature oil windows, respectively, and the Pucar in the late-mature oil window and top of the main gas generation window ..................................................................................................... 115

Figure 83: Maturity versus Time plot in the Orellana 3X Well ................................................ 115 Figure 84: Maturity burial in the Piraa 1X well shows most of the Cretaceous in the late-mature oil

window and the Pozo in the mid-mature oil window ....................................................... 117 Figure 85: Maturity versus Time plot in the Piraa 1X Well ................................................... 117 Figure 86: Maturity versus Depth plot in the Piraa 1X Well.................................................. 118 Figure 87: Maturity burial in the Santa Catalina 2X well shows the Cretaceous Chonta and Raya

Formations in the early- and mid-mature oil windows, respectively, and the Pucar in the main gas generation window................................................................................................ 119

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Figure 88: Maturity versus Time plot in the Santa Catalina 2X Well ....................................... 119 Figure 89: Maturity burial in the Santa Lucia 2X Well shows the Cretaceous mainly in the early-

mature oil window and the Pucar in the late-mature oil window..................................... 121 Figure 90: Maturity versus Time plot in the Santa Lucia 2X Well ........................................... 121 Figure 91: Maturity burial in the Shanusi 2X Well shows the Pozo and Chonta Formations in the

early-mature oil window, the Raya Formation in the mid-mature oil window and the Pucar between the late-mature oil window and the main gas generation window......................... 122

Figure 92: Maturity versus Depth plot in the Shanusi 2X well................................................. 123 Figure 93: Maturity burial in the La Frontera 3X Well shows the Cretaceous Chonta and Raya

Formations in the early-mature oil window and the Devonian Cabanillas in the main gas generation window ..................................................................................................... 124

Figure 94: Maturity versus Depth plot in the Tapiche 2X Well................................................ 125 Figure 95: Maturity burial in Tucunare 1X Well shows the Pozo in the early-mature oil window, the

Cretaceous between mid- and upper late-mature oil windows and the Pucar in the top of the main gas generation window........................................................................................ 126

Figure 96: Maturity versus Depth plot in the Tucunare 1X Well ............................................. 126 Figure 97: Maturity burial in Valencia 25X Well shows the Pozo and Chonta Formations in the

early-mature oil window and the Raya Formation in the mid-mature oil window............... 128 Figure 98: Maturity versus Time plot in the Valencia 25X Well .............................................. 129 Figure 99: Maturity burial in the Yanayacu 27X Well shows the Pozo Shale in the early-mature oil

window, the Cretaceous Chonta in the early- to mid-mature oil window and the Raya in the mid-mature oil window ............................................................................................... 129

Figure 100: Maturity versus Depth plot in the Yanayacu 27X Well.......................................... 130 Figure 101: Maturity burial in the Yaez 14X Well shows the Pozo in the early-mature oil window,

all the Cretaceous in the mid-mature oil window and the Pucar mainly in the late-mature oil window entering the top of the main gas generation window............................................ 131

Figure 102: Maturity versus Depth plot in the Yaez 14X Well ............................................... 132 Figure 103: Maturity burial in the Yarina 2X Well shows the Chonta and Raya in the early-mature

oil window and the Devonian Cabanillas in the main gas generation window..................... 133 Figure 104: Detailed Maturity burial chart for the Yarina 2X Well ......................................... 133 Figure 105: Maturity versus Depth plot in the Yarina 2X Well................................................ 134 Figure 106: Temperature Gradient map in the Maraon Basin w/Data from over 100 NFW (only

modeled wells shown).................................................................................................. 135 Figure 107: Seismic Line through Huitayacu 1X Well showing present day structure (left) and a

paleo-structural section (right) which has been flattened on the Pozo. Note the absence of a paleo-structure associated with the Huitayacu 1X Well ................................................... 136

Figure 108: Seismic Line Oxy-23 through several productive structures in the northern Maraon Basin. The upper display is in present-day 2WT section and the lower display is flattened on the Pozo showing structure development during early Tertiary time................................. 137

Figure 109: Location of Seismic Line Oxy 23 ........................................................................ 138 Figure 110: Seismic Line through the Corrientes structure showing present day structure (above)

and paleo-structure (below) which has been flattened on the Pozo. Productive reservoirs are highlighted. Note the absence of paleo-structure. ........................................................... 138

Figure 111: Seismic Line through the Capirona and Pavayacu structures showing present day structure (above) and paleo-structure (below) which has been flattened on the Pozo. Productive reservoirs are highlighted. Note the absence of paleo-structure. ...................... 139

Figure 112: Unflattened and Flattened (Pozo) seismic line (PK3-256) through the Yanayacu field. Note the lack of any paleo-structure at Pozo depositional time ......................................... 141

Figure 113: Pozo to Base Cretaceous Isochron showing the presence of a large paleo-structure just north of the Pastococha well. The seismic line highlighted is shown in Figures 114 and 115 . 142

Figure 114: Seismic Line PHI-10 flattened on the Pozo showing the presence of a sizable paleo-structure that existed in the Pastococha/Samiria area in early Tertiary time...................... 143

Figure 115: Present day time section of Seismic Line PHI-10 showing how the high as mapped in Figure 113, has disappeared......................................................................................... 143

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Figure 116: Amplitude time slices through the Tucunare 3D survey showing how Tucunare Structure disappears at shallower depths ...................................................................... 144

Figure 117: Composite log through the Cabanillas section of the Tapiche 1X well ..................... 147 Figure 118: Location of the Picuro group of prospects ........................................................... 149 Figure 119: TWT Top Vivian Map showing the Picuro Vivian Prospect................................... 150 Figure 120: 3D display of the Picuro Vivian Prospect. This Map was generated from the one

displayed in Figure 119. .............................................................................................. 150 Figure 121: TWT Structure Map on top of the Pucar ........................................................... 151 Figure 122: Seismic Line AH73-1 (Figure 121) through the east verging fault trend that creates the

series of closures at Pucar level, colored yellow in Figure 121......................................... 151 Figure 123: Location of the recommended Block in the Pastococha/Samiria area ...................... 152 Figure 124: TWT Structure Map on the Pozo. Note the structural elevation of the Nutria structure

relative to the one tested by the Samiria Sur 1X well. Highlighted seismic line displayed in Figure 9..................................................................................................................... 153

Figure 125: 3D TWT map on the Base Cretaceous (from seismic map on Enclosure 2 of 3 this series) with cross sections AA and BB of wells (Pozo to Base Cretaceous in depth) projected onto the surface. Note the off-structure locations of the Samiria 1X and possibly the Viracocha 1X wells................................................................................................................................. 154

Figure 126: composite seismic line (located on Figure 7) through the Nutria Prospect, the Samiria 1X well and the Samiria Sur 1X wells................................................................................. 155

Figure 127: Location Map showing seismic lines used for this evaluation (thick dark blue); examined Prakla and GSI lines not used due to serious mistie problems (thin dark blue); and the seismic lines that were not available for this evaluation (thin black)............................................. 156

Figure 128: The maximum size of the structure when mapped on the top of the Vivian if closed at the 2655ms level as indicated above, is approximately 100 km2 ........................................ 156

Figure 129: Composite line (Figure 128) across the corner of the Majaz prospect and Diana Mae locations .................................................................................................................... 157

Figure 130: West to east seismic line GW95-Q4 (Figure 128) across the Majaz structure............ 157 Figure 131: Shanusi area time-structure map on top of Pucar. The Shanusi 1X well tested gas on a

small satellite structure that opens up to a much larger feature to its SE. .......................... 158 Figure 132: Subsea structural map on Top Vivian showing the relative structural relationship of the

Yurimaguas well to that of the Shanusi 1X well. Highlighted area is potential reservoir fairway trend of the Pucar identified in the Shanusi well ............................................... 159

TABLES Table 1: List of Maraon Basin wells penetrating the Paleozoic Section and the Formation tops .. 27 Table 2: Seismic acquisition history of the data used by PARSEP in the Maraon Basin ............. 66 Table 3: Summary of Source Rock Data ................................................................................ 81 Table 4: Geochemical Characteristics of Genetic Oil Families in the Maraon, Santiago and

Huallaga Basins (CoreLab, 1996) ................................................................................... 86 Table 5: Chambira Este 123X Well Formations and Events...................................................... 99 Table 6: Chapuli 1X Well Formations and Events ................................................................. 100 Table 7: Corrientes 1X Well Formations and Events.............................................................. 102 Table 8: Forestal 3X well Formations and Events .................................................................. 104 Table 9: Jibaro 1X Well Formations and Events ................................................................... 105 Table 10: La Frontera 3X Well Formations and Events.......................................................... 107 Table 11: Loreto 1X Well Formations and Events ................................................................. 109 Table 12: Mahuaca 3X Well Formations and Events.............................................................. 111 Table 13: Maraon 110-1 Formations and Events ................................................................. 113 Table 14: Orellana 3X Well Formations and Events .............................................................. 114

9

Table 15: Piraa 1X Well Formations and Events ................................................................. 116 Table 16: Santa Catalina 2X Well Formations and Events...................................................... 118 Table 17: Santa Lucia 2X Well Formations and Events .......................................................... 120 Table 18: Shanusi 2X Well Formations and Events................................................................ 122 Table 19: Tapiche 2X well Formations and Events ................................................................ 124 Table 20: Tucunare 1X Well Formations and Events ............................................................. 125 Table 21: Valencia 25X Well Formations and Events ............................................................. 127 Table 22: Yanayacu 27X Well Formations and Events ........................................................... 129 Table 23: Yaez 14X Well Formations and Events ................................................................ 131 Table 24: Yarina 2X Well Formations and Events ................................................................. 132

ENCLOSURES

1. Maraon Basin Location Maps a. Location map of blocks, wells, and seismic b. Location map of cross-sections, wells, and seismic c. Location map of seismic profiles, wells, and seismic

2. Bouguer Gravity Map Maraon Basin 3. Magnetic Intensity Map Maraon Basin 4. Top Vivian Structural Map 5. Top Chonta Limestone Marker Structural Map 6. Top Cushabatay Structural Map 7. Pozo Shale to Top Cretaceous Isopach Map 8. Pozo Shale to Chonta Limestone Marker Isopach Map 9. Cretaceous Isopach Map 10. Top Cretaceous to Chonta Limestone Marker Isopach Map 11. Chonta Limestone Marker to Base Cretaceous Isopach Map 12. Chonta Limestone Isopach Map 13. Top Cretaceous to Chonta Limestone Marker Sand/Shale Ratio Map 14. Chonta Limestone Marker to Top Cushabatay Sand/Shale Ratio Map 15. Pozo TWT Structure Map 16. Chonta TWT Structure Map 17. Chonta Limestone TWT Structure Map 18. Base Cretaceous TWT Structure Map 19. Pozo to Base Cretaceous Isochron Map 20. Upper Sarayaquillo Isochron Map 21. Lower Sarayaquillo Isochron Map 22. Pucar Group

a. Pucar Facies Map NE Peru. b. Isochron Map

23. Cabanillas TWT Structure Map 24. Contaya TWT Structure Map 25. Base Cretaceous to Cabanillas Isochron Map 26. Seismic Profiles

a. Profile 1 Orellana to Nahuapa b. Profile 2 Samiria Sur to Bolognesi c. Profile 3 NW Ucayali to Tapiche d. Profile 4 Shanusi to Zapote e. Profile 5 Tangarana to Huangana f. Profile 6 Nanay to Nahuapa

10

g. Profile 7 Santiago Basin to Arabela h. Profile 8 Ungumayo to Otorongo i. Profile 9 Paiche to Piraa j. Profile 10 Arabela to Corrientes

27. Maraon Geochemical Modeling Montage 28. Southern Maraon Basin - Seismic Examples of Producing Fields 29. Representative Seismic line through several Block 1AB Structures 30. Picuro Prospect Western Maraon Basin

a. Vivian Prospect b. Pucar Prospects

31. Pastococha/Samiria Area Southeast Maraon Basin Hydrocarbon Accumulations and Leads (3 sheets)

32. Diana Mae Area Majaz Prospect Digital

33. Maraon Basin SEGY Data on Exabyte Tape 34. CD containing

a. Report b. Appendices c. Enclosures

APPENDIX

HARDCOPY

1. Wells drilled in the Maraon Basin and their status 2. Cross sections across the Maraon Basin

a. Section: Chapuli - Paiche A-A b. Section: Chapuli-Zapote B-B c. Section: Mahuaca-Paiche C-C d. Section: Paiche-La Frontera D-D e. Section: Pauyacu-Belen E-E f. Section: Santa Catalina-Yarina F-F g. Section: Yaez-Nanay G-G h. Section: Forestal-Sta Elena H-H i. Section: Shanusi-Nahuapa I-I

3. Graphical presentation of wells drilled between 1990 and 2000 in the Maraon Basin a. Listing and Location Map of Wells b. Pucacuro 1X c. Tigre 131X d. Arabela 1X e. Diana Mae 1X f. Limonyacu 1X g. Zorro 1X h. Santa Catalina 1X i. Santa Martha 1X j. Orellana 1X k. Sungaroyacu Norte 1X l. Tucunare 1X m. Block 67 Wells

i. Dorado 1X ii. Piraa 1X

iii. Paiche 1X 4. PARSEP third party studies

a. ChemTerra Intl. Consultants Oil Generation in Sub-Andean Basins of Peru b. Tankard Enterprises Ltd. Tectonic Framework Of Basin Evolution in Peru

11

c. Rakhit Petroleum Consulting Ltd. Maraon Basin Hydrodynamic Study DIGITAL CD (Enclosure 34)

5. Listing of PARSEP Seismic Lines in SEGY Excel Spreadsheet 6. Access Well Database of Maraon New Field Wildcats (NFW) Access DB 7. Composite Well Logs LAS Files of Maraon NFW 8. Erwin Ebner Evaluation Gravity and Magnetic Study ASCII Data & Maps 9. Seismic Interpretation ASCII Data

a. Horizon File b. Fault File

10. Maraon Basin SEGY Seismic Navigational Data 11. Perupetro Maraon Basin Archived Files Excel Spreadsheet

12

EXECUTIVE SUMMARY Project Description The Maraon Basin Technical Report was conducted approximately over a two-year span by PARSEP, Proyecto de Asistencia para La Reglamentacin del Sector Energtico del Per which is a joint venture between the governments of Peru and Canada. The objective of this study was to reexamine the geological and geophysical data from within the archives of Perupetro and produce a final report on the future hydrocarbon potential of the Maraon Basin. Due to the immense quantity of data and limited time and resources, a decision was made early in the study to handle the well and seismic data in only a digital format so interpretation could be done using computer workstations. Almost the first year of the project was spent on data collection, quality control and review. LAS files for all new field wildcats were gathered and when not available, well curves were digitized. Standardized composite well logs were made for all from this data set, which were utilized to create a cross-section grid tied to seismic across the Basin. Seismic SEGY data collection and quality control was considerable more problematic. As much of this study was seismic driven, it was difficult to make any forward progress in the project until a reasonable amount of seismic data was loaded on the workstation. Of the more than 50,000 km of data in the Maraon Basin it took at least one year to locate just over 12,000 km of data and get it loaded. Seismic SEGY data collection is an ongoing process and at the time of the this report, over 30,000 km of 2D seismic lines and nine 3D seismic surveys have been loaded for the Maraon Basin. Within the context of this report, however, as there were time constraints, a cutoff date of December 1, 2001 was set after which no new data was be utilized in the interpretation. By this date, 22,723 km (777 lines) from approximately 30 different seismic surveys had been loaded and constitutes the SEGY data set included in this report. It was proposed that any data acquired after that date be utilized in future studies when a much more detailed evaluation of Maraon Basin could be completed. To supplement the work of PARSEP Group, four additional studies were conducted by outside consultants who are considered to be experts in their field. The four studies are all included as Appendices in this report, and were as follows,

1. Geochemical: by Hans Von Der Dick, ChemTerra International Ltd. 2. Tectonics: by Tony Tankard, Tankard Enterprises 3. Hydrodynamics: by Kaush Rakhit, Rakhit Petroleum Consulting Ltd. 4. Magnetic and Gravity: by Erwin Ebner, ELS Consulting

Interpretation The Maraon Basin is a large sub-Andean Basin extending north from the Ucayali Basin, through Peru into Ecuador and Colombia where it is know as the Oriente and Putumayo Basins respectively. The Basins evolution begins in the Late Permian to Early Triassic with a major extensional event that dissected the underlying Paleozoic platform and basement rocks into a series of roughly northwest-southeast grabens and half grabens. In the western extremes, deep rift basins were formed containing sequences of synrift

13

continentally derived sediments that are overlain by a Triassic to Jurassic-aged marine to transitional (sabkha) unit dominated by carbonate deposition and evaporites. This in turn is overlain by regressive continental redbeds of Jurassic age. The eastern Maraon is very different with the remnants of the Late Permian to Early Triassic extensional event being persevered only as a series of half grabens that contain a preserved section of Paleozoic rocks within the lows with early Cretaceous peneplanation stripping off most if not all, of the intervening sediments. In the eastern Maraon the amount of preserved Paleozoic rocks beneath the Cretaceous decreases considerably from south to north to the point where the Cretaceous is seen overlying rocks of only basement affinity as the border with Ecuador is approached. With this difference it is easy to divide the Basin into two distinct regions, the western and eastern Maraon Basin divided by a major hinge zone. This hinge zone is supported with both magnetic and gravity data. It represents the line of flexure separating the stable Maraon platform in the east from the subsiding Basin to the west during the Basins thermal sag phase from Late Triassic to Jurassic (+Cretaceous?) time and the rapidly subsiding Maraon foredeep during Tertiary time. The Maraon Basin started to take on its present-day configuration through a sequence of tectonic events that spans the Tertiary and culminated in the Miocene to near Recent with the highly deforming Quechua orogeny. The present day western margin was formed through a complex combination of wrench related high angle faults, basin inversions and thin-skinned deformation fronts that now separate the Maraon Basin from the Santiago Basin to its northwest and the Huallaga Basin to its southwest. To standardize the Cretaceous stratigraphy of the Maraon Basin, nine regional cross-sections were constructed across the Basin and datumed just above the Chonta Limestone, which is close to the maximum flooding surface during the Cretaceous. When possible, this data was tied to seismic. The data was exported to a database from which a series of maps were generated. These maps were found to support previous interpretations provided in literature on the Basin. When seismic data was integrated into the stratigraphic interpretation, however, several important issues surfaced that were not evident with just well data.

1. The significance of the Maraon Hingeline across which there are major changes in stratigraphy within the Cretaceous

2. The Hingeline fault system was intermittently active through geological time and affects more of the geological column than just the Cretaceous

3. A significant Upper Cretaceous to Early Tertiary WNW-ESE trending wrench related extensional event can be documented in the northwestern Maraon and Santiago Basins that greatly effect the stratigraphy of the Cretaceous section

4. The presence of a Chonta-aged patch reef, which nucleated on the Chonta Limestone. These features significantly affected later depositional patterns in the overlying Chonta and Vivian sections.

Geochemical studies in the Basin have recognized two significant petroleum source rocks that have generated the hydrocarbons found in the Cretaceous reservoirs of the Maraon Basin. These are, the Cretaceous Chonta/Raya Formations and the Triassic/Jurassic Pucar Group. A third less known source rock for the Maraon Basin is also present within the Devonian Cabanillas sequence. It, however is confined exclusively to

14

southeastern portion of the Basin. The Chonta and Pucar source rocks in the Basin and neighboring areas are sufficiently rich enough to have generated the commercial amounts of hydrocarbons presently found in the oil fields of the Maraon Basin in addition to a sizeable amount of as of yet, undiscovered reserves. A long-range migration from these source rock kitchen areas to reservoir is implied for the accumulations found to date. Three major episodes of HC generation and migration can be documented in the Basin. The first event occurs during Carboniferous/early Permian time with the generation of hydrocarbons from the Devonian Cabanillas and Ordovician Contaya Formations. The survival of this early hydrocarbon generation phase due to tectonics and over-maturity is questionable, however. The second event occurred in late Jurassic time, which triggered Pucar hydrocarbon generation. The third hydrocarbon generation event occurred during Neogene time and affected the Mesozoic and partially the Tertiary sequences. It generated a second pulse of mature oil and gas from the Pucar where Pucar hydrocarbon generation had not terminated. Chonta HC generation and migration, however, is an ongoing process that has continued through to the present. Exploration models in the Maraon Basin for last 20 years have been more or less driven by the same concepts. This is quite evident when one examines literature and reviews the NFW wells drilled in the Basin between 1990 and 2000. The critical criteria for defining Cretaceous exploration targets historically in the Maraon Basin, was the presence of paleo-structures. The logic behind this is sound in that the paleo-structures needed to be in place in the Early Tertiary, to catch the primary and principal pulse of Chonta generated oils. This is a philosophy that has dictated exploration in Maraon Basin for quite some time despite the numerous accumulations with,

No paleo-structure Paleo-structures too small to account for the amount of presently trapped oil Present day structures with well developed paleo-structures that are dry or with

insignificant oil columns. With these inconsistencies there are clearly other mechanisms at work. Where oil has been found in younger structures, the explanation is one utilizing the remigration of oil from an older breached or tilted accumulation. This is widely accepted and in this report, one of the most critical aspect for future oil exploration in the Maraon Basin. The shortcomings of the paleo-structure hypothesis are that it misses two very important issues, large-scale paleo-stratigraphic traps and paleo-structures that are no longer closed. As long as traps of both these styles were in place and proximal to the later developing Andean Late Tertiary aged structures, the remigration from these paleo-accumulations into younger aged structures is far from difficult to imagine. Obviously, some of these paleo-traps would be coincidental with the younger structures and others not. The key to exploration in the Maraon Basin is in the definition of paleo-traps, not just structures, and in the remigration route of that hydrocarbon during the Quechua deformation. The other shortcoming concerning past exploration activities in the Maraon Basin has been its focus on Cretaceous reservoirs. In this and a previous PARSEP study in Huallaga Basin and surrounding area, it became evident that carbonates of the Pucar Group represent viable exploration targets in western Maraon Basin. In the south half of the Maraon Basin for example, there are only four penetrations into the Pucar and all are located in the southwestern most corner of the Basin. Of these, three intersected the

15

Pucar in a non-prospective supratidal to continental facies and the one well, Shanusi 1X, which intersected the Pucar in a prospective facies encountered gas bearing porous carbonates. Our current model has the Shanusi 1X well penetrating a high-energy intratidal carbonate along a paleo-high trend created by the late Permian to early Triassic rifting event. This is a potentially productive fairway that may be extrapolated to both the north and south of the well. The remaining significant under-explored section in the Maraon Basin is that of the Paleozoic. Although studied little in this investigation, it is acknowledged that just to the east across the border in Brazil, a similar section is productive and that similar potential may exist in the Maraon Basin of Peru. Through the hydrodynamic study sponsored by PARSEP, it was possible to identify areas where hydrodynamic tilting occurs. Tilts are expected to be very severe in the western Maraon Basin where high hydrologic heads can be mapped within the Cretaceous section, near the highly elevated recharge areas in the fold and thrust belt of the western Basin margin. The effect diminishes to the east and southeast across the Basin and the measured data fits closely with what is observed in the fields. Tilted oil/water contacts have only been found in the productive area of the northern Maraon Basin (Block 1AB Area) and not in the southern production area (Block 8 Area). Hydrodynamics are clearly an important component to understanding the dynamics of the petroleum systems operative in the Basin. The Maraon Basin Study was intended to be a regional work, integrating as much data as possible within the Basin to investigate whether new exploration concepts, exploration fairways, etc., could be defined. It was not intended to be an exploration exercise where the ultimate goal is in defining drillable prospects. However, prospects and leads did emerge and identified as the a) Picuro Vivian Prospect, b) Picuro Pucar Prospect, c) Nutria Prospect, and d) Majaz Prospect. The later two have multiple objectives within the Cretaceous section.

16

1.0 INTRODUCTION The Maraon Basin Technical Study is the last in a series of reports released by the PARSEP Group on the evaluation of the hydrocarbon potential of NE Peru. The three basins evaluated in this study were, the Huallaga, Santiago and Maraon Basins (Figure 1). PARSEP is an acronym for Proyecto de Asistencia para La Reglamentacin del Sector Energtico del Per and is a joint venture between the governments of Peru and Canada. The parties comprising PARSEP are: the Canadian International Development Agency (CIDA), the Canadian Petroleum Institute (CPI), Teknica Overseas Ltd. (TOL), and PERUPETRO. The technical work on this project is being done by personal from TOL and PERUPETRO Figure 1: Areas of investigation of the PARSEP Group Huallaga, Santiago and Maraon Basins, and intervening areas Unlike other projects done in this area in recent years, such as the Robertson Research 1990 Study Informe Final Evaluacion Geologica y Geofisica por Hidrocarburos Selva Peruana, the goal of this project was to complete the interpretation of the study area utilizing a standardized digital database that could later be exported with ease to any interested outside party. One of the challenges in the early stages of the Maraon project was in the gathering and the quality control of the available digital data such as seismic SEGY data and log curve data. Where digital well data was not available, well curves were digitized and included in the database. The seismic data interpreted was almost done exclusively with workstations. Where SEGY data was not available from

Maraon Basin Study

17

Perupetro, paper sections of selected lines were scanned to fill in important holes in the data set. In only one area, the west central Maraon Basin, were paper copies used exclusively for interpretation. This was done as no SEGY data was available in this critical area that was needed to link the seismic interpretation done in the Huallaga and Santiago Basins together via the Maraon Basin. The horizons from this interpretation were later digitized and are included as a subset to the workstation interpreted horizons. All the SEGY data utilized in this project was supplied by Perupetro and was interpreted primarily on a Schulmberger GeoQuest Workstation. Seismic line tying (bulk shift, amplitude and phase rotation) was done with Kernel Technologys WinPics and SMAC seismic interpretation software. On the geological side, Geographixs and DigiRule software were used extensively for mapping, well log preparation and cross-section construction, Platte Rivers 1D BasinMod software was used as our basin-modeling tool and finally, Microsoft Access was utilized to design a standardized, exportable well database. Apart from the above-mentioned objectives, a secondary goal of this study is to assist Perupetro in the promotion of this area to Industry. This includes making recommendations to Perupetro concerning block size, configuration and location for tendering purposes. The PARSEP Team would like to thank Perupetro for their support on this project and for making all the data so readily available to us, despite our never ending demands for more. Furthermore we would like to thank CPI for their logistical support, Teknica for their technical support and finally, CIDA for their financial support and making this project a possibility.

18

2.0 SCOPE OF PROJECT When this project was first conceived, it was intended to be a regional geological and geophysical evaluation of the northeastern Peruvian Sub-Andean Basins focusing on the identification of new play types. It was hoped not to be a rework of previous Maraon Basin studies of which there have been a number of excellent ones. The focus was to examine the Basin in a slightly different manner than others had before in the past. Figure 2: Map showing location of 2D SEGY Seismic Data set and the new field wildcats utilized in the Maraon Basin Evaluation

Santa Catalina 2X

Santa Clara 1Santa Clara 1A

Santa Elena 1

Santa Lucia 1

Santa Martha 1X

Shanusi 1

Shiviyacu 01

Shiviyacu Norteste 1

Shiviyacu Sureste 1X

Sungachi 1XSungaroyacu Norte 1X

Tamanco 1

Tambo 1Tambo Sur XD 1

Tangarana 1

anguintza 1X

Tapiche 1

Tigre 1

Tigre 131X

Tigrillo 1

Tuncheplaya X 1

Ungumayo 1

Valencia 1

Viracocha X 1

Yanayacu 2

Yanayacu Sur 2X

Yanez 1

Yarina 1

Aerico 1

Andoas 1

Arabela 1X

Bartra 01

Belen 4

Bolognesi 1

Bretana 1

Capahuari S 01

Capahuari Central 1

Capahuari Norte 1

Capirona 2X

Carmen 1Carmen Central 5X

Caterpiza 1X

Ceci X 1

Chambira 4X

Chambira Este 123

Chapuli X-1

Copal 19XCorrientes X 1

Cuinico N 1

Cuinico S 1

Cunambo 1

Diana Mae 1

Dominguza 1

Dorissa 01

Envidia 1

Forestal 01

Forestal Extension 1

Huangana102X

Huasaga 1

Huayuri 19X

Huayuri S 33X

Nucuray 1

Huitoyacu 2X

Intuto 23X

Jibarito 27X

Jibarito Sur X 1

Jibaro 1X

La Frontera 1

Limonyacu 1X

Loreto 1

Macusari 1X

Mahuaca X 1

Manseriche 1X

Maranon 1 Maranon 22 1

Margarita 1X

Martha X 1

Maynas 1X

Nahuapa 1

Nanay 26X

Nueva Esperanza 1

Orellana 3X

Otorongo X 1

Palmera 1

Palo Seco 1X

Pastococha 1X

Patoyacu 1

Pauyacu 1

Pavayacu X 3

Pilar 1X

Piuntza 1

Plantayacu X 1

Pucacuro 1

Pupuntas 1X

Putuime 1

Rayo 1

Samiria Sur 3X

Samiria 5X

San Jacinto 01

San Juan 1

Yurimaguas 2-1

Zapote 3X

Zorro 1X

Dorado 1X

Paiche 1X

Piraa 1X

Concordia 17X

Tucunare 1X

Maranon 110

0 km 100 km

0 Miles 100 Miles

ECUADOR

Location of Figure 3

Location of Figure 4

19

The manner in which to do this was through the interpretation of a seamless digital seismic and well data set, with each being tied to one another combined with an analysis on the lack of exploratory drilling success in the Basin since the late 1980s. Supplementing the work done by the PARSEP Group were four additional studies:

Figure 3: Location of the Amerada and Oceanic data sets in the western Maraon Basin that were interpreted off of paper copies. The results of this interpretation are included in montages (Enclosures 30a and 30b) outside of the digital data set interpretation.

5. Magnetic and Gravity: by Erwin Ebner, ELS Consulting 6. Geochemical: by Hans Von Der Dick, ChemTerra International Ltd. 7. Tectonic: by Tony Tankard, Tankard Enterprises 8. Hydrodynamics: by Kaush Rakhit, Rakhit Petroleum Consulting Ltd.

Shanusi 1

Tigrillo 1

Ungumayo 1

Caterpiza 1X

Nucuray 1

Limonyacu 1X

Mahuaca X 1

Manseriche 1X

Maranon 1

Pauyacu 1

Yurimaguas 2-1

0 km 50 km

0 Miles 30 Miles

Amerada Data

Oceanic Data

20

Each of the above were focused on looking on the Basin in manner slightly differently than previous similar studies and with each contributing in varying degrees in this manner. The first of theses studies is included as a digital data set in Appendix 5 and the others as Appendix 4a to 4c respectively, in this report. One of the more time consuming aspects of this evaluation was the standardization and quality control of the data. Digital curve data was complied and corrected for each of the New Field Wildcats in the Basin (Figure 2). A composite well for each was constructed, which if available included a Caliper, SP, Gamma Ray, Deep and Shallow Resistivity, Density, Neutron and Sonic curve. A series of 9 cross-sections were strung across the Basin to standardize the stratigraphy that was to be utilized in the geological mapping module of this project. Where possible, a synthetic for each of the wells made and tied to seismic.

Figure 4: Map of the Block 1AB area showing the lack of available SEGY seismic data The principal seismic data set utilized and interpreted in the project consisted of 22,723 kilometers of 2D SEGY data, which represents coverage throughout most of the Basin (Figure 2). Despite this abundance of seismic coverage, two very large holes in seismic data set existed. The first was in the western Maraon Basin where the Oceanic and Amerada surveys (Figure 3) were not available in digital format and consequently the interpretation was done off of paper sections. Subsequent to the completion of the interpretation, most of the Oceanic survey was received in SEGY format, which has now been incorporated (uninterrupted) into the PARSEP digital seismic database. The second major hole in seismic coverage was in area of Block 1AB. Very limited SEGY data was available for this area (Figure 4) and the navigational data supplied for the location of the other lines was largely unusable.

Shiviyacu 1X

Shiviyacu Norteste 1X

Shiviyacu Sureste 1X

Tambo 1XTambo Sur 1XD

Tangarana 1X

Tigre 1X

Yanez 1X

Andoas 1X

Bartra 1X

Capahuari S 1X

Capahuari Central 1X

Capahuari Norte 1X

Carmen 1XCarmen Central 1X

Ceci 1X

Cunambo 1

Dorissa 1X

Forestal 1X

Forestal Extension 1X

Huasaga 1X

Huayuri 1X

Huayuri S 1X

Jibarito 1X

Jibarito Sur 1X

Jibaro 1X

Macusari 1X

Margarita 1X

Martha 1X

Maynas 1X

Pilar 1X

Plantayacu 1X

San Jacinto 1X

P

Tucunare 1X

0 km 50 km

0 Miles 50 Miles

21

Unfortunately time constraints on the Project did not allow us to correct and interpret this data set. This was obviously a serious deficiency in the data set as this area contains many of the producing oil fields of the Maraon Basin. As part of the standardization process, a number of Maraon Basin wells were renamed to maintain consistency throughout the PARSEP database. Numerous numbering systems had been use previously by industry and Petroperu creating inconsistencies in reference to certain well in later studies. In our system the first well drilled on each structure has the designation suffix 1X with the X being representative of the wells exploration status. All subsequent wells increase numerically in sequence and generally maintain their suffix designation that is currently in place. To avoid any confusion, each well within the Access database included with this report is referenced to the UWI being used by Perupetro. All attempts were made in this report to maintain consistency when referring to wells with this new system. Some, however, were not corrected as such in some of the earlier work done in the project, due to the magnitude of effort needed to regenerate maps already finalized. Where this has occurred it is duly noted in the text of this report. Due to the significant volume of wells drilled in this Basin it was beyond the scope of this project to do a comprehensive analysis of all exploratory wells drilled in the Basin as has been done for the other studies. Instead a study was undertaken as part of this project to evaluate the wells drilled between 1990 and 2000, and to analyze their results. The study is summarized in Section 6.0 of this report and a more detailed evaluation on each individual well is presented in Appendix 3.

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3.0 PREVIOUS WORK IN THE STUDY AREA Drilling activity in the sub-Andean Basins of Peru began in 1937 with the drilling of Agua Caliente #1 to test a mapped surface structure located in the Ucayali Basin. This well discovered oil pay in Cretaceous Cushabatay Formation at 311 meters. Subsequent to this during the 40s and 50s, numerous companies were doing fieldwork in the sub-Andean Basins of Peru and as a result, several more wells were drilled. The next discovery, however, was not until 1957 with the discovery of the Maquia Field. This was made by the El Oriente Oil Company just west of the Contaya Arch in the northern Ucayali Basin bordering on the southern Maraon Basin. Texaco (Texas Petroleum Co.) was the first company to begin drilling in the Maraon Basin with the spudding of the Maraon 8-1X well in 1955. They followed this well with two additional NFW wells between 1956 and 1957. All four wells were dry holes. Although the Basin didnt experience the drill bit for another 23 years, Mobil Oil drilled three dry exploratory wells in the neighboring Santiago Basin, an intermountain basin located to the northwest of the Maraon (Figure 1), in the early 1960s. With the discovery of significant reserves in the Oriente Basin, the Ecuadorian equivalent of the Maraon Basin in the late 1960s and early 70s, Petroperu, the national oil company of Peru was awarded acreage in Maraon Basin in 1971. Shortly thereafter Occidental Petroleum was awarded Block 1A and Union Oil Block 1B. After a 23-year drilling hiatus in the Maraon Basin, the Corrientes Field was discovered with Petroperus first well in the Basin in 1971. As Petroperu was quickly following up their initial success with a series of other discoveries, Oxys first well in the Basin resulted in the discovery of the Capahuari field in 1972. Union Oil joined the list of successful companies with the discovery of the Jibaro Field with their first well. Activity and discoveries continued at a rapid pace until 1989 after which the Basin experienced a drilling lull until 1993. The legal framework, which currently governs the exploration and exploitation of hydrocarbons, was passed in August 1993. It allows companies to operate under either Service or License contracts. In January 1994, the Peruvian government set up a new state agency, Perupetro, to deal with contract negotiations, on the governments behalf, talking over Pertroperus former role. As a result, industries interest in Peru was heightened and several new blocks were signed. Activity further increased in 1996, which also saw the initialization of the privatization process of Petroperu. Although never completed, Petroperu sold all their producing properties and left the upstream sector. Drilling and leasing remained active through the rest of 90s. Unlike the earlier years, however, discoveries were minimal and limited to the three Barrett Resources heavy oil discoveries, which were found in the northeastern Maraon Basin in 1998. A chronological listing of new field wildcats drilled in the Maraon Basin and a review of their results is presented in Appendix 3.

23

4.0 GEOLOGY OF THE MARANON AREA

4.1 GENERAL BASIN DESCRIPTION The Maraon Basin is a large sub-Andean Basin (Figure 5) extending north from the Ucayali Basin, through Peru into Ecuador and Colombia where it is know as the Oriente and Putumayo Basins respectively. The Basins evolution begins in the Late Permian to Early Triassic with a major extensional event that dissected the underlying Paleozoic platform and basement rocks into a series of roughly northwest-southeast grabens and half grabens. In the western extremes, deep rift basins were formed containing sequences of synrift continentally derived sediments that are overlain by a Triassic to Jurassic-aged marine to transitional (sabkha) unit dominated by carbonate deposition and evaporites. This in turn is overlain by regressive continental redbeds of Jurassic age. Figure 5: Geology of the Maraon/Santiago/Huallaga Basin Area

ECUADOR

BRAZIL

IQUITOS

GEOLOGICAL LEGEND

Tertiary

Intrusive

U. & L Carboniferous (CsP,Ci)

Cambrian (e)

U.M & L Jurassic (Js,Jm,Ji)

U. Jurassic L. Cretaceous (JsKi)

Cretaceous (ki,kiks,ks)

PreCambrian (PeA,PeB)

L. & U Permian (Pis)

U. Permian (Ps)

U. Triassic & L. Jurassic (TsJi)

Devonian, Silurian, Ordovician (d,sd,o)

Evaporite Outcrops

GEOLOGICAL LEGEND

Tertiary

Intrusive

U. & L Carboniferous (CsP,Ci)

Cambrian (e)

U.M & L Jurassic (Js,Jm,Ji)

U. Jurassic L. Cretaceous (JsKi)

Cretaceous (ki,kiks,ks)

PreCambrian (PeA,PeB)

L. & U Permian (Pis)

U. Permian (Ps)

U. Triassic & L. Jurassic (TsJi)

Devonian, Silurian, Ordovician (d,sd,o)

Evaporite Outcrops

0 km 50 100 150 200 km

(Oriente Basin)

Santiago Basin

Huallaga Basin

Ucayali Basin

Maraon Basin

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The eastern Maraon on the other hand is very different with the remnants of the Late Permian to Early Triassic extensional event being persevered only as a series of half grabens (tilted fault blocks) that contain a preserved section of Paleozoic rocks within the lows with early Cretaceous peneplanation stripping off most if not all, of the intervening sediments. In the eastern Maraon the amount of preserved Paleozoic rocks beneath the Cretaceous decreases considerably from south to north to the point where the Cretaceous is seen overlying rocks of only basement affinity as the border with Ecuador is approached. With this acute difference between the western and eastern Maraon Basins, it is easy to divide the Basin into two distinct regions divided by a major hinge zone. This hinge zone is identifiable on seismic and with both magnetic (Figure 6) and gravity data (Figure 7). It represents the line of flexure separating the stable Maraon platform in the east from the subsiding Basin to the west during the Basins thermal sag phase from Late Triassic to Jurassic (+Cretaceous?) time and the rapidly subsiding Maraon foredeep during Tertiary time. The Maraon Basin started to take on its present-day configuration through a sequence of tectonic events that spans the Tertiary and culminated in the Miocene to near Recent with the highly deforming Quechua I, II and III orogenies. The present day western margin was formed through a complex combination of wrench related high angle faults, basin inversions and thin-skinned deformation fronts that now separate the Maraon Basin from the Santiago Basin to its northwest and the Huallaga Basin to its southwest. 4.2 REGIONAL GEOLOGY The geological evolution of the greater Maraon Basin area is controlled by two regional tectonic systems recognized in the sub-Andean basins of Peru. The first, the pre-Andean System, encompasses three cycles of Ordovician, Devonian and Permo-Carboniferous ages overlying the Precambrian basement of the Guyana and Brazilian Shields. The second, the Andean System, was initiated with the beginning of subduction along the western margin of Peru. It encompasses several mega-stratigraphic sequences and numerous minor sedimentary cycles, ranging from Late Permian to the Present. The stratigraphic column that has been used by PARSEP in the Maraon Basin is representative of all NE Peru and is presented in Figure 8. The exception to this is when reference is made to the productive reservoir intervals within the Chonta section and then, the terminology of the original operator is used. 4.2.1 Pre-Andean System The pre-Andean System begins with the Ordovician cycle and is represented by the siliciclastic Contaya Formation. In NE Peru as found within the Maraon Basin, the Contaya Formation has a thickness of up to 150m A maximum thickness of 4500m, however, has been reported for the cycle in the Eastern Range of southern Peru. The Contaya Formation outcrops in the Contaya Mountains of the northern Ucayali Basin and in the Shira Mountains. Within the Basin itself, it has been drilled by four wells, the Palmera 1X, Maraon 110-1, La Frontera 1X and Tapiche 1X wells and as with all the

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Figure 6: Magnetic Intensity Map of the Maraon Basin and surrounding area Figure 7: Bouguer Gravity Map of the Maraon Basin and surrounding area

26

Figure 8: Stratigraphic Column of the NE Peruvian basins - highlighted in yellow is the nomenclature used in this report

Maraon A

GE PARSEP

NE Peru Oxy PetroperuHuallaga Ucayali Santiago

Q Corrientes Corrientes Maraon Maraon Nieva

Pebas Pebas Ipururo

Chambira Upper Red Beds

Chambira

Capas RojasSuperiores

Chambira Upper Puca

Pozo Shale Pozo Shale Pozo Shale Pozo Shale Pozo Shale

Pozo

Pozo Sand Pozo Sand Pozo Sand Pozo

Pozo Sand Pozo

Pozo Sand

Santiago SS

TER

TIA

RY

Yahuarango Lower Red Beds Yahuarango Capas Rojas Inferiores Yahuarango

Low

er P

uca

Upper Vivian Basal Tertiary Upper Vivian Casa Blanca Huchpayacu Huchpayacu Huchpayacu Cachiyacu

Cachiyacu Cachiyacu

Cachiyacu Cachiyacu

Cachiyacu

Viv

ian

Lower Vivian Vivian Lower Vivian Vivian Vivian Vivian Pona

Lupuna Upper Chonta Chonta shale Upper Cetico

Chonta Lmst Chonta Lmst Caliza Chonta Sand

LowerChontaSand

Cho

nta

Lower Chonta BasalChontaSand

Lower Cetico

Chonta Chonta

Agua Caliente Agua Caliente Agua Caliente Agua Caliente Agua Caliente Raya Raya Raya Raya Raya

Chonta

CR

ETA

CEO

US

Cushabatay Cushabatay Cushabatay Cushabatay Cushabatay Cushabatay

Red Beds Red Beds

Sara

yaqu

illo

Sarayaquillo Sarayaquillo Sarayaquillo Sarayaquillo

Sara

yaqu

illo

Evaporitic Unit Evaporitic UnitJUR

AS

Condorsinga Condorsinga

Aramachay AramachayPuca

r

Chambara

Pucar Pucar Pucar Pucar

Puca

r

Chambara

TRIA

S

Mitu Mitu Mitu Mitu Mitu Mitu

Ene Ene Ene Ene Ene Ene

PER

M

Copacabana Copacabana CopacabanaTarma Tarma Tarma

Copacabana Copacabana /Tarma Copacabana

?

CA

RB

Ambo Ambo Ambo Ambo Ambo

DEV

Cabanillas Cabanillas Cabanillas Cabanillas

OR

D

Contaya Contaya Contaya Contaya Contaya

Basement

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Maraon Basin Paleozoic penetrations (Table 1), these are located in the east to southeastern portion of the Basin (Figure 9). Next in the succession is the Silurian cycle (not present in northern Peru), which is represented by argillites, flysch and tillites, and can reach thicknesses up to 1000m in southern Peru (Laubacher, 1978). This depositional cycle ends with an erosional episode in the Peruvian Oriente that is the result of tectonic movement during the Caledonian/Taconian Orogeny. The Silurian cycle merges with that of the Devonian, which is comprised of sediments of the Cabanillas Group that have been deposited in the Madre de Dios, Ucayali and Maraon Basins. In the south of Peru, Devonian sediments reach thickness of up to 2000m, while in northern Peru, the maximum thickness attained is 1000m. Within the study area, rocks of Devonian age have been encountered only in a minimal number of wells, but only within those drilled along the southeastern margin of the Basin (Table 1).

Ene Copacabana Tarma Ambo Cabanillas Contaya Well Name Permian Carboniferous Devonian Ordovician

Tamanco 1X 3654 3730 Orellana 1X 3592 3803 Zapote 1X 3723 Palmera 1X 3266 3280 3655 Yarina 1X 3034 3288 Palo Seco 1X 3120 Maraon 110-1 2911 3048 3233 La Frontera 1X 2572 2591 2935 Tapiche 1X 3158 3589 Nahuapa 1X 3077

Table 1: List of Maraon Basin wells penetrating the Paleozoic Section and the Formation tops The Permo-Carboniferous succession rests unconformably over the Devonian Cycle and/or Ordovician sediments and Basement in the uplifted areas, and has widespread distribution throughout the Andean Range, the subsurface of the Peruvian eastern basins, and in the Brazilian Acre and Solimoes Basins. In the Peruvian basins the earliest Carboniferous sedimentation began with the Ambo Group, which was deposited as continental to shallow marine, fine-grained sandstones, with interbedded siltstones, gray shales, and occasional thin coal beds. These sediments are followed vertically by the thin transgressive, clastic-rich Tarma Formation, which is overlain, usually conformably, by the normally thick, massive shelf carbonates of the Copacabana Formation. The Tarma-Copacabana Group is widely distributed in most of the Andean basins. It is predominantly a marine carbonate sequence although the cycle begins with a basal fine- to coarse-grained sandstone, the Green Sandstone Unit. This is overlain by a thick sequence of dark gray, fossiliferous limestones (wackestones, packstones and grainstones), and thin interbeds of dark gray shales and anhydrites. The unit contains several intervals with characteristic fusulinid forams of Permian age. The Copacabana limestones covered most of Sub-Andean Peru with the exception of the Contaya Arch and several other structural highs, where the Cretaceous overlies rocks of lower Paleozoic age. The Copacabana Formation in turn, was conformably overlain by the Ene Formation, a sequence containing black organic rich shales, dolomites and minor sandstones. Only three wells in the Maraon Basin have intersected a Tarma/Ambo section, the Palo Seco 1X, Maraon 110-1, and La Frontera 1X. The Copacabana Group,

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however has seen a number of penetrations, with the Tamanco 1X, Orellana 1X, Zapote 1X, Palmera 1X, and the Yarina 1X wells all having intersected this sequence. Finally, the uppermost of the Paleozoic sequences, the Ene Formation has only been penetrated by the Tamanco 1X and Orellana 1X wells. Figure 9: Location of the Paleozoic penetrations in the Maraon Basin 4.2.2 Andean System The Andean System was initiated simultaneously with the beginning of the Andean subduction. A major change in the tectonic regime along the northwestern border of the South-American plate, promoted isostatic rearrangements. In a global scale, the initial phase of the Andean System developed during the Pangaea break up (M. Barros & E. Carneiro, 1991). The development of the Andean subduction zone during late Permian to early Triassic times is supported by geological information gathered by Audebaud, et. al. (1976) along the Peruvian Eastern Range, where they recognized a Permo-Triassic continental volcanic arc. The volcanic Lavasen Formation, which is seen in outcrops unconformably underlying the Mitu Group t