ACTAUNIVERSITATISUPSALIENSISUPPSALA2006

Digital Comprehensive Summaries of Uppsala Dissertationsfrom the Faculty of Science and Technology 195

Impact of Diagenetic Alterationson Reservoir Quality andHeterogeneity of Paralic andShallow Marine Sandstones

Links to Depositional Facies and SequenceStratigraphy

KHALID AL-RAMADAN

ISSN 1651-6214ISBN 91-554-6588-9urn:nbn:se:uu:diva-6928

To my wife & parents

List of Papers

This thesis is based on the following papers, which will be referred to in the following text by their Roman numerals.

Al-Ramadan, K., Morad, S., Proust, J.N. and Al-Asam, I. (2005) Distribution of diagenetic alterations in siliciclastic shoreface depos-its within a sequence stratigraphic framework: evidence from the Upper Jurassic, Boulonnais, NW France. Journal of Sedimentary Research, 75, 943-959. Al-Ramadan, K., Morad, S. and Piret Plink-Björklund (2007) Distribution of Diagenetic Alterations in Relationship to Deposi-tional Facies and Sequence Stratigraphy of Wave- and Tide-Dominated Siliciclastic Shoreline Complex: Upper Cretaceous Chimney Rock Sandstones, Wyoming and Utah, USA. International Association of Sedimentologists Special Publication: Linking Diagenesis to Sequence Stratigraphy of Sedimentary Rocks. Ac-cepted.Al-Ramadan, K., Morad, S. A. Kent Norton and Michael Hul-

ver (2007) Linking Diagenesis and Porosity Preservation to Se-quence Stratigraphy of Gas Condensate Reservoir Sandstones, the Jauf Formation (Lower to Middle Devonian), Eastern Saudi Arabia. International Association of Sedimentologists Special Publication: Linking Diagenesis to Sequence Stratigraphy of Sedimentary Rocks. Accepted.

V Al-Ramadan, K., Morad, S. and Essam El-Khoriby. Distribution of Diagenetic Alterations in Sequence Stratigraphic Context of Tidal Flat Sandstones: Evidence From The Adedia Formation (Cambro-Ordovician), Sinai, Egypt. Manuscript.

V Al-Ramadan, K., Morad, S. and J. Marcelo Ketzer. The Impact of Diagenesis on Heterogeneity of Sandstone Reservoirs: A Review of the Links to Depositional Facies and Sequence Stratigraphy. Manuscript.

Paper is published with permission from the publisher

Contents

Introduction.....................................................................................................9

Aims of the study ..........................................................................................13

Key concepts of sequence stratigraphy.........................................................14

Methodology.................................................................................................19

Summary models of diagenetic alterations within systems tracts.................21Important eogenetic alterations linked to sequence stratigraphy..............21Important mesogenetic alterations linked to sequence stratigraphy.........24

Reservoir quality and heterogeneity models .................................................28Model 1: Diagenetic and reservoir-quality evolution pathway of shoreface sandstones (paper )..................................................................................28Model 2: Diagenetic and reservoir-quality evolution pathway of wave-dominated delta and tide and mixed-energy estuaries sandstones (paper

)..............................................................................................................32Model 3: Diagenetic and reservoir-quality evolution pathway of shoreface HST and tidal estuarine, TST and HST sandstones (paper )................33Model 4: Diagenetic and reservoir-quality evolution pathway of tidal flat sandstones (paper V)...............................................................................38

Summary of the papers .................................................................................41Paper Distribution of Diagenetic Alterations in Siliciclastic Shoreface Deposits Within Sequence Stratigraphic Framework: Evidence From The Upper Jurassic, Boulonnais, NW France..................................................41Paper Distribution of Diagenetic Alterations in Relationship to Depositional Facies and Sequence Stratigraphy of Wave- and Tide-Dominated Siliciclastic Shoreline Complex: Upper Cretaceous Chimney Rock Sandstones, Wyoming and Utah, USA ...........................................42Paper Linking Diagenesis and Porosity Preservation to Sequence Stratigraphy of Gas Condensate Reservoir Sandstones, the Jauf Formation (Lower to Middle Devonian), Eastern Saudi Arabia................................43Paper V Distribution of Diagenetic Alterations in Sequence Stratigraphic Context of Tidal Flat Sandstones: Evidence From The Adedia Formation (Cambro-Ordovician), Sinai, Egypt .........................................................44

Paper V The Impact of Diagenesis on Heterogeneity of Sandstone Reservoirs: A Review of the Links to Depositional Facies and Sequence Stratigraphy ..............................................................................................44

Concluding remarks ......................................................................................46

Summary in Swedish ....................................................................................48

Acknowledgements.......................................................................................49

References.....................................................................................................51

9

Introduction

Assessment and, particularly, prediction of the spatial and temporal distribution of reservoir quality in paralic and shallow-marine sandstones are fairly difficult, but crucial tasks for hydrocar-bon exploration and production. Nevertheless, these tasks have been addressed successfully during the past three decades using, separately, the techniques of sequence stratigraphy and diagenesis. The sequence stratigraphic approach enables: (i) unraveling and predicting the dis-tribution of facies-controlled, reservoir-quality distribution, which is attributed to variations of grain size and sorting of the sand, and (ii) high-resolution stratigraphic correlation of reservoir, seal and source rocks (Posamentier et al., 1988; Posamentier and Allen, 1999; Plint and Nummedal, 2000).

The depositional reservoir quality of sandstones is, however, modified to various extents by a variety of mechanical and chemical post-depositional (diagenetic) alterations that occur at near-surface conditions and during progressive burial (i.e. increase in temperature). The diagenetic modifications have been shown to be controlled by porewaters chemistry (McKay et al., 1995), detrital composition (Amorosi, 1995; Zuffa et al., 1995), depositional environment (Morad et al., 2000), paleoclimatic conditions (De Ros et al., 1994; Morad et al., 2000; Reed et al., 2005), and burial-thermal history of the basin (Morad et al., 2000). The new approach introduced by Morad et al. (2000) and Ketzer et al., (2002, 2003a and 2003b) for the assessment and prediction of reservoir-quality distribution, which is based on the integration of diagenesis into the sequence stratigraphic framework of sandstones, was employed in this study. This approach allows the re-finement of our ability to assess and predict the spatial and temporal distribution of diagenetic alterations and of their impact on reservoir-quality and heterogeneity in paralic and shallow-marine sandstone successions. The employment of this approach is possible because, like for the sequence stratigraphic framework, parameters controlling diagenetic alterations and their impact on reservoir quality of sand-stones are controlled by changes in the relative sea level (RSL) and rates of sedimentation. These parameters include: (i) Porewaters chemistry, which can shift between meteoric, marine and brackish composition (McKay et al., 1995; Morad et al., 2000).

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Fall in RSL during regression may lead to subaerial exposure and flushing of paralic and shallow marine sediments by meteoric waters, causing dissolution and kaolinitization of siliciclastic grains, clay in-filtration, and cementation by calcrete and dolocrete (Morad et al., 2000). Conversely, rise in the RSL during transgression renders pore-waters in such sediments to be dominated by marine composition fa-voring the formation of marine calcite and dolomite cements (Morad et al., 1992). (ii) Detrital composition, particularly regarding the proportion and types of intra-basinal grains, which include mud intraclasts, carbonate bioclasts, and glaucony (Amorosi, 1995; Zuffa et al., 1995), imposes important impact on the mechanical and chemical properties, and hence diagenetic and reservoir quality evolution, of sandstones (Sur-dam et al., 1989). (iii) Residence time of sediments under certain geochemical condi-tions, and hence the duration of diagenetic reactions, such as below the seafloor and below surfaces of sub-aerial exposure, which are en-countered during transgression and regression, respectively (Taylor et al., 1995; Morad et al., 2000; Wilkinson, 1989). (iv) Degree of bioturbation, and hence: (a) changes in the sediments texture through mixing up of mud, silt and/or sand, and (b) creation of local sub-oxic to anoxic, porewater conditions that aid the nucleation and growth of certain minerals, such as carbonates and sulfides (Berner, 1968; Wilkinson, 1991).

Eogenetic alterations in siliciclastic deposits are strongly influ-enced by depositional environment (Curtis, 1987), variations of depo-sitional water owing to rise and fall of RSL and influx of meteoric water (McKay et al., 1995; Ketzer et al., 2002, 2003a), organic matter content (Curtis, 1987; Morad et al., 2000), sedimentation rate (Curtis, 1987) and paleoclimatic conditions (Morad et al., 2000). These eoge-netic alterations impose, in turn, a profound control on the distribution pattern of mesogenetic alterations (depth 2 km; T 70°C; Morad et al., 2000), and hence on reservoir quality evolution pathways of sand-stones (Morad et al., 2000; Ketzer et al., 2003a).

A key goal of reservoir characterization is to predict the spatial and temporal distribution patterns of diagenetic alterations and of their effects on fluid flow within a gross reservoir unit. Therefore, in order to predict the subsurface distribution of diagenetic alterations that in-fluence porosity and permeability, it is necessary to understand the diagenetic processes involved and the parameters controlling their spatial distribution. The integration of eogenetic alterations into se-quence stratigraphic framework allows better elucidation and predic-tion of the spatial and temporal distribution of diagenetic alterations and of related reservoir quality modifications in paralic and shallow-

11

marine clastic sediments (Taylor et al., 1995; Ketzer et al., 2002; Ket-zer et al., 2003a; Al-Ramadan et al., 2005).

13

Aims of the study

The aims of this thesis are to: (i) integrate the distribu-tion of diagenetic alterations into the sequence stratigraphic frame-work of shallow marine and paralic sandstone successions, and (ii) demonstrate that the impact of diagenesis on reservoir-quality and heterogeneity evolution pathways can be better elucidated and pre-dicted when linked to depositional facies and sequence stratigraphic framework of the sandstones. Four siliciclastic successions represent-ing different depositional facies have been studied for the purpose of this work, including: (i) Upper Jurassic siliciclastic shoreface deposits including Grès de Connincthun, Grès de Chatillon and Grès de la Crèche formations from NW France, (ii) Upper Cretaceous Rock Springs Formation from USA of wave-dominated delta and tide and mixed-energy estuaries facies, (iii) Lower to Middle Devonian Jauf Formation from Saudi Arabia (shoreface to tidal estuarine facies), and (iv) Cambro-Ordovician Adedia Formation (subtidal-intertidal) from Sinai Egypt. Diagenetic studies were conducted on sandstones sam-ples extracted from cemented and poorly lithified sandstones within systems tracts and along key sequence stratigraphic surfaces in these four successions.

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Key concepts of sequence stratigraphy

Prior to the integration of diagenesis and related impact on res-ervoir quality evolution into sequence stratigraphic framework of the studied siliciclastic successions, it is essential to provide definitions of key concepts of sequence stratigraphy. The sequence stratigraphy tool is used to correlate genetically related sedimentary successions bounded at top and base by unconformities or their correlative con-formities (Van Wagoner et al., 1990). Sequences and their stratal pat-terns are interpreted to form in response to the interaction of three major factors such as eustatic change of sea level, sediment supply and tectonic subsidence (Van Wagoner et al., 1990). Each depositional sequence is the record of one cycle of RSL rise and fall that allow for integrating and correlating a range of depositional environments, such as coastal plains, continental shelves, and submarine fans.

The stacking pattern of sediments is controlled by the interplay between the rate of sediment supply and rate of changes in the RSL, which is controlled by basin-floor subsidence/uplift and/or by changes in the eustatic sea level. These parameters control the space available for sediment deposition and preservation, referred to as accommoda-tion (Jervey, 1988). In the paralic and shallow marine realm, accom-modation can be created by rise in RSL owing to increase in eustatic sea level or basin-floor subsidence.

The stacking pattern within sedimentary packages depends on the rates of accommodation creation and sediment supply. If the rate of sediment supply is greater than the rate of accommodation creation, the deposits prograde, i.e. the shoreline migrates seawards (Van Wag-oner et al., 1990). The depositional facies display trend of shallowing upward stacking pattern, and the depositional environments are being referred to as regressive. Regression of depositional environments occurs either due to: (i) higher rates of sediment supply than the rate of accommodation creation, and is referred to as normal regression (Fig. 1a), or (ii) fall in the RSL owing to fall in eustatic sea level or tectonic uplift of basin floor, being referred to as forced regression (Fig. 1b; Hunt and Tucker, 1992). Retrogradational depositional facies is encountered owing to lower rate of sediment supply than the rate of

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accommodation creation (Fig. 1c; Posamentier and Allen, 1999; Jervey, 1988). The shoreline will migrate landward, and the deposi-tional facies display upward deepening trend; the depositional envi-ronments are referred to as transgressional. Aggradation of deposi-tional facies occurs if the rate of sediment supply is equivalent to the rate of accommodation creation (Fig. 1d; Posamentier and Allen, 1999). The shoreline is stationary, and the depositional facies will have fixed position upwards in the stratigraphic section.

The sequence stratigraphic approach aims to divide basin fill successions into depositional sequences. A depositional sequence is a stratigraphic unit composed of relatively conformable successions of genetically related strata that are bounded at bottom and top by uncon-formities or their correlative conformities (Mitchum, 1977). The un-conformities, referred to as sequence boundaries, are formed by rapid and considerable (several tens of meters) fall in the RSL (Van Wag-oner et al., 1990). If the RSL falls below the shelf edge, the uncon-formity surface may develop across the whole shelf, being marked by non deposition or the occurrence of pronounced erosion of the shelf by rivers (i.e. formation of incised valleys). Sediment derived from shelf erosion and from the hinterland will be by-passed across the shelf to form turbidite deposits on the slope and basin floor (Posamen-tier and Allen, 1999).

Fall in the RSL and formation of sequence boundary will be ultimately followed by rise in the RSL and sediment deposition. Sequences are comprised of parasequences, which are relatively con-formable successions of genetically related beds or bedsets bounded by “minor” marine flooding surfaces (Van Wagoner et al., 1990). Each parasequence is progradational, and hence shallows upward (Fig. 1e).

Parasequence sets make up systems tracts, which are defined as contemporaneous depositional systems linked to a specific segment on the curve of changes in the RSL. Four systems tracts are recog-nized (Fig. 1f), including lowstand (LST), transgressive (TST), high-stand (HST), and forced regressive wedge (FRWST). The LST is de-posited during RSL lowstand and initial rise, and shows prograda-tional-aggradational facies stacking. The TST is deposited during rapid rise in the relative sea level, and is bounded below by the trans-gressive surface and above by the maximum flooding surface (MFS). The MFS, which separates the TST from the overlying HST, repre-sents condensed section formed due to very low rates of sediment supply, and marks the point of maximum landward advance of the strandline. The TST is comprised of a retrogradational parasequence set of shelf sediments, including marine sandstones and mudstones. Peat (coal) layers are developed during transgression of coastal plain,

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and are hence common within the TST, particularly below marine flooding surfaces.

The HST, which is deposited during stable high and slowly falling RSL, is bounded below by MFS and above by the upper se-quence boundary, and formed owing to initial fall in the RSL. The HST is comprised of initial aggradational and later, as the accommo-dation created by rise in the RSL diminishes, progradational parase-quence sets. Commonly, the HST is partly preserved owing to erosion during formation of the upper sequence boundary. The forced regres-sive wedge systems tract (FRWST), also referred to as the forced re-gressive systems tract (FRST; Hunt and Tucker, 1992), was proposed to include deposits formed during RSL fall, between the highstand and the point of maximum rate of sea-level fall (i.e., formation of the suc-ceeding sequence boundary). The most typical sediments of this sys-tems tract are sharp-based sandstones deposited in shoreface environ-ments above erosional surfaces formed during regression (Plint, 1988). The sequence boundary is usually drawn above the FRWST (the subaerial unconformity and its seaward extension), because this surface is formed when the RSL reaches its lowest point coinciding with the surface of subaerial erosion.

The application of sequence stratigraphy techniques to the paralic and marine realm resulted in a better understanding of the spa-tial and temporal distribution of sedimentary facies (Posamentier and Allen, 1999). The sequence stratigraphic terminology used throughout this thesis is that defined by Posamentier et al. (1988) and Hunt and Tucker (1991) (Table 1). In papers and , the depositional sequences are divided into four systems tracts including FRWST, LST, TST and HST. In papers and IV, the depositional sequence is divided into three systems tracts (Posamentier et al., 1988).

proximal distalRAMP MARGIN

(d) aggradation

sea-level 4

sea-level 3

4

sea-level 2

sea-level 1

3

2

1

(c) retrogradation

sea-level 1

sea-level 4

sea-level 2

sea-level 34

3

2

1

(b) progradation due to forced regression1

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sea-level 1sea-level 2sea-level 3sea-level 44

silt f m

sand

ccla

y

parasequence2

parasequence1

(e)

(f)

sea-level 4sea-level 3sea-level 2sea-level 1

432

1

(a) progradation due to normal regression

highstand systems tract (HST)

transgressive systems tract (TST)

lowstand systems tract (LST)

forced regressive wedge systems tract (FRWST)

maximum flooding surface (MFS)

transgressive surface (TS)

sequence boundary (SB)

regressive surface of erosion (RSE)

HST

FR WS T

(FR S T) SB LS T

TST

HS T

MFShigh

low

relativesea-level

TSRSE

K E Y

alluvial and coastalplain sediments

offshore-marinesediments

shallow-marinesediments

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Abbreviation Definition

Forced regressive wedge systems tract

FRWST Or

FRST

Sediment deposited between the onset and the end of relative sea-level fall on ramp margins, i.e., gently sloping into deeper wa-ter, and composed of progradational facies stacking with downward shift

Lowstand systems tract LST

Sediment deposited during relative sea-level lowstand and initial rise, and shows progra-dational-aggradational to retrogradational facies stacking

Transgressive systems tract TST

Sediment deposited during rapid relative sea-level rise that shows an overall retrograda-tional facies stacking

Highstand systems tract HST Sediment deposited during relative sea-level highstand resulting initially in aggradational and, later, in progradational facies stacking

Regressive surface of marine erosion RSE

Erosion surface located at the base of the FRWST formed by wave erosion during relative sea-level fall

Sequence boundary SB

Erosional unconformity at the inner shelf located at the base of the LST created by emersion during a major fall in relative sea level (basinward correlative conformity)

Transgressive surface of marine erosion TSE Surface located at the base of the TST and

formed during relative sea-level rise

Maximum flooding sur-face MFS

Surface located at the base of the HST and formed by nondeposition and sediment star-vation during maximum relative sea-level highstand

Parasequence boundary PB Local marine flooding surface at the top of a progradational, elementary sediment package

Sharp-based shoreface SBS Shoreface sediments preserved in FRWST and LST during forced regression, i.e., dur-ing net relative sea-level fall

Ravinement shoreface Shoreface sediments preserved in TST dur-ing relative sea-level rise. It is thin, coarse-grained lags

Table 1: Table summarizing the main sequence stratigraphy terms (Posamentier et al., 1988; Hunt and Tucker, 1992; Proust et al., 2001).

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Methodology

Sandstone samples were collected from both outcrops and sub-surface cores that represent various depositional facies, systems tracts and key sequence stratigraphic surfaces. Core plugs were selected for He-porosity and permeability measurements (paper ). Thin sections were prepared for all samples subsequent to vacuum impregnation with blue epoxy. Modal analyses of most sandstone samples were pre-formed by counting 300 points in each thin section. Scanning electron microscope (SEM) was used to study crystal habits and paragenetic relationships among diagenetic minerals in representative samples.

Polished thin sections represent sandstones from the various depositional facies and systems tracts encountered were coated with a thin layer of carbon for the purpose of electron microprobe (EMP) analyses. Cameca SX50 instrument equipped with three spectrometers and a back-scattered electron detector (BSE) was used to determine the chemical compositions and paragenetic relationships of different cement types. Operating conditions during analysis were an accelerat-ing voltage of 20 kV, a measured beam current of 10 nA for carbon-ates and 12 nA for silicates, and a spot size of 1-5 m. The standard and count times used were wollastonite (Ca, 10 s), MgO (Mg, 10 s), strontianite (Sr, 10 s), MnTiO3 (Mn, 10 s), and hematite (Fe, 10 s). Analytical precision was better than 0.1% for all elements.

Stable carbon and oxygen isotope analyses were carried out on carbonate-cemented sandstones representative of the various deposi-tional environments and systems tracts in order to determine the geo-chemical conditions, porewaters composition and temperature of pre-cipitation. Sampling using micro-drilling techniques was attempted to avoid contamination of carbonate cements with carbonate grains and, when possible, to analyze carbonate cements with different textures. Calcite-cemented samples reacted with 100% phosphoric acid at 25˚Cfor one hour, and Fe-dolomite/ankerite and siderite-cemented samples were reacted at 50°C for one day and six days, respectively (e.g. Al-Aasm et al., 1990). The CO2 gas released was collected and analyzed using a Delta plus mass spectrometer. Samples containing calcite, dolomite and siderite were subjected to sequential chemical separation treatment (Al-Aasm et al., 1990). The phosphoric acid fractionation factors used were 1.01025 for calcite at 25˚C (Friedman and O’Neil,

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1977), 1.01060 for dolomite at 50˚C and 1.010454 for siderite at 50˚C(Rosenbaum and Sheppard, 1986). Precision of all analyses was better than ±0.05‰ for both 13C and 18O. Oxygen and carbon isotope data are presented in the notation relative to the V-PDB and V-SMOW standards.

The 87Sr/86Sr isotopes ratio was analyzed (papers and ) us-ing an automated Finnigan 261 mass spectrometer equipped with 9 faraday collectors. Some of calcite-cemented samples from different systems tracts were washed with distilled water and then reacted with dilute acetic acid in order to avoid silicate leaching. Correction for isotope fractionation during the analyses was made by normalization to 86Sr/88Sr = 0.1194. The mean standard error of mass spectrometer performance was ±0.00003 for standard NBS-987.

A JEOL JEM 2010 200KV transmission electron microscope (TEM) was used for a detailed grain-by-grain characterization of the two separated < 2 micron clay mineral fractions, their morphology and for control of the grain-size distribution within the fractions (paper

). Stable oxygen isotope analyses and K-Ar dating were determined for illite from sandstone samples to provide information on the tem-perature and composition of precipitating fluids (paper ). Sulfur isotope ratios in anhydrite-cemented sandstones were analyzed to un-ravel the source of sulfate (paper ). X-ray diffraction (XRD) analy-ses were preformed on the fine fraction (< 20 µm) from representative sandstone samples using a Siemens D5000 diffractometer (papers and V).

A high sensitivity hot-cathode CL microscope was used to study zonation in various quartz cements (paper ). Microthermom-etric analyses of the fluid inclusions were preformed in the Jauf sam-ples (paper ) using a Linkam MDS 600 fluid inclusion heating-freezing stage mounted on a Leitz Ortholux II petrographic micro-scope. The temperatures were measured using the procedure described in Shepherd et al. (1985).

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Summary models of diagenetic alterations within systems tracts

Unraveling the distribution pattern of diagenetic alterations within facies and systems tracts in the four studied siliciclastic succes-sions reveal that important alterations including the dissolution and kaolinitization of framework silicates, are closely associated to spe-cific facies and systems tracts. Mesogentic alterations are encountered in deeply buried successions studied in papers and V. This thesis shows that the distribution of mesogenetic alterations within deposi-tional facies and sequence stratigraphic framework of paralic and shal-low marine siliciclastic deposits is controlled by the distribution pat-tern as well as type and extent of eogenetic alterations, burial-thermal history, and formation water chemistry.

Important eogenetic alterations linked to sequence stratigraphy

The most common and abundant eogenetic alterations in the paralic and shallow marine successions are carbonates (e.g. calcite, dolomite, siderite), kaolinite, pseudomatrix, and infiltrated clay coat-ings. Calcite cement has mainly coarse crystalline to poikilotopic tex-ture in the FRWST and LST sandstones (papers and ), TST and HST (papers and V) and in upper part of HST (paper ) and occurs mainly as stratabound concretions (papers and ). Sandstone beds hosting the concretions in the FRWST, LST and upper part of HST sandstones contain trace amounts of carbonate grains, whereas the poorly lithified sandstones that are overlying and underlying the con-cretionary-cemented sandstones contain considerable amounts of car-bonate grains (av. ~ 10%; paper ). Cementation by marine intergranu-lar microcrystalline as well as grain-coating fibrous (papers and V)and scalenohedral/dogtooth (paper V) calcite occur mainly in the TST and lower part of HST.

Dolomite occurs in all depositional facies and systems tracts, but is most common in the TST and HST sandstones (papers and

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and ) particularly below the MFS (paper ). The isotopic signa-tures of dolomite in HST sandstone (papers , and ) were inter-preted to indicate precipitation under marine-meteoric mixing condi-tions, which is achieved through progradation and concomitant mete-oric water incursion into the shoreface sandstones during times of sea-level lowstand. The 18OV-PDB values of pre-compactional, Fe-dolomite/ankerite (-10.4‰ to -8.4‰) in the tidal estuarine TST sand-stones and below the MFS (paper ) indicate wide range of inferred precipitation temperatures (40-60°C), which can be explained as fol-lows: (i) formation of Fe-dolomite/ankerite by replacement of near surface calcite during progressive burial and increase in temperature, or (ii) precipitation of Fe-dolomite/ankerite started below the seafloor and provided nuclei for further precipitation of Fe-dolomite/ankerite during progressive burial.

Eogenetic siderite (paper ) is encountered in the fluvial and tide-influenced fluvial channel sandstones (LST) and estuary mouth barrier sandstones (TST) and in the paleosols of the marginal tidal-flat and marsh sandstones (TST). Siderite occurs in few samples mainly as pore filling cement (av. 3%) and, in some cases, as tiny crystals around the framework grains (av. 1%). This type of siderite is charac-terized by 18OV-PDB values of -6.8‰ to -5.4‰, suggesting precipita-tion from brackish porewaters that are dominated by meteoric water component.

Kaolinite is most abundant in the distributary channels of HST and FRST sandstones, the upper shoreface sandstones below the SB (paper ), the shoreface of the HST sandstones (paper ), and tidal HST sandstones (paper V). The loosely expanded texture of the kao-linitized micas in the studied sandstones suggests formation during near-surface diagenesis. Abundant kaolinite in the distributary chan-nels of HST and FRST and in the upper shoreface sandstones, particu-larly below the SB (paper ), is attributed to the flux of meteoric wa-ter into the paralic sediments during RSL fall. Meteoric water flux occurs also into the outer-estuarine tidal bars below coal layers (TST), which induce mineral dissolution aided by the generation of organic acids and CO2 derived from the decay of the peat deposits (paper ).Extensive dissolution and kaolinitization of mica, feldspar and mud intraclasts in the shoreface and tidal HST sandstones (papers and V) are attributed to incursion of meteoric waters during RSL fall and

progradation of the shoreface and tidal flat complex. Pseudomatrix, which has been formed by the deformation and

squeezing of ductile mud intraclasts between the rigid quartz grains, occurs in the LST and FRSWT sandstones (paper ), the HST, FRST sandstones and above the SB (paper ), and the shoreface HST, tidal estuarine TST and HST sandstones (paper ).

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Mechanically infiltrated clay minerals occur mostly in the tidal estuarine, TST and HST sandstones (paper ). These clay minerals occur in the TST marginal tidal-flat and marsh sandstones (paper )and the poorly lithified FRWST and LST sandstone beds (paper ).Infiltrated clay minerals in tidal estuarine TST and HST sandstones were presumably introduced into the sands by tidal pumping (paper

). Another possible mechanism is subaerial exposure and infiltra-tion of surface water rich in suspended mud. Although this latter mechanism cannot be totally discarded, subaerial exposure is unlikely to occur during rise in the RSL and deposition of TST. The tangential arrangement of clay flakes around detrital grains in the marginal tidal-flat and marsh sandstones suggests formation by infiltration of run off water during soil formation at the regressive surface (paper ; Moraes and De Ros, 1990; Ketzer et al. 2003b).

Iron oxide cement occurs in all studied sequences as pore fill-ing cement in poorly lithified FRWST sandstones (below the SB) and in the LST sandstones (paper ), as coatings around the framework grains, as pore filling cement and as pelloidal grains (400 to 600 macross) in all systems tracts, but particularly in TST and HST sand-stones (paper ), as platy specularite (5-10 µm across) being mainly grain replacive and in some cases fills the intergranular pores in the coastal plain HST sandstones (paper ). Extensive cementation by Fe-oxides has occurred below marine flooding surfaces of tidal flat sandstones (paper V), which is attributed to precipitation owing to diffusion of Fe2+derived from the reduction of detrital Fe-oxides and oxidation at the seafloor. Hence, this pattern of Fe-oxide precipitation resembles the mechanism of Fe-Mn nodules formation in abyssal plains of modern oceans.

Pyrite occurs in trace amounts in all systems tracts (papers ,and ). Pyrite in the FRWST and LST sediments is often partly oxi-dized (paper ), or almost completely weathered into jarosite and iron oxides (paper ). Abundant jarosite concretions below the SB and coal layers are thus presumably derived form complete weathering of pyrite, which was facilitated by subaerial exposures and desulfurisa-tion of coal (paper ). Glaucony in the TST and the lower part of HST sediments, was formed in situ, whereas glaucony in the FRWST, the LST, and the upper part of HST sandstones was reworked and altered (oxidized and dissolved) presumably through interaction with mete-oric waters (paper ).

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Important mesogenetic alterations linked to sequence stratigraphy

The most common and abundant mesogenetic alterations in the paralic and shallow marine successions include Fe-dolomite, rare ankerite, Mg-rich siderite, illite, chlorite, quartz overgrowths and out-growths, dickite, albite and anhydrite. Fe-dolomite and ankerite ce-ments ( 18OV-PDB -16.8‰ to -13.5‰) have mainly coarse crystalline to poikilotopic texture and occur in the tidal estuarine TST and HST and below the MFS sandstones (paper ) and was precipitated subse-quent to considerable increase in burial depth from evolved brackish to marine porewaters. Mg-siderite occurs in TST and HST (paper )as scattered, grain-replacing patches comprised of coarse crystals that fill intergranular pores. Mg-siderite ( 18OV-PDB = -13‰ to -11.4‰) is mesogenetic in origin as evidenced by occurrence in sandstones with close packed grains, and engulfment, and hence postdating of quartz overgrowths that precipitated at temperature of 105°C to 162°C (paper

).The various textural habits of illite (platelet-like, fibrous, fila-

mentous, honeycomb-like, booklets-like and mat-like), which occurs in the tidal estuarine TST and HST sandstones (paper ), suggest formation by various processes including transformation of a clay pre-cursor, precipitation from porewaters (authigenesis), replacement kao-linite and feldspar (e.g. Worden and Morad, 2003). The platelet-like illite occurs as continuous tangential coatings around the framework grains and at the grain-to-grain contacts, indicating formation by transformation of infiltrated clay (Moraes and De Ros, 1990). The honeycomb-like illite has most likely been formed by the transforma-tion of authigenic smectite (Worden and Morad, 2003) during pro-gressive increasing in burial depth (Burley and MacQuaker, 1992). Fibrous and filamentous illite, which cover the honeycomb-like illite, have likely been formed by precipitation from porewaters as evi-denced by their absence at grain-to-grain contacts (Güven, 2001). The occurrence of fibrous and mat-like illite on the scale of few mm’s ex-cludes formation of the latter by collapse during sample preparation, which was suggested by De Waal et al. (1988) and Kantorowicz (1990).

Grain coating and grain replacing chlorite is more abundant in the tidal estuarine, HST sandstones than in the TST sandstones (paper

). The occurrence of continuous chlorite coatings as platelet-like crystals that are arranged perpendicular to ultra-thin layer ( 1 µm thick) of poorly characterized clay mineral substrate supports the im-portance of substrate in the nucleation and growth of chlorite. Sub-strates with similar molecular surface configuration to chlorite mini-

25

mize the interfacial energy between the growing nucleus and the sub-strate (Wilkinson and Hazeldine, 2002). The absence of perpendicular aligned chlorite crystals at grain-to-grain contacts indicates that chlo-rite nucleation and growth occurred from porewaters.

Various occurrence habits of quartz cements (overgrowths, outgrowths, discrete crystals and rare micro-quartz) within the differ-ent depositional facies and systems tracts indicate different origin. Quartz overgrowths are most abundant in the shoreface to coastal plain, HST sandstones (paper ) and TST and HST sandstones (pa-per V), whereas quartz outgrowths occur mainly in the tidal estuarine TST and HST sandstones (paper ).

Abundant quartz overgrowths in the shoreface, HST sand-stones compared to their rare occurrence in the tidal estuarine, TST and HST sandstones is attributed to facies-controlled variations in the distribution of clay coatings and extent of intergranular pressure disso-lution (paper ). Quartz overgrowths and intergranular pressure dis-solution are known to be significant at temperature of about 90-130°C and burial depths greater than 3 km (McBride, 1989; Walderhaug, 1996). The amounts of quartz overgrowths (0-25%; av. 14%; paper

) in the shoreface, HST sandstones are controlled mainly by avail-ability of quartz grains with clean surfaces, which could act as nuclei for growth of quartz overgrowths (Bloch et al., 2002). The common presence of intergranular pressure dissolution and stylolites together with quartz overgrowths in the shoreface, HST sandstones suggests that silica required for quartz cement was derived internally (Walder-haug, 1994; Walderhaug and Bjørkum, 2003).

Fibrous and platelet-like illite and chlorite coatings around the quartz grains have retarded the precipitation of quartz overgrowths but not of prismatic and coarse-crystalline quartz outgrowths in the tidal estuarine, TST and HST sandstones (paper ). Healed fractures in the quartz grains have apparently provided substrates for the nucleation and growth of coarse-crystalline to poikilotopic quartz (paper ). The formation of quartz outgrowths, which occurred subsequent to the overgrowths, may have required higher degree of silica supersatura-tion, which is commonly achieved during deep-burial diagenesis (Bjørlykke and Egeberg, 1993).

Fluid inclusion thermometry indicates that quartz cementation occurred at temperatures of 105-162°C (paper ). The wide variation in salinity of fluid (4 to 28 eq. wt.% NaCl) involved in precipitation of quartz cements at temperatures of 105-162°C corresponding to depths of 2.9 to 5 km (paper ) is difficult to constrain, but could be due to episodic flux of saline fluid from the overlying Permian anhydrites and/or to dilution of formation waters by the expulsion of water de-rived from the illitization of smectite in the mudstones (Boles and

26

Franks, 1979) and from maturation of organic matter (Hanor, 1994; Burley et al., 1989). The incursion of meteoric water is unlikely in deeply buried sandstones (Hanor, 1994), and hence cannot account for the lower-salinity formation waters.

Anhydrite, which occurs as coarse to poikilotopic crystals that fill intergranular cement and strongly replace the framework grains, is restricted to the tidal estuarine, HST sandstones (paper ). Anhydrite engulfs, and hence postdates quartz overgrowths, suggesting precipita-tion during mesodiagenesis at temperature > 105°C, which is the minimum homogenization temperature obtained for quartz over-growths (paper ). The sulfur isotope values ( 34SCDT = +10‰) of the anhydrite cement in the tidal estuarine HST sandstones are much lower than the contemporary, Lower to Middle Devonian seawater ( 34SCDT = +22‰; Claypool et al., 1980), but consistent with the Late Permian seawater ( 34SCDT = +10‰; Claypool et al., 1980). Therefore, dissolved Ca2+ and SO4

2- needed for anhydrite cement formation have likely been derived from dissolution of anhydrite in the overlying Permian Khuff Formation, which is in contact, through faulting with the upper HST of the Jauf Formation (Wender et al., 1998). Accord-ingly, the restricted occurrence of anhydrite in the tidal estuarine HST sandstones that stratigraphically overly the tidal estuarine (TST) and shoreface (HST) sandstones does not reflect a sequence stratigraphic control but rather the structural control on anhydrite cementation. Dis-solution of halite–anhydrite sequences in the deep subsurface nor-mally produces sulfate-rich brines (Hanor, 1994). Such sulfate source has been adopted for mesogenetic anhydrite cement in deeply buried sandstones from other basins (Dworkin and Land, 1994; Morad et al., 1994; Sullivan et al., 1994; Rossi et al., 2002).

Dickite, which is distinguished from kaolinite by two strong reflections (2.50 and 2.32 ), occurs as blocky crystals (5-20 µm) with vermicular stacking pattern containing etched kaolinitic remnants (paper ). Kaolin is engulfed by, and hence predates, quartz over-growths. With increase in burial depth, kaolinite has been transformed progressively into dickite through small-scale dissolution and repre-cipitation (Ehrenberg et al., 1993; Morad et al., 1994), which is evi-denced by: (i) the association of dickite and etched kaolinite, and (ii) preservation of vermicular and booklet stacking pattern of kaolinite in dickite.

Albite occurs as numerous small, lath-like crystals (1-15 µm across) that are parallel aligned to each other and to remnants of se-verely etched K-feldspar and plagioclase grains, and can hence be considered as albitized feldspar (e.g. Morad, 1986). Albitized feldspar was encountered in the tidal estuarine, TST and HST sandstones (pa-per ). Partly albitized plagioclase grains have preserved their origi-

27

nal twining pattern, whereas partly albitized K-feldspar contain irregu-lar patches of albite and of the detrital host feldspar. Albitized feld-spars, particularly plagioclase, contain variable amounts of intragranu-lar pores. Completely albitized feldspars are untwined, vacuolated and display patchy extinction patterns. These feldspars display petro-graphic features similar to albitized feldspars described by Morad (1986), Morad et al. (1990) and Saigal et al. (1988). Albitization of K-feldspar has acted as a source of potassium needed for the formation of illite (up to 8%; Morad et al., 1990; Bjørlykke and Aagaard, 1992).

28

Reservoir quality and heterogeneity models

This thesis has shown that linking diagenesis to sequence stratigraphy of paralic and shallow marine siliciclastic sediments has important implications for unraveling and predicting the spatial and temporal distribution of diagenetic alterations and of their impact on reservoir quality evolution. Four predictive conceptual models have been obtained from the studied successions, which illustrate the dif-ferent evolution pathways of reservoir quality in relationship to depo-sitional facies and sequence stratigraphic frameworks (Figs. 2 to 5).

Model 1: Diagenetic and reservoir-quality evolution pathway of shoreface sandstones (paper )

A summary model that integrates the spatial and temporal dis-tribution of diagenetic alterations in Upper Jurassic siliciclastic shore-face sediments into the sequence stratigraphic framework is proposed (Fig. 2). Changes in RSL have resulted in changes in porewaters chemistry, which in turn have had a significant impact on the diagenetic alteration of siliciclastic deposits. The proposed model em-phasizes: (i) the distribution of eogenetic alterations within FRWST, LST, TST, and HST, (ii) the distribution of cemented vs. non-cemented sandstones, and hence reservoir-quality evolution pathways (e.g., reservoir rocks and diagenetic trap), and (iii) the cementation pattern (e.g., concretionary-cemented versus continuously cemented layers) and texture (microcrystalline vs. poikilotopic) of calcite ce-ments.

Formation of stratabound, poikilotopic calcite concretions with dominantly meteoric isotopic signatures occurred in FRWST, LST and the upper part of the HST (Fig. 2A, C). Poikilotopic calcite ce-ment was sourced by complete dissolution of carbonate bioclasts in the host sand beds as a result of considerable meteoric-water flux un-der a warm, humid paleoclimate. Mechanical infiltration of clays and cementation by vadose micritic calcite and by opal, chalcedony, and gypsum occurred in the interbedded, poorly lithified sandstones under an arid to semiarid paleoclimate (Fig. 2B). Microcrystalline calcite

29

cement in sandstones and mudrocks of the TST and the lower part of the HST, which has dominantly marine isotopic signatures, is sug-gested to be sourced through diffusion of Ca2+ and HCO3

- from over-lying seawater (Fig. 2D, E). Glaucony in the TST and the lower part of HST sediments was formed in situ, whereas glaucony in the FRWST, the LST, and the upper part of HST sandstones was re-worked and altered (oxidized and dissolved) through interaction with meteoric waters.

Shoreface deposits are common hydrocarbon systems in which the distribution of reservoirs, seals, and source rocks is strongly con-trolled by changes in the RSL (Proust et al., 2001). Therefore, the Ju-rassic shoreface deposits from NW France serve as an analogue that provides further insight into reservoir and seal-rock development ow-ing to diagenetic alterations (Fig. 2). Although the Jurassic succession discussed here was not buried deeper than 500 m (El Albani, 1991), the anticipated burial-diagenetic modifications that could be encoun-tered to depth of 3 km and related reservoir-quality evolution path-ways were envisaged. The speculative depth of 3 km is chosen bec-ause it encounters a number of key modifications, including pressure dissolution and concomitant quartz cementation, as well as the forma-tion of deep-burial illite and chlorite (Morad et al., 2000).

Sandstones of the TST and the lower part of the HST have poor depositional reservoir quality owing to their high mud matrix content, and/or pervasive cementation by microcrystalline calcite. The continuously calcite-cemented layers are expected to act as fluid-flow baffles during diagenesis and hydrocarbon production (Fig. 6). Diagenetic alterations, which are expected to occur in such sandstones during burial to the arbitrary depth of 3 km, include: (i) recrystalliza-tion of the microcrystalline calcite into coarse-crystalline calcite, (ii) illitization and chloritization of infiltrated smectite, and (iii) mechani-cal compaction of the poorly cemented, very fine-grained sandstones, resulting in further deterioration to reservoir quality.

The present-day reservoir quality of the FRWST and LST sandstones varies widely, being related mainly to variations in the amounts and distribution patterns of poikilotopic calcite. Coalesced calcite concretions (100-200 cm in diameter) in these sandstones might act as fluid-flow baffles (Kantorowicz et al., 1987; Ketzer et al., 2003a). Conversely, the friable to poorly lithified sandstone beds would likely evolve to excellent reservoir quality, as evidenced by the well interconnected primary and secondary pores (total porosity is up to 50%) and the dominant point contacts between the framework grains. Diagenesis during progressive burial to the arbitrary depth of 3 km of the poorly lithified sandstone beds would probably result in dissolution of calcite bioclasts and precipitation of calcite cement

30

(Walderhaug and Bjørkum, 1998). Opal and, to certain extent, chal-cedony are metastable phases, and will thus be dissolved and repre-cipitated initially as grain-coating micro-quartz (e.g., Lima and De Ros, 2003). Micro-quartz is concluded to retard mechanical and chemical compaction as well as precipitation of quartz overgrowths, and hence preservation of reservoir quality even when the sandstone is buried deeply (Aase et al., 1996; Bloch et al., 2002).

Stratabound concretionsInfiltrated clayMud intraclastIntense bioturbationContinuously cemented layerPoorly lithified sandstoneSiltstoneMudstoneMicrocrystalline calcite cementPoikilotopic calcite cementIn-situ glauconiteReworked glauconiteOpal/Chalcedony and gypsumVadose calcite cement

Sequence stratigraphy:RSESBTSEMFSPBFRWSTLSTTSTHST

Regressive surface of marine erosionSequence boundaryTransgressive surface of marine erosionMaximum flooding surfaceParasequence boundaryForced regressive systems tractLowstand systems tractTransgressive systems tractHighstand systems tract

relativesea level

low

high FRWST

TST

HST

SL1

SL4

SL2

SL6

SL5

MCPCIGRGO/C+GVC

SL3

SL4

SL3

16

14

12

8

6

4

2

0m

10

18 RSE

SB

MFS

RSE

PC, RG

PC, RG

PC, RG

MC, IG

MC, IGMC, IG

MC, IG HST

TST

LST

FRWST

MC, IG

MC, IG

MC, IG

MC, DG

MC, IG

PC, RG

PC, RG

O/C+G, RG

O/C+G, RG

PC, DG

O/C+G, RG, VC

PC, RG

PC, RG

RG

RG

HST

TSE

PC, RG

MC, IGMC, IG

RG

O/C+G, RG

mud silt fg mg cg

Grain Size

A. Cementation by phreatic poikilotopic calcite

meteoric water

warm humid

SL1

SL2

FRWST

arid to semi arid

SL2SL3

B. Infiltration of clays and cementation by vadosecalcite and phreatic opal/chalcedony and gypsum

FRWST

C. Cementation by phreatic poikilotopic calcite

warm humid

meteoric water FRWSTLST

LSTD. Cementation by marine microcrystalline calcite

FRWSTLST SL4

SL5Diffusion

Ca2+ and HCO3-

Grain sizeFine-grained sandstonesMedium-grained sandstonesCoarse-grained sandstones

fgmgcg

TST

SL5SL6

E. Cementation by marine microcrystalline calcite

RSE

SBTSE

MFS

FRWSTLST

TST

RSE

Depositional

Sequence Lower part of HST

Upper part of HST

Lower part of HST

Meteoric water

SBSB

32

Model 2: Diagenetic and reservoir-quality evolution pathway of wave-dominated delta and tide and mixed-energy estuaries sandstones (paper )

The diagenetic evolution of the Upper Cretaceous sandstones has followed five main pathways (Fig. 3). The summary model of the diagenetic evolution pathways illustrates the distribution of eogenetic alterations in sandstones within FRST, LST, TST, and HST (Fig. 3). Emphasis is also made on diagenetic alterations below coal layers and SB.

The most important diagenetic alterations in the sandstones in-clude two patterns of carbonate cementation that resulted in continu-ously cemented and concretions layers depending on depositional en-vironments and type of systems tract. Carbonate concretions in the fluvial channels (LST) and outer estuarine tidal bar (TST) show in-creasing-upward trend in number and size, as well as in the volume of dolomite and calcite cements towards the marine flooding surfaces. This trend of carbonate cement distribution is attributed to the long residence time of sediments below the flooding surfaces that enhance the diffusion of dissolved carbon and Ca2+ from the overlaying sea-water (Kantorowicz et al., 1987; Taylor et al., 1995; Morad et al., 2000; Ketzer et al., 2003a). The coarse calcite cement in all systems tracts was derived from the recrystallization of the microcrystalline calcite by meteoric water incursion and/or burial diagenesis.

Poorly lithified sandstones, particularly below SB and coal layers, have been subjected to a significant dissolution and kaolinitiza-tion of mica, feldspars and mud intraclast and dissolution of detrital dolomite and carbonate cements. Increase in the amounts of secondary porosity in paralic sandstones lying below the SB and below the coal layer (TST) is attributed to the flux of meteoric water during RSL fall and to the generation of organic acids and CO2 during percolation of meteoric waters in the peat deposits, respectively, which resulted in the silicate grains dissolution (Staub and Cohen, 1978). Conversely, mechanical compaction has been extensive in samples of the HST and FRST that are enriched in low-grade metamorphic rock fragments, which have been squeezed between the rigid framework grains (e.g. quartz) and resulted in the formation of pseudomatrix. Infiltrated clay coatings occur around detrital grains in the marginal tidal-flat and marsh sandstones and formed during soil formation at the regressive surface (Moraes and De Ros, 1990; Ketzer et al., 2003a).

Zoned dolomite rhombs

Dissolved dolomite

Siderite

Detrital dolomite

Dissolved detrital dolomite

Iron oxides

Pyrite

Sequence stratigraphy:FRSTLSTTSTHSTSB

Forced regressive systems tractLowstand systems tractTransgressive systems tractHighstand systems tractSequence boundary

Kaolinite

Infiltrated clay coating

Quartz grains

Dissolved silicate grains

Feldspar

Low-grade metamorphicrock fragments

TST

HST

FRST

LST

Carbonate

cemented

sandstones HST

FRSTLSTTST

Porous

sandstones HST

FRSTLSTTST

Sandstones

belowSB

&coallayer

Mechanically

compacted

sandstones

HSTFRST

Carbonate concretionCarbonate continuously-cemented layerPoikilotopic calcite cementDissolved calcite cement

Paleosol&

infiltrated

claycoating

Regressive

surface

Grain replacive calcite

Less porous Moderately porous Highly porous

Carbonate continuously cementedlayers in the shoreface sandstone

Carbonate concretions in the tidedominated estuarine TST

Pyrite concretions

Coal fragments

Coal layer

Pyrite concretions in the whitesandstones of upper shoreface HST

SB

HST

LST

HST

LST

FRST

TST

Tide-influenced fluvial channel

Outer-estuarine tidal bars

SB

SB

Eod

iage

nesi

sE

odia

gene

sis

Eod

iage

nesi

sE

odia

gene

sis

Eod

iage

nesi

s

Tidal bar & outer estuarinetidal channel

FRST delta, SB and Fluvial LST

HST delta, SB and fluvial LST

34

Model 3: Diagenetic and reservoir-quality evolution pathway of shoreface HST and tidal estuarine, TST and HST sandstones (paper )

Recently, there have been increasing number of studies dem-onstrating that the spatial and temporal distribution of diagenetic al-terations can be better elucidated and predicted when linked to the systems tracts and key sequence stratigraphic surfaces (Taylor et al., 2000: Ketzer et al., 2002; Al-Ramadan et al., 2005; Ketzer and Morad, 2006). Grain coating minerals (chlorite, illite and micro-quartz) play decisive role in reservoir quality preservation in deeply buried sand-stones (Ehrenberg, 1993; Aase et al., 1996; Anjos et al., 2003; Salem et al., 2005). Despite the importance of these grain-coating minerals, little is known about their spatial and temporal distribution within se-quence stratigraphic framework of sandstones, and hence of their im-pact on reservoir quality evolution.

Establishment of the links between diagenesis and sequence stratigraphy will, thus, refine the assessment and prediction of the res-ervoir quality distribution patterns, amounts, texture, and composition of diagenetic minerals within the systems tracts and below the MFS of the Jauf Formation (Fig. 4). The Jauf sandstones have followed five main diagenetic evolution pathways involving variable types and ex-tents of compaction, cementation, mineral alteration and dissolution and formation of grain-coating clay minerals. These diagenetic altera-tions have induced various extents of porosity creation, destruction and preservation (Fig. 4).

Porosity preservation occurred in the tidal estuarine, TST and HST sandstones and is attributed to the retardation of quartz over-growths by grain-coating illite and chlorite (pathways A and B; Fig. 4; Ehrenberg, 1993; Bloch et al., 2002). Grain-coating, platelet-like and fibrous illite are the main reservoir-qulaity preserving agents in the tidal estuarine TST and HST. Tidal estuarine HST sandstones with chlorite and illite coatings have the highest He-porosity (up to 21%) and intergranular porosity (up to 7%) compared to the tidal estuarine TST sandstones in which the grains are coated only by illite (He-porosity up to 17% and intergranular porosity up to 5%). Chlorite is most commonly described in the literature as the effective type of clay mineral coatings in preventing quartz precipitation (Ehrenberg, 1993; Pittman et al., 1992). Despite its effect on porosity preservation, grain-coating, fibrous illite may induce considerable permeability deteriora-tion by occluding the pore throats partially to completely (Kan-torowicz, 1990; Worden and Morad, 2003).

35

Wide variations in porosity and permeability of the tidal estua-rine TST and HST sandstones are presumably related partly to varia-tion in the efficiency of grain coating minerals in preserving porosity. This efficiency depends on amounts, completeness of coating, as well as grain size and abundance of quartz grains (Walderhaug, 1996; Worden and Morad, 2000; Bloch et al., 2002). Grain coating illite with 3% is an arbitrary limit that apparently separates the sandstones into groups with various amounts of quartz overgrowths. Small to moderate volumes of intergranular porosity in TST and tidal estuarine HST sandstones is occluded by poikilotopic quartz outgrowths rather than by overgrowths and, in some cases, by Fe-dolomite/ankerite, siderite and anhydrite cementation (pathways A and B; Fig. 4). Clay mineral coatings have no effect on reservoir quality preservation in sandstones that are rich in mud intraclasts (up to 28%), which induce porosity-permeability reduction owing to ductile deformation.

Conversely, porosity destruction occurred in the shoreface HST sandstones that lack of thick grain-coating clays, which were, consequently, cemented extensively by quartz overgrowths (pathway C; Fig. 4). The shoreface, HST sandstones are also characterized by: (i) abundant microporosity in kaolinitized and illitized mud intraclasts, and illitized kaolin that resulted in reduction of permeability (pathway D; Fig. 4), and (ii) presence of isolated intragranular and moldic pores formed by partial to complete dissolution of feldspar and mica that were prevented from compaction by the presence of quartz over-growths (pathway D; Fig. 4), which helped supporting the sandstones framework (Souza et al., 1995).

Porosity destruction in sandstones that occur below MFS (He-porostiy = 2-5%) is attributed to extensive cementation by Fe-dolomite/ankerite (up to 44%; pathway E; Fig. 4), presumably form-ing reservoir baffles on top of the tidal estuarine TST, which is the most important reservoir facies in the Jauf Formation (Rahmani et al., 2003). Consequently, the MFS has compartmentalized the TST reser-voir sandstones from the above lying tidal estuarine HST sandstones, which are characterized by fairly good reservoir porosity (up to 21%). Sandstones lying below the MFS are subjected to extensive cementa-tion by eogenetic carbonates owing to diffusive flux of Ca2+ and HCO3

- from the overlying seawater, which is facilitated by long resi-dence time of sediment below the seafloor (Morad et al., 2000; Taylor et al., 2000; Ketzer et al., 2003a). However, the 18OV-PDB values of pre-compactional Fe-dolomite/ankerite indicate wide range of inferred precipitation temperatures (40-60°C), which can be attributed to: (i) formation of Fe-dolomite/ankerite by replacement of near surface cal-cite during progressive burial. Similar origin of Fe-dolomite was in-ferred by Morad et al. (1996) based on the presence of belemnite that

(B) Tidal estuarine HST(A) Tidal estuarine TST

Illitization & chloritization of clay coatings& retardation of quartz overgrowths

Clay infiltration

Illitization of clay coatings &retardation of quartz overgrowths

Eodiagenesis

Mesodiagenesis

Eodiagenesis

Mesodiagenesis

Quartz grain

K-feldsapr

Plagioclase

Mica

Mud intraclasts

Quartz overgrowths

Quartz outgrowths

Albitized feldspar

Kaolinitized mica

Illitized kaolinite

Stylolitic surface

Fe-dolomite/ankerite

Rock fragments

Replacive Fe-dolomite/ankerite

Ultra-thin clay coating

Infiltrated clay (IC)

Illitized IC

Pseudomatrix

Kaolinite

Fibrous illite

Chlorite+illite

Dickite

Siderite

Replacive siderite

Anhydrite

Pyrite

Porosity

LegendClay infiltration

oxygen isotope

Meteoric water flux &kaolinitization of mica, feldspar

grains & mud intraclasts

(C & D) Shoreface HST (E) MFS

Post compactional Fe-dolomitecementation

Mechanical compaction &formation of pseudomatrix

Dickitization of kaolinite

Eodiagenesis

Mesodiagenesis

Intensive pressure dissolution &precipitation of quartz overgrowths

Intensive pressure dissolution

38

Model 4: Diagenetic and reservoir-quality evolution pathway of tidal flat sandstones (paper V)

Rapid rise in the RSL has resulted in partial cementation by marine intergranular microcrystalline as well as grain-coating, fibrous and scalenohedral/dogtooth calcite in the TST sandstones (pathway A; Fig. 5). Extensive cementation by Fe-oxides has occurred below ma-rine flooding surfaces of tidal flat sandstones, which is attributed to precipitation owing to diffusion of Fe2+derived from the reduction of detrital Fe-oxides and oxidation at the seafloor. Subsequent fall in RSL resulted in the progradation of the tidal flat complex and mete-oric water incursion that induced pervasive dissolution and kaoliniti-zation of framework silicates as well partial dissolution of marine cal-cite cement, and hence creation of secondary intra- and intergranular porosity. The amounts of kaolinite increase considerably towards the sequence boundary. Mesogenetic alterations include intergranular pressure dissolution and formation of variable amounts of syntaxial quartz overgrowths in all systems tracts (pathway B; Fig. 5).

Cambro-

-

1sea-level 1

TST and lower part of the HST

MesodiagenesisLegend

Quartz

Mica

Feldspar

Mud intraclasts

Porosity

Altered mica

Fibrous & scalenohedralcalcite

Microcrystalline calcite

Coarse crystalline calcite

Kaolinite

Well crystallized kaolinite

Quartz overgrowths

Iron oxide

Marine

Eodiagenesis

Meteoric

Eodiagenesis

Upper part of the HST

Meteoric water flux

2 sea-level 2sea-level 3

sea-level 1

Pathway A Pathway B

3

1

K E Y

alluvial and coastalplain sediments

offshore-marinesediments

shallow-marinesediments

RSE

RSE

SBTSE

MFS

Depositional

Sequence

FRWST

LSTTST

HST

??

??

Partial diageneticcompartmentation/sealing

Diageneticcompartmentation/sealing

Reservoir rocks

Bioclasts

In situ glauconite with microcracks

Framboidal pyrite

Reworked glauconite

Microcrystalline calcite cement

Poikilotopic calcite cement

Bioturbated site cemented bymicrocrystalline calcite cement

Vadose calcite cement

Sand grains dominated byquartz

Pseudomatrix

Infiltrated clay coatings

Quartz overgrowth

Gypsum

Continuously calcite cementedsandstones/mudrocks

in TST and HST

Calcite-cementedsandstones inFRWST and LST

Poorly lithified sandstonesthat host the concretions

in FRWST and LST

Poorly lithified sandstonesthat overlie and underlie the

concretions in FRWST and LST

Opal and chalcedony cement

Dolomite rhombs

Dissolved silicate grains

Sequence stratigraphy:

RSESBTSEMFSPB

FRWSTLSTTSTHST

Regressive surface of marine erosionSequence boundaryTransgressive surface of marine erosionMaximum flooding surfaceParasequence boundary

Forced regressive systems tractLowstand systems tractTransgressive systems tractHighstand systems tract

41

Summary of the papers

Paper Distribution of Diagenetic Alterations in Siliciclastic Shoreface Deposits Within Sequence Stratigraphic Framework: Evidence From The Upper Jurassic, Boulonnais, NW France The distribution of diagenetic alterations in Upper Jurassic, siliciclas-tic shoreface sediments from NW France has been linked to the se-quence stratigraphic framework. Calcite cement in mudrocks and sandstones of the transgressive (TST) and lower part of the highstand (HST) systems tracts has microcrystalline and occurs as continuously cemented layers and stratabound concretions. The average 18OV-PDB(-2.6‰) and 87Sr/86Sr (0.7078) compositions of microcrystalline cal-cite indicate precipitation from largely marine porewaters.

Calcite cement in sandstones of the forced regressive wedge (FRWST) and lowstand (LST) systems tracts has poikilotopic texture and occurs mainly as stratabound concretions. Complete dissolution of the carbonate grains and concomitant precipitation of poikilotopic calcite cement with low average 18O (-5.3‰) and more radiogenic Sr-isotope (0.70882) signatures suggest incursion of meteoric waters into the sandstones during RSL lowstand. The poorly lithified sand-stones interbedded with sandstones cemented by poikilotopic calcite concretions display evidence of diagenesis under episodes of arid to semiarid paleoclimate, including: (i) partial cementation by opal, chal-cedony, gypsum, and minor vadose calcite cement, (ii) mechanically infiltrated clays and Fe-oxides, and (iii) secondary porosity owing to partial dissolution of carbonate grains. The integration of diagenesis into sequence stratigraphy allowed better elucidation and prediction of the spatial and temporal distribution of diagenetic alterations and re-lated reservoir-quality modifications in shoreface sediments.

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Paper Distribution of Diagenetic Alterations in Relationship to Depositional Facies and Sequence Stratigraphy of Wave- and Tide-Dominated Siliciclastic Shoreline Complex: Upper Cretaceous Chimney Rock Sandstones, Wyoming and Utah, USA This study constrains the distribution of diagenetic alterations and their impact on reservoir-quality evolution in relation to depositional environments (wave-dominated delta and tide and mixed-energy estu-aries) and sequence stratigraphy (systems tracts and key sequence stratigraphic surfaces) of Campanian sandstones from Wyoming-Utah, USA. The diagenetic alterations include cementation by calcite, dolo-mite, pyrite, micro-quartz, and iron oxides, dissolution of carbonate cement and detrital dolomite, dissolution and kaolinitization of framework silicates, mechanical compaction of argillaceous grains, and infiltration of grain coating clays.

Calcite, which is the dominant cement, is most abundant in the shoreface sandstones of HST and FRST. Oxygen and strontium iso-tope values ( 18O = -15.9‰ to -3.7‰ and 87Sr/86Sr = 0.7095-0.7112) suggest that the calcite cement precipitated from dominantly meteoric waters. Diagenetic dolomite is more abundant in shoreface HST than in the FRST, LST and TST sandstones and is attributed to the precipi-tation of dolomite under marine-meteoric mixing conditions, which is achieved through progradation and concomitant meteoric water incur-sion to the shoreface sandstones during times of sea-level highstand. Kaolinite is most abundant in the distributary channels of HST and FRST and in upper shoreface sandstones below the SB, which is at-tributed to the flux of meteoric water. The flux into the paralic sedi-ments occurs during RSL fall and in outer-estuarine tidal bars below coal layers (TST) aided by the generation of organic acids and CO2during percolation of meteoric waters in the peat deposits. Iron oxide cement occurs in all systems tracts, but particularly in TST and HST. Pyrite occurs below coal layers and SB. Infiltration of grain coating clays is restricted to the TST marginal tidal-flat and marsh sandstones. Micro-quartz occurs in trace amounts in all systems tracts.

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Paper Linking Diagenesis and Porosity Preservation to Sequence Stratigraphy of Gas Condensate Reservoir Sandstones, the Jauf Formation (Lower to Middle Devonian), Eastern Saudi Arabia Diagenetic alterations play a critical role in porosity preservation and destruction in the deeply buried (present day depths 4154-5130 m) gas condensate reservoir sandstones of the Jauf Formation (Lower to Middle Devonian), eastern Saudi Arabia. This study aims to link the spatial and temporal distribution of these alterations to the deposi-tional facies and systems tracts of the sandstones in order to achieve a better understanding and prediction of reservoir quality distribution. Eogenetic alterations (depth < 2 km; T < 70°C) include: (i) infiltration of grain-coating clays in tidal estuarine sandstones of the transgressive systems tract (TST) and highstand systems tract (HST), (ii) cementa-tion by ferroan dolomite/ankerite, particularly below maximum flood-ing surface in the tidal estuarine TST sandstones, and (iii) dissolution and kaolinitization of mica, mud intraclasts and feldspars in the HST sandstones, which are attributed to meteoric water flux during fall in the RSL.

Mesogenetic alterations (depth 2 km; T 70°C) include the formation of grain-coating illite and chlorite as well as quartz, Fe-dolomite/ankerite, anhydrite and siderite cements. Oxygen isotopic composition (-9.1‰) and age (101 Ma)-related of illite (4.2 km) sug-gest precipitation from evolved formation waters with 18OSMOW value of +1.24‰. Quartz overgrowths are most abundant in the shoreface to coastal plain, HST sandstones (poor in grain-coating clays), whereas quartz outgrowths occur mainly in the TST and tidal estuarine, HST sandstones (rich in grain-coating clays).

Sandstones with the best-preserved reservoir quality are en-countered in the tidally influenced, channel and estuarine facies of the TST and HST sandstones, whereas sandstones with pervasive reser-voir quality destruction occur in the HST, shoreface facies. Reservoir quality preservation in the TST and tidal estuarine HST sandstones is attributed to the presence of significant amounts of grain-coating clays, which prevented extensive cementation by quartz overgrowths. This study illustrates that linking diagenesis to sequence stratigraphy allows better elucidation and prediction of the spatial and temporal distribution of diagenetic alterations and their impact on porosity preservation versus destruction in tidal estuarine and shoreface sand-stones.

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Paper V Distribution of Diagenetic Alterations in Sequence Stratigraphic Context of Tidal Flat Sandstones: Evidence From The Adedia Formation (Cambro-Ordovician), Sinai, Egypt

This study aims at unraveling the temporal distribution of diagenetic alterations within the sequence stratigraphic framework of tidal flat sandstone-dominated of the Adedia Formation (Cambro-Ordovician) Sinai, Egypt. Initially, a rapid rise in the RSL resulted in transgression and deposition of transgressive systems tract (TST; dominantly tidal flat sand) directly on the crystalline basement. Diagenetic alterations of the TST include partial cementation by ma-rine intergranular microcrystalline as well as grain-coating fibrous and scalenohedral/dogtooth calcite. Subsequent fall in RSL resulted in the progradation of the tidal flat complex and deposition of highstand sys-tems tract (HST) sandstones and in meteoric water flux into the TST and HST sandstones. Meteoric water incursion induced pervasive dis-solution and kaolinitization of framework silicates as well partial dis-solution of marine calcite cement, and hence creation of secondary intra- and intergranular porosity. The amounts of kaolinite increase considerably towards the sequence boundary. Extensive cementation by Fe-oxides has occurred below marine flooding surfaces of tidal flat sandstones, which is attributed to precipitation owing to diffusion of Fe2+derived from the reduction of detrital Fe-oxides and oxidation at the seafloor. Mesogenetic alterations include intergranular pressure dissolution and formation of variable amounts of syntaxial quartz overgrowths in all systems tracts.

This study revealed that the high primary reservoir quality of sand flat deposits can be further improved due to dissolution of car-bonate cement and framework silicates by meteoric waters that perco-late into the sand during fall in the RSL and progradation of flat com-plex.

Paper V The Impact of Diagenesis on Heterogeneity of Sandstone Reservoirs: A Review of the Links to Depositional Facies and Sequence Stratigraphy Heterogeneity in sandstone reservoirs includes variability in porosity, permeability, capillarity, and mineral-recovery fluid interactions. Un-ravelling the parameters controlling the distribution and variability of

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reservoir heterogeneity and quality is of decisive importance for opti-mal development of hydrocarbon fields. The vertical and lateral distri-bution patterns of reservoir heterogeneity in sandstone successions, which determine fluid flow rates and volumes, are controlled by two main parameters, including depositional facies (grain size, sorting, degree of bioturbation) and the diagenetic evolution pathways. Varia-tions in the shallow- and deep-burial diagenetic evolution pathways are, in turn, strongly linked to variations in: (i) depositional facies, and hence in porewaters chemistry (marine, meteoric and mixed marine-meteoric), degree of bioturbation, and rate of deposition, and (ii) detri-tal composition of the sand, particularly the amounts and types of in-tra-basinal grains (carbonate grains, glaucony and mud intraclasts). Detrital composition of the sand controls the physical (e.g., mechani-cal compaction of ductile grains) and chemical properties (e.g. grain dissolution and alteration of feldspars into clay minerals) of sand-stones, and (iii) rate of deposition (i.e. residence time of sediments at certain, near-surface, geochemical conditions). Depositional facies, degree of bioturbation, rate of depo-sition as well as the amounts and types of intra-basinal sand grains, which are controlled, particularly in paralic environments, by changes in the RSL, can be predicted in a sequence stratigraphic context. Hence, changes in the RSL exert significant control in the types and extent of near-surface diagenetic alterations, which will influence, in turn, the deep-burial diagenetic and reservoir-quality evolution path-ways of the sandstones, such as tight gas reservoirs. Assessing the impact of heterogeneities in sandstone reservoir can lead to appropri-ate enhanced oil recovery (EOR) strategies.

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Concluding remarks

Better elucidation and prediction of the distribution of eogenetic alterations, which in turn impose a profound impact on mesogenetic alterations and related reservoir quality evolution pathways of paralic and shallow marine sandstones, is possible when linked to sequence stratigraphy. Linking diagenetic alterations and their impact on reser-voir quality to depositional facies and sequence stratigraphy in four siliciclastic successions have revealed these important findings:

1. Diagenetic alterations, such as the dissolution and kaolinitiza-tion of framework silicates, are closely associated to specific facies (shoreface), systems tracts (LST and upper HST) and below the sequence boundary.

2. Shoreface sandstones of the FRWST, LST and upper part of the HST were cemented by poikilotopic calcite that was sourced by complete dissolution of carbonate bioclasts in the host sand beds as a result of considerable meteoric-water flux under a warm, humid paleoclimate. Conversely, TST and lower part of the HST mudrocks and sandstones were ce-mented by microcrystalline that have precipitated from marine porewaters.

3. Extensive carbonate cementation below marine and maximum flooding surfaces has shown systematic increase that may lead to highly compartmentalized and layered reservoir units. Dis-solution of carbonate cement and detrital dolomite, by mete-oric water were associated with rapid and considerable fall in the RSL and subsequent sub-aerial exposure.

4. The distribution of grain-coating illite and chlorite in the sand-stones, which exerted the main control on reservoir quality preservation (~ 5 km) through inhibition of quartz cementa-tion, are most abundant in the TST sandstone and the tidal es-tuarine sandstones of the HST. The grain coating illite and chlorite have been interpreted to form by the transformation of clay precursor and precipitation on poorly identified clay sub-strates. The platelet-like illite was derived from smectite pre-cursor that was presumably introduced into the sand by tidal pumping. Illite formation occurred concurrently with the al-bitization of K-feldspar, which thus acted as a source of potas-

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sium. The honeycomb-like illite has most likely been formed by the transformation of authigenic smectite during progres-sive increasing in burial depth. Fibrous and filamentous illite, which covers the honeycomb-like illite, have likely been formed by precipitation from porewaters as evidenced by their absence at grain-to-grain contacts

5. Intergranular pressure dissolution and stylolites formation (chemical compaction) mainly in the shoreface HST sand-stones have acted as sources of Si4+ needed for cementation by quartz overgrowths.

6. Anhydrite is restricted to the tidal estuarine HST sandstones but does not reflect link to sequence stratigraphic context but rather indicates structural control, which is supported by the

34SCDT (+10‰) that is consistent with the overlying Permian anhydrites.

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Summary in Swedish

Med utgångspunkt från fyra paraliska och silicioklastiska successioner från det marina grundhavet visas i denna avhandling hur fördelningen av diagenetiska förändringar och deras påverkan på reservoirkvalitetoch olika utvecklingsvägar kan begränsas relativt avsättninggsmiljö och sekvensstratigrafi (”system tracts” och kritiska sekvensstratigra-fiska ytor).

Typiska eogenetiska förändringar inkluderar upplösning och kaolinitisering av rymdsilikater nära associerade med ”shoreface faci-es of forced systems tract” (FRMST), ”lowstand systems tract” (LST), övre delen av ”highstand systems tract” (HST), samt under sekvens-ytan. Dessa förändringar tros orsakas av inflöde av meteoriskt vatten på grund av hastiga och omfattande fall i relativa havsytenivån. Om-fattande karbonatcementering är tydligast urskiljbar under marina maxflödesytor, medan upplösning av karbonatcement och detritisk dolomit uppstår i anslutning till LST och HST, samt under sekvens-ytan. Parametrar som kontrollerar mönstren och texturen (mikrokris-tallin vs poikilotopisk) hos kalcitcement har kunnat begränsas till sandstenenarnas sekvensstratigrafiska uppträdande. Grovkristallina till poikilotopiska kalcittexturer härrörande från meteoriskt vatten kan alltså nära knytas till FRWST, LST, samt den övre delen av HST sandstenarna och uppträder framför allt som stratabundna konkretio-ner, medan mikrokristallin kalcit, vilken fälldes ut från marint porvat-ten, uppträder som kontinuerligt utfällda lager i ”the transgressive systems tract” (TST) ochi den under delen av HST sandstenarna.

I sin tur kommer de eogenetiska förändingarna att utöva omfattande kontroll på fördelningsmönstret av mesogenetiska förändringar, alltså även på reservoirsandstenarnas kvalitativa utvecklingsmöjligheter (destruktion vs bevarande). Eogenetiskt infiltrarade leror, vilka uppträder i tidvatten-estuariska TST och HST sandstenar, har bidragit till att bevara porositeten hos djupt begravda sandstensreservoirer ( 5 km) genom att omfattande cementering av kvarts förhindras. Andra viktiga rön som fram-kommit i denna avhandling inkluderar utredandet av hur bildan-det av autigenetisk illit och klorit kontrolleras av ultratunna (1µm tjocka) substrat av lermineral.

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Acknowledgements

I wish to thank my supervisor Professor Sadoon Morad for endless discussions, guidance, support, constructive criticism, and encouragement during this study. I truly want to thank you for your always being there, for always being such a fast reader of my manu-scripts and for having all the patience.

I thank the King Fahd University of Petroleum and Minerals (KFUPM) for granting the Ph.D. studies at Uppsala University and to the Saudi cultural attaché in Germany represented by Dr. Ahmed Ashy and Dr. Osman Omar for their concern and support during the four years of my Ph.D. studies. I also acknowledge the NordForsk for granting some courses in Norway. I wish to gratefully acknowledge Saudi Aramco for access to the well core, thin section collection and data. I would like to express my gratitude to Ali Al-Hauwaj for assis-tance with the subsurface Jauf data.

I wish to thank the faculty and staff members of the Depart-ment of Earth Sciences for making me feel welcome and at home in Uppsala. Special thanks go to Hans Harryson for help with the EMP analysis, Örjan Amcoff for Swedish translation, Per Nysten for help in identification of ore minerals and to Kersti Gløersen for her adminis-trative help. I also thank Dr. J.D. Martín-Martín for assisting me with the XRD of clay minerals. I am very grateful to Anna, Taher, Johan, Pär and Leif for all the help with printing and technical issues.

Thanks to all my friends in Saudi Arabia for support and en-couragement. Sincere thanks go to my former and present colleagues and friends, Abbas, Ali-reza, Erik, Faramarz, Hesam, Howri, Mo-hamed, Osama, Sara, Sofia, Tomasz, Ulf, Yassir and Zurab.

I would like to extend my thanks to my co-authors of the pa-pers, Jean-Noel Proust, Ihsan Al-Aasm, Piret Plink-Björklund, A. Kent Norton, Michael Hulver, Essam El-Khoriby and Marcelo Ketzer, for their valuable contribution and thoughtful discussions on sequence stratigraphy and diagenesis.

At KFUPM, there were many professors from whom I learned a lot including Dr. Mustafa Hariri, the former chairman of Earth Sci-ences Department, Dr. Mahbub Hussain, Dr. Badrul Imam, Dr. Mohammad Makkawi, Dr. Salih Saner and Dr. Nazrul Islam Khan-

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daker. Also, I am indebted to the present chairman Dr. Abdul-Aziz Al-Shaibani for his concern and support. Thanks to you all

Finally, the warmest thanks must go to my wife Zainab, for her love, encouragement, support and understanding. I thank our families in Saudi Arabia for the great continuous encouragement. This Ph.D. would not have been possible without the help and support of my wife and our families.

Last but certainly not least, I would like to express my grati-tude towards our very special friends outside the academic world, Dr. Hassan, Fairouz, Hani, Mahdi, Nazem, Raad, Razaq, Reda, Sajad, Salah, Salam, Shareef, Waled, Shaker, and their families for all kind-ness and great moments we spent together in Sweden.

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