Surprise-1Re-Entry HST1

WELL COMPLETION REPORT

(Basic)

EP 115

Amadeus Basin

Northern Territory

21st Dec. 2011 – 13

th Jan. 2012

Central Petroleum Limited

Well Name: Surprise-1Re-Entry HST1

Well Classification: Exploration

Interest Holders: Central Petroleum Limited (Operator - 100%)

Petroleum License: EP 115, Northern Territory

Location: Northing: 7377073m

Easting: 601261m

Latitude: 23º 42’ 50.758”S

Longitude: 129º 59’ 36.091”E

Australian Map Grid Zone : GDA 94, Zone 52

Ground Level (GL): 545m asl

Kelly Bushing (KB): 548.7m asl - Datum

Total Depth (KB): 2853m MD RKB

Drilling Contractor: Hunt Energy

Drilling Rig: Hunt Rig 3 (See Rig Specifications in Appendix 9)

Contractors: Drilling Fluids: Australian Mud Company

Mud Logging: Geoservices

Wireline Logging: Schlumberger

Cementing: Trican

Casing: Premium Casing Services

MWD: PathFinder Schlumberger

Directional Drillers: PathFinder Schlumberger

Spud Date: 21st December 2011

Total Depth Reached: 01st January 2012

Rig Released: 13th

January 2012

Well Status: Completed (Waiting Extensive Production Testing).

Table of Contents

1.0 Introduction and Summary 5

2.0 General Data 7

3.0 Drilling 8

3.1 Summary of Drilling and Related Operations 8

3.2 Particulars of Drilling 9

3.2.1 Particulars of the equipment installed in or on the well 9 3.2.2 Casing strings in situ/run. 9 3.2.3 Cementing operations 12

3.2.4 Bit Records 12 3.2.5 Deviation Surveys 12 3.2.6 Drilling Fluids 12

3.2.7 Lost Time 12

3.2.8 Water Supply 13

4.0 Logging, Sampling and Testing 14

4.1 Cuttings Samples Inventory 14

4.2 Conventional Cores 14 4.3 Sidewall Cores 14 4.4 Mudlogging 14

4.5 Wireline Logging 14

4.6 Vertical Seismic Profile 14 4.7 Drill Stem Testing 14

5.0 Geology and Formation Evaluation 15

5.1 Regional Geological Setting and Discussion of the Surprise Prospect 15

5.1.1 Structural Elements 15 5.1.2 Lithology and Formation Tops 16 5.1.3 Undifferentiated Recent Alluvium and Pertnjara Group 17

5.1.4 Brewer Conglomerate/Hermannsburg Sandstone 17 5.1.5 Parke Siltstone (mid Devonian) 18

5.1.6 Mereenie Sandstone (early Devonian) 18

5.1.7 Stokes Siltstone (late Ordovician) 18

5.1.8 Upper Stairway Sandstone (Early Ordovician) 19 5.1.9 Middle Stairway Sandstone (Early Ordovician) 19 5.1.10 Lower Stairway Sandstone (E Ordovician) 19

5.2 Hydrocarbon Indications and Sample Analysis 20

5.2.1 Gas while drilling 20

5.2.2 Fluorescent Hydrocarbon Shows 20

6.0 Reference 21

Tables Table 1: Surprise-1Re-Entry HST1 Well Index Sheet ..................................................... 7

Table 2: Surprise-1Re-Entry HST1 Formation tops, actual and predicted .................... 16

Figures Figure 1: Surprise-1Re-Entry HST1 Location and Permit Map ...................................... 5

Figure 2: Surprise-1Re-Entry HST1 Location and Seismic lines Map............................ 6

Figure 3: Surprise-1Re-Entry HST1 Completion Status Diagram ................................ 11

Figure 4: Surprise-1Re-Entry HST1 Time breakdown .................................................. 12

Figure 5: Amadeus Basin structural elements map ........................................................ 15

Figure 6: Cross Section Surprise-1Re-Entry to Johnstone West-1 ................................ 16

Appendices 1. Daily Drilling Report

2. Daily Geological Reports

3. Cuttings Descriptions

4. MWD Logs

5. Bit records

6. Survey listing

7. Drilling Fluid Recap, RMS Pty Ltd

8. Mudlogging

9. Rig Specifications

1.0 Introduction and Summary

Surprise-1Re-Entry HST1 is a side-track of Surprise-1Re-Entry well drilled by Central

Petroleum Ltd in Exploration Permit EP-115 in the western part of the Amadeus Basin, Northern

Territory, approximately 400km west of Alice Springs (Figure-1). Surprise-1Re-Entry was side-

tracked on the 21st December 2011 and it reached a horizontal TD of 2853m MD on 1

st January

2012.

The aim of the horizontal side-track was to further explore the hydrocarbon potential of the

Lower Stairway sandstone away from the existing Surprise-1Re-Entry wellbore radius believed

to be damaged due to drilling fluid invasion of the Formation.

Surprise-1Re-Entry HST1 confirmed hydrocarbon bearing zone in the Lower Stairway sandstone

and was completed as a production well with a barefoot horizontal section.

Initial production test stabilized rate of 380bbl/d was achieved and an Extended Production

Testing (EPT) is being planned for the well.

Basic well results are summarised in the Well Index Sheet (Table-1).

Figure 1: Surprise-1Re-Entry HST1 Location and Permit Map

Surprise-1 Re-Entry HST1

Figure 2: Surprise-1Re-Entry HST1 Location and Seismic lines Map

Surprise-1 Re-Entry HST1

Surprise-1 Re-Entry HST1

Location Map

2.0 General Data

Table 1: Surprise-1Re-Entry HST1 Well Index Sheet

WELL NAME: Surprise-1 Re-Entry HST1

OPERATOR: Central Petroleum Limited CLASSIFICATION: Exploration (Side-track)

Location: Latitude: 23º 42’ 50.758”S

Longitude: 129º 59’36.091”E

GDA 94 Zone 52

Rig Details:

Rig Name: Hunt Rig#3

Contractor: Hunt Energy

Rig Type: Land D-E SCR

Dates: Spud Date: 21

st Dec. 2011

TD Date: 01st Jan. 2012

Released: 13th

Jan. 2012

Basin: Amadeus

Field: Wildcat

Permit: EP-115, Northern

Territory, Australia

Depths: Surface Elevation (asl): 545m

Rig Datum, KB : 3.7m AGL

Total Depth: 2853m MD

Status: Completed and suspended for

Extended Production Testing.

Casing/Liner Details: Size Depth

20”Conductor 21.3m

13⅜” 493.82m

9⅝” (KoP) 2423m

7 “ 2729.2m

Mud Details: Mud Type: 3% KCL brine (Brine

8.5ppg = 1.02sg).

Trajectory:

Vertical (3 deg. @ TD).

Coring Details: None

Sidewall Cores:

None

Cuttings Interval Sample Rate 2489-2853 m 3m

FORMATION MD

KB (m)

TVD

KB (m)

Isopach

TVD (m)

SubSea

TVD (m)

TWT

msec Comments

Undiff Recent alluvium

Undiff Pertnjara Group

Brewer/Hermannsburg

Parkes Siltstone

Mereenie Sandstone

Stokes Siltstone

Upper Stairway Sst

Mid Stairway Sst

Lwr Stairway Sst

Total Depth

3.7

70

780

1296

1760

2275

2447

2493

2570

2853

3.7

70

780

1295.6

1757

2270

2443

2484

2535

2534

66.3

710

515.6

461.4

513

172.7

43.8

51.5

545

478.7

-231.3

-746.9

-1208.3

-1721.3

-1894.0

-1937.8

-1989.3

Nd*

Nd

100.6

319.6

506.6

742.7

811.5

822.0

854.0

Recent-Quaternary

Mid- Late Devonian

Mid Devonian

E Devonian

Sil-E Devonian

Late. Ordovician

E. Ordovician

E Ordovician

E Ordovician

LOGGING

Date Depth (m)

Description Remarks From To

01.01.2012 2423 2853 MWD GRC + Az/Incl Svy NBGR failed

3.0 Drilling

3.1 Summary of Drilling and Related Operations

A 7” retrievable whipstock assembly was set in the 7” casing at 2423m MDRT on 20th

December

2011. The milling assembly was RIH and a window was milled to 2428m MDRT. The milling

assembly was POOH and the directional assembly was RIH. The drilling mud was displaced

with a brine system so the directional section would be drilled at balance.

FIT was conducted at the milled window to test the integrity of the 7” casing. The build section

of the horizontal was drilled to 2564m MDRT and the directional assembly was then POOH due

to inability to increase the build any further.

A new directional assembly was picked up and RIH, and drilled ahead the build section to

2593m MDRT. The assembly was POOH after achieving the desired inclination. A new

assembly was RIH to drill the horizontal section. However, it was POOH due to being plugged

while RIH with a mud plug.

The assembly was RIH again and the horizontal section was drilled to 2764m MDRT before the

assembly was POOH due to sloughing shales in the build section. A new BHA was RIH and

some tight spots had to be reamed and washed prior to getting back on bottom. Then the

horizontal hole was drilled to TD of 2853.9m MDRT. The tight spots were reamed and washed

again prior to POOH.

A new assembly was picked up and RIH to clean and ream the well prior to being POOH. A 7”

casing scraper was RIH to clean up the 7” casing prior to running the completions. A 2 7/8”

tubing liner and 7” packer assembly was run to the milled window to protect the shaly formation

in the build section from caving in.

The upper completion was then picked up and RIH on 2 7/8” tubing to 2327m MDRT. The

tubing hanger was made up, landed into the well head, BOPs nipple down and the BPV installed.

However, there was an issue with installing the THAF as it was not the suitable THAF for the

tubing hanger. While waiting on a replacement tubing hanger to arrive on location, the BOPs

was nipple up and pressure tested.

After the replacement tubing hanger arrived on location, the BOPs were nipple down and the

THAF was installed with the Xmas tree. Two separate circulations of diesel cushion had to be

circulated into the well to allow it to flow under its own pressure. Gauges were RIH and the well

was flowed on multiple choke sizes to monitor well performance. The well was then shut in for a

PBU survey.

Prior to running two slick line plugs to suspend the well, the pressure gauges were removed. The

master valves on the Xmas Tree were closed and the Hunt Rig #3 was released at 0230hrs on

13th

January 2012.

3.2 Particulars of Drilling

3.2.1 Particulars of the equipment installed in or on the well

Other than casing, the following completion components were installed in/on the well:

Upper Completion

Equipment Depth MDRT

2 9/16” Xmas tree Surface

7 1/16” x 2

7/8” tubing hanger 3m

2 7/8” J55 6.5# EUE pup joints 3.01m

2 7/8” tubing 6.5ppf J-55 EUE 8.56m

2 7/8” CXD EUE sliding sleeve (PX Plug/Prong) 2280.44m

2 7/8” tubing 6.5ppf J-55 EUE 2281.40m

2 7/8” J55 6.5# EUE pup joint 2290.89m

7” Arrowset Packer 2293.14m

2 7/8” J55 6.5# EUE pup joints 2294.40m

2 7/8” tubing 6.5ppf J-55 EUE 2298.70m

2 7/8” Owen EUE Surge Valve 2308.27m

2 7/8” tubing 6.5ppf J-55 EUE 2308.45m

2 7/8” X-Nipple Profile 2318.02m

2 7/8” tubing 6.5ppf J-55 EUE 2318.39m

2 7/8” EUE Packer tagging guide 2327.93m

Lower Completion

Equipment Depth MDRT

Top of stinger on Arrowset Packer 2329.95m

Stinger length from MPP 2330.40m

7” Arrowset Packer MPP 2331.43m

2 7/8” tubing 6.5ppf J-55 EUE 2332.68m

Finned Re-entry Guide 2569.79m

3.2.2 Casing strings in situ/run.

Conductor Casing

- 20” conductor casing in situ at 21.3m MDRT.

Surface Casing

- 13 3/8” surface casing in situ at 493.8m MDRT.

Intermediate Casing

- 9 5/8” intermediate casing in situ at 1,443.44m MDRT.

Production Casing

- 7” production casing run and set at 2729.2m MDRT.

Lower Completion

- 2 7/8” tubing was run and set at 2572.48m MDRT.

Suspension

The well was suspended with two slick line plugs set in the completion string. Figure 3 below

shows the schematic of the completion diagram for the Surpris-1Re-Entry HST1.

Figure 3: Surprise-1Re-Entry HST1 Completion Status Diagram

3.2.3 Cementing operations

No cementing operations were performed on this section of the well.

3.2.4 Bit Records

A record of drilling bits used on Surprise-1Re-Entry HST1 is presented in Appendix 5.

3.2.5 Deviation Surveys

Deviation surveys were taken using an MWD survey tool. Survey results are tabulated in

Appendix 6. Maximum deviation was 92.59 deg at 2646.8m MDRT.

3.2.6 Drilling Fluids

6” Horizontal Hole, 2423m – 2853.9m MDRT

Brine

Mud weight was maintained at 8.5ppg to keep the well at balance. Gel sweeps were run to assist

with hole cleaning. The details of daily record of drilling fluid properties are provided in

Appendix 7.

3.2.7 Lost Time

A total of 86.5 hours were summed as actual lost time. The big items that contributed to the lost

time were related to the whipstock where the wrong BHA was picked up and the whipstock BPV

malfunctioned at 26 hours. The other big item is related to the deteriorating hole condition due to

sloughing shale amounting to 25.5 hours. This is graphically illustrated on the following pie

chart in Figure 2.

Figure 4: Surprise-1Re-Entry HST1 Time breakdown

Time Delays on Surprise 1 REH ST1

Rig Repair

18%

Directional Equipment

2%

Whipstock

29%

Wellhead

7%

BOP

3%

Misc

13%

Hole Condition

28%

3.2.8 Water Supply

Water for drilling purposes and human consumption was taken from the high flow water bore

past the Surprise 1 lease and the road side bore on the CPL private road, 30km from the Surprise

1 lease. Water from these bores was carted to the turkey’s nest built at the well site where it was

then pumped to the rig to be used as drill water. Water was also pumped to the RO plant at the

camp to be treated for human consumption as the water had a high salt content.

4.0 Logging, Sampling and Testing

4.1 Cuttings Samples Inventory

S/N Sample date Sample type Depth (mMDRT) Remarks

1 25/12/11 Oil/brine 2564m Sample from bell nipple after

trip/BOP test, Scum on surface.

2 25/12/11 Oil/brine 2560 bU after trip at 2564m

3 25/12/11 Oil/brine 2423 Circulation after trip at 2564m

4 25/12/11 Oil/brine 2423 As above

5 25/12/11 Oil/brine 2423 As above

25/12/11 Brine 2579 Mud brine, small jar.

6-15 27/12/11 Oil/brine 2593 Oil collected at shakers from

circulation at 2593m.

Samples were sent to Weatherford Laboratories, Bassendean, WA for analysis.

4.2 Conventional Cores

No cores were cut in Surprise-1Re-Entry HST1.

4.3 Sidewall Cores

There were no sidewall cores taken in Surprise-1Re-Entry HST1.

4.4 Mudlogging

Mudlogging services were contracted to Geoservices who supplied a Standard Unit module

monitoring drilling parameters, continuous gas monitoring, pit levels, cuttings sampling and

bagging. 4 x remote VDUs serviced the Drill floor, Tool pusher, Company man and Well-site

Geologist with real time drilling data. Daily reports and Mudlogs were supplied to Central

Petroleum onsite and Perth office. The final Mudlog and gas datasheets are contained in

Appendix 8.

4.5 Wireline Logging

No wireline logging done on this well.

4.6 Vertical Seismic Profile

No Check shot/VSP survey conducted.

4.7 Drill Stem Testing

No drill stem tests were conducted.

5.0 Geology and Formation Evaluation

5.1 Regional Geological Setting and Discussion of the Surprise Prospect

5.1.1 Structural Elements

The Amadeus Basin is a part of series of Neoproterozoic intracratonic basins on the Australian

continent that share their origins in the breakup of the supercontinent Rodinia. Strong

stratigraphic ties have been made between the Officer, Ngalia and Georgina Basins, leading to

them being referred to collectively as the Centralian Superbasin. The Amadeus Basin is a broad

intracratonic structure in the north-westerly trending Amadeus Transverse Zone and is the

product of a number of tectonic cycles. The basin was formed by a series of tectonic events

incorporating a variety of mechanisms.

The Amadeus Basin is a multiphase rift-foreland basin with thrusting occurring in the Late

Neoproterozoic and Devonian-Carboniferous eras. The basin hosts thick sequences of

Proterozoic to Carboniferous sediments. The tectonic elements of the Amadeus Basin in the

Neoproterozoic are shown in the following figure.

Figure 5: Amadeus Basin structural elements map

Surprise-1 Re-Entry HST1

Figure 6: Cross Section Surprise-1Re-Entry to Johnstone West-1

5.1.2 Lithology and Formation Tops

Table 2: Surprise-1Re-Entry HST1 Formation tops, actual and predicted

Formation Top

Actual Prognosis

Depth

KB (m)

Depth

GL (m)

Isopach

(m)

TVDSS

(m) TVDSS

(m)

TVDR

(Tm)

Hi/Lo

(m)

Undiff. Surficial Sediment 3.7 0 66.3 +545 550 3.7 -

Undiff. Perthjara Group 70 66.3 710 +478.7 -

Brewer/Hermannsberg 780 776.30 515.6 -231.3 -210 760 21.3 L

Parkes Siltstone 1296 1292.3 461.4 -746.9 -754 1304 7.1 H

Mereenie Sandstone 1760 1756.3 513 -1208.3 -1234 1784 25.7 H

Stokes Siltstone 2275 2271.3 172.7 -1721.3 -1901 2451 179.7 H

Upper Stairway Sandstone 2447 2443 43.8 -1894.3 -2031 2581 137.0 H

Middle Stairway Sandstone 2493 2484 51.5 -1935.3

Lower Stairway Sandstone 2570 2535 Pp -1986.3

Total Depth 2853 2534 -1985.3 Elevations: GL 545m ASL, KB 3.7m AGL. Depths are driller’s from mudlog. Pp (Partially penetrated).

NOTE: Lithology Summaries extracted from Surprise-1Re-Entry Well Completion Report.

5.1.3 Undifferentiated Recent Alluvium and Pertnjara Group

5.2-70m This section comprised Aeolian alluvium down to 70m. This is essentially the Quaternary to

Recent dune deposits seen at surface, comprising white to light grey quartz grains stained

yellow-orange and common reworked grey brown siltstone grains. The grains are fine to coarse

and rounded, subspherical and frosted. There are abundant composite grains of quartz sand and

siltstone grains weakly bound with yellow-orange iron oxide cement. Many grains are irregular

and broken indicating it is possibly pebbly. Gypsum appeared in the form of white to offwhite,

chalky, soft material. It is occasionally micro to coarsely crystalline and abundant in parts,

commonly with a vuggy porosity possibly after halite crystals. It is probably distributed as

nodular clumps, and often exposed at the surface in that manner.

70-230m Firm bedrock was observed at 70m in the form of weathered arkosic sandstone. It is white to

light grey, dark brown grey where silty and argillaceous, friable to firm, fine to coarse,

subangular to subrounded, moderately sorted, with occasional pebbly conglomeratic lags. It is

slightly calcareous and carbonaceous with common kaolin and mica flakes and lithic grains.

Porosity is poor to fair. This is variably interbedded with claystone and siltstone and becomes

predominantly interbedded sandstone and siltstone with depth.

The claystone is medium red brown, mottled greenish grey in parts, soft to firm, blocky, silty and

micaceous. The siltstone is similar being medium to dark red brown, soft, blocky to subfissile,

very argillaeous and very micaceous.

230-780m This is predominantly a siltstone sequence with various thin interbeds of sandstone, claystone

and gypsum.

The siltstone is medium grey brown to dark grey, soft to hard, generally blocky, argillaceous and

sandy, grading to very fine sandstone in parts. It is micaceous and occasionally gypsiferous with

occasionally carbonaceous laminae and coarse sandy lamination.

Sandstone is generally light brown to light grey with clear to translucent white quartz grains,

loose to friable, fine to very coarse, predominantly medium grained, subangular to rounded and

poorly sorted. Grains are commonly frosted. It is slightly calcareous, with argillaceous and silty

matrix, traces of mica and traces of crystalline pyrite. Porosity is generally poor. The claystone is

light to medium grey, soft, blocky, silty, micromicaceous with traces of carbonaceous specks.

Gypsum occurs as white chalky nodular material and coarsely crystalline fibrous material.

5.1.4 Brewer Conglomerate/Hermannsburg Sandstone

780-1296m This section is stratigraphically part of the Pertnjara Group and is essentially similar to the

overlying units. It comprises predominantly siltstone with thin sandstone and claystone interbeds

and intergradations and minor limestone interbeds. The siltstone is medium brown to dark grey

brown, firm to hard, blocky, argillaceous, sandy, and slightly calcareous with common dark mica

flakes. Sandstones are light grey green and dark brown, translucent in parts, loose to friable and

hard in parts, very fine to coarse, predominantly fine, subangular to rounded, poorly to

moderately sorted, silty, argillaceous, slightly calcareous, with traces of feldspar grains, mica and

microcrystalline pyrite. Porosity is generally very poor. Claystone are light grey, light yellowish

brown and dark brown in places, soft to firm, blocky, silty, micromicaceous, calcareous in parts

and occasionally with traces of gypsum.

5.1.5 Parke Siltstone (mid Devonian)

1296-1768m The Parke Siltstone is predominantly a siltstone sequence although the top 25 m is

predominantly very fine sandstone. It is pale red brown and grey-orange, firm to hard, fine to

coarse, subangular to subrounded, moderately well sorted, trace calcareous cement, poor visible

porosity. This is underlain by a thick siltstone/claystone sequence with minor gradations to

sandstone.

The siltstone is medium grey and dark blue grey, hard to very hard, subfissile in part,

interbedded with pale brown to dark red brown claystone, soft, calcareous and sandy. Claystone

is the dominant lithology from 1400m to the base of the unit.

5.1.6 Mereenie Sandstone (early Devonian)

1768-2282m This is a generally Aeolian sand unit with some marginal marine argillaceous inundations. The

sandstone is clear to translucent, commonly with red ferruginous staining. It is generally loose,

fine to very coarse, predominantly medium, moderately sorted, spherical and frosted grains,

commonly with ferruginous cement and good visible or inferred porosity. The claystone are

white to pale grey, mottled orange in part, soft, occasionally sandy, micromicaceous. Some

minor siltstone occurs toward the base of the interval. It is black, brittle, carbonaceous and

pyritic.

5.1.7 Stokes Siltstone (late Ordovician)

2282-2450m

This is an argillaceous unit, comprising mostly claystone in the upper section, becoming

predominantly siltstone in the lower part. Minor sandstone and carbonate beds are also present.

The claystone is medium to dark reddish brown, orange brown and medium grey in parts,

moderately hard to hard, but occasionally soft and plastic. It is slightly calcareous and dolomitic,

subfissile, micaceous and silty. It becomes marly in places. Minor thin sandstone bands are

medium grey brown, hard, siliceous, very fine to fine, subangular to rounded, moderately sorted

with poor visible porosity. The siltstone that occurs towards the base of the interval is moderate

red, pale red brown, hard to moderately friable. Arenaceous with local to common argillaceous

matrix, laminae in parts with very fine quartz sandstone, generally granular, moderately strong to

strong dolomitic and siliceous cement, occasional lithics. Rare carbonate bands are dolomite,

mottled pale pink and offwhite, occasionally medium dark grey, hard, with a coarsely crystalline

(sucrosic) texture and silty to sandy in parts.

5.1.8 Upper Stairway Sandstone (Early Ordovician)

2450-2475m This unit is sandstone with interbedded siltstone claystone, dolomite and limestone. A good gas

show with a weak oil show was observed in the lower sandy unit of this sequence.

The Upper sandstone unit is patchy pale pink with clear to translucent grains, also light to

medium grey and dark reddish brown and hard. It is generally very fine to fine with some

medium, angular to subrounded, moderately sorted, silica cemented, minor silt, trace lithic grains

with poor visible porosity. This is in turn underlain by dolomitic sandstone with dolomite bands.

The dolomitic sandstone is offwhite to pale grey, red brown in parts, hard, very fine grained,

angular to subrounded, well sorted, with strong dolomitic cement and poor visible porosity. The

middle unit of this formation is mostly siltstone and claystone interbeds. The siltstone is

described as being moderate red brown, medium grey, firm to brittle, argillaceous and

occasionally sandy, subfissile, slightly dolomitic. The claystone is medium to dark grey,

commonly red brown, moderately hard, silty to sandy, trace micromicaceous, slightly dolomitic.

The basal 10m of this unit is sandy and contains gas and displays oil fluorescence. The sandstone

is clear to translucent, light grey to pale brown, moderately hard, very fine to coarse,

predominantly fine, angular to subrounded, poor to moderate sorting, strong calcareous and

siliceous cement, slightly dolomitic, with common interstitial brown bitumen grain coatings

which were fluorescent.

5.1.9 Middle Stairway Sandstone (Early Ordovician)

2475-2542m This unit comprises siltstone and sandstone interbeds and seems to provide an effective seal to

the hydrocarbons contained in the lower Stairway sands underlying. The siltstone is dark grey,

blocky to laminated (with fine sandstone), hard, siliceous, argillaceous, micaceous, trace pyrite

and dolomitic. The sandstones are pale to medium grey, friable to hard, very fine to fine, angular

to subrounded, well sorted, variable dolomitic cement, silty, trace pyrite, poor visible porosity.

Traces of hydrocarbon fluorescence were observed.

5.1.10 Lower Stairway Sandstone (E Ordovician)

2542-2853m The unit is composed of sandstone, light grey and light brownish in part, loose, very fine to

coarse, but predominantly fine, well sorted, angular to rarely rounded, very common broken

grains, rare siliceous aggregates and shards, trace carbonaceous material. It is friable to hard,

cemented with silica, trace pyrite in parts, poor to good visible porosity. Good oil shows were

observed with constant breakout of oil droplets at shaker ditch in varying degrees and free oils

was noted in the mud with weak to strong petroliferous odour form cuttings while drilling.

5.2 Hydrocarbon Indications and Sample Analysis

5.2.1 Gas while drilling

Gas readings were closely monitored while drilling this well, especially in the horizontal section.

There were significant shows of heavy components up to the limit of the chromatograph (i.e. C1-

C5) indicating liquid hydrocarbons.

This confirms the some of the assumption made on the Surprise-1Re-entry mud analysis results

indicating the Lower Stairway sandstone to be productive oil zone. But decreasing values

indicate it is possibly non-productive (ref. Surprise-1 Re-Entry WCR).

Considerable presence of life oil in the mud and cuttings at surface coupled with the gas reading

indicating liquid components point to a productive zone.

Formation damage was minimized by drilling with balanced mud weight brine which affords the

reservoir a good chance to flow during production testing.

5.2.2 Fluorescent Hydrocarbon Shows

The Lower Stairway Sandstone was penetrated at 2570mRT, build-up angle to 90 deg and drilled

horizontal. Circulate bottom up, sample oil at shakers. Turn off pump and test at 2593m,

connection gas evident. Fluorescence/cut in sample continues, oil at shakers after trip and

constant breakout of oil at shakers further observed during circulation with strong petroliferous

odour.

Continuous stream of oil on surface of possum belly 2-3cm wide, mud discoloured to pale brown

over shakers, observed black oil on shakers after drilling break at 2676m. Good shows to TD and

oil show continued at surface during circulation from wiper trip.

6.0 Reference

- Surprise-1 Well Completion Report, (CTP 2012).

- Surprise-1Re-Entry Well Completion Report, (CTP 2012).