Relinquishment Report P1967 Block 2/4b. December 2014

Transcription

1 Relinquishment Report P967 Block 2/4b December 204

2 Block 2/4b Relinquishment Report General. Introduction.2 Commitments 2 2 Summary Exploration Activities 4. Wells Drilled 4.2 Seismic Database 5 4 Prospectivity Analysis 7 4. Play Summary Prospectivity 5 Reserves Summary 6 6 Clearance 8

3 List of figures. 2/4b Location Map Well Database Seismic Database Synthetic Seismogram 2/ Stratigraphy Column East Shetland Basin Tectonic Elements Source Map Seismic section: East Shetland Platform to Broom Base Tertiary TWT Map SW-NE Seismic Line /4b Jurassic Terrace Seismic dataset quality comparison

4 List of tables. L i c e n c e S u m m a r y W e l l r e s u l t s S e i s m i c d a t a s u m m a r y / 4 b T e r r a c e M M R A I n p u t P a r a m e t e r s / 4 b T e r r a c e S T O I I P a n d R e s o u r c e s / 4 b T e r r a c e R i s k

5 General. Introduction This report documents the relinquishment of licence P967, UK Block 2/4b. The location map can be seen in Fig.. and the licence summary in the table below. A review of the prospectivity of the block concluded that there was no economically viable prospectivity and the block should be relinquished. ± 2/6 2/ 2/ 20/26 20/27 EQ Operated Licensed Blocks 2/7 2/2 2/ Km 2/8 2/ 2/ 20/28 20/29b 2/4b 2/9 2/4 20/24a HUDSON WESTERN ISLES 20/29a CLADHAN 20/29c 2/5F BROOM NORTH TERRACE 2/5 HEATHER SOUTH WEST 2/0a 2/5b 20/0b 20/0c 2/0b TERN 2/4a HEATHER 2/4aF CHEVIOT 2/5a /6 002/0 (Area ) Text CORMORANT FIONN 2/22a5 EAST 2/22 DUNLIN (Area ) 2/2a SKYE CORMORANT 2/2e NORTH 2/26b 2/2a4 2/26c 2/28b 2/29e 2/26aW 2/26aF CORMORANT - SOUTH 2/26d 2/5F2 2/26a PELICAN /an /a /c 2/27a 2/27c HUTTON 2/27b NORTH 2/27b WEST 2/27b HUTTON 2/27f 2/27e DARWIN /2a /b /a /F /a /d LYELL WEST LYELL /2c /7d /7c /2a /2b /2b /7aF /c /8b COLUMBA B /8aF /8g COLUMBA D COLUMBA E /8d /7bF STAFFA 00/07 (Area ) 00/2 /b (Area 2) NINIAN 00/08 (Area 2) ORLANDO 00/0 (Area 8) /4c /9c 2/29a 2/29F 2/29f 2/29d BRENT OIL /4aF /4aF /4b STRATHSPEY /4aF2 /9a /9d 2/24b STATFJORD STATFJORD (UK) /5 /4d /0c ALWYN 00/0 NORTH (Area ) 00/09 /9e /0a (Area 7) /4a /4j /5b /5a /4b DUNBAR /4i ELLON /4h GRANT /4d JURA 6 0'0"N 6 0'0"N 60 50'0"N 60 40'0"N 0 0'0" 0 2'0"E 0 24'0"E Fig.. 2/4b Location Map 0 6'0"E 0 48'0"E 0'0"E 2'0"E 24'0"E 6'0"E 48'0"E Table.: Licence Summary Licence Number Licence round Licence Type P967 27th Traditional Block Number(s) 2/4b Operator / Partners % EnQuest Ltd 50% (operator), MOL Growest (II) Ltd 50% Block 2/4b Relinquishment Report - General Page

6 .2 Commitments The firm work commitment at award was to carry out subsurface work to delineate the Jurassic potential. This work has now been carried out and the partnership agree that no commercially viable prospectivity lies within the licensed area. Page 2 Block 2/4b Relinquishment Report -.2 Commitments

7 2 Summary Licence P967 was awarded to the partnership on the st of January 20 as a 27th round traditional licence. An evaluation of all the prospectivity within the licence was undertaken by the partnership following the acquisition of licence P967. The review recognised no commercially viable prospectivity within the licenced area. Block 2/4b Relinquishment Report - 2 Summary Page

8 Exploration Activities. Wells Drilled Two wells have been drilled on Block 2/4 (Fig..), these along with a number of offset wells have been used in the subsurface evaluation of licence P967. Table. summarises the well results. ± 2/7 2/2 2/8 2/ 2/9 2/4b 20/29c 4Z 4Y 4 6 CLADHAN 2 4 4Y 4Z 4X 5 2 2/5F2 2/5F 2 4 2A 4Z 2/4a H6 2/4aF H62Y 5 2 H9 H4 4 HEATHER 5 H4 6 7 H4 H42 7 BROOM H45 26 NORTH TERRACE 8B 27 6ST 0 6ST2 6 HEATHER SOUTH WEST 2/0a 20/0b 2/5 Z A9 A27 CORMORANT - SOUTH 2 2/26d 2/5F2/b /6 5 6B 6 5A 6Z 2/26c UZ 2/26aF A AY AZ CORMORANT NORTH A2Z PELICAN 2/26a P4 4 P9R PZ P P20Z P2() P /an /a 2 WEST LYELL 2/27d 8ST A0 2/27a 8 4 A20Z 6 4A A26 A4 A A49 HUTTON 5 NORTH 5A 7 WEST /7aN 2 2Z Z Y 2 4 2/27f HUTTON 2/27e DARWIN 2 Z A LYELL 2 A0 A08 B02Z A08Z 4 /2c /7d /2a /2b 6 EQ Operated Licensed Blocks Km Text 9 5 A 002/0 (Area ) COLUMBA B 4 COLUMBA E 5 /7bF Fig.. Well Database Page 4 Block 2/4b Relinquishment Report - Exploration Activities

9 Text Relinquishment Report 2/4b Table.: Well results Well Year Drilled Status Target TD Formation Results 2/- 987 P&A Oil Shows Middle Jurassic Brent Group Sands Pre- Cambrian Basement Base of Tertiary: 20ft thick unconsolidated sand encountered - top 2ft was oil bearing. Brent sands were absent. Palaeocene sands were present and oil bearing. OWC of 2070ft observed from logs giving a gross oil column of 2ft. A limited DST was carried out to recover an oil sample from the interval ft RKB. This test was unsuccessful. Analyses on an oil sample from a SWC showed the oil was biodegraded and severely water-washed and as a result is heavy and viscous. An oil gravity of approx 6.5 API has been estimated for the top of the column. 2/4-982 P&A with oil shows in the Upper Triassic Palaeocene Sandstone and Devonian Sandstone 2/ P&A Dry Middle Jurassic Brent Sands Pre- Cambrian Basement Pre- Cambrian Basement Palaeocene sandstone had no shows. The Triassic formation had HC shows from ft and ft. U Triassic section cored top 6ft saturated with brown-black tarry oil. DST was performed with pressure charts indicating a flow of 8. BOPD from Triassic. The Brent Sandstone was absent at this location. No significant HC shows were noted..2 Seismic Database D and 2D seismic coverage exists over Block 2/4b as shown in Fig..2 and the seismic database available for this study is summarised in the table below. ± 2/2 2/ 2/7 2/8 5 6B 6 4Z 5A 6Z 2/26c 2/27d 4Y 4 UZ 6 CLADHAN 2/26aF A AY AZ 2/27a 8ST 8 4 CORMORANT 4Y 4Z NORTH 4X 2 4 A20Z 6 A2Z 4A A9 A26 A4 A 20/29c 20/0b A27 A49 HUTTON NORTH 5A CORMORANT 7 WEST - SOUTH Z 2 2/26d PELICAN Z Y 2 4 2/26a 2/27f P4 4 HUTTON PZ 2/27e P9R P P20Z DARWIN 2 P2() Z P /4b 2/5F2 2/5F2 2/5F /b /an /2a /2b 2 /a 4 2A 4Z 7 2/4a H6 2/4aF H62Y 5 2 H9 H4 4 A0 HEATHER 5 H4 6 H42 7 H4 7 BROOM H45 26 NORTH TERRACE 8B A 5 2/5 LYELL 2 A0 A08 B02Z 2 27 WEST A08Z 4 LYELL /2c 6ST 0 6 6ST2 6 HEATHER SOUTH WEST 8 2/9 2/0a /6 /7d /7aN 2 2Z 2D Lines PGS Geostreamer proposed 202 EQ Operated Licensed Blocks Km 9 5 A 002/0 (Area ) COLUMBA B 4 COLUMBA E 5 /7bF Fig..2 Seismic Database Block 2/4b Relinquishment Report -. Wells Drilled Page 5

10 Table.2: Seismic data summary Survey Name Data Description Data Types available Year Areas Covered Total (km 2 ) Block coverage (km 2 ) PGS Heather Geostreamer D D Geostreamer data PSDM, PSTM, Angle Stacks, time and depth /9c, 20/0b, 2/4b, 2/4a, 2/5 & /b TOC86 Tricentol 2D 2D data Amplitudes 986 2/4b, 2/, 2/2, 20/28, 20/ Seismic well ties were evaluated in the vicinity of the application area provided that the wells had a suitable suite of logs. An example well tie for well 2/4-2 is shown in Fig... The polarity of the data is North Sea Normal, that is an increase is Acoustic Impedance (hardening) is represented by a trough and is coloured red throughout the application. Fig.. Synthetic Seismogram 2/4-2. The poor tie below the BCU is due to the charcterless nature of the sonic log. Page 6 Block 2/4b Relinquishment Report -.2 Seismic Database

11 4 Prospectivity Analysis 4. Play Summary Regional studies of this area of the Northern North sea have shown that there are two primary plays that can work in this province. The partnership identified notional prospectivity in Middle and Upper Jurassic reservoirs (Fig. 4.) along the margin of the East Shetland bounding fault and in zones where a possible strike-slip element has been recognised offsetting the platform. Only in the most easterly portion of the block would it be expected to see small downfaulted terraces as one steps rapidly down into the basin where Middle Jurassic Emerald sandstones may be preserved in small scale footwall collapse terraces or "lick-ups". Additionally at least two candidate fault intersection offsets in the platform occur in this block which may provide conduits for erosive products to enter the basin during Volgian and Kimmeridgian times (Fig. 4.2). Some of these channel sandstones associated with these fault junction entry points have been found to be oil bearing and productive in the Cladhan field which is located to the north of block 2/4b. Both playfairways are sourced by the prolific Kimmeridge Clay Formation and oil charge is considered to be a small risk. The playfairways investigated as part of this analysis are summarised below. Block 2/4b Relinquishment Report - 4 Prospectivity Analysis Page 7

12 Fig. 4. Stratigraphy Column. Page 8 Block 2/4b Relinquishment Report - 4. Play Summary

13 Relinquishment Report 2/4b 0 24'0"E 0 6'0"E 0 48'0"E 0'0"E 24'0"E 20/29c CORMORANT NORTH 2/27b 2/26a 2/27f 2/27e PELICAN 2/4b 2/5F2 2/5F /an /2a /c East Shetland Basin /a 2/5 WEST LYELL /a LYELL 00/0 (Area 8) COLUMBA B 2/0a /6 /7d /7aN /4aF2 ALWYN NORTH /8a /7aF 002/0 (Area ) /8b /8aF /8aF4 COLUMBA E STAFFA /9d Platform/Intra Basinal High /8c 2/0b Sub-basin '0"E 2 2/4 2/5b 6 Km 0 6'0"E CHEVIOT 2/5a /b /a 0 48'0"E 0'0"E /c 00/08 (Area 2) /8f 00/07 (Area ) /b 00/2 (Area 2) /2a 2'0"E Text 60 50'0"N /9a /8d /7bF 2/ /9c /8g COLUMBA D /7c Shelf 6 0'0"N STRATHSPEY /d NINIAN East Shetland Platform 60 40'0"N 2/29a /4aF /4c ORLANDO /F /2c SOUTH WEST HEATHER 2/9 /b /4aF 2/5F2 NORTH BROOM TERRACE 2/8 /2b HEATHER 2/4a 60 50'0"N BRENT OIL HUTTON DARWIN 2/ 2/27b 2/27b 2/27c 2/26d Pobie Platform 2/29a 2/27c HUTTON NORTH WEST 20/0b CORMORANT - SOUTH 6 0'0"N 6'0"E 2/26aW CLADHAN Unst Basin 2'0"E 2/27a Tern-Eider Horst 00/09 (Area 7) /8e /4a 60 40'0"N /4j DUNBAR 24'0"E 6'0"E Fig. 4.2 East Shetland Basin Tectonic Elements Source and migration Although the Upper Jurassic Kimmeridge Clay formation (KCF) is immature in the vicinity of Block 2/4b, the discovery of oil in wells 2/- and 2/4- in addition to the producing discoveries (Heather and Broom) in block 2/5 immediately to the east indicates that the area sits on an active hydrocarbon migration pathway out of the East Shetland Basin (Fig. 4.). 0 20'0"E 0 40'0"E 0'0"E 20'0"E FALCON2/2aF 20/24a 20/24b 2/2b TERN HUDSON 6 5'0"N 2/2aF CORMORANT EAST 20/29b 20/0c 2/26b 2/26aF CLADHAN 20/29c 2/27d HUTTON NORTH WEST CORMORANT - SOUTH 20/0b 2/27f PELICAN 2/4b 2/5F2 2/4a 2/4aF BROOM 2/5F2 2/5F 2/27b /an /a HUTTON BRENT OIL /2a /2b /c ORLANDO /7d /7aN /7aF /8a /8aF COLUMBA D /8aF4 /7bF /7c COLUMBA E 00/08 (Area 2) /a /c /2a 00/07 (Area ) 00/2 (Area 2) 0/2c 6 0'0"N 0/dLW 0/bLW 29/aLW /8b /9c 0/c ALWYN NORTH /8g 0/bUP 0/e 0/2b 0/4e 0/4d 0/5c 29/6bLW 0/4fUP /0c /9a 00/0 (Area ) 29/cUP 0/fUP 29/cLW /8d STAFFA 0/fLW 29/6dUP 60 45'0"N /9e /8f /8e /b /0a 00/09 (Area 7) /4a /5b /4j DUNBAR /5a 40'0"E 0/4fLW ELLON GRANT /4d 20'0"E 29/6bUP /5e /4i /4h /2b 0'0"E VALEMON 29/b /4b 0 40'0"E 4/0-2 VALEMON 0/dUP /9d 2/0b /b 4/0eLW /4aF2 /8c CHEVIOT 4/0-52 B 4/0gLW /4aF /6 4/0-52 A 4/0gUP 29/- 00/0 (Area 8) NINIAN 2/5a 4/0fUP 4/0fLW 0/bUP LYELL COLUMBA B 0 20'0"E /2-8 S 4/0-5 A SKINFAKS S 29/aUP 4/g STRATHSPEY /d 002/0 (Area ) 2/5b /4b /5 GULLFAKS SØR 4/0-5 S /2b /4aF /F NORTH TERRACE 2/0a 4/0-K-2 H GULLVEIG 6 5'0"N 4/0-4 S 4/0-5 A /2aF2 /2-9 S 4/0-7 RIMFAKS /2f 2/29a /4aF /4c /b /a SOUTH WEST HEATHER 2/4 2/29a /2h /2e /2c HEATHER 60 45'0"N 2/ 2/29c 2/27e WEST LYELL /2c 2/9 /2-8 A SKINFAKS 2/27b DARWIN 2/5 2/8 BARNACLE 2/29a 2/29F 2/27c 2/27b 2/27c 2/26a 2/ 2/29a 2/29b 2/27a 2/26aW 2/26d 6 0'0"N /2d /2- STATFJORD STATFJORD SKYE 2/28b ± VISUND VISUND SØR 4/7-22 4/8-4 S TORDIS VISUND SØR ØST GIMLE 4/7-25 S 4/0a 4/0-40 S 4/0c 4/0-48 4/0-4 4/0b S GIMLE GULLFAKS 4/-2 VEST GULLFAKS S NØKKEN 4/0-45 S 4/0- GULLFAKS 4/0-47 4/0-2 S GULLTOPP GULLFAKS 4/0-7 SØR 4/0eUP GULLVEIG 4/0-46 A STATFJORD (UK) 2/2a 2 20'0"E 4/7b 4/7-2 TORDIS 4/7-2 TORDIS BORG 2/25b 2/2c 2/2e 2/2aS 2/2a4 2/26aN 2/26c 2/25a FIONN 2/22 (Area ) CORMORANT NORTH 20/29a 2/24a DUNLIN CAUSEWAY 2/2f 2/22a5 20/28 MERLIN2/2a 2/22aSE 2/22b 2 0'0"E STATFJORD /9-7 ØST VIGDIS STATFJORD 4/7-2 ØST /9e BORG 2/2a2F 2/2a2F2 2/2a2 2/2b 2/2aF WESTERN ISLES 40'0"E OSPREY KERLOCH KESTREL 20/25aF 20/24aF JURA /6cCS 0/4cUP 2 0'0"E 5 00/4bLW 5 20 Km 2 20'0"E Fig. 4. Source Map. Expelled oil from KCF at the present day Block 2/4b Relinquishment Report - 4. Play Summary Page 9

14 Severely biodegraded migrant oil is abundantly present in cutting samples from the Rogaland and lower Late Palaeocene intervals in 2/- and the Triassic of 2/4-, owing to shallow reservoir depths at the time of the migration. Oil recovered from both wells has a gravity of 2-20º API and appears to have been expelled from rocks of similar maturity (upper oil window) within the Kimmeridge Clay Formation though it is believed the oil came from different kitchen areas. Middle Jurassic: Emerald Group Sandstones Reservoir Callovian sandstones of the Emerald Group are present along the western margin of the East Shetland Basin in Quadrants 2 and, where they are productive in the Emerald Field (blocks 2/0a, 2/5a and /b). These shallow marine/estuarine sandstones comprise an upward-fining medium to very-fine grained sequence between 2-8 m thick that transgressed across the surface of outcropping Precambrian and Old Red Sandstone rocks. The sequence is very uniform in thickness and forms a sheet sandstone of nearshore to offshore marine origin. The reservoir lies at a depth of m and is of good quality with porosities of 25-0% and permeability in the range md. The sandstones shale out eastwards into Heather mudstones. In West and Southwest Heather, oil-bearing Emerald sandstone directly overlies eroded basal Brent, which forms the primary producing horizon in these fields, e.g. in the 2/5-8B and 2/5-0 wells. Seal Seal can be provided by either Heather or Kimmeridge Formation mudstones and ultimately Lower Cretaceous Shetland Group shales and marls. Upper Jurassic: Volgian "Cladhan"/"Ivy" Sandstones Reservoir Volgian-age sandstones in Upper Jurassic channel systems and wedges may also form reservoir in this area. Interbedded sandstones and conglomerates within the Kimmeridge Clay Formation reflect the erosion of the East Shetland Platform during intermittent uplift episodes which were subsequently deposited as submarine fans by gravity-flow processes. Fault intersection offsets in the East Shetland boundary fault provide conduits for these erosive exposed hinterland platform products to enter the basin during Volgian and Kimmeridgian times. Reservoir quality is generally moderate to poor depending on depth of burial, diagenetic history and timing of hydrocarbon migration. Volgian-age "Cladhan" sandstones provide the reservoir in the Cladhan field which is located to the north of 2/4b. The 20/29a-4z (Cladhan appraisal) well encountered a gross hydrocarbon column of 59ft with 02ft of net hydrocarbon bearing sandstones. Reservoir quality is described as excellent with average porosities of 2% and average oil saturations of 86%. However the 2/5-27 (Ivy) well, which tested a sediment entry point to the south of Broom, encountered 28ft of clean, extremely tight, water bearing Volgian sandstones. It is thought that the sands seen at both Cladhan and Ivy were deposited in a similar depositional environment, with deposition at "Ivy" occurring in a more proximal location i.e. a feeder channel rather than a lobe/fan. Reservoir quality is proven to be a key risk for this play. Page 0 Block 2/4b Relinquishment Report - 4. Play Summary

15 Seal Seal is provided by a blanket of pelagic Kimmeridge Clay, up-dip mud plugging, sediment by-pass or complete structural dislocation of the channel systems. 4.2 Prospectivity EnQuest have evaluated the prospectivity of block 2/4b and concluded that there is no economically viable prospectivity within the licence area. One weak lead was identified immediately to the west of well 2/4-2 and is discussed below. Seismic Interpretation Seismic horizons were interpreted and TWT grids created for the following horizons (Fig. 4.4): Seabed Top Balder Fm Base Tertiary (2D dataset only) Nr Top Danian (D dataset only) Base Upper Cretaceous (D dataset only) BCU Top Brent (D dataset only) Basement (2D dataset only) NW SE NE 2/4-2/4-2 2/5-5 2/5-z 2/5-4z T50 Base Tertiary Basement T50 Danian Base U. Cret BCU Top Brent Fig. 4.4 Seismic section: East Shetland Platform to Broom. West to east composite line from the East Shetland Platform across the Broom field. Seismic attribute analysis has been shown to aid the identification of Upper Jurassic submarine channels, seismic attributes were calculated at the BCU level in order to delineate any high amplitude events which may be associated with Volgian-age turbidite sands. Block 2/4b Relinquishment Report - 4. Play Summary Page

16 2D Interpretation Interpretation of the 2D dataset identified a fault bounded high with dip closure to the north at the Base Tertiary level (Fig. 4.5 & Fig. 4.6), however as shown by the current mapping this structure appears to be part of the same large fault block drilled by well 2/- in which the Brent Group or it's equivalent was absent. This well was dry, but with strong oil shows in the Palaeocene Sands, where the well encountered 2ft of oil bearing sand but failed to flow on test. This structure has therefore been classified as unprospective. Part of same large fault block drilled by 2/-. Fig. 4.5 Base Tertiary TWT Map. ci = 25ms Page 2 Block 2/4b Relinquishment Report Prospectivity

17 SW 2/- NE T50 Base Tertiary Basement Fig. 4.6 SW-NE Seismic Line. TOC86-7 D Interpretation Mapping of the 202 PGS Heather Geostreamer D was carried out to delineate any potential within the Jurassic where notional prospectivity had been identified in the eastern portion of the block along the margin of the East Shetland boundary fault. A single weak lead was identified immediately to the west of well 2/4-2, this well was dry and the Brent sands absent. The structure is a small scale collapse terrace on the footwall of the East Shetland Boundary fault (Fig. 4.7). Initial mapping was carried out on the PGS Heather Geostreamer D PSTM, however re-mapping on the PGS Heather Geostreamer D PSDM shows no apparent change in the structure. Southwest-northeast seismic sections through the structure are shown in Fig. 4.8 which compare the quality of the two datasets. Reservoir may be provided by Emerald or Brent Group sandstones, sealed by Heather or Kimmeridgian formation mudstones or ultimately Lower Cretaceous Shetland Group shales and marls. Volumetrics have been calculated using parameters from offset well data and can be seen in 5 Reserves Summary. Block 2/4b Relinquishment Report Prospectivity Page

18 2/4b 2/4-2: Middle Jurassic sands absent and no significant HC shows 2/5-8b: Middle Jurassic sands present Fig /4b Jurassic Terrace. Base Cretaceous TWT map and W-E Seismic Line W 2/5-8 E Jurassic Terrace: Reservoir: Brent Gp; possibly Emerald Fm Risk: Reservoir absent. Fault seal. T50 Danian Base U. Cret BCU Top Brent Page 4 Block 2/4b Relinquishment Report Prospectivity

19 PSTM Jurassic Terrace T50 Danian Base U. Cretaceous BCU Top Brent PSDM Jurassic Terrace T50 Danian Base U. Cretaceous BCU Top Brent Fig. 4.8 Seismic dataset quality comparison. SW-NE seismic sections illustrating the quality of the PSTM and PSDM 202 PGS Heather Geostreamer D volumes. Block 2/4b Relinquishment Report Prospectivity Page 5

20 5 Reserves Summary The partnership have concluded that this small scale fault terrace is unprospective due to the small scale of the structure and its associated volumes in addition to risks on reservoir presence and fault seal. The calculated volumes are shown in the tables below. Table 5.: 2/4b Terrace MMRA Input Parameters Variable P90 P50 P0 Comments NRV (MM m ) Calculated using area-depth pairs for the top reservoir surface Gross interval (m) Lognormal NTG (%) Lognormal Porosity (%) 2 27 Lognormal Hydrocarbon saturation (%) Lognormal FVF (vol/vol)..2. Lognormal Recovery factor (%) Lognormal Table 5.2: 2/4b Terrace STOIIP and Resources STOIIP (MMbbls) Resources (MMbbls) P P P Reservoir presence and fault seal are seen as the main factors carrying the risk for this lead. EnQuest define the geological probability of success (Pg), as the probability of getting onto the predicted range defined by the P90-P0. Table 5.: 2/4b Terrace Risk Component Chance (%) Source 00 Timing/Migration 00 Reservoir 0 Page 6 Block 2/4b Relinquishment Report - 5 Reserves Summary

21 Component Chance (%) Closure 70 Containment 50 Overall Chance of Success 0.5 Block 2/4b Relinquishment Report - 5 Reserves Summary Page 7

22 6 Clearance EnQuest and MOL approve the release of this document by DECC. Page 8 Block 2/4b Relinquishment Report - 6 Clearance