Relinquishment Report. for. Licence P.272 Block 20/7a

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1 Relinquishment Report for Licence P.272 Block 20/7a February of 16

2 CONTENT 1 - Introduction 2 - Exploration Activities Purchase 130km2 of Aker 1999 survey 2.2 Reprocessing of 3D Aker data Biostratigraphic Study Well 20/7a-4 Results, Squirrel Prospect Well 20/7a-6 tight hole 3 - Prospectivity Analysis LIST OF FIGURES AND TABLES Figure 1: Location Map Figure 2: Middle Volgian J73B MFS Depth Map Figure 3 : 3D Seismic Data - Aker 1999 Figure 4 : Aker D Seismic Reprocessing Results Figure 5: Upper Jurassic Well Correlation Figure 6: 20/7a-4 CPI Figure 7: Attic Volume up-dip of Well 20/7a-4 Figure 8: Top Triassic Depth Map Figure 9: Pre-Jurassic Lithology February of 16

3 1 - Introduction Licence Number: P.272 Licence Round: 5 th Round Awarded 14 th February 1978 Licence Type: Traditional Block Number: 20/07a Equity Holdings: Nexen Petroleum U.K. Limited (Operator) % Nexen Ettrick U.K. Limited % Hunt Petroleum UK Ltd % Bow Valley Petroleum (UK) Limited % Initial and Second Term Working Obligations: The Licensee shall before the expiry of the initial term of this Licence carry out not less than 200 kilometres of seismic survey work in the licensed area. The Licensee shall before the expiry of the second term of this Licence carry out not less than 200 kilometres of seismic survey work in the licensed area and drill therein one exploration well. Fallow Status at time of relinquishment: N3 Not Fallow Well drilled Licence P.272 was fully relinquished on 1 st November 2006 and no outstanding obligations remained on the Licence. Three wells were drilled on the Licence and a total of 6 wells were drilled in block 20/7 (Figure 1), which were all Plugged and Abandoned Dry. The Licence obligations were fulfilled by the original group of Licensees by the drilling of well 20/7-1 in Wells 20/7a-4 and 20/7a-6 were drilled by the current operator in 2003 and 2006 respectively. Block 20/7a is divided into two main structural elements by a major north throwing, NE- SW oriented, normal fault, which separates the Ettrick Graben to the north and the Peterhead Graben to the south. Wells 20/7-1, 20/7-2, 20/7a-3 and 20/7a-4 were drilled on the footwall of the major fault (Figure 2). February of 16

4 2 - Exploration Activities: Purchase 130km2 of Aker 1999 survey 130 square kilometers of full fold 3D Aker 1999 seismic data were purchased in 2002 over block 20/7a (Figure 3), in order to define the Squirrel and Black Cat leads. The data in the Upper Jurassic section appeared to be very noisy and the reflectors critical for the mapping of the leads showed a lot of discontinuity. Reprocessing of the Aker 1999 data started in Reprocessing of 3D Aker data The Aker D seismic reprocessing was completed by CGG in It was part of a bigger project including the adjacent acreages operated by Nexen. Only the NW corner of 20/7a was reprocessed, over the Black Cat prospect. Pre-processing paid careful attention to editing of noisy traces; correcting for variations in shot strength an/or receiver sensitivity and maximising resolution of data (zero phase/q phase only correction). A lot of effort was directed (pre- and possibly post-stack) towards the attenuation of multiples. As well as conventional xt and tau-p methods, typical UKCS processing sequence were used, including full Kirchhoff 3D PSTM. A true amplitude processing sequence was required to allow for any subsequent AVO investigation. A line comparing the original and the reprocessed version shows that there is significant improvement in the resolution and continuity of the Upper Jurassic section as well as far better noise attenuation (Figure 4) Biostratigraphic Study A revised Humber Group stratigraphy of wells 20/7-1, 20/7-2, 20/7a-3, 20/7a-4, 20/1-2, 20/2-4 was carried out in 2003 by BVR International Ltd (Les Riley). In 2006, biostratigraphic analysis was carried out on 20/7a-6. Three major sequences were identified in the Upper Jurassic (Figure 5): the Kimmeridgian-Early Volgian sequence (J56-J66B Maximum Flooding Surfaces of Partington et al, 1993) during which the Buzzard Sands were deposited, the Middle Volgian sequence (J66B-J73B MFSs) including the Ettrick Sands and the Late Volgian- February of 16

5 Early Ryazanian sequence (J73B-J76 MFSs) corresponding to the Burns Sand unit. The Burns Sand is not present in the block Well 20/7a-4 Results, Squirrel Prospect 20/7a-4 was drilled by the Sedco 714 semi-submersible and spudded on 9 th March TD was reached on 27 th March 2003 at a depth of 8909ft MDBRT in the Kimmeridge Clay Formation. 20/7a-4 was plugged and abandoned as a dry hole. The Squirrel structure was a stratigraphic pinchout in Upper Jurassic Ettrick and Buzzard sands towards the crest of a major east-west fault (Figure 2). The prospect contained up to 1300 ft of vertical relief updip and 2 km to the west of well 20/7-2. The latter encountered thick, good quality Jurassic sands with hydrocarbon shows, but was interpreted as being too far down dip. Two other wells, 20/7-1 and 20/7a-3 were drilled too far west of the pinchout and failed to encounter any sand (Figure 5). The top Ettrick/Buzzard sandstones was penetrated at 8495 ft MDBRT (-8407 ft TVDSS), with a 196 ft gross vertical thickness of reservoir section. The reservoir section consisted of interbedded claystones and good quality sandstones. No hydrocarbon shows were observed (Figure 6). Because of problems with borehole stability in the 12 ¼ section wireline logs were not run. After petrophysical analysis of the LWD logs the reservoir was confirmed as water bearing. The well reached TD at a depth of 8909 ft MDBRT (-8820 ft TVDSS) having penetrated 214ft MD of the Pre-Buzzard Unit Kimmeridge Clay Formation. After evaluation of the logs the well was plugged and abandoned Well 20/7a-6 Black Cat Prospect 20/7a-6 was drilled by the John Shaw rig and spudded on 9 th January 2006 as a tight hole. February of 16

6 3 - Prospectivity Analysis P.272 Group drilled Squirrel well 20/7a-4 in 2003, operated by EnCana. The well objectives were the pinch-out of the Volgian sands to the west, between 20/7-2 water-wet Volgian sands and 20/7-1 condensed Upper Jurassic shale section. The well penetrated the reservoir target but was P&A dry. The potential remaining attic volume on the Squirrel structure ranges from 4 mmbo and 9 mmbo of STOIIP (Figure 7). No prospectivity in the pre-jurassic section was identified because of a lack of structural closure (Figure 8) and a lack of potential reservoir in the Triassic and Permian sections (Figure 9) February of 16

7 Figure 1: Location Map Block 20/7a Nexen Operated Blocks February of 16

8 Figure 2 : Top Middle Volgian J73B MFS Depth Map Ettrick Field Ettrick Basin Peterhead Graben 0 2km Top Ettrick Silt J73B MFS Depth Map Contour interval 50ft February of 16

9 Figure 3 : 3D Seismic Data - Aker 1999 Block 20/7a 3D Aker 1999 Nexen Operated Blocks February of 16

Figure 4 : Aker 1999 3D Seismic Reprocessing

10 Figure 4 : Aker D Seismic Reprocessing Results Far better noise attenuation, apparent at BCU BCU Top Buzzard BUJ Aker 1999 Far more resolution & continuity Reprocessed version February of 16

11 Figure 5: Upper Jurassic Well Correlation February of 16

12 Figure 6: 20/7a-4 CPI February of 16

13 Figure 7: Attic Volume up-dip of Well 20/7a-4 February of 16

14 Figure 8: Top Triassic Depth Map 0 2km Base Upper Jurassic Depth Map February of 16

15 Figure 9: Pre-Jurassic Lithology February of 16

16 REFERENCES Partington, M.A., Mitchener, B.C., Milton, N.J. and Fraser, A.J Genetic sequence stratigraphy for the North Sea late Jurassic and Early Cretaceous: distribution and prediction of Kimmeridgian-Late Ryazanian reservoirs in the North Sea and adjacent areas. In: Parker, J.R. (ed) Petroleum Geology of Northwest Europe: Proceedings of the 4 th Conference, Petroleum Geology 86 Ltd. Published by the Geological Society, London. February of 16

Relinquishment Report. for. Licence P.1046 Block 20/2c

Relinquishment Report. for. Licence P.1046 Block 20/2c Relinquishment Report for Licence P.1046 Block 20/2c Submitted to DTI in September 2006 September 2006 1 of 14 CONTENT 1 - Introduction 2 - Exploration Activities 2.1 - Purchase 100km2 of Aker 1999 survey