Wytch Farm Field Development Project Photo courtesy of Howard Johnson Wytch Farm Field Development Project Friday 2nd of March 2012 This photo is from East Sidmouth and shows the gradational contact between the Mercia Mudstone and the Sherwood Sandstone. TEAM B Mohammed Alshawaf , Lanray Hammed Bakare, Francsico J. Barroso Viseras, Aristeidis Karamessinis, Ha Nguyen and Shi Su

Introduction Cultural information Location Dorset, Wessex Basin (50°69’,-1°98’) 44 km2, onshore and offshore Environment outstanding beauty, tourism, wild life Cultural information Location Dorset, Wessex Basin (50°69’,-1°98’) 44 km2, onshore and offshore Environment outstanding beauty, tourism, wild life Underhill & Stoneley, 1988 Source Seal Reservoir Geological overview Reservoir Sherwood Sandstone Seal Mercia Mudstone Source Lias Formation Play type Tilted fault blocks Geological overview Reservoir Sherwood Sandstone. Seal Mercia Mudstone Source Lias Formation Play type Tilted fault blocks 11.8km Wytch Farm Field Google Earth, 2011 Mention the age of the formation (Triassic) Mention the recovery factor Field appraisal Producers 1X-02, 1D-02 Appraisal wells 3 3D seismic survey Depth 1585 m Pressure 2400 psig Oil column thickness 39 m Areal extend 40 km2 API gravity 38.1° @ 15°C GOR 320 scf/stb   P90 P50 P10 STOIIP (MMbbl) 580 795 1040 Reserves (MMbbl) 215 290 385

Wytch Farm - Development phase - Team B Aims and Objectives Develop the geological model Investigate viable development options Assess associated static and dynamic uncertainties Propose a development and production plan Justify additional data acquisition requirements Wytch Farm - Development phase - Team B

Drive mechanism determination Develop model Limitations of material balance Oil expansion and aquifer drive are the most plausible No assumption can be validated Investigate options N=645 MMBbl N=300 MMBbl Propose plan Use the material balance to present the drive mechanism but keep in mind that with two points any drive mechanism assumption is right. We do not have enough pressure data available. No pressure equilibrium is observed Present a (nice) graph with the data No decision can be made based upon MB. Assess uncertainties Justify data acquisition Wytch Farm - Development phase - Team B

Recovery mechanism Primary recovery => secondary recovery methods Develop model Primary recovery Low primary recovery: 4.6% => secondary recovery methods Secondary recovery Water injection preferred Gas injection not advised: under-saturated oil and low GOR Possibility of using artificial lift Investigate options Propose plan Why do we use water injection: we have an aquifer (uncertain extent and nature), water available on surface Why do we use artificial lift: maintain bottom hole pressure just above the bubble point Why do not we use gas injection: low GOR (so where would the gas come from), under-saturated oil (most of the gas injected would be dissolved in the oil), modest dip… Assess uncertainties Justify data acquisition Wytch Farm - Development phase - Team B

Building the simulation model Main assumptions Input Fine model (2.5M cells) Upscaled properties Φ, facies, Kh and Kv Fluid model Dead oil, relative permeabilities Capillary pressure neglected for simplification purposes Output coarse model (82,000 cells, 8 faults) Develop model Investigate options Propose plan Explain the method used for permeability upscaling Assess uncertainties Justify data acquisition Fine hor. permeability model - Sector Coarse hor. permeability model - Sector Coarse horizontal permeability model within Flooding event 1 Fine horizontal permeability model within Flooding event 1

Upscaled model consistency Develop model Static properties Geology Volumetrics Upscaled properties kh, kv Φ Facies Dynamic properties Cumulative production Bottom-hole pressure Oil saturations Sweep efficiency Water cut Coning water Numerical diffusion Investigate options Propose plan QC of upscaled volumetric properties (make a table, a bar graph maybe?) QC of the sector (think about main conclusions) History match Assess uncertainties Justify data acquisition Wytch Farm - Development phase - Team B

Coarse model consistency (history match) Develop model Oil rates: good match Water rates: calibrate the model Limits: well history, no flow control Investigate options Propose plan Assess uncertainties Justify data acquisition Wytch Farm - Development phase - Team B

Development strategy Solution 25 producers / 10 injectors 2 wells/m Develop model Parameter Constraint Solution Drilling strategy Number of wells Recovery factor vs economics 25 producers / 10 injectors Schedule Rates and rigs 2 wells/m Well location Geology and oil distribution Uniform Production strategy Plateau Maximise recovery & 5% recovery 3-year plateau Water injection Pressure maintenance After 15 m Production time Lease 25 years Investigate options Propose plan Number of wells Compromise between recovery factor target and economics Every single well has to increase the production by at least 1 MMBbl Well placement A uniform well distribution allows to maintain the pressure better. After trial no pattern was followed Location optimise based on: geology , pressure drop and oil distribution Production five meters above the OWC Injection just below the OWC Production strategy 3-year-plateau in order to maximise the recovery and get 5% STOIIP per year Surface facility limitations Water injection after 15 months Selected layer completion to reduce water production, no artificial lift Drilling schedule Well sequence based upon rates and rig position Recovery factor Results Assess uncertainties Justify data acquisition Wytch Farm - Development phase - Team B

Development strategy results Develop model 3-year plateau Injection starts after 15 months 345 MMBbl recoverable 43% recovery factor based on P50 Investigate options STOIIP 795 MMBbl Recovered 345 MMBbl Propose plan STOIIP (MMBbl) Recovered (MMBbl) Recovery factor P90 580 239 41% P50 795 345 43% P10 1 040 452 Assess uncertainties Justify data acquisition

Sweep efficiency analysis Develop model Injection after 15 months 89% sweep efficiency achievable over 25 years Investigate options Propose plan Assess uncertainties Water breakthrough Start of water injection Justify data acquisition

Uncertainty analysis Develop model Approach combines both static and dynamic parameters Parameters considered GRV Porosity Sw kH, kV Corey parameters Sor, Swc, Swcr Transmissibilities Investigate options Static properties Dynamic properties Propose plan Assess uncertainties Justify data acquisition Wytch Farm - Development phase - Team B

Reducing uncertainties Data acquisition plan Reprocess seismic data Coring of the first few wells SCAL Logging Fluid analysis Develop model Investigate options Propose plan Core the First 3-5 Wells Utilize NMR Logging Tool Independent Source for Permeability and Porosity Detailed Special Core Analysis Reduce Relative Permeability and Capillary Pressure Uncertainty RFT All Wells Evaluate Reservoir Connectivity, Faults transmissibility, Aquifer Strength Aid in History Match Adequate Fluid Sampling for Detailed PVT Analysis SBHP/T Measurements Twice Yearly Rate Test Wells on a Monthly Bases Run PLTs Every 3-4 Years Separator and Wellhead Samples Solid production Composition Temperature surveys Wellhead Integrity Tests Annuli Surveys Assess uncertainties Justify data acquisition

Wytch Farm - Development phase - Team B Conclusions High recovery factor High sweep efficiency Only water injection used Good understanding of uncertainties Number of wells 25 producers / 10 injectors Drilling schedule 2 wells/m Well location Uniform Plateau 3-year plateau Water injection After 15 m Production time 25 years Recovered (MMBbl) Recovery factor P90 239 41% P50 345 43% P10 452 Wytch Farm - Development phase - Team B

Wytch Farm - Development phase - Team B Thank you Any questions ? Wytch Farm - Development phase - Team B

Geology and upscaled properties: facies Develop model Fine grid Coarse grid Investigate options Propose plan Assess uncertainties Justify data acquisition Wytch Farm - Development phase - Team B

Volumetrics QC 2.8% 1.4% 0.8% Wytch Farm - Development phase - Team B Develop model Investigate options Propose plan 2.8% 1.4% 0.8% Assess uncertainties Justify data acquisition Wytch Farm - Development phase - Team B

Upscaled properties: kh Fine grid Coarse grid Develop model Investigate options Propose plan Assess uncertainties Justify data acquisition Wytch Farm - Development phase - Team B

Upscaled properties: Φ Develop model Porosity distribution: Fine vs Coarse grid Investigate options Propose plan % Assess uncertainties Justify data acquisition Wytch Farm - Development phase - Team B

Cumulative production Develop model Investigate options - Fine grid Propose plan - Coarse grid Assess uncertainties Justify data acquisition Wytch Farm - Development phase - Team B

Bottom-hole pressure - Coarse grid - Fine grid Injectors Producers Develop model - Coarse grid Investigate options - Fine grid Propose plan Assess uncertainties Injectors Producers Justify data acquisition Wytch Farm - Development phase - Team B

Oil saturations Fine grid Coarse grid Develop model Investigate options Propose plan Assess uncertainties Justify data acquisition Wytch Farm - Development phase - Team B

Sweep efficiency Wytch Farm - Development phase - Team B Develop model Investigate options Propose plan Assess uncertainties Justify data acquisition Wytch Farm - Development phase - Team B

Water cut - Fine grid - Coarse grid Develop model Investigate options - Fine grid Propose plan - Coarse grid Assess uncertainties Justify data acquisition Wytch Farm - Development phase - Team B

Coning water Fine grid Coarse grid Develop model Investigate options Propose plan Assess uncertainties Justify data acquisition Wytch Farm - Development phase - Team B

Numerical diffusion Coarse grid Fine grid Develop model Investigate options Propose plan Assess uncertainties Justify data acquisition Wytch Farm - Development phase - Team B

History match per well Wytch Farm - Development phase - Team B Develop model Investigate options Propose plan Assess uncertainties Justify data acquisition Wytch Farm - Development phase - Team B

Justify data acquisition Drilling schedule Priority based on rate and rig location (two rigs: E, W) Develop model Investigate options Propose plan Assess uncertainties Justify data acquisition

Well location Well positioning based on the geology and the properties (kh) Develop model Investigate options Propose plan Assess uncertainties Justify data acquisition Wytch Farm - Development phase - Team B

Water injection strategy Water injection after 15 months in order to ensure pressure maintenance Develop model Investigate options Propose plan Assess uncertainties Justify data acquisition Wytch Farm - Development phase - Team B

Buckley-Leverett analysis Develop model Investigate options Propose plan Assess uncertainties Justify data acquisition Wytch Farm - Development phase - Team B

Relative permeability analysis Develop model Investigate options Propose plan Assess uncertainties Justify data acquisition Wytch Farm - Development phase - Team B