How to get the most out of your Oil Rim Reservoirs? Reservoir management and hydrocarbon recovery enhancement initiatives Rahim Masoudi Principal Reservoir Engineer 1 Outline:  Oil Rim definition/concept/Challenges  Guidelines/best practices/key technologies/success factors  Reservoir and business management and exploitation strategies  Successful field application and examples  Closing Remarks 2 Oil Rim Opportunity and Headache! •Limited Thickness •Overlain by Gas Cap •Underlain by Aquifer 3 Forces Balance Mechanism: Gas Cap Expansion •Preservation of Reservoir Energy •Maximizing the hydrocarbon recovery Withdrawal Aquifer Drive Indicates regions of high flow into the well bore Indicates regions of low flow into the well bore 4 Technical Challenges: • • • • • • Water/Gas Coning and Break-through Spread Out Resources Complicated Production Mechanism Transition and Invasion Zones Oil Smearing Low Recovery Factor (<18%) Business Challenges: • • • • Different focus for the host company and the operator Narrow window of opportunity for “Oil rim” development Early gas commitment vs. oil rim IOR development Expensive Field Development and marginal economy 5 Oil Recovery Factor: Main Affecting Parameters •Oil Thickness •Permeability •Aquifer support •Kv/Kh •Gas Cap Size •Viscosity and mobility •Sor, Pc, Kr •Well Placement •Production Strategy •GIGP •Reservoir well Contact •HW vs VW Permeability and Thickness effect Aquifer effect SPE 128603 6 Oil Recovery Factor: Main Affecting Parameters (Cont.) Oil viscosity effect Kv/Kh effect Gas cap size effect 7 Available Screening Tools Traffic Light Guideline Oil Column size < 30 ft 30-70 ft > 70 ft Gas cap size m>7 and/or FGIIP > 1 TSCF m>2 and/or FGIIP > 200 BSCF M<=2 and/or FGIIP <= 200 BSCF Mobility Perm < 500 mD Visc > 1cP Perm 500-1000 mD Visc > 1cP Perm > 1000 mD Visc < 1cP Aquifer Strength Weak, <25% of total drive Mid, ~50% of total drive Strong, >70% of total drive Reservoir Geometry/Dip Complex geometry Large dip uncertainty Complex geometry Small dip uncertainty Simple geometry None or small dip uncertainty 8 Available Screening Tools M Factor Gas Concurrent Oil & Gas Oil and then Gas Rim Thickness [ft] Source : SPE 128603 Development Strategy 9 Available Screening Tool: Shortcomings Thickness <30 ft M Factor •Successful development in: Thickness < 30 ft K < 375 mD •Not in line with the guide line •4 to 10 m oil column development Rim Thickness [ft] Frequency Source : C&C Reservoir and IHS Energy •Technical Initiatives •Technology Roles Permeability, mD 10 Oil Rim Development Success Factors Phasing development to understand the reservoir/well behaviors Robust geological understanding and input rock/fluid data Proactive real time reservoir management & monitoring (PLT, Tracer, PDG, etc.) Innovative Technical Initiatives (force balancing efforts, dual smart comp, multi-zone production with FCV, etc.) Well/completion design/type/length/ offset Holistic and Integrated development concept Adequate and reliable simulation/prediction (Grid, CTZ, HZ well, smart comp.,etc.) Transition Zone Characterization and modeling New well technology applications (long HZ, multi lateral/target, etc.) 11 Production/Depletion Strategy Gas Cap Blowdown -Early Gas prod. -Oil prod. Ignored! -Oil smearing concern -Low oil RF Sequential Development -Early oil prod. -Gas come later -Commitment concerns -Different contractual interest -Higher oil/gas RF Concurrent Development -Early oil and gas prod. -Limited gas prod. -Up to 10% of the GIIP per annual -Might suit to both operator and host company interest -Lower oil RF Swing Development -Cyclic oil and gas prod. -Balance the energy -Suitable for reservoir with big gas cap -Lower oil RF •The FDP, well design and philosophy, RMP is highly dependent on selected strategy 12 Oil Rim Reservoir and Business Management Reservoir Management Contract & Policy Field Development Strategy Reservoir Energy Balance and Optimum Production •Well type •Well length , spacing , stand off •Contact movements •GOR and production constraint •Coning, Cusping, Cresting •IOR/EOR •Gascap Blowdown •Sequential •Concurrent •Swing •Incorporated with IOR/EOR? •Robust static/dynamic models •Gas cap size •Aquifer size and extension •Driving mechanism contributions 13 Fluid Sampling, Analysis and PVT • • • • • • • • Usually simplified! Surface sample can be misleading Both phases need to be sampled Recombined with the GIIP/STOIIP ratio Reliable fluid model is a must Modeling just Oil can be misleading on the RF evaluation Oil and Gas need to be modeled together Compositional grading and nonequilibrium concerns (after Amyx, Bass and Whiting, 1960; courtesy of McGraw-Hill ) 14 Transition Zone and Oil Smearing Concerns •Saturation modeling? •Can oil rim move upward to the gas producing well? •How much is the Sor? Soi/Sor relation to be considered. •Mobile oil and displaced oil zone? •Dry oil production! Performance better than prediction! SPE 143983 SPE 145867 15 Capillary Transition Zone Flow Dynamic •Dry oil production! Performance better than prediction! •Sw Modeling: •Resistivity index and wettability effects (esp. in carbonates) •SHF from resistivity log using water wet derived n exponent can be different from that derived from drainage PC curve •This can over estimate the HC saturation above the transition zone •Saturation dependent n exponent may need to be used •Displaced Oil Zone •Imbibition curves and hysteresis effects •Pseudo Kr with artificial high immobile Sw may produce HM but can give poor prediction •How much is the Sor? Soi/Sor relation to be considered. 16 Sw Determination and Modeling in Carbonates (IPTC 14588) Non-Archie effects Rock Type Permeability Heterogeneity Pore size and Geometry Wettability Saturation history Hysteresis 17 Sw Determination and Modeling in Carbonates (IPTC 14588) Resistivity Index 100 10 1 1 10 100 Water Saturation, % pore volume 18 Sw Determination and Modeling in Carbonates (IPTC 14588) Formation Resistivity Index 100 10 1 1 10 100 Water Saturation, % pore volume 19 Capillary Transition Zone Flow Dynamic (1) SPE 77545 IPTC 10238 SPE 143983 20 Capillary Transition Zone Flow Dynamic (2) SPE 143983 21 Capillary Transition Zone Flow Dynamic (3) SPE 143983 Rock/fluid/Sor characterization Typical Well Water cut % 0.30 Sor 0.25 0.20 New Model Original Model 0.15 0.10 0.00 0.20 0.40 0.60 0.80 Soi OPR, OPT EP-F HZ well and smart comp modeling 3000 3.2E+06 2500 2.4E+06 2000 OPR OPT OPR-MC_GI_PERM_ICD3_1 OPT-MC_GI_PERM_ICD3_1 OPR-MC_GI_MSW_1 OPT-MC_GI_MSW_1 1500 1000 1.6E+06 OPT (STB) Oil Prod Rate (STB/DAY) Typical Well Oil Prod total 3.01 2.79 2.60 800000 500 0 2010 2015 2020 2025 Date (YEARS) 2030 0 2035 22 Reservoir Modeling and Simulation • Girding scheme • Horizontal or non-horizontal corner point geometry grids • Horizontal grids capture the contact movement more accurately (SPE 39548) • Local grid refinement (LGR) • Finer layering scheme (SPE 93137) • Multi Segmented Well (MSW) approach SPE 89755 SPE 50646 23 Modeling of Horizontal wells with smart completion Conventional modeling Hydrostatic only No slip and friction along the well Uniform mixture density Excessive oil production in early stages Proposed Technique Multi segmented well (MSW) model Segment topology to honor the well path Coupled to the reservoir model 24 Modeling of Horizontal wells with smart completion (cont.) MSW Capability •Reliable wellbore pressure gradient and fluid mixture properties •Proper representation of the well trajectory. •Ability to model smart completions (ICD, Inflow Control Device, ICV, Inflow Control Valve) •Coupled to the reservoir simulation equations 25 Key Technologies/ Methodologies • Horizontal and Lateral Wells • Thin Column Drilling • Inflow Control Well Design • Smart Completion Design • Modeling New Technologies • Real-Time Reservoir Management • Real Time Reservoir Modeling • Improved Sweep 26 Horizontal Well Basis of Design Basis of Design Optimum Fluid Rate Well Spacing K-10 top of Main Porosity Distance to GOC/WOC Lateral/perforation length Smart Completion A-02 A-01 Gas Phase I wells Phase II wells East Belumut-3 A-07 1105 Perforations Belumut-2 11 10 A-03 st3 East Belumut-1 1115 A-05 1120 A-10 A-06 11 25 Contours = 5m Oil Water 15 11 1130 A-04 113 5 Gas Oil Water 1 kilometer Long Well Length (Madsen and Abtahi- 2005) 27 Horizontal Well with Smart Completion Smart Completion (ICD, ICV): Without ICD With ICD •Transmit delta-P along well • Heel-to-Toe effect reduction •Higher well PI. • Better sweep efficiency. World wide Installation Forecast! Iron Duke Field (SPE 81107) (OTC-19172 ) 28 ICD Minimizes Toe-Heel Effect (OTC-19172 ) World wide Installation Forecast! Uniform Drawdown along the well 29 Improve the well contact with the reservoir-1! •Brunei Shell Iron Duke Field (SPE 81107) •One H well with smart completion •Five zones in two blocks with different reservoir characteristics (Henriksen et al., 2006) (SPE 112616) •StatoilHydro Troll Field (SPE 112616) •Known as gas field! •110 HZ sub sea wells with 53 MLT wells •Over 13 km well contact •Up to 7 HZ branches in different zones 30 Improve the well contact with the reservoir-2! •Total of 41 wells in 3 phases •Optimal well off set from contacts •250 m average well distance •EUR increases with well No. 31 IOR/EOR Considerations • • EOR plan integrated in FDP Improve IOR through force balance  Minimize coning, cresting and cusping  Control fluid contact movement • Produced Gas Injection  GIGP Ratio • Water Injection  Injection at GOC (water fencing scheme)  • Injection at WOC Water Alternative Gas Injection  Gravity Assisted Simultaneous WAG  Lowering residual HC • Surfactant augmented water flood Water & Gas Injection No Injection 32 Field A: Real Time RMS in a Field in Malaysia Phase I wells 2500 A-01 2000 Oil Rate, STB/D A-02 Phase II wells A-07 A-03 st3 111 0 1105 15 11 A-06 1000 A-04 0 50 100 150 200 250 Days 10 113 5 1 kilometer 14 m oil column Known as non-commercial asset! Optimization of well spacing and landing 200 m lateral spacing for Well A05 & A10 4 m, 6 m and 8 m above WOC More oil production and delay WBT A05 1 WOR 11 25 • • • • • • 1500 0 A-05 A-10 1120 1130 A10 500 1115 Contours = 5m A05 A10 0.1 0.01 0.001 1 10 Days 100 1000 33 Field A: Horizontal well length optimization and tracer application •1.6 km horizontal well with ICD completion •Toe section contribution •Tracer application in the toe section •Toe flow contribution in the early stage Tracer Test at the toe of the well •Smart completion allows longer HZ wells •PLT is planned post WBT. 34 Field A: Horizontal well A performance with ICD post WBT •Well-A with 1.9 km length, 4000 BPD, 5% W-cut, Np of 750 MSTB •Coil Tubing Unit clean out and PLT •Low (2.5 KBPD) and high (4.5 KBPD) rate flowing condition tested •Flow contribution from the entire wellbore 35 Horizontal well04 performance with ICD post WBT- Field A •Well-04 with 1.6 km length, 4500 BPD, 70% W-cut, Np of 1.5 MMSTB •Coil Tubing Unit clean out and PLT •Low (2.5 KBPD) and high (4.5 KBPD) rate flowing condition tested •Flow contribution from the entire wellbore •Even with ICD, there are more water from the heel 36 Pressure and Temperature Proifile- Well04 •Although claimed horizontal by drilling contractor, the static pressure/temp/resistivity shows downward deviation •Big ICD pore size (4/32 Inch in this case) create small drawdown and it is a challenge to have uniform drawdown along the well (15 psi vs 18 psi, 17% different) 37 Pressure and Temperature Profile- Well08 •Although claimed horizontal by drilling contractor, the static pressure/temp/resistivity shows downward deviation •Smaller ICD pore size (3/30 Inch in this case) create bigger drawdown and it is better for having uniform drawdown along the well (58 psi vs 55 psi, 5% different) 38 Field A: Improving the hydrocarbon recovery Horizontal wells with ICD completion MSW approach for well modeling 11% RF increase on “No ICD” case. This happened through:  Draw down management  Gas suppression  WBT control • ICD pore size can be further optimized! • Reservoir heterogeneity along the well • • • • 39 Field A: Journey of recovery factor improvement Water injection Mobility control Idle well re-activation 42 Wells Phase 3 prospect Long HZ Well 6-8 m offset from OWC Project Phasing 23% 20 32% >34% Accurate TZ characterization Proper HZ and smart well modeling Economical phase 3 Optimizing the number of wells 16% 27 Wells Horizontal wells + ICD Gas cap gas reinjection 4 m offset from OWC 40 Field B: Optimized Production Strategy in a Malaysian Carbonate Oil Rim GAS Oil Recovery Well Recovery ( MMSTB) No. (BSCF) Cases Original FDP 41 375.4 7+4 Opt. attempt (1) 38.3 383.1 7 •Known as gas field! •Concurrent Oil and Gas development •Oil and gas production through the same well •Dual smart completion with ICV •Development cost reduction Optimized Well Design FDP well design GAS CAP OIL RIM Aquifer 41 Well Position vs EUR in Field B •2 km HZ well •Gas offtake effect •Aquifer effect •ICD vs SSD 42 Field C: Withdrawal control from different zones Z1 Z2 U9.1 Z1 U9.2 Z2 U8.0 2500 U7.0 50 45 2000 40 35 1500 30 25 1000 20 Wcut (%) 10 m oil column FCV with PDG application Close performance monitoring Valve optimization PBU survey Oil Rate (stb/d) • • • • • 15 500 10 5 0 0 19-Sep-1019-Oct-1018-Nov-10 18-Dec-1017-Jan-1116-Feb-11 18-Mar-11 17-Apr-11 17-May-11 Oil Rate (stb/d) W/CUT 43 Improving the hydrocarbon recovery in Field C Horizontal wells with ICD completion Multi zone production with Flow Control Valve HZ well and smart completion modeling 6% RF increase upon “No ICD” case. Recommend longer HZ well, PDG, optimum well placement, pilot hole and contact monitoring  Recommend static/dynamic model revisit      44 Field D: Improving the hydrocarbon recovery • Recovery factor vs GI/GP Reactivate Idle Wells Side Tracks Infill Wells >50% 46% Selective Water Injection • Journey of recovery factor improvement 34% Fencing at GOC Periphery at WOC No Further Action 75% Idle Wells 45 RF Sensitivity to GI/GP in Field D  GI/GP Management  Recovery factor vs GI/GP 46 Field E: Smart HZ Well Application in Small Oil Pocket • • • • • • • 4 MMSTB STOIIP 8 m oil column Gas cap size M ratio=1.7 Vertical well EUR=0.17 MMSTB 500 m Smart HZ Well EUR=0.9 MMSTB UDC= USD 18/bbl Oil column thickness as low as 5 m with HZ well with ICD 47 Field G: New EOR Scheme EOR Scope: • • • • • • 50 MMscfd Gas Inj. 4 Downdip Injectors 50 kbwpd Water Inj. 5 Updip Injectors 22 Reactivations 4 Infill Producers Gravity Assisted Simultaneous Water And Gas Injection Recovery mechanisms • Re-pressurizing reservoir • Sweeping remaining oil towards new wells • Improved vertical sweep using gravity assistance • Pushing attic oil back down to producers • Reduced Sor with respect to gas in water swept layers Field K: Do we need HZ well with ICD?      Oil column = 6 m m = 2.0 Phi avg = 25 %, k avg = 500 md Pini = 2100 psia, Tres = 226 deg F Strong aquifer With Equalizer RF,% Standard Sandscreen Standard Screen 15.46 Equalizer 18.75 49 OPR, OPT Oil Rim Case 9: Smart Horizontal Well modeling in a Malaysian EP-F 3000 3.2E+06 3.01 2.79 2.60 2.4E+06 2000 OPR OPT OPR-MC_GI_PERM_ICD3_1 OPT-MC_GI_PERM_ICD3_1 OPR-MC_GI_MSW_1 OPT-MC_GI_MSW_1 1500 1000 1.6E+06 OPT (STB)  7% error over conventional methods  16% gain with ICD in well level  6% gain with ICD in field level Oil Prod Rate (STB/DAY) 2500 800000 500 0 2010 2015 2020 2025 2030 0 2035 Date (YEARS) OPR, OPT MC_GI_2013_PHASE.UNSMRY 08 Mar 2011 FIELD 12500 2E+07 18.5 17.9 17.4 ICD+MSW No ICD 1.6E+07 MSW 7500 1.2E+07 OPR OPT OPR-MC_GI_PERM_ICD3_1 OPT-MC_GI_PERM_ICD3_1 OPR-MC_GI_MSW_1 OPT-MC_GI_MSW_1 5000 2500 0 2010 8E+06 OPT (STB) ICD Design • Tubing OD 5.5”, ID 4.892” • ICD port size 3/32” • ICD interval 11m Oil Prod Rate (STB/DAY) 10000 4E+06 2015 2020 2025 Date (YEARS) 2030 0 2035 50 Case 5: Withdrawal Mis-Management in Field F  Gas Cap production  Oil loss to the gas cap  Lower RF Z1 ~ 2m TV GOC has receded Original Field GOC @ 1686.6 m TVDSS Z2 Z3 Z4 Highest Known Water in NL_A3ST2 @ 1695.2 m TVDSS Z5 Original Field OWC @ 1700.6 m TVDSS Z6 51 Innovative Well Design and Off take Strategy East WEST C12 J18/19/2 0 C17 C20 B12 & B12ST1 C12ST1 K2025 52 Closing Remarks: •Oil rim: good business opportunity with sweet headaches! •Integration of innovative technical initiatives and new technologies •Real time/integrated reservoir management, monitoring and surveillances •Several gas fields and un-commercial assets turned in to attractive oil rim developments •Success cases on oil column thickness as low as 3 m and STOIIP as low as 3 MMSTB •Time to change our culture/mindset! Lets follow all the success factors Oil rim development can be reality now! Lets move toward breaking the hydrocarbon recovery limit with lower cost! 53 Thank You! Question? -1.5 m -Can we develop?! 54 Back Up Slides 55 Your Feedback is Important Enter your section in the DL Evaluation Contest by completing the evaluation form for this presentation : Click on: Section Evaluation Society of Petroleum Engineers Distinguished Lecturer Program www.spe.org/dl 57