Presentation on theme: "Westport Oil and Gas Co., L.P."— Presentation transcript:
1Westport Oil and Gas Co., L.P. Evaluation of Oil Reservoir Characteristics To Assess North Dakota Carbon Dioxide Miscible Flooding PotentialRalph Nelms Westport Oil and Gas Co.Randy Burke North Dakota Geological SurveyNorth Dakota Geological Survey Geologic Investigations Number 21
2North Dakota CO2 Mini-Test Pilot 1981 Gulf Oil Company.Little Knife North Field .Five Acre 5 Spot.Mission Canyon Formation.Recovered 13% of OOIP.MMP 3,100 psi.Gulf Projected Recovery of 8% of OOIPon 160-acre Well Spacing.
3Previous North Dakota CO2 Studies 1988 and 1990 Basin Electric Cooperative.North Dakota and Montana 26 Fields.4,467 MMbo In Place.858 MMbo Produced as of 1988.1,038 MMbo Primary + Sec. EUR (~24% OOIP)3,549 MMbo Remaining In Place232 MMbo Potential CO2 Flooding Recoverable. (5.2% of OOIP)
4Dakota Gasification Co. CO2 Pipeline Location CANADAM.T.N.D.CO 2 PIPELINE
6Favorable Reservoir Characteristics for Empirical Screening Reservoirs with good waterflood response are best Candidate for CO2. 20% OOIP< Recovery Factor <50% OOIP.Depth >2500 ft to reach MMP.Oil Gravity >27 Degrees API.Oil Viscosity <10 cp.Porosity >12%.Permeability >10 md.
7Quick Rules of ThumbRecovery factor using miscible CO2 is 8% -11% OOIP. Immiscible CO2 50% of miscible.MMP equals initial bubble point pressure.CO2 requirement is 7-8 Mcf/bo plus 3-5 Mcf/bo recycle.Water injection required to fill gas voidage and increase reservoir pressure to original BHP.WAG is alternative but 10 Mcf/bo still required.Top down CO2 injection alternative is effective but requires more capital investment for higher CO2 volume.
8Unfavorable Reservoir Characteristics for Empirical Screening High concentrations of vertical fractures.Very high, or very low, permeability.(Vertical segregation or fracture channeling)Thick reservoirs with no layered horizontal permeability barriers.Reservoirs with poor connectivity.Well spacing >80 acres.Poor material balance during water flood. (High water loss out of zone, water influx or high water cut during primary production)
10Summary of US CO2 Active Floods (CEED 2002) Total Active CO2 Floods = 66Total Successful = 38Total Successful Carbonates = 29Total Successful Sandstones = 9Of 29 Successful Carbonate Units, 18 are in San Andres Dolomite.
11Reservoir Characteristics of 29 Successful Carbonate CO2 Floods 2002 US Average North Dakota MadisonPorosity % (7%-13.5%) %Permeability 9 Md (1.5-62) MdDepth ,281 feet ( ) ,500 feetAPI degrees (28-41) degreesBHT degrees F (86-134) degrees FViscosity cp (0.5 –2.6) cpSo at start of CO2 flood = 55% (35%-89%)
12Reservoir Parameters of Carbonate CO2 Floods Well Spacing for 38 Successful CO2 Floods:1 Field at 130 acres2 Fields at 75 acres2 Fields at 50 acres32 Fields < 40 acres38 Well average was 27.6 acres
14Favorable Reservoir Characteristics for North Dakota Carbonate Reservoirs MMP is Easily AchievableDepth, API Gravity and BHT all Favorable for CO2 Flooding.Porosity, Permeability and So are all within Range of other Successful Carbonate Reservoirs.H2S in Sour Crude in not a constraint.Deeper Reservoirs offset Higher BHT for MMP
15Unfavorable North Dakota Reservoir Characteristics Large Well Spacing averages 160 acres.Many Reservoirs are Vertically Fractured.Depth Increases Well Costs for Infill Drilling New Wells : $100/ftSour Gas Recycling Costs.Heterogeneity limits sweep efficiency.
16Weyburn CO2 Project, Saskatchewan, Canada Started in $1.3 billion Encana project. $100 million DGC project. 25 year life.1,300 MMbo in place. CO2 recovery 130 MMbo. 10% OOIP from CO2 flood.723 wells, 179 horizontal, 221 injection.Injecting MMcfpd CO2.95% Quality CO2 from Great Plains in Beulah. 198 mile pipeline4,655’ deep. 10’-89’ thick. Sour API gravity.Vuggy Limestone: 15% porosity 30 md.Marly Dolomite: 26% porosity 10 md.SSWAG injection due to fractures.
17CO2 Reservoir Excel Database NDIC Derived Data Author’s Data InputUnit Name/ Pool/ OOIP CO2 Oil Recovery (8% OOIP)Peak Rates, CO2 Oil Reserve CategoryPrimary EUR, RF Favorable/UnfavorableSecondary EUR, RF CO2 Flood CharacteristicsUnit size Porosity, Permeability, BoiEffective Date uo, uw, M, h, BHT, API, RwWOR, Soi, Soirr Swirr,P*, Pbp, Non-Unitized FieldsDistance to CO2 Pipeline,Fracture Description
18North Dakota Highest Ranked Reservoirs for CO2 Flooding Mississippian -Madison GroupMission CanyonGlenburnSherwoodRatcliffeDevonian - DuperowPermian/Triassic -SpearfishPennsylvanian -Tyler “Health”
19North Dakota Lowest Ranked Reservoirs for CO2 Flooding Silurian - InterlakeDevonian - WinnipegosisMadison with Cross-seal FracturesOrdovician - Red River B with Cross-seal Fractures
20CO2 Potential Oil Reserve Classification Probable, Possible, UnfavorableProbable (>2MMbo and <2MMbo): Highest probability of success based upon empirical analysis and comparison to other successful projects.Possible (>2MMbo and <2MMbo): Feasible but have less favorable reservoir characteristics. May have lower oil recovery.Unfavorable: Significant reservoir problems.Projects with greater than 2 MMbo recoverable best candidates.
21Probable Top Ten North Dakota Units for CO2 Flooding Beaver Lodge - Madison MMboTioga - Madison MMboBig Stick - Madison MMboFryburg - Heath (Tyler) MMboBeaver Lodge - Devonian MMboNewberg - Spearfish & Charles MMboWiley - Glenburn MMboBlue Buttes - Madison MMboNorth Tioga - Madison MMboCharleson North - Madison MMbo
22Possible Top Ten North Dakota Units for CO2 Flooding Cedar Hills South - RRB MMboCedar Hills North - RRB MMboAntelope - Madison MMboCedar Creek - Ordovician MMboMedicine Pole Hills West - RRB 3.4 MMboMedicine Pole Hills - RRB MMboMedicine Pole Hills South - RRB 3.1 MMboEland - Lodgepole MMboLignite - Madison (PA) MMboRough Rider East- Madison MMbo
23Unfavorable North Dakota Units for CO2 Flooding Horse Creek Red RiverRed Wing MadisonFryburg MadisonTR Madison (South)
24Constraints to North Dakota CO2 Development Most oil reservoirs are 7,500 feet and many have well spacing >80 acres requiring high cost infill drilling.Only Nesson Anticline fields are less than 10 miles to existing CO2 pipeline. Fields not on the Nesson anticline will be burdened with large pipeline installation costs.Most existing waterflood units are in mature waterflood stages at high water cuts.Low permeability and highly heterogeneous.Many reservoirs have strong water influx from vertical fractures outside of pay zone boundaries.
25Conclusions55 fields in North Dakota have Probable CO2 recoverable reserves of 171 MMbo.26 fields in North Dakota have Possible CO2 recoverable reserves of 106 MMbo.One successful CO2 pilot has been conducted to date.Comparison of North Dakota reservoir characteristics to successful Texas and Canadian reservoirs utilizing CO2 flooding is favorable.Future North Dakota CO2 development constraints are principally economic and will require large capital investments over long time periods plus the ability to manage both oil price and CO2 price risks. A long term economic perspective will be required since CO2 projects require long payouts on investment.