Development Strategies for Maximizing East Texas Oil Field Production

Transcription

1 Development Strategies for Maximizing East Texas Oil Field Production Fred Wang The University of Texas at Austin, Bureau of Economic Geology 1 RPSEA Onshore Production Conference: Technological Keys to Enhance Production Operations April 10, 2012 Midland, Texas rpsea.org

2 Outline 2 Background Geologic setting Field history Production technologies Water encroachment Petrophysical properties Original oil in place and reserve estimate ETOF strategy project Depositional trends Field tests Summaries

3 Location Map (a) East Texas Basin (b) East Texas field Upshur Co. Woodbine outcrop Dallas (4) Lanthrop #1 x X East Texas field East Texas Basin Sabine Uplift Smith Co. (3) L. D. Crim #1 Gregg Co. Rusk Co. 20 mi 3 Basin axis Cherokee Co. (2) Ashby #1 (1) Discovery well Daisy Bradford #3 Cored wells for this study

4 Reservoir Parameters Discovery October 5, 1930 Counties Gregg, Rusk, Upshur, Smith and Cherokee Acreage mi (130,444 ac) Producing formation Fluvial/Deltaic Woodbine Trap type Stratigraphic Drive mechanism Water drive Top of formation ~-3,200 ft (~3,500 ft) Dip 05º 0.5 Original oil-water contact ft Gross oil-sand thickness 51 ft (max. 125 ft) Net oil-sand thickness 39 ft Formation temperature º F Oil gravity 39 º API Saturation pressure 750 psi Initial reservoir pressure 1,620 psi Original oil in place BSTB 4 Modified from ETEA (1953)

5 Wedge-Shape Stratigraphic Trap SP Austin Chalk Resistivity 3500 Unconformity Top of Woodbine E Main Woodbine fluvial-channel sandstone Gravel Gravel 3600 W Original oil-water contact, 1930 Aquifer ft Woodbine Oil Lower stringer 100 ft 1 mi 5 From Halbouty (2000)

6 Impacts After discovery, the field rapidly developed with 3,612 wells completed in 1931 and 9,372 wells completed in Overproduction in the field brought oil prices to 13 cents per barrel in 1931, and the field was shut down to stabilize the market. Nevertheless, its profound impacts have undoubtedly far exceeded all the turmoil that it engendered. It was the birthplace of many technologies as well as paved the way to a new era of oil exploration with strategy to go deeper and look for subtle, updip stratigraphic traps, which has led to several large discoveries including the giant Prudhoe Bay field in Alaska. 6

7 Top of Woodbine Sandstone (a) East Texas Basin (b) ETOF 7 Modified from ETEA (1953)

8 Woodbine Sandstone Isopach and Pay (a) Woodbine Isopach (b) Woodbine Pay Pay (ft) 8 After ETEA (1953) After ETEA (1953)

9 Engineering Parameters No. of wells 31,243 Well spacing 4.3 ( ) ac Porosity 25.2% Permeability 2,098 (1,000 3,000) md Initial water saturation 14.1% Residual-oil saturation 13.6% Oil-water contact -3,324.5 ft Cumulative oil 5.43 Bbbl Ultimate predicted oil recovery ~5.49 Bbbl by 2030 Recovery efficiency 80% Data from ETEA (1953) 9

10 Rock Properties (a) Core porosity and permeability Permeabilit ty (md) (b) Capillary-pressure curves lary Pressure (ps si) Capil Kinney #88 Lawson #1 Watson # Water Saturation (frac) (c) Residual oil saturation Residua al Oil Saturation (%) Property name Mean Residual oil saturation a 13.6% Permeability 2459 md Porosity(%) Permeability (md)

11 Statistics Number of wells 31,243 Proratable wells 3,895 Marginal wells 680 Off-production wells 2,135 Plugged wells 23,765 Dry holes 768 Deepened >3000 Daily oil ~10,000 STB Daily water production ~1,000,000 bbl Daily water injection ~1,000,000 bbl 11 Data from ETEA (1953)

12 ETOF Production Methods 12 Plug back To prevent water production Downdip water injection To maintain aquifer strength Deepening Lower sand stringers untapped oil Waterflooding South Kilgore unit, Daisy Bradford area South pilot area, Siler, W.H.R./A area Miniwaterflooding To inject water into poorly connected stringer sandstones S P Deepening Watered out in 1947 Poorly swept zone? Deepened from ,281 ft and perforated from -3,303 to -3,309 ft Polymer flooding To divert water into poorly swept sandstones: Hunt Pilot Daisy Bradford area, 1982 Kinney, I. L. #70 area, 1985 Resistivi ty Unconformi ty Initial TD ft 497 BOPD in 1947 and 37,509 STB produced as of Nov. 5, 1951 Smith Co. Cherokee Co. Cored well Upshur Co. (3) L. D. Crim #1 (2) Ashby #1 (4) Lanthrop #1 North pilot area Gregg Co. Rusk Co. South Kilgore area (1) Discovery well Daisy Bradford #3 South pilot area Siler area

13 Well Statistics 30, er ut-in or s Produce No. of 20,000 eted or Shu ned Wells of Comple Abando 10,000 No pre-1951 deepenings not included. Completed More than 2640 wells have been deepened. "Shut-in" No. of deepening wells after 1998 are not well reported to ETEA. Abandoned Producer Deepened s Wells No o. of Deepe ened Well Year Year Data from ETEA (1953)

14 Production and Injection Reservoir pressure (psia) Yearly production days Reservoir pressure Yearly production days , ,000 Annual Oil, or Water Production or Injection (MMSTB) Production (MMSTB) Oil production rate Water production rate Water injection rate Cumulative 14 Oversupply & Conservation Cumulative oil 0 0 WWII Year 2,000 Data from ETEA (1953)

15 Water Encroachment Woodbine Oil Original oil-water contact, 1930 Aquifer ft 1 mi Aquifer Data from ETEA Oil Water encroachment

17 OOIP, EUR and Recovery Factor OOIP= 7.0 BSTB Cumulative Production, BSTB, 77.5% Remaining Mobile Oil BSTB, 5.8% Residual Oil 1.10 BSTB, 13.6% Remaining Reserve 0.07 BSTB, 1.0% 17

18 Factors for Stunning Recovery Single, thick and homogeneous sandstone Favorable wedge-shaped trap geometry, thickness, and stratigraphic dip Effective water drive Top-grade crude Low residual-oil saturation High sweep efficiency Successful production management 18

19 What We Have Learned A surreal field with great reservoir quality excellent oil properties low residual-oil saturation high oil recovery efficiency many mysteries remaining 19 Aging giant with 99% of water cut >120 small producers Lack of geological and engineering supports

20 ETOF Strategy Project To unlock remaining mobile oil through economically viable technologies for ETOF and other mature fields: To map depositional o trends and reservoir architectures To locate depositional-trend-guided workovers, and deepening and waterfloods and To study the feasibility of EOR methods and their environmental impacts 20

21 Study Area (b) Wells used in phase I and II study areas (a) Project areas Upshur Co. Cored wells in BEG Castleberry Survey 1 st yr 2nd yr Smith Co. 3rd yr Gregg Co. Rusk Co. South Kilgore Unit Cherokee Co. 21

22 Well Completion Depths Wells used 754 Deep wells 220 Shallow wells 534 Top of Woodbine Base of Woodbine 22

23 23 Stratigraphic Units

24 24 Stratigraphic Units

25 (a) Upper Stringer Sandstone (c) Total Castleberry Survey (b) Lower 25

26 Recovery Strategies Stringer Sandstones Depositional-trend-guied recompletions Efficiently managed waterfloods, both small and large (Zone Energy Inc.) Main Woodbine and Stringers Enhanced oil recovery 26

27 Results of Field Tests - Danmark Highlights Cost Share $700,000 Cost of Tests $752,000 Production >80,000 STB Turner #15 Cost: $105,000 IP: 13 BOPD Cum.: ~2,500 STB Moncrief #22 Cost: $135,000 IP: 40 BOPD Cum.: ~9,000STB Boston Moore #9 Cost: $9,000 IP: 50 BOPD Cum: ~14,400 STB Rev: ~$1.44 M Boston Moore #2 IP: 31 BOPD EUR >120, STB 12/11: 17 BOPD Boston Moore #10 12/11: 18 BOPD Boston Moore #14 Not deep enough Moncrief #38 Cost: $35,000 Castleberry Survey IP: 90 BOPD Cum.: ~16,000STB Akin #10 Cost: $92,000 IP: 39 BOPD Cum.: ~12,000STB Boston Moore A- #1 IP: 10 BOPD New deepening with oil New deepening with water Selected future targets Estimated Profit ~$12 M 27

28 Other Operators Field Results Tuttle (06404) # # Bander (06354) #2 18 #3 20 #10 25 Todd-Stinchcomb , ,252 #1 22 #2 17 # #4 28 #6 27 # # # #10 65 #14 80 #16 18 #17 27 # # # #21 30 #22 50 Akin (06352) #2 15 #4 14 # # # #19 32 #20 20 Burnside -B- (0675) Other operators # workovers # # Danmark workovers Zone Energy Waterflooding Near South Kilgore Unit 28

29 Future Prospects Danmark 2012 Prospects Akin -A- no. 5 Bassham no. 8 Boston Moore -B- no. 17 Hays no. 66 Moncrief no. 53 South Kilgore Unit Waterflood Danmark workovers Other operators workovers Prospects 29

30 Mid-Term Strategies for ETOF Production Enhancement Laboratory tests t of CO 2 flooding Minimum miscible pressure Immiscible Miscible Laboratory tests of Surfactant flooding Alkaline-surfactant-polymer (ASP) 30

31 ETOF Crude and CO 2 Phase Behavior (a) Swelling factor (b) Minimum miscibility pressure (MMP) Slimtube tests 31

32 ETOF CO 2 Flooding in ETOF 32 Mechanism Bi Brine Pure CO 2 CO Remaining 2 vaporizing oil oil components Brine Brine Estimated Recovery Efficiency 1.2 HCPV Injected % Re ecovery at CO 2 condensing into oil Recovery efficiency from Miscibleibl immiscible CO 2 flooding at current ETOF pressure will be less than half of that from CO 2 MMP miscible CO 2 flooding. Pressure (psia) Immiscible 1,000 1,400 1,800 2,200 2,600 ETOF Pressure ~1250 psia

33 CO 2 Flooding Pro High-quality reservoir and low gravity effect Con Most likely immiscible process Low reservoir pressure of ~1250 psi MMP~1780 psi (for 38 o API at 130 to 146 o F) Low residual oil saturation Unfavorable mobility ratio Lateral CO 2 containment Casing leaks 33

34 Casing Leaks (a) Locations of casing-leak wells One out of every four wells has had a casing leak (ETEA study, 1976). (b) Frequency of casing-leak wells vs. year ly Number of Leaks Yearl ks Data from ETEA, Year (c) Frequency of casing-leak wells vs. depth Number of Lea Data from ETEA, tive Number of Leaks Cumulat 34 Data from ETEA, Depth (ft)

35 Surfactant/Polymer Flooding Mechanism Residual oil Brine Surfactant/ Oil/surfacant/bri Polymer Slug ne emulsion Brine Upshur Co. Estimated Recovery Efficiency Recove ery Effic ciency Smith Co. (3) L. D. Crim #1 (4) Lanthrop #1 Gregg Co. Rusk Co. Areas for the ASP pilot test (2) Ashby #1 (1) Discovery well Daisy Bradford #3 % Interfacial Tension Decreasing

36 Alkaline-Surfactant Flooding (ASP) 36

37 Summaries 37 Best Giant Oil Field Recovery efficiency Current 78% Ultimate 80% Reservoir Architecture t Upper Woodbine sandstone Lower stringer sandstones Production Strategies Depositional-system guided recompletion Waterfloods EOR Field Demonstration Results fluvial channel deltaic Danmark >80, STB produced, EUR >120, STB Other operators Basa, SND, Zone