非常規(guī)油氣藏（英文）

1、1,“UNCONVENTIONAL OIL AND GASRESERVOIRS”,PETE 689/602FALL 2003Lecture 9 ”Coalbed Gas”,LECTURE: Dr. Walter Ayers,2,Outline,Importance of coalbed gas sands Locations of USA coalbed gas basins What is coalbed gas

2、 Controls on coalbed gas occurrence and producibility Thermogenic, biogenic and mixed gas systems Examples from several US CBM plays,3,U.S. COALBED GAS RESOURCES,4,5,1998 GAS RESERVES, USA,UNCONVENTIONALGAS = 3

3、1%,,,Data from EIA,6,UNCONVENTIONALGAS = 23%,1998 GAS PRODUCTION, USA,Data from EIA,7,,U.S. COALBED METHANE PRODUCTIONAND RESERVES, 1989 THROUGH 2001,Ayers, 2002; data from U.S. DOE / EIA,8,TOTAL U.S. AND SAN JUAN BASI

4、N COALBED GAS PRODUCTION,1989 - 2000,9,COMPARISON OF COALBED GAS WITH CONVENTIONAL NATURAL GAS,,10,COMPARISON OF SANDSTONE ANDCOAL RESERVOIRS,11,Sorption isotherm for Gulf Coast Wilcox coalis similar to that for Fort

5、Union coal.(Pratt and other, 1999; Warwick and others, 2000),12,From Kuuskraa and Brandenburg, 1989,SCHEMATIC PRODUCTION HISTORY FORA COALBED METHANE WELL,,,,,,,13,INTEGRATED COALBED GAS PROJECT,Ayers, 1994,14,,,Fairwa

6、ys or sweetspots occupy less than 10% of a producing basin.The roles critical factors in fairway delineation may vary between high- and low-rank coal beds.,,,,,CRITICAL FACTORS FOR COALBED GASEXPLORATION AND PRODUC

7、TION,,Gas Composition Source Rock Gas Content Thermal Maturity Coal Occurrence Structural Setting Cleat Characteristics In-Situ Stress Hydrologic Setting,,15,COAL OCCURRENCE,Ayers, 1994,RESOURCE DELINEATI

8、ON QUESTIONS: What is total coal thickness? What is thickness of the thickest (maximum) coal? Does the coal occur in a few, grouped beds, or is it in many, thin beds distributed over an immense

9、interval? How continuous are the coal seams? What is the depth of the prospective interval?,,16,STRUCTURAL SETTING,Ayers, 1994,QUESTIONS What is structural complexity? Can compartments accommodate enough we

10、lls to support infrastructure? Are there fault blocks isolated from recharge? Are the faults sealing or transmissive? Is there evidence of structural traps? Is coal degassed below unconformities?,,1

11、7,From Ayers andAmbrose, 1990,18,STRUCTURE ON HUERFANITO BENTONITE, SAN JUAN BASIN,From Scott and others, 1994;after Ayers and others, 1991;and Palmer, 1992,OVERBURDENFort Union: 150 to 2,000 ft(Ayers, 1986)Gu

12、lf Coast:Calvert Bluff:150 to 3,500 ftThick coal > 2,000 ftdeep(Ayers and Lewis, 1985),,,19,Net Coal ThicknessFruitland Formation,San Juan Basin,From Ayers et al., 1994,20,Modified from Tyler and others, 19

13、95, after Ayers, 1984,Face Cleat Orientation,,,POWDER RIVER BASINSTRUCTURAL ELEMENTS,,,21,POWDER RIVER BASIN, FORT UNION FM,From Ayers, 1984,TOTAL COAL THICKNESS:Fort Union = 50 to +300 ftGulf Coast:Calvert B

14、luff = 3 to 20 ftAyers, 1984; Ayers and Lewis, 1985,,COAL ISOLITH,TONGUE RIVER MEMBER,THICKNESS,22,23,POWDER RIVER BASIN, FORT UNION FM,From Ayers, 1984,NUMBER OF COAL BEDS:Fort Union = 1 to 32 Gulf CoastCalve

15、rt Bluff1 to 16 Coal beds > 2 ft thick 0 to 4 Coal beds > 5 ft thickAyers and Lewis, 1985,,COAL ISOPLETH,TONGUE RIVER MEMBER,COALBEDS,24,COAL STRATIGRAPHY,Ayers, 1998,25,,,,,Pictured Cliffs Tongue,Lewis Shale

16、,Swamp,,,Wave-DominatedDelta,Depositional ModelFruitland Fm /Pictured Cliffs Ss,26,From Ayers, 1986,RELATIONS BETWEEN FRAMEWORK SANDSAND COAL BEDS, SANDOW MINE,27,JACKSON GP LIGNITE, SAN MIGUEL MINE, S. TEXAS,Photo b

17、y W. Ayers,28,GAS RESOURCES,Ayers, 1994,QUESTIONS What is the gas content of the coal? Is biogenic or migrated thermogenic gas present? What is the relation between gas content and depth? Is gas cont

18、ent measured or inferred,,29,THERMAL MATURITY,Ayers, 1994,QUESTIONS Are coal-rank maps available or are there sufficient data to make these maps? Has the coal produced thermogenic gas; is it high-volatile&

19、#160;A bituminous or greater (Ro > 0.78)? What is the relationship between maturation level and present burial depth?,,30,Gulf Coast Coal Rank: Lignite to Subbituminous,31,FRUITLAND COALRANK,

20、 SAN JUANBASIN,Modified from Scott, 1993,,,,,0.78,32,ADSORPTIVE CAPACITY OF COALAS RELATED TO RANK AND DEPTH,,Gulf Coast Coal is low-rank (lignite to subbituminous) Coalbed gas origin isbiogenic or migratedthermoge

21、nicKaiser and others, 1980; Tewalt, 1986;Mukopadhyay, 1989,33,From Mavor, 1990,SORPTION ISOTHERM, FRUITLAND COAL,NEBU WELL 403,34,From Warwick and others, 2000,,GAS STORAGE CAPACITY OFWILCOX LIGNITE, PA – 1 WELL,35,

22、Modified from Levine, 1993; After Ruppel and others, 1972,ADSORPTION CAPACITY OF COALFOR METHANE AND ETHANE,36,Fusinite (%),Percentage of methane desorbed in first 10 hours,PERCENTFUSINITE vs. DESORPTION RATE,SELE

23、CTEDWESTPHANIANCOALS, UK,From Creedy, 1991,,37,Modified from Creedy, 1988,GAS COMPOSITION, TOP HARD COAL,WITHAM, UK,38,From Ayers and Ambrose, 1990,GAS IN-PLACE,FRUITLAND FMCOAL BEDS,San Juan Basin,BASED ON:a. Co

24、al thickness, andb. gas content,GIP in Gulf Coast Coalis unknown Limited gas content measurements range from a trace to 11 Scf/t (daf)Warwick and others, 2000,39,SOURCE ROCK AND RESERVOIR,QUESTIONS What ar

25、e the maceral types? Are they liquid- or gas-prone? Have they generated hydrocarbons? What is the moisture content?,Ayers, 1994,,40,GAS COMPOSITION,Ayers, 1994,QUESTIONS What is the gas origin? What is its com

26、position? Will carbon dioxide or other noncombustibles have to be removed?,41,From Boreman and Powell, 1993, after Stach and others, 1975,MACERAL GROUPS AND HYDROCARBON POTENTIAL,42,From Rightmire, 1984; after Hun

27、t, 1979,GAS GENERATION FROM SAPROPELICAND HUMIC MATTER,43,Gulf Coast Coal Rank: Lignite to Subbituminous,44,COMPOSITION AND CONTENT OF GASIN COAL BEDS,,Ayers, 2000,45,Modified from Kotabarba and Rice, 1993; after Whi

28、ticar and others, 1986,ISOTOPIC CHARACTERIZATION OF GASES,46,From Scott, 1993, after Scott and others, 1991; Hanson, 1990,,GAS DRYNESS AND CARBON DIOXIDERANGES FOR COALBED GAS,47,,After Creedy, 1988,TYPICAL COMPOSITION

29、OF BRITISH COALBED GAS,48,FRUITLAND COAL GAS, DRYNESS INDEX,From Scottand others, 1994,49,CARBON DIOXIDE CONTENT,FRUITLAND COALBED GAS,From Scottand others,1994,50,CLEAT CHARACTERISTICS,Ayers, 1994,QUESTIONS What

30、 are the face and butt cleat orientations? What are the face and butt cleat spacings? Are cleats open? Are the cleats mineralized? Do cleat properties change areally and vertically?,,51,CLEA

31、T CHARACTERISTICS,,,,,,,,,C O A L,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,FACE CLEAT,MASTER FACE CLEAT,,TONSTEIN,,,,SH,BRIGHT,BRIGHT,DULL,,THIN,BRIGHTCOAL,,,,PALEOSTRESS,,THICKCOAL,BUTT CLEAT,,,,,,,,,,,,,

32、,,,Sh,From Ayers, 2002,52,CLEATS IN FRUITLAND COAL,Photo by W. Ayers,53,VITRINITE REFLECTANCE vs. MEANSPACING, FACE CLEATS,54,FACE CLEAT DOMAINS, SAN JUAN BASIN,From Tremain andothers, 1994,2 face cleat domains are pre

33、sent in the San Juan Basin,Face cleat characteristicsare poorly known forGulf Coast low-rank coals,55,IN-SITU STRESS,Ayers, 1994,QUESTIONS What is the coal depth (overburden stress)? Is the regional stress regime

34、 compressional or extensional? If compressional, what is the magnitude of minimum horizontal stress relative to overburden stress? What is the orientation of maximum horizontal stress relative to f

35、ace cleat,,56,Modified from McKee, 1989,COMPLEX FRACTURE,Complex (T-shaped) fractures may occur where minimum horizontalstress exceeds overburden stress,57,58,BLACK WARRIOR BASIN, POTTSVILLE COAL,From Sparks and others,

36、 1993,,59,BLACK WARRIOR BASIN, POTTSVILLE COAL,From Sparks and others, 1993,60,61,62,63,CONTROLS ON OVERBURDEN STRESS,Ayers, 1995,64,GAS AND WATER PRODUCTION,MANY coalbed gas projects require: Water production Water h

37、andling (and possibly, treatment) Water disposal,,65,HYDROLOGIC SETTING,Ayers, 1994,QUESTIONS Is the water fresh, brackish, etc.? Are there hydrochemical maps or data? Is there a potentiometric surface map?

38、 What is reservoir gradient? Is the ground-water system dynamic? What is the relationship between ground-water flow paths and coal-rank? Is there evidence of reservoir compartments?,,66,Modified from

39、 Scott and Kaiser, 1993; after Law and others, 1989,GROUND-WATER FLOW, COMPLEX MODELBASED ON WASHAKIE BASIN,67,From Scott and others, 1994; after Kaiser and others, 1991,FRUITLAND COALBED METHANE - HYDROLOGIC ELEMENTS,6

40、8,69,70,MAXIMUM DAILY WATER PRODUCTION,NORTHWEST SAN JUAN BASIN,From Scott and others, 1997,71,From Kaiser, 1993,GROUND-WATER FLOW AND GAS ORIGINS, SAN JUAN BASIN,72,From Scott and others, 1994,GAS SATURATIONOF COAL,73

41、,,,HOGBACK MONOCLINE, NORTHERNSAN JUAN BASIN,74,TRAPS AND EXPLORATION CONCEPTS:,,,Ayers, 2000,75,STRUCTURE ON HUERFANITO BENTONITE;FRUITLAND CBM FAIRWAY,76,FRUITLAND FORMATION, SAN JUAN BASIN,From Kaiser and others, 19

42、90,77,FRUITLAND COALBED GAS PRODUCTION,78,79,INTEGRATION: DEFINING POTENTIAL FAIRWAYS AND COMPARTMENTS AND OPTIMIZING RECOVERY,Ayers, 1994,80,Powder River Basin - Fort Union CoalProduction HistoryCoal OccurrenceStruc

43、tural SettingHydrologyTongue River Coals - Reservoir CharacteristicsPowder River Basin Coalbed PlayPrimary Economic FactorsConclusions,FORT UNION FORMATION, POWDER RIVER BASIN,81,Activity outline modified from Mon

44、tgomery, 1999Base map is Maximum Coal Thickness Map, Ayers, 1986,,POWDER RIVER BASIN,COALBED GAS PLAYS,82,NUMBER OF COALBED GAS WELLS,POWDER RIVER BASIN,Data from WOGCC, 2002,83,COALBED GAS AND WATER PRODUCTION,Powd

45、er River Basin,Data from WOGCC, 2002,84,From Ayers, 1986,COAL OCCURRENCEIN THE TONGUE RIVERMEMBER, FORT UNION FM,,Sand,85,POWDER RIVER BASIN, FORT UNION FM,From Ayers, 1984,TOTAL COAL THICKNESS:Fort Union = 50 to

46、 +300 ftGulf Coast:Calvert Bluff = 3 to 20 ftAyers, 1984; Ayers and Lewis, 1985,,86,NUMBER OF COAL BEDS:FORT UNION = 1 to 32 Gulf CoastCalvert Bluff1 to 16 Coal beds > 2 ft thick 0 to 4 Coal beds &g

47、t; 5 ft thick,,POWDER RIVER BASIN, FORT UNION FM,Ayers and Lewis, 1985,87,POWDER RIVER BASIN,FORT UNION FM,From Ayers, 1984,88,GAS QUANTITIES GENERATED DURING COALIFICATION,89,Modified from Tyler and others, 1995, aft

48、er Ayers, 1984,Face Cleat Orientation,,,POWDER RIVER BASINSTRUCTURAL ELEMENTS,,,90,Modified fromLobmeyer, 1985,POTENTIOMETRICSURFACE,TERTIARY STRATA,POWDER RIVER BASIN,91,COALBED GAS EXPLORATION IN THEPOWDER RIVE

49、R BASIN,Ayers, 2000,92,FLOWING ARTESIANWELLS, POWDERRIVER BASIN,Modified from Choateand others, 1984,93,ISOTOPIC CHARACTERIZATION OF GASES,Modified from Kotabarba and Rice, 1993; after Whiticar and others, 1986,,Therm

50、al,,Fermentation,,,Fort Union CBM(Warwick et al., 2000),,,,,Gulf CoastWilcoxUSGS-PA-2(Warwick and others, 2000),94,Sorption isotherm for Gulf Coast Wilcox coalis similar to that for Fort Union coal.(Pratt and ot

51、her, 1999; Warwick and others, 2000),95,SCHEMATIC: THICK COAL COMPLETIONS, DEEP vs SHALLOW,NO SCALE - GREAT VERTICAL EXAGGERATION,Ayers, 2000,Biogenic gas Low gas content Depressurization of deep coal,96,STRATIGRAPH

52、IC AND STRUCTURALCOMPLEXITY IN COAL RESERVOIRS,POWDER RIVER BASIN,Ayers, 2000,97,POWDER RIVER BASIN COALBEDGAS DEVELOPMENT STRATEGIES,98,Activity outline modified from Montgomery, 1999Base map is Maximum Coal Thick

53、ness Map, Ayers, 1986,,POWDER RIVER BASIN,COALBED GAS PLAYS,99,BIOGENIC ENGINE - MAP VIEW(Gas-Cap Recharge: Thin vs Thick Coal),100,BIOGENIC ENGINE - CROSS SECTION(GAS CAP RECHARGE),101,TONGUE RIVER COALBED RESERVOIR

54、 CHARACTERISTICS,Low rank (subbit.; 8,200 - 9,600 BTU, as rec’d)Low ash (4 - 11%)Low Sulfur (0.4 - 0.6%)High moisture (22 - 30%)Maceral Content: Vitrinite = 69 - 78%; inertinite =19 - 26% (Canyon coal) (Pratt et al.

55、, 1999)Thick (commonly > 50 ft), laterally continuous coalWell cleated for low-rank coalShallow; low overburden stressHigh permeability (100 - 1,000 md) (Pratt et al., 1999),102,COALBED RESERVOIR CHARACTERISTICS

56、(cont.),Gas content < 70 Scf/tBiogenic gasProduced gas < 1% carbon dioxide (Montgomery, 1999)Desorbed gas composition (Pratt et al., 1999)Limited data, Canyon coal bedApproximately 90% methane8% Carbon dioxi

57、de?1-2% nitrogen,103,DRILLING & COMPLETION METHODS*,80-acre spacingDepths commonly 200 to 900 ftTruck-mounted rigs drill in ~ 2 daysDrill 9 7/8-inch hole 1 ft into coal and set 7-inch surface casingDrill

58、 coal with 6 1/4-inch bit using air, air-mist, or waterUnder-ream coal to 10 or 12 inches and clean hole,104,DRILLING & COMPLETION (cont.)*,Use service rig to set tubing and submersible pumpProduce for 1-2 months t

59、o clean near-wellbore areaPull tubing and pumpStimulate with 500 bbl water at rate of 30 - 40 bbl/min. and surface injection pressure of 130 psigUse no proppantClean up*Pratt et al. (1999),105,WELL SCHEMATIC,

60、106,POWDER RIVER BASINCOALBED GAS PRODUCTION*,3,390 producing wells - August 2000Average gas production - 135 Mcf/d per well (August 2000)1.28 MMbw/d (average 518 bw/d per well; March 2000)Water/gas ratio is 3-4 bbl

61、/Mcf early, dropping to 1-2 bbl/Mcf Reserves are 200 - 400 MMcf/well,Data from Dwight’s, after Pratt et al. ,1999; Montgomery, 1999;Rice and others, 2000,107,PRIMARY ECONOMIC FACTORS,Drilling and completion costs $45,0

62、00 - $65,000Facilities costs $20,000 - $30,000Low Water disposal costsProduce at low wellhead pressuresCompression costs may be significantGas prices $1.15 - $2.00 / MMBTU at wellhead (early 2000; higher in late 200

63、0 and early 2001),108,ACCOUNTING FOR PRODUCTION RATES AND VOLUMES,HIGH GAS PRODUCTION RATES IN PRBGas rates are high owing to high values of kHCoal is very thickpermeability is high because (1) coal is relatively well

64、 cleated (low ash) and (2) in-situ stress is lowHIGH CUMULATIVE GAS PRODUCTIONDrainage area is greater than well spacing?Migration updip through high permeability coal?Low-rank coal has gas stored in pores that is u

65、naccounted for in desorption?Exsolution from water (Pratt et al., 1999; Bustin and Clarkson, 1999)?Active gas generation by microbial bacteria?,109,CONCLUSIONS,CBM activity is robust in the Powder River Basin in post-

66、tax credit eraReserves per well are low compared to those in other basinsThe play is economic because: Coalbeds are shallow and stress is low: open cleatPermeability is high and coal beds are thick and contin

67、uousShallow wells - low drilling costsCompletions are simpleStimulation is minor and relatively inexpensiveProduced water is fresh - disposal costs are lowPipeline access to markets has improved.Powder River Basin