Wattenberg Field Area, A Near Miss & Lessons Learned After 35 Years of Development History Stephen A. Sonnenberg Robert J. Weimer
Front Wattenberg Field DJ Basin WYOMING Pay PIERRE SHALE Typical Depth -5000-4000 -3000-2000 NEBRASKA SUSSEX (TERRY) SS 4300-6000 6000 PIERRE SHALE SHANNON (HYGIENE) SS 4800 PIERRE SHALE Range WATTENBERG NIOBRARA A NIOBRARA B 6800 DENVER NIOBRARA C -6000-5000 5000-4000 4000-3000 3000-2000 2000 KANSAS Source Rock FT HAYS LIMESTONE CODELL SAND CARLILE SHALE GREENHORN LS GRANEROS SHALE D Sand 7100 COLORADO Source Rock J 2 SAND J 3 SAND SKULL CREEK SHALE 7600 DAKOTA SAND 7800 Sonnenberg, 2002
A A Diagrammatic Cross-Section Denver Basin West WATTENBERG FIELD Basin Center Accumulation with: Six Potential Reservoirs Main Pays: J Sandstone with Codell commingle Secondary Objectives: Dakota, Niobrara, Sussex, Shannon East Basement Sussex Shannnon Niobrara Codell J Sandstone Dakota Source Rock Source Rock Basement Gustason and Sonnenberg, 2003
Weimer & Ray, 1997
History of Wattenberg Gas Field A Near Miss! All DSTs or cores taken in the J indicated shows of gas Core analyses of the J compared with those of the Dakota in the SJB Original Est. EUR 1.3 TCF Old wells in area remarkably similar Earlier discovery at Roundup - 1967 Wattenberg discovered - 1970 Matuszczak, 1973
Conventional & Unconventional Reservoirs & The Resource Triangle Conventional reservoirs Small volumes that are easy to develop Unconventional large volumes difficult to develop Increased pricing Improved technology Holditch, 2005
Currently Productive Areas-GWA Wright, 2005; Modified after Ladd, 2001
Dakota Discovery Codell Discovery Sussex/Shannon Discovery J SS Discovery Wright, 2005
Cumulative Production GWA 1302 220 180 786 1524 Sussex/Shannon Codell/Niobrara D SS J SS Other Cum: 4012 BCFe (34%) Modified from Wright, 2005
GWA Spacing History 1970: 320 acre units for drilling & spacing of J Sand 1979: Additional J Sand well allowed per 320 acre unit 1980: Section 29 tax credit; Tight gas sand designation (exp. 2002) 1983: Codell spaced on 80 acre 1984,85: Niobrara added to Codell spacing order 1991: J Sand wells can be recompleted to C-N & commingling of all downhole zones allowed 1998: Rule 318A allows 5 wells per quarter section in GWA for all Cretaceous age formations (81 townships) 2005: Rule 318A modified to allow for section line & quarter section line wells (~ 20 acre spacing 27 townships) Modified from Wright, 2005 & Weimer, 2005
Oil & Gas Field Growth Low High Produced Level of technology required High Reserves Step outs Infill drilling New horizons Improved economics Improved geologic model Improved reservoir model Improved technologies Fracture stimulation Drilling & completion Recompletions Changing operator Enhanced recovery Reserve Growth Resource quality Low Sonnenberg, 04
The Wattenberg Geothermal Anomaly Vitrinite Reflectance Values, %Ro Higley & Cox, 2005
Wattenberg Thermal Anomaly Related to igneous masses in basement Located where CMD intersects Denver Basin Direct temperature measurements in wells Ro values GORs Modified from Weimer, 1995
0 HYDROSTATIC GRADIENT (0.43 psi/ft) 1000 2000 3000 Pierre Shale 4000 DEPTH 5000 Sussex (Terry) 6000 7000 8000 UNDERPRESSURED OVERPRESSURED Migration Paths Source Rock Shannon (Hygiene) Sharon Springs Mbr Niobrara Codell Benton Gp. Muddy J SS 9000 10000 0 1000 2000 3000 4000 5000 6000 7000 PRESSURE PSI Weimer, 1995
Overpressuring in Rockies Basins INCREASING THERMAL METAMORPHISM VOLUME OF GENERATED FLUID HYDROCARBONS MATURE VOLUME OF ORIGINAL UNMETAMORPHOSED IMMATURE ORGANIC MATERIAL (KEROGEN) VOLUME OF METAMORPHOSED ORGANIC MATERIAL ASSUMES GENERATED HYDROCARBONS ARE RETAINED IN SYSTEM & CONVERT TO STABLE SPECIES SAS, 04 Modified from Spencer, 1987 and Meissner, 1980
? Structural Overview North-trending structural axis Northeast trending right lateral wrench faults Antithetic and synthetic horsts and grabens 2000 Boulder Be.? 3000 2500 2750 3750 Golden Fort Collins 2500 17.5 1500 5 10 1500 2750 3250 2500 27.5 2000 3500 2500 2750 N 2750 S B.H. 3250 RM A 3000 300 3000 C.G. WFZ P. 3000 3000 3000 3000 2750 Greeley 27.5 W. WFZ 2750 J. WFZ Longmont Fault Zone 2500 2500 7N 5N Lafayette Fault Zone 1N 1S 3S 3N Denver Contours represent subsea depths to top J SS S.L. 68W 66W 64W 5S
T 5 N T 4 N
Codell Faulting Density is Greater than J Sand Ladd, 2001
J Sandstone Stratigraphic Nomenclature 7900 7950 Mowry Shale Huntsman Shale D Sand 8000 J Sandstone Skull Creek A 8050 Skull Creek Marker Skull Creek Ash 8100 Skull Creek Shale Sec 9 2N 67W Sec 31 1N 65W Gustason and Sonnenberg, 2003
J SS LSE/SB Skull Creek
Sequence Stratigraphy of J Sandstone 7900 TSE / LSE J Sandstone Skull Creek A 7950 Mowry Shale FC2 FC1 8000 8050 Huntsman Shale D Sand Horsetooth Member (LST/TST) Fort Collins Member (HST) TSE LSE Skull Creek Skull Creek Ash 8100 Sec 9 2N 67W Sec 31 1N 65W Gustason and Sonnenberg, 2003
T 1 N J Sandstone Original Gas in Place T 1 S T 2 N T 3 N T 4 N R 68 W R 67 W R 66 W R 65 W R 64 W A A B B EUR Red > 15 Bcf / sec. Green 10-12 Bcf / sec. Blue < 8 Bcf / sec. Hu, 2002
Gustason and Sonnenberg, 2003 Sequence Stratigraphy of Fort Collins Member W SW10 2N 67W SE11 2N 67W SW12 2N 67W SE12 2N 67W SW7 2N 66W SE7 2N 66W SW8 2N 66W SE8 2N 66W SW9 2N 66W SE9 2N 66W SW10 2N 66W SE10 2N 66W SW11 2N 66W SE11 2N 66W SW12 2N 66W SE12 2N 66W E Huntsman Shale (Graneros) Mowry Shale Fort Collins 1 Skull Creek A Skull Creek FC 3 FC2 FC 2A FC 1 100 Ft. 0 5000 10000 ft.
Kugel 21-18
Horsetooth Valley Cross Section SW NE25 1N 67W SW19 1N 67W NE19 1N 66W SW17 1N 66W NE17 1N 66W NE8 1N 66W SW4 1N 66W NE4 1N 66W SE33 1N 66W NE33 2N 66W SE27 2N 66W NE27 2N 66W NE Huntsman Shale (Graneros) Mowry Shale Fort Collins Member Skull Creek A FC3 FC2 FC2A FC1 100 Ft. Skull Creek 0 5000 10000 ft. Gustason and Sonnenberg, 2003
T 1 N J Gas Trap Is Stratigraphic (Facies Pinch-out & Muddy Valley-fill) R 68 W R 67 W R 66 W R 65 W R 64 W T 1 S T 2 N T 3 N T 4 N Paleovalley Paleovalley Paleovalley Paleovalley Stacked FC 1 and FC 2 A A B B FC FC 1 strandline strandline Paleovalley Paleovalley Paleovalley Stacked FC 2 & 3 J %Ro > 1 (blue line after Higley & Cox, 2005) modified from Hu, 2002; Gustason and Sonnenberg, 2003
Pertinent Data Muddy J Sandstone, Wattenberg Field Depth 7,600 8,400 ft BHT, o F 260 BHP, psig 2,900 Gross sand, ft 50 to 100 Net pay, ft 10 to 50 Porosity, % 8 to 12 Permeability, md 0.05 0.005 Original spacing 320 Est. original reserves 1.3 TCF Current Est. Cum 1.3 TCF modified from Matuszczak, 1976
Production Sweet Spot
Dome # 1-13 Frank Sec. 13-T4N-R65W
Niobrara & Codell Type Log NIOBRARA A CHALK 6900 B CHALK C CHALK 7000 NW SE NW Sec. 8, T3N-R67W 7100 FT. HAYES CODELL CARLILE G.R. 7200 Resis. 3 0 Dens. Neut. 30 10% -10 Gustason and Sonnenberg, 2003
Birmingham, 2000 Codell Pressure Gradient Based upon P-buildupsP Range: 0.366-0.669 0.669 psi/ft. Coincident with basin axis Most north of Wattenberg High Follows J Ro =1% outline (blue) High GOR, sweet spot (gray area) coincident with temperature anomaly
Pertinent Data Codell Sandstone, Wattenberg Field Depth 7,100 7,300 ft BHT, o F 220 BHP, psig 4,600 Gross sand, ft 10-15 Net pay, ft 5-12 Porosity, % 8 to 12 Permeability, md 0.05 0.005 Original spacing 80 Est. original reserves NA
Lessons Learned Bypassed pay Technology Field growth Long range migration Reservoir compartmentalization LRLC pays Geothermal anomalies