Gas Reservoir Compartmentalization in Lowstand ProgradingWedge Deltaic Systems: Oligocene Frio Formation, South Texas Ursula Hammes, Bureau of Economic Geology, Jackson School of Geosciences, University of Texas.
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Gas Reservoir Compartmentalization in Lowstand ProgradingWedge Deltaic Systems: Oligocene Frio Formation, South Texas Ursula Hammes, Bureau of Economic Geology, Jackson School of Geosciences, University of Texas Contributors and Sponsors Frank Brown (sequence stratigraphy) Bob Loucks (sequence stratigraphy) Ramón Treviño (geology) Patricia Montoya (geophysics) Randy Remington (geophysics) STARR Project Western Geco (seismic) IBC Petroleum Railroad Commission (logs, production data) OUTLINE Develop exploration model for Oligocene Frio deltaic lowstand sands. Assess exploration potential of growthfaulted basins. Establish structural and stratigraphic architecture. Define reservoir compartmentalization. DATA 3-D seismic data set. Well logs. Production and engineering analyses. Regional Overview Schematic NW-SE Cross Section Sea level Pleistocene Anahuac ? Pw Pw Pw Pw sf Pw sf sf On-shelf deposits (highstand and transgressive sands) Off-shelf deposits (lowstand sands) sf sf sf sf Mobile shale ridge Basin-floor fans Modified from Bebout and Loucks (1981) Frio Formation (Oligocene): Prograding wedge deltaic sediments and slope and basin-floor fans Study Area Study Area and Regional Tectonics 20 Miles 30 Km Outer Limit of Texas State Waters Study Area Salt Domes Corpus Christi Corpus Christi Bay Exploration in Growthfaulted Subbasins Growthfaulted subbasins in Corpus Christi area 1 TEXAS 2 CORPUS CHRISTI PORTLAND 3 3 Aransas Pass Oso Bay 4 4 Grass Flats Laguna Madre MUSTANG ISLAND PADRE ISLAND PORT ARANSAS 5 6 0 0 5 mi 5 km Faults cutting Frio Fm. are generalized QAd2176c Idealized Cross Section NW SE 6 Shingled turbidites on clinoform toes Incipient intraslope subbasin no. 6 1 ? ? 2 ~1000 ft ~1 mi ? ? ? Unexpanded older deep-water systems ? ? ? 3 4 5 ? Strike Line SW ms twt NE 0 500 1000 1500 2000 Prograding wedge Slope Fan Complex 2500 3000 Anatomy of a growth-faulted subbasin 3rd-order sequence composed of three mini-basins set up by growth faults New 3rd-order sequence Mobile shale Mobile shale Mobile shale Red Fish Bay Fault Map Seismic survey outline • Major growth faults (blue, green) • Antithetic and synthetic crestal faults (yellow) • Orthogonal fault (red) N Strike Line SW ms twt NE 0 500 1000 1500 2000 Prograding wedge Slope Fan Complex 2500 3000 Dip Line 0 0 500 500 1000 1 000 1500 1 500 2000 Crestal Faults 2 000 2500 2 500 3000 3 000 Prograding Wedge Exploration Depth Structure at mfs 3 (2460 ms) (Below 34 sand) Top Prograding Wedge Structure Map ft Contour Interval: 30 ft Isopach map of Frio Formation showing inferred sediment input (red arrows) and depocenters (blue contour fill) along growth faults (yellow) 0 2 Miles C.I. = 40 ft pw = lowstand prograding wedge Section of Red Fish Bay S5-Benchmark Charts Approximate microfossil biozones (benthics) Age of Stratal surfaces (Ma) Depositional sequences, systems tracts, and surfaces 2nd order Based on local subbasin (T/R cycles) Composite log 3rd order# with some component 4th orders SP Log section selected from well Res. 7000 24.78 Ma Marginulina idiomorpha, M. vagulata, H. howei 25.2 Ma 6 3 TS 25.2 Ma 25.38 Ma T1 Camerina sp. Miogupsinoides Cibicides hazzardi 26.62 Ma HST 10A 10B 9 8 LST:ivf 4 TST LST:ivf 2 TST 25.59 Ma 25.98 Ma TST T1 mfs = mcs 5E T1 Marginulina texana 3 4 TS 7 6 8000 13 HST 4 TST 5 5D LST:ivf HST TST 14 15 17 19 18 20 21 22 23 25 27 5C LST:ivf 28 29 30 31 4 HST Bolivina mexicana 27.33 Ma 27.49 Ma 27.51 Ma Hackberry unconformity 5B mfs = mcs 3\4T1 TST Base of Shelf 2 TS 4 & 5 pw’s AOI 3 LST:pw 32 8500 9000 9500 33 34 35 10,000 36 37 38 39 40 10,500 41 42 Nonion struma 3 4 & 5 pw’s with thin distal 4 HST’s and TST’s top sf and local mcs 28.0 Ma 7500 43 11,000 44 11,500 45 28.26 Ma 4 46 12,000 4 & 5 slope fans =3 sf system Nodosaria blanpedi, Discorbis “D” & Anomalina “F” cocoaensis 28.5 Ma 47 Lithostratigraphic “Frio” boundaries are diachronous Subbasin floor 28.58 Ma 2 LST 13,000 top bff and local mcs 28.4 Ma 28.6 Ma 12,500 28.5 Ma T1 3 LST:bff Distal HST 48 13,500 Pay zones Cross Section – Dip Line A A' Well A Well B Well C -100 SPnorm 20 0 GR 150 0.3 SFL 3 -100 SP 20 0.3 SFLA 3 -100 SPnorm 20 GR 0 150 -100 SP 20 0.3 SED Well D 3 -100 SPnorm 20 GR 150 0 -100 SP 20 0.3 ILM Well E 3 -100 SPnorm 20 -100 SP 20 0.3 ILD Well F -100 SPnorm 20 -100 SP 20 3 0.3 ILD 0 1 mi 0 1.5 km 3 Cross Section - Strike Line STRIKE SECTION B Well A SPnorm -100 20 SP -100 20 ILM 0.3 ohm.m 3 Well B SPnorm -100 20 SP -100 20 SN 0.3 ohm.m 3 Well C SPnorm -100 20 SP -100 20 ILM 0.3 ohm.m 3 Well D SPnorm -100 20 SP -100 20 SFLU 0.3 3 ILM 0.3 ohm.m 3 Well E SPnorm -100 20 SP -100 20 SFLU 0.3 3 ILM 0.3 ohm.m 3 Well F SPnorm -100 20 SP -100 20 SFLA 0.3 3 ILM 0.3 ohm.m 3 Well G SPnorm -100 20 GR 0 150 SP -100 20 ILM 0.3 ohm.m 3 Well H SPnorm -100 20 SP -100 20 ILM 0.3 ohm.m 3 B' Well I SPnorm -100 20 GR 0 150 SP -100 20 SED 0.3 ohm.m 3 ILD 0.3 ohm.m 3 Well J GR 0 150 ILM 0.3 ohm.m 3 Well K SPnorm -100 20 SP -100 20 Well L SED 0.3 3 ILM 0.3 ohm.m 3 0 2 mi 0 3 km SP -100 20 ILM 0.3 ohm.m 3 Reservoir Engineering and Production Analysis Production history and characteristics Reserve calculations Reservoir compartmentalization Volumetrics estimation Reservoir pressure performance Initial Bottom-hole Pressure Initial Bottom Hole Pressure (psi) 8,500 Lithostatic Pressure Gradient 9,000 351_McMoran_1 342_Phoenix_1 Nov. 1978 Jul. 1970 352_McMoran_1 Jun. 1977 343_McMoran_2 Feb. 1977 9,500 342_McMoran_2 Nov. 1979 343_McMoran_1 Feb. 1971 Sand 35 344_McMoran_2 Apr. 1975 Sand 36 334_McMoran_1 Nov. 1971 345_McMoran_1 Aug. 1973 10,000 344_McMoran_2 Apr. 1975 343_McMoran_2 Mar. 1976 342_Phoenix_1 Jul. 1970 343_McMoran_1 Feb. 1971 344_McMoran_1 Sep. 1984 345_Corpus_1 Jun. 1986 10,500 344_McMoran_1 Jan. 1972 343_McMoran_3 Dec. 1980 Sand 38 Sand 39 Sand 40 Sand 42 345_Corpus_1 Dec. 1982 344_Brock_1 Apr. 1984 342_McMoran_2 Jun. 1979 11,000 Hydrostatic Pressure Gradient 11,500 Overpressure zone Sand 43 Sand 44 Hydrocarbon Phases by Region North Area N South Area North Area 74.4% South Area 25.6% Natural Gas: 47.8 BCF North Area 5.4% North Area 60.8% South Area 39.2% Condensate: 1,328 MBC South Area 94.6% Water: 1,055 MBC Reservoir Drive Mechanism Well X – top sand – Sand 35 Well 422_Energy_6 Strong Ty pi ca Moderate l Weak Bottom Hole Pressure/Z (psi) Bottom Hole Pressure / Z (psi) P/Z plot for a waterdrive gas reservoir 7,000 6,000 5,000 4,000 3,000 2,000 1,000 0 Cumulative Gas Production (MMCF) Source: Miller, 2002 0 250,000 500,000 750,000 1,000,000 Cumulative Gas Production (MMCF) Reservoir Compartmentalization Reservoir Compartmentalization Indicators 3000 100,000 (A) (B) Homogeneous reservoir 2500 Homogeneous reservoir 2000 10,000 1500 Compartmentalized reservoir 1000 1000 Compartmentalized reservoir 500 100 0 1 10 100 Time (days) 1000 10,000 0 1000 2000 3000 4000 Cumulative gas production (MMcf) After Jenkin (1997) Red Fish Bay Compartments Zone A Zone B 7000 7000 6000 6000 5000 5000 4000 4000 3000 3000 2000 2000 1000 1000 0 0 0 900,000 1,800,000 2,700,000 3,600,000 Cumulative gas production (Mcf) 4,500,000 0 1,800,000 3,600,000 5,400,000 7,200,000 Cumulative gas production (Mcf) Reservoir Compartments North Area South Area Production and Pressure History Zone A Zone B 6000 8400 2800 10,400 4500 6300 2100 7800 3000 4200 1400 5200 1500 2100 700 2600 0 Jun-70 0 Jun-72 Jun-74 Jun-76 Jun-78 Jun-80 0 0 Jun-80 Jun-84 Jun-88 Jun-92 Production Analysis Well 1 Well 2 VSH_BEG VSH_BEG 1 Feet 0.3 0 TVD SP -100 0.3 20 SN ILD ohm.m 0 1 Feet 3 3 SP -100 20 TVD 0.3 3rd-order mfs 3rd-order mfs 10000 (A) Log and systems mfs tracts characteristics Trap styles (B) 9500 mfs ILD ohm.m 3 CONCLUSIONS Compartmentalization of Frio reservoirs is due to interplay of sediments and tectonics. Compartments are related to different sandstone bodies deposited at different times and to a common sandstone body that has several pressure compartments defined by fault segregation. Sequence stratigraphic correlation established framework for distribution of sand compartments. Best reservoirs occurred in late lowstand to transgressive deposits. Fault mapping from 3-D seismic provided crucial evidence to define compartments.