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Sequence and Seismic Stratigraphy of the Bossier Play (Tithonian), Western East Texas Basin*
By
George D. Klein1 and Kenneth R. Chaivre2
Search and Discovery Article #10045 (2003)
*Adapted from presentation by the senior author at East Texas Geological Society TECH 2003, April, 2003, and an earlier version published in GCAGS Transactions, 2002 (Klein and Chaivre, 2002).
1SED-STRAT Geoscience Consultants, Inc., Sugar Land, TX, 77479-6238 ([email protected])
2ConocoPhillips Company, Houston, TX
Abstract
The Bossier Formation of the western East Texas basin consists of two sequences separated by a major sequence boundary (SB-2). Its base and its top are defined by two sequences, SB-1 and SB-3, respectively. The former separates the Bossier from the Gilmer Lime (Cotton Valley Lime), and the SB-3 separates the Bossier from the overlying Cotton Valley Sand. SB-2 was identified in seismic sections by tracing seismic reflectors and geometries representing basin floor and slope fans. This boundary on the shelf is below a series of stacked deltaic sands. In well log sections, basin floor fan log patterns were traced laterally into slope fan and stacked delta log signatures. The fans represent a lowstand systems tract; the lower Bossier, a transgressive systems tract; and the upper Bossier, a prograding complex.
Analysis of burial history suggests that the lower Bossier accumulated when the East Texas basin was underfilled. Lowering of sea level associated with SB-2 is related to a major climate shift from tropical to cooler conditions that favored a rapid influx of sands from the ancestral Mississippi, Ouachita, and Red River systems. These sands formed within prograding deltaic packages, outer incised valley fill stacked deltas, and submarine fan systems. The stacked deltas and basin fan sand systems represent prospective gas plays.
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Objectives1). Establish sequence stratigraphic framework. 2). Identify major sand facies. 3). Map sand facies and identify potential exploration fairways. 4). Tie stratigraphy and facies to basin history.
Methods and Tasks• Detailed interpretation of well-log cross-sections (13 lines, 151 wells) • Detailed analysis of 13 seismic lines (~840 Mi.) • Identify all major sequence boundaries and systems tracts (methods of Mitchum et al., 1995; Van Wagoner et al.,1990). • Map log facies and seismic facies. • Identify best prospective fairways.
Regional to Global Setting (Figures 1, 2, and 3)Characteristics of time during deposition of Bossier Formation include: • Global high stand of sea level (Kimmeridgian) • Time of generation of major source beds • Tropical/humid paleoclimate • Deep weathering - shale-dominated system; Bossier - Low net/gross sand
Bossier Sequence Stratigraphy (Figures 4, 5, 6, 7, 8, 9, 10, and 11)The Bossier Formation is divided into two sequences by a mid-Bossier sequence boundary (SB-2) (Figures 5, 6, 7, 8, and 9).. The base and the top of the Bossier are also delineated by sequence boundaries (SB-1 and SB-3, respectively). The lower Bossier Formation (below SB-2) formed during rapid subsidence when mud was the dominant sediment deposited in the basin. On the other hand, the upper Bossier was deposited after a drop of seal level. The basin then was characterized by areas of deep water fan sedimentation as well as shelf to shelf-edge, stacked deltas, which together represent the fairways of the Bossier play (Figures 9, 10, and 11).
Basin Influence: Burial History Data (Figures 12 and 13)• Bossier was deposited during time of rapid mechanical subsidence. • Deposition could not keep up with subsidence until sea level dropped (SB-2). • PGC (prograding complex) formed during time when deposition kept up with or exceeded subsidence rate. • SB-2 may signify possible climate change favoring influx of sand (Figure 13).
Conclusions
GeneralIn mud-dominated systems, a drop in sea level will extend fluvial systems basinward. An associated change in climate is the driver that disperses sand into such settings. The exploration potential of this finding opens up many new sandy reservoir possibilities in mud-dominated systems.
Bossier FormationWithin the shelf region (mostly in Freestone County), the upper Bossier Formation is characterized by sandy deltaic units that organized as combined progradation, aggradational, stacked units composing a major gas producing fairway system. Within the slope, well developed basin floor fans, slope fans, and channel/levee complexes define a potential deep-water gas-producing fairway system. In the East Texas basin, deposition of the Bossier occurred during a time of relatively rapid fault-controlled subsidence, modified by salt movement. These developments, when combined with a lowering in sea level and moderate climate change resulted in the distribution of sand reservoirs in the shale-prone Bossier system.
Future of Bossier Play? (Figures 14 and 15) Some of the factors in determining the future of the Bossier play are: • Gas price: > $4.00 to $4.50 • Acreage Costs • Engineering at depths > 19,000 ft. • Consideration of creaming curves (Snedden et al., 2003) (Figures 14 and 15), in view of the potential fairway of deep-water Bossier reservoirs.
Status of Bossier Play in 2002 (Figure 16) Figure 16 shows the occurrence of major gas fields of the Bossier Play in the East Texas basin, as of 2002. Our analysis shows that the Nan Su Gail, Dowdy Ranch, Mimms Creek and Dew Fields occur within Highstand Systems Tracts, whereas the Bear Grass field occurs in a Transgressive Systems Tract. Bald Prairie field represents a Lowstand Systems Tract field. Application of the sequence stratigraphic creaming curve (Figure 15) suggests that the current status of the Bossier play is presently at the nick point between the Transgressive Systems Tract and the Lowstand Systems Tract. Likely, the Bossier Play has an estimated four to five years left.
AcknowledgementsConocoPhillips Company (Phillips Petroleum Company at the time of this study [David R. Fox, Scott McCullough, Lisa Ashabranner, Campbell Huntington]). John Havens, Seismic Exchange Inc. Doug Barnhouse, G.A.S Unlimited. C.R. Scotese (www.scotese.com). Robert W. Stancil, Anadarko Petroleum Corporation. Norman C. Rosen, GCSSEPM Foundation.
Anderson, E.G., 1979, Basic Mesozoic study in Louisiana, the northern, and the Gulf Basin province: Louisiana Geol. Survey Folio 3, 58 p. Ewing, T.E., 2001, Review of Late Jurassic Depositional Systems and Potential Hydrocarbon plays, Northern Gulf of Mexico: Gulf Coast Assoc. Geol. Soc. Trans., v. 51, p. 85–96. Forgotson, J.M., Jr., 1954, Regional stratigraphic analysis of Cotton Valley Group of Upper Gulf Coastal Plain: AAPG Bull., v. 38, p. 2476–2499. Galloway, W.W., and D.K., Hobday,1996, Terrigenous clastic depositional systems: New York, Springer-Verlag, 489p. Garner, H.F., 1959, Stratigraphic-sedimentary significance of contemporary climate and relief in four regions of the Andes Mountains: Geol. Soc. America Bull., v. 70, p.1327–1368. Haq, B. U., J. Hardenbol, and P.R Vail, 1987, Chronology of fluctuating sea levels since the Triassic: Science, v. 235, p. 1156–1167. Jackson, M.P.A., and S.J. Seni, 1983, Geometry and evolution of the salt structures in a marginal rift basin of the Gulf of Mexico, east Texas: Geology, v. 11, p. 131–135. Klein, G.D., and K.R. Chaivre, 2002, Sequence and seismic stratigraphy of the Bossier Formation (Tithonian), western East Texas Basin: GCAGS Transactions, v. 52, p. 551-561. Mann, C.J., and W.A. Thomas, 1964, Cotton valley group (Jurassic) nomenclature, Louisiana and Arkansas: Gulf Coast Assoc. Geol. Soc. Trans., v. 14, p. 143–152. Mitchum, R.M., J.B. Sangree, P.R. Vail, and W.W. Wornardt, 1995, Recognizing sequences and systems tracts from well logs, seismic data, and biostratigraphy: examples from the Late Cenozoic of the Gulf of Mexico: in Posamentier, H.A., and Weimer, P., eds., Siliciclastic Sequence Stratigraphy: AAPG Mem. 58, p. 163–197. Montgomery, S.L., and R. Karlewicz, 2001, Bossier play has room to grow: Oil and Gas Jour., January 29, 2001 issue, p. 36–43. Presley, M.W., and C.H. Reed, 1984, Jurassic exploration trends of East Texas: in Presley, M.W., ed., The Jurassic of East Texas: East Texas Geol. Soc. p. 11–22. Scotese, C.R., 2000, Paleomap Project: Earth History—Late Jurassic: C.R. Scotese Publications: www.scotese.com, http://www.scotese.com/late1.htm) Scotese, C.R., 2002, Climate History (Chart): C.R. Scotese Publications: www.scotese.com; http://www.scotese.com/climate history.htm (04/20/02). Snedden, J.W., J.F. Sarg, and X. Ying, 2003, Exploration play analysis from a sequence stratigraphic perspective: Search and Discovery Article #40079 (http://www.searchanddiscovery.net/documents/snedden/index.htm). Stevens, K.M., J.B. Wagner., T.D. Sheffield, L.L. Brooks, P. Zippi, M.A. Dablain, B. Brown, and R. Offenberger, 2002, Integrated analysis of the Upper Jurassic Bossier deltaic complex, East Texas (Abstract): Houston Geol. Soc. Bull., v. 44, No. 6, p. 21. Thomas, W.A., and C.J. Mann, 1964, Late Jurassic depositional environments, Louisiana and Arkansas: AAPG Bull., v. 50, p. 178–182. Todd, R.G., and R.M. Mitchum Jr., 1977, Seismic stratigraphy and global change of sea level, Part 8: Identification of Upper Triassic, Jurassic, and Lower Cretaceous Seismic Sequences in Gulf of Mexico and offshore West Africa: in Payton, C. E., ed., Seismic Stratigraphy—applications to hydrocarbon exploration: AAPG Mem. 26, p. 145–164. Ulmishek, G.F., and H.D. Klemme, 1990, Depositional controls, distribution, and effectiveness of world’s petroleum source rocks: U.S. Geological Survey Bull. 1931, 59 p. Van Wagoner, J.C., R.M. Mitchum, K.M. Campion, and V.D. Ramanian, V.D., 1990, Siliciclastic sequence stratigraphy in well logs, cores, and outcrops: concepts for high-resolution correlation of time and facies: AAPG Methods in Exploration Series, No. 7, 55 p. Williams, R.A, M.C. Robinson, E.G. Fernandez, and R.M. Mitchum, 2001, Cotton Valley/Bossier of East Texas: sequence stratigraphy creates depositional history: Gulf Coast Assoc. Geol. Soc. Trans., v. 51, p. 379–388. Williams, R, and R.M. Mitchum, 1997, Sequence-stratigraphic controls on Cotton Valley tight gas sandstones, Carthage Field, Panola County, Texas: in Shanley, R.A., ed., Shallow marine and nonmarine reservoirs: GCSSEPM Foundation 18th Ann. Res. Conf. Proceedings, p. 409–425. |
Figure 1. (Left) Bossier study area on map of
East Texas Basin showing regional tectonic features (after Montgomery
and Karlewicz, 2001). (Right) Isopach map of Bossier Formation, in seven
county area and location of Well Log Section 6-6’
Figure 2. Global context of Bossier Formation
(~ 150 Ma) (from
Figure 3. Regional setting for Bossier
facies,
as shown by a map of depositional systems early Cotton Valley
(Tithonian)
(from Ewing, 2001).
Figure 4. Stratigraphy of Bossier Formation: Two approaches. (Left)
Columnar section showing intertonguing interpretation of upper Bossier
contact (after Montgomery and Karlewicz, 2001). (Right) Sequence
stratigraphic model for Bossier Formation (from Williams and Mitchum,
1997). 
Figure 5. NW-SE dip-line Well Log
Cross-Section 6–6’, Bossier Formation, Freestone and Leon Counties,
Texas
Figure 6. Interpreted, updip part of NW-SE seismic dip line. Segpolar display (published with
permission of Seismic Exchange, Inc). Division of Bossier Formation is
shown, along with shelf edge, salt features, and seismic stratigraphic
features.
Figure 7. Interpreted, downdip part of NW-SE seismic dip line. Segpolar display
(published with permission of Seismic Exchange, Inc). Division of
Bossier Formation is shown, along with seismic stratigraphic features.
Figure 8. Interpreted seismic strike line, oriented SW to NE. Segpolar display
Figure 9. Bossier Formation sequence
stratigraphic model, East Texas Basin, developed by analysis of seismic
and well-log data. 
Figure 10. Map of depositional systems of
upper Bossier Formation (SB-2 to SB-3), East Texas Basin, Texas (after
Ewing, 2001,
Figure 11. Map of seven county area, East
Texas Basin, showing depositional units defining prospective plays in
the Bossier Formation and location of well log cross-sections in red)
used in this study.
Figure 12. Burial history and tectonic
subsidence curves, depocenter, East Texas Basin, Texas. Curve derived
from stratigraphic sonic log markers at southeast end of dip-oriented
seismic line
Figure 13. Average global temperature during
the Phanerozoic and part of the Precambrian, with one of the changes
from warm to cool during the latter part of the Jurassic (from Scotese,
2000;
Figure 14.
Conventional discovery curve (i
Figure 15. Creaming curve and sequence
stratigraphy (after Snedden et al., 2003).
Figure 16. East Texas Bossier play, as of
2002, showing fields, discovery wells, pipeline, and Anadarko Petroleum
Corporation acreage (from J.N. Seitz, Banc of America, Security Energy
and Power Conference, with permission of Anadarko Petroleum
Corporation).