25th International Meeting on Organic Geochemistry IMOG 2011

P-375
Integration of basin modeling and geochemistry to describe dual
sourcing of granite wash reservoirs, Anadarko Basin, USA
Tony McClain 1,2 , Harris Cander 3,4 , Jonathan Evenick 5,6
1 Texas A&M University, College Station, United States of America, 2 Brigham Young University, Provo,
United States of America, 3 University of Texas, Austin, United States of America, 4 SUNY, Stony Brook,
United States of America, 5 University of Tennessee, Knoxville, United States of America, 6 University of
Buffalo, Buffalo, United States of America (corresponding author:tony.mcclain@bp.com)
In the onshore of the United States, exploration and
development plays rich in liquid hydrocarbons are
rapidly taking the spotlight away from dry gas plays in
the present economic environment. The
Pennsylvanian (PENN) Granite Wash (GW) is one
such play in the Anadarko Basin of Oklahoma and
Texas, U.S.A. Reservoir lithologies are highly
variable, and were shed northward into the basin as
the Wichita Mountains to the south were eroded. The
range was stripped down to the Precambrian
basement before being buried by Permian carbonates
and Mesozoic clastics [1] . Reservoirs were deposited
as alluvial fans and fan-deltas into the sea
immediately adjacent to the mountain front [1] .
The most important source rock in the Anadarko
basin has long been understood to be the Woodford
(WDFD) shale (Devonian-Mississippian). Wang and
Philp [2] established geochemical evidence for
significant generative capacity of the oil-prone Viola
Group (Ordovician), as well as the gas-prone Springer
Formation and Morrow Group (lower PENN) which lie
immediately below the GW. Burruss and Hatch [3] also
discussed the source potential of middle PENN
shales equivalent to and inter-bedded with GW
reservoirs. They demonstrated geochemically that
many oils in the Anadarko basin are mixtures, having
been sourced from up to three different source
intervals.
Twenty gas samples from PENN and deeper
formations were acquired and analyzed for
composition and stable carbon isotopes. Figure 1
shows two different gases, as distinguished by stable
carbon isotopes data. Related to source rock kinetics
(curves on the graph), the two families are interpreted
to represent gases originating from the WDFD and
PENN shales. The WDFD gases were obtained from
GW and other Pennsylvanian reservoirs as well as
deep Arbuckle and Hunton reservoirs. Whole oil gas
chromatography data from GW reservoirs also reveal
at least two different sources, consistent with the
interpretation from the gas isotopes samples. Basin
modeling suggests that while much of the WDFD
charge moved laterally out of the basin via pre-WDFD
strata, some also migrated vertically, focused by local
structures near the mountain front. Thus, petroleum
in GW reservoirs can be explained by charging from
proximal PENN shales, from the deeper WDFD shale,
or a varying mixture of the two.
Fig. 1. Del C13 ethane vs. Del C13 methane crossplot.
References
[1] Sorenson, R.P., 2005, A dynamic model for the
Permian Panhandle and Hugoton fields, western Anadarko
basin, AAPG Bull., v. 89, No. 7, pp. 921-38.
[2] Wang, H.D., and Philp, R.P., 1997, Geochemical
Study of Potential Source Rocks and Crude Oils in the
Anadarko Basin, Oklahoma, AAPG Bull., v. 81, No. 2, pp.
249-75.
[3] Burruss, R.C., and Hatch, J.R., 1989,
Geochemistry of oils and hydrocarbon source rocks, greater
Anadarko basin: evidence for multiple sources of oils and
long-distance oil migration, Oklahoma Geological Survey
Circular 90, pp. 53-64.
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