Kansas Geological Survey
Open-file Report 2001-38
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Kansas Geological Survey Open-file Report 2001-38 |
Lansing-Kansas City oolitic reservoirs exhibit geometries and architectures similar to modern oolites. Reservoirs usually contain multiple stacked, or en echelon shoals which formed in response to sea level fluctuations. It appears that two such lobes are stacked in the Plattsburg Limestone at the planned CO2 miscible flood site. Oomoldic reservoirs formed across the entire Kansas Pennsylvanian ramp, however, thicker, porous and permeable oolite deposits are commonly associated with the flanks or crests of small and large paleostructural highs. These structural highs, such as that underlying the Hall-Gurney Field, may have influenced the intensity of early diagenesis and may have been responsible for development of good reservoir properties. Grain size variation, location on oolite buildups and interbedded carbonate mud (aquitards) influenced the nature and extent of diagenetic overprinting.
Subaerial exposure and meteoric water percolation led to cementation around the aragonite ooids and often dissolution of the ooids and variable development of matrix and vuggy porosity. Resulting oomoldic grainstones, the principal reservoir lithofacies, underwent variable degrees of early or later fracturing and crushing, providing connection between otherwise isolated oomolds.
Porosities in these oomoldic limestones range up to 35% and permeabilities range from 0.01-400 md. Permeability is principally controlled by porosity, oomold connectivity, and connection created by matrix crushing and fracturing. Permeability is also influenced by oomold diameter, oomold packing, and matrix properties. Increasing bioclastic constituents within and bounding oolite beds are often associated with increasing mud matrix and decreasing porosity and permeability. Individual wells exhibit porosity-permeability trends with less variance than the overall trend exhibited by L-KC oomoldic limestones.
Within the L-KC 'C' zone in the Hall-Gurney field and the CO2 demonstration site permeability decreases from the top to the bottom of the LKC 'C' interval. Lower permeability with increasing depth in the reservoir interval is attributed to increased dense bioclastic limestone content.
Correlations of “irreducible” water saturations (measured at pressures equivalent to 60-120 feet above free water level) indicate that Swi increases with decreasing permeability follwing the trend: log Sw50 (%) = 0.22 log k(md)) - 0.43
Lansing-Kansas City oomoldic limestones exhibit a near log-linear trend between wetting phase saturation and oil-brine height above free water level with capillary pressures decreasing with increasing permeability at any given saturation and can be modeled using the relation: Pc = 10(A Sw + B) (rhowater-rhooil).
Residual oil saturation to waterflood (Sorw) is a critical variable for carbon dioxide miscible flooding since this represents the target resource. Most L-KC waterfloods in Kansas have only involved 1-5 pore volumes (PV) throughput before reaching their economic limit. At 5 pore volumes throughput Sorw averages near 30%. Though sampling is limited, Sorw may increase then decrease with increasing permeability (k).
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Byrnes, A.P., Watney, W.L., Dubois, M.K., Bujis, G., Guy, W.J., Gerlach, P., Franseen, E.K., Magnuson, M., “Geologic and economic aspects of the potential for carbon dioxide miscible flooding in central Kansas”: Kansas Geological Survey Open File Report 2000-46, p. 195.
Dubois, M.K., A.P. Byrnes, R.E. Pancake, G.P. Willhite, and L.G. Schoeling, 2000, Economics show CO2 EOR potential in central Kansas, Oil & Gas Journal, V. 98.23, pp. 37-41.
Dubois, M.K., A.P. Byrnes, and W.L. Watney, 2001, Field development and renewed reservoir characterization for CO2 flooding of the Hall-Gurney Field, central Kansas (abs), 2001 American Association of Petroleum Geologists Annual Convention, V. 10, p. A53.
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(map). Kansas Digital Petroleum Atlas, Kansas Geological Survey,
http://www.kgs.ku.edu/DPA/Plays/ProdMaps/lgkc_oil.html
Harris, P. M., 1979, Facies anatomy and diagenesis of a Bahamian ooid shoal: Sedimenta (University of Miami, Comparative Sedimentology Laboratory), 1-163 p.
LeBeau, J.A. 1997. Geologic controls on porosity and permeability in the Bethany Falls Limestone, Collier Flats oil field, Comanche County, Kansas. Unpubl. M.S. thesis, Department of Geology, University of Kansas, Lawrence, KS 205 pages, (available as Kansas Geological Survey, Open-file Report, no. 1997-76)
Riggs. C.H., L.J. Heath, and D.C. Ward, 1963, Petroleum-engineering study of the Hall-Gurney Oilfield, Russell County, Kansas, U.S. Department of Interior, Bureau of Mines, Report of Investigations, No.6134, 86 p.
Scholle, P.A., N. P. James, eds., 1995, Marine Carbonates I: Models, seismic response and Quaternary of Florida-Bahamas SEPM CD No. 1 SEPM, Society of Sedimentary Geology. (Photograph credit)
Watney, W.L., French, J.A., Doveton, J.H., Youle, J.C., and Guy, W.J., 1995, Cycle hierarchy and genetic stratigraphy of Middle and Upper Pennsylvanian strata in the Upper Mid-Continent, in Hyne, N., ed., Sequence Stratigraphy in the Mid-Continent, Tulsa Geological Society, Special Publication #3, p. 141-192.
Watney, W.L., French, J.A., and Guy, W.J., 1996, Modeling of
Petroleum Reservoirs in Pennsylvanian Strata of the Midcontinent,
USA, in, Forester, A., and Merriam, D.F., eds., Spatial Modeling
of Geologic Systems, Plenum Press, p. 43-77. (reference to 3-D
diagrams of Victory Field)
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Last updated December 2001
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