--> Abstract: Integration of 3-D Seismic, Well Data and Reservoir Simulation Results for Delineation of Carbonate Khuff-C Porosity in Ghawar Field, by S. N. Dasgupta and M. R. Hong; #90942 (1997).

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Abstract: Integration of 3-D seismic, well data and reservoir simulation results for delineation of carbonate Khuff-C porosity in Ghawar Field

DASGUPTA, S. N., HONG, M. R.

The Khuff-C reservoir in Ghawar Field falls within a sequence of cyclic carbonate-evaporite deposits of the Permian Khuff Formation. The reservoir interval is comprised of interbedded tight and porous limestone and dolomite sandwiched between thicker anhydrite rich intervals. Syndepositional stratiform diagenetic changes, rather than depositional environment, were responsible for Khuff-C reservoir porosity

Several wells in the north-central field area penetrated Khuff-C reservoir. Two of these wells encountered the tight Khuff-C reservoir interval. Cores from Khuff-C in these wells show anhydrite cement filling the grainstone matrix and layers of fine-grained dolomite. A stratigraphic zero porosity edge is presently interpreted to the east of these two wells and the eastern flank of the structure has been condemned for further Khuff-C reservoir development.

Reservoir simulation history match results, however, suggest extra sources of reservoir energy in the eastern flank. More pore volume, larger reserves and water invasion from the aquifer are suspected in explaining the 200-300psi additional pressure.

The 3-D seismic data that was recently acquired in the area, show an abrupt termination of amplitude at Khuff-C near these two tight wells Acoustic impedance computed from the sonic and density logs at wells were used to calibrate the impedance derived from inversion of the seismic traces. The 3-D seismic shows an increase in acoustic impedance from known, porous, gas filled, Khuff-C reservoir to tight Khuff-C. The higher acoustic impedance is interpreted as a tight Khuff-C interval and is seen as an island with tight porosity localized at the crest of Khuff structure. These results conclude that Khuff-C porosity extends to the entire eastern flank of Khuff anticline and opens up a large fairway for porous Khuff-C reservoir delineation. The Khuff-C reservoir could potentially add 35% to the pore volume in the east flank.

AAPG Search and Discovery Article #90942©1997 AAPG International Conference and Exhibition, Vienna, Austria