--> ABSTRACT: Outcrop Analogs of Turbidite Petroleum Reservoirs for Assessing Volumetric, Development Drilling, and Simulation Scenarios, by R. M. Slatt, P. Weimer, H. A. Al-Siyabi, and E. T. Williams; #91021 (2010)

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Outcrop Analogs of Turbidite Petroleum Reservoirs for Assessing Volumetric, Development Drilling, and Simulation Scenarios

SLATT, ROGER M., PAUL WEIMER, HISHAM A. AL-SIYABI, and EUGENE T. WILLIAMS

The Pennsylvanian upper Jackfork Formation has been mapped in detail in superbly exposed quarries, dam exposures and other outcrops in the DeGray Lake-Hollywood area, Arkansas, to develop 3D analog models of turbidite reservoirs. If it is imagined that the floor of quarry or dam exposures are fluid/water contacts, and their upper ground surfaces are unconformities, then it is possible to map 'fluid' contacts, and when standing on these contacts, to imagine yourself within a turbidite reservoir. On this basis, 'volumetrics' can be calculated and 'development drilling' and 'simulation' scenarios under the different observed geologic conditions can be assessed. Two examples are presented.

Hollywood Quarry sits near the crest of a faulted anticline. A lower interval of shallow-dipping, thick, amalgamated, lenticular sandstones is separated from an upper interval of thin, laterally continuous, interlayered sandstones and shales by a thick, laterally continuous shale. Numerous faults dissect the quarry and compartmentalize strata over short distances. 'Volumetrics' have been calculated at about 300 MSTBOOIP for this 'reservoir' using pseudo values for P, Sw and Bo. For 'reservoir simulation', a two layer geologic model is adequate. Several 'development drilling' scenarios are possible owing to complex fault and stratigraphic compartmentalization.

At DeGray Lake Spillway, a 1000 ft. thick, steeply-dipping outcrop succession of thin- and thick-bedded sandstone intervals separated by thick shales has been correlated with numerous shallow core borings from the DeGray Lake Dam area, about one mile away. 'Volumetrics' for this 'reservoir' have been calculated at about 2 MMSTBOOIP using pseudo values for P, Sw, and Bo. A number of vertical, deviated, and horizontal 'development drilling' scenarios can be applied to this analog of a steeply-dipping, unconformity-capped turbidite reservoir.

AAPG Search and Discovery Article #91021©1997 AAPG Annual Convention, Dallas, Texas.