Assessment of fault sealing capacity in Structure A, Oligocene reservoir, Northeastern Cuu Long Basin
Abstract
Statistics indicate that more than 85% of hydrocarbon traps are juxtaposed against and/or directly dependent on the sealing capacity of fault systems. Therefore, the interpretation and quantitative assessment of fault sealing capacity in prospective structures is critical in petroleum geology. At present, fault seal capacity is commonly evaluated using two main approaches: direct and indirect approach. The direct approach determines fault sealing capacity based on experimental capillary pressure measurements on core samples collected directly from the fault damage zone or fractured zone. The indirect approach predicts fault sealing capacity by comparison with the sealing characteristics of nearby discovered structures through correlations between quantitative attributes on the fault surfaces, particularly the shale gouge ratio (SGR), and the pressure differential across the fault. Threshold values established from field data provide the basis for evaluating the sealing potential of undrilled structures.Quantitative assessment of fault sealing capacity not only improves the calibration of the probability of geological success for undrilled structures but also provides a scientific basis for predicting the hydrocarbon column height that can be retained within prospective structures.
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