Density Modeling of the Basement of Sedimentary Sequencesand Prediction of Oil-Gas Accumulation:Evidence from South Sakhalin and West Siberia

摘要

The zones of deconsolidation and consolidation in the lower parts of the sedimentary cover and inthe basement are considered as an important exploration indicator of oil–gas accumulation zones. The describedzones are mapped using geodensity modeling (in a gravity field) in the MZ–PZ basement and Cretaceous depos-its of South Sakhalin, as well as in the pre-Jurassic basement and plate complex of the central part of West Sibe-ria. It was found that the most promising zones are confined to the Central Sakhalin Fault and Krasnoleninskarch in Sakhalin and to the Visim megaswell in the West Siberian plate. Recent prospecting drilling revealedthat deconsolidation zones arc correlated with hydrocarbon reservoirs. The presented technique of geodensitymodeling can be applied for petroleum-geological explorations of structures formed in different geological andtectonic settings.