Conceptual Model for the Formation of an Oil and Gas Accumulation Zone at the Junction of the Sedimentary Cover and Basement on Southwestern Margin of Pogranichniy Trough, Sakhalin Shelf

Given the high degree of exploration maturity of conventional reservoirs on the Sakhalin shelf, further expansion of the resource base is increasingly associated with the search for and development of unconventional targets, among which reservoirs hosted by fractured basement rocks and their weathering crusts are of primary importance. Global experience (basement reservoirs in the Cuu Long Basin, Vietnam; the Lancaster Field in the Atlantic; and analogs in Brazil) confirms the industrial significance of such reservoirs provided that an effective source rock, migration pathways, and well-developed weathered zones are present. For the first time, an integrated concept is proposed for the southwestern margin of the Pogranichniy Trough that explains the feasibility of hydrocarbon accumulations within the basement. The conceptual petroleum system model is based on hydrocarbon generation within the siliceous Pilengskaya formation and scenarios of lateral migration into the Cretaceous deposits of the Polevoi Uplift, followed by accumulation within the weathering crust developed along the Laramide unconformity surface. By integrating ۲D/۳D seismic interpretation, constructing and analyzing a “pseudo” ۳D seismic cube, performing attribute analysis, and incorporating potential-field data, zones of probable weathering-crust development were predicted. The most prospective accumulation area is identified as the segment of the Polevoi Uplift adjacent to the Pogranichniy Trough. A comprehensive quantitative assessment using basin modeling is planned as the next stage.

کلیدواژه ها:

Petroleum geology ، weathering crust ، Basement ، Sakhalin Shelf ، Pseudo-۳D ، Seismic interpretation with attribute clustering analysis