Evaluating preservation conditions of the Upper Permian oil and gas in the highly steep and complex structural belt,eastern Sichuan Basin
There exist highly steep structures with complex forming mechanisms in eastern Sichuan Basin,making the exploration challenging.Thus,the evolution was discussed for the highly steep structural belt in an effort to unlock main controls on hydrocarbon preservation conditions in the Upper Permian Changxing Formation under the complexity.Then,the planar and sectional structural interpretation was performed,and the formation-water salinity in specific wells,formation denudation,and regional caprock extension were analyzed in combination with facies distribution and oil/gas testing of relevant wells.A system was established to evaluate the preservation conditions in such complex belt.At last,the conditions were comprehensively analyzed and classified by means of this system.Results show that(i)the preservation in the study area is principally constrained by structure,and its conditions mainly by faults and fault-induced fluid response characteristics;(ii)despite in this belt where experienced multiple-episode tectonism,the bulk of caprock is still conserved,bioreef-shoal reservoirs are massively extended,and structural traps are also developed,indicating great exploration potential;and(iii)some cores in the highly steep anticline possess very ordinary preservation conditions due to serious de-nudation and plentiful faults,while good conditions in the wide and gentle synclinal area among various structural belts,standing for a significant exploration prospect when the other favorable reservoir-forming assembly is available.
万方数据
维普
