川口油田西南区成藏条件及主控因素分析

Basic conditions and main control factors of the hydrocarbon accumulation in the southwestern area of Chuankou Oilfield

川口油田西南区三叠系延长组长6-长4+5储盖组合邻近主要烃源岩层(长7),且在烃源岩大量生排烃期位于油气运移的指向区,具有较好的成藏条件.储油砂体两侧及上部为漫滩沼泽及分流间湾沉积的泥岩、致密粉砂岩,构成上倾岩性遮挡,形成良好的岩性圈闭.油层主要分布在北北东走向的三角洲平原分流河道砂体和北东向的三角洲前缘水下分流河道砂体内,主要受沉积相带、优质储盖组合和运移输导条件3大因素控制.

The reservoir-seal assemblage composed of Chang 4+5 and Chang 6 of Triassic in the southwestern area of Chuankou Oilfield is near to main hydrocarbon source rock(Chang 7).Because it is in the oriented region of hydrocarbon migration in the generation-expulsion period of a large amount of hydrocarbon,it has good basic conditions of hydrocarbon accumulation.There are mudstone and dense siltstone with back swamp and distributary estuary deposits in the two sides and the upper of oil-bearing sandbodies,and they are composed of updip lithologic shielding and form good lithologic trap.The reservoirs are lithologic reservoirs.The oil reservoirs mainly distribute in the delta plain distributary channel sandbodies in NNE and the delta front subaqueous distributary channel sandbodies in NE.Their hydrocarbon accumulation is mainly controlled by depositional microfacies,high-quality reservoir-seal assemblage and hydrocarbon migration conditions.