塔里木盆地北部雅克拉地区海相油气成藏特征与运聚过程

在前人研究基础上,结合塔里木盆地雅克拉地区海相油气地球化学特征,利用流体包裹体法对雅克拉海相油气的成藏期次进行厘定,并通过分析该区油气关键成藏期的构造演化过程,来确定油气聚集和调整的有利勘探区。雅克拉地区主要存在喜马拉雅早期(45.5~16.5Ma)和喜马拉雅中—晚期(22~4Ma)2期海相油气成藏过程,具有多期充注和晚期成藏的特点。雅克拉地区在喜马拉雅晚期的“构造翘倾”作用控制了海相油气的晚期充注和成藏有利区。喜马拉雅早期,雅克拉地区前中生界构造呈北东高、西南低的构造格局,油气充注范围广,雅克拉—雅东构造圈闭群均处于海相油气充注的有利范围内。喜马拉雅晚期受库车坳陷快速沉降,雅克拉地区中新生界构造发生了“翘倾”作用,前中生界构造由原来的北东高和西南低格局转变为北东低和西南高的构造格局,轮台断裂构造带及其以南圈闭是晚期海相油气充注的有利区。同时构造“翘倾”使喜马拉雅早期充注的海相油气藏遭受破坏或向南调整聚集。

Marine oil and gas accumulation in Yakela area,northern Tarim Basin

The filling and accumulation process of marine oil and gas was studied using oil and gas geochemistry, fluid inclusions and tectonic evolution in Yakela area of northern Tarim Basin. Marine hydrocarbon accumulation took place in Yakela area in two stages:the early (45.5-16.5 Ma) and the middle-late (22-4 Ma) Himalayan, and was featured by multi-stage filling and late accumulation. The late filling and accumulation of marine oil and gas were controlled by the "structural tilting" in Yakela area in the late Himalayan. In the early Himalayan period, the pre-Mesozoic structure was higher in the northeast and lower in the southwest. The range of marine oil and gas filling was wide, and the Yakela and eastern Yakela tectonic traps were favorable in the early Himalayan. In the late Himalayan, the Mesozoic tectonics in Yakela area warped and tilted due to the rapid subsidence of Kuqa Depression. The pre-Mesozoic structure became higher in the southwest and lower in the northeast. The Luntai fault belt and its southern traps are favorable for marine oil and gas filling in the late stage. Meanwhile, the earlier oil and gas reservoirs were damaged or adjusted southwards due to tilting.