塔里木盆地台盆区构造变动与油气聚散关系

塔里木盆地台盆区不同时期构造变动对不同目的层系不同成藏期次油气聚散影响不尽相同,油气在不同目的层系不同成藏期次成藏机制与分布规律也各有特点。奥陶系目的层第二成藏期等早期原生油气藏,由于遭受交替差异沉降运动和较大剥蚀速率影响,油气在地层平均剥蚀速率为25～35 m/Ma构造平衡叠合区较易成藏;石炭系目的层第三成藏期等晚期原生油气藏,受盆地继承性古隆起影响,高部位多次构造变动和剥蚀,油气很难在高部位聚集成藏,但在平均剥蚀速率为10～25m/Ma的低隆起和斜坡地带储盖条件较好的地区,油气极易聚集保存成藏。石炭系目的层第四成藏期等晚期原生油气藏,由于成藏最晚,一部分油气受东河砂岩、不整合面等优势通道影响,聚集在较高的构造部位,一部分油气由于排出较晚或没有优势通道,还来不及长距离运移就在凹陷周围有利部位聚集成藏。

A discussion on the relationship between tectonization and hydrocarbon accumulation and dissipation in the platform-basin transitional area of Tarim basin

The effect of tectonization in different periods on the accumulation and dissipation of hydrocarbons in different reservoirs varies in different accumulation periods. The accumulation mechanism and distribution pattern of hydrocarbons also vary in different reservoirs in different accumulation periods. For the early primary Ordovician reservoirs formed in the second accumulation period, hydrocarbons were prone to accumulate in superimposed area of relatively weak tectonization with an average erosion rate of 2.5 - 3.5m/50Ma due to alternate differential subsidence and great erosion rate. For the late primary Carboniferous reservoirs formed in the third accumulation period, hydrocarbons were prone to accumulate in low uplift and slope zones with an average erosion rate of 1.0 -2.5m/50Ma, rather than in structural high, due to multiple tectonization and erosion resulted from the successive paleohigh in the basin For the late primary Carboniferous reservoirs formed in the fourth accumulation period, some hydrocarbons accumulated in the structural high because of the existence of favorable migration pathways, such as the Donghe sandstone and unconformities, and some accumulated in the peripheral area of the depression without long migration because of late expulsion and lack of favorable migration pathways.