塔里木盆地麦盖提斜坡西段成藏演化与有利勘探区域:以巴什托普油田为例

Hydrocarbon accumulation and favorable exploration areas in the western Maigaiti slope of Tarim Basin:A case study of Bashituopu oilfield

塔里木盆地麦盖提斜坡寒武系盐上、盐下是目前研究和勘探的热点区域。本文从二维地震资料解释入手,进行断裂详细刻画,对断裂性质及其作用进行分析,结合构造、沉积、埋藏热演化史研究,以巴什托普油田为例,进行成藏演化研究,借以有机地球化学实验分析数据佐证,探讨油气成藏过程。研究表明,麦盖提斜坡西段加里东期油气运聚主要发生在寒武系盐下,自北向南运移聚集;海西期油气经过巴什托普油田南北两侧的北西向走滑断裂垂直向上运移,然后经过不整合界面和砂岩层向巴什托普背斜运聚,形成古油藏;喜山期油气除了自西向东调整外,还有少量侧向油气充注,形成了现今的巴什托普残余油藏。因此,巴什托普油田南北两侧的走滑断裂带和巴什托普滑脱断裂之下的圈闭是麦盖提斜坡西段寒武系盐上和盐下有利勘探区域和目标。

The strata above and below the Middle Cambrian salt are the current research and exploration hotspots in the Maigaiti slope,Tarim Basin.The fracture characteristics were analyzed on the basis of seismic interpretation.Combined with the study results of structural geology,sedimentology and the thermal evolution history,the accumulation history of Bashituopu oilfield was analyzed.The Caledonian hydrocarbon migration and accumulation mainly occurred below the Cambrian salt at the western Maigaiti slope from north to south.Oil-gas migrated vertical upwards through northwestward strike-slip faults in the north and south sides of Bashituopu oilfield,and accumulated at the Bashituopu anticline forming an ancient oil reservoir in Hercynian Period.The present residual Bashituopu reservoir was formed in the Himalayan Period,besides the oil-gas adjusted from west to east,a small amount of lateral oil-gas filling.Both strike-slip fractures at the north and south sides of Bashituopu oilfield and traps under the Bashituopu main detachment faults are the favorable exploration objectives in the western segment of Maigaiti slope.