塔里木盆地深层奥陶系走滑断裂区与非走滑断裂区储层流体超压演化差异特征与成藏机制

Differential fluid overpressure evolution and hydrocarbon accumulation mechanisms of deep Ordovician reservoirs in areas with and without strike-slip faults， Tarim Basin

薛一帆 赵海涛 黄亚浩 文志刚 刘宇坤 张银涛 乔占峰 罗涛

Yifan XUE Haitao ZHAO Yahao HUANG Zhigang WEN Yukun LIU Yintao ZHANG Zhanfeng QIAO Tao LUO

塔里木盆地深层奥陶系走滑断裂区与非走滑断裂区储层流体压力演化特征存在显著差异，目前勘探开发实践表明非断裂区具有较好的深层油气勘探开发潜力，但对该区域油气成藏和超压演化过程缺乏系统研究。基于测井响应数据和储层发育特征，运用流体包裹体古压力恢复和方解石U-Pb同位素定年，对比分析了富满油田断裂区和非断裂区油气成藏及超压演化过程。研究结果表明：①塔里木盆地非断裂区可以划分为“常压-弱超压-强超压”3个关键压力演化阶段。断裂区可以划分为“常压-弱超压-常压”3个关键压力演化阶段。②断裂区和非断裂区储层都在加里东中、晚期由于一期油气充注发育弱超压，随后断裂区碳酸盐岩储层在构造破碎作用和沿断裂输导的流体溶蚀的共同作用下，扩容形成大量孔洞和裂缝，连通的储集体使超压在沟通的断裂体系内再分配，地层压力逐渐降至正常状态。③非断裂区由于燕山早期深部油裂解气通过断裂-不整合面侧向运移至奥陶系储层，与构造挤压活动共同作用使得地层压力迅速提高至强超压，并一直延续至今。④塔里木盆地非断裂区经历了“早期成油、晚期气侵、侧向调整”的成藏演化过程。

The deep Ordovician reservoirs in areas with and without strike-slip faults in the Tarim Basin exhibit significant difference in fluid pressure evolution characteristics. Existing exploration practices have shown areas without strike-slip faults hold significant potential for deep hydrocarbon exploration and exploitation. However， there is a lack of systematic studies on the hydrocarbon accumulation and overpressure evolution processes in these areas. In this study， we examine these processes in areas with and without strike-slip faults within the Fuman oilfield based on log data， reservoir characteristics， paleo-pressure reconstruction from fluid inclusions， and the calcite U-Pb isotopic dating. The results are as follows. First， the areas without strike-slip faults in the Tarim Basin underwent three critical pressure evolution stages， namely normal pressure， weak overpressure， and strong overpressure in sequence. On the other hand， the areas with strike-slip faults in the basin also experienced three critical pressure evolution stages： normal pressure， weak overpressure， and normal pressure in sequence. Second， during the Middle-to-Late Caledonian， crude oil charging occurred for reservoirs in these areas， resulting in weak overpressure. In the late stage， numerous pores and fractures are formed in carbonate reservoirs in these areas under tectonic fracturing combined with the dissolution of fluids migrating along faults. The interconnected reservoirs facilitate the redistribution of overpressure within the connected fault systems. As a result， the formation pressure in these areas was gradually reduced to be normal. Third， in the areas without strike-slip faults， the formation pressure increased rapidly to strong overpressure during the Early Yanshanian due to two factors： the lateral migration of deep gas from oil cracking to the Ordovician reservoirs along faults and unconformities and the tectonic compression. The overpressure has been maintained up to now. Fourth， hydrocarbon accumulation in the areas without strike-slip faults followed a sequence characterized by early-stage oil generation， late-stage gas invasion， and lateral adjustment.

10.11743/ogg20250315