哈拉哈塘奥陶系缝洞型成岩圈闭及其成因

Ordovician Fractured-vuggy Diagenetic Trap and Its Genesis in Hanikatam Formation

针对塔里木盆地塔北哈拉哈塘油田碳酸盐岩缝洞型成岩圈闭,综合利用区域地质、钻录井、酸化压裂、压力测试、生产动态等动静态资料,探讨圈闭的动态识别方法、特征及成因。研究认为,由于碳酸盐岩缝洞型储层渗透率高,一定条件下可以利用井口油压数据绘制 Np-△ p 图,并以此判断油藏属于开放性油藏还是封闭性成岩圈闭油藏;研究区缝洞型成岩圈闭规模总体较小,储层类型以洞穴型为主,圈闭盖层岩性、储盖组合及遮挡条件多样,发育多种圈闭要素组合模式;多期充填叠加是研究区缝洞型成岩圈闭封闭的根本原因,新近纪以来大规模快速沉降引发的成岩充填可能是大多数缝洞型成岩圈闭封闭的直接原因,沉降同时导致部分油藏形成异常高压。

This study focuses on the analysis of Ordovician fractured-vuggy carbonate diagenetic trap of the Halahatang oil reservoir in the north of Tarim Basin. By combining static and dynamic information such as regional geology, drilling time log, acid fracturing, pressure testing, and production dynamics, we discuss the dynamic identification method, characteristics, and genesis of traps. We hold that the wellhead oil pressure drop can be used to replace the formation pressure drop for plotting the Np p diagram due to the high permeability of fractured-vuggy carbonate oil reservoir. The diagram can be further used to determine if the oil reservoir is an open reservoir or a closed diagenetic trap reservoir. The total number of fractured-vuggy diagenetic traps is relatively small in the area. Cave reservoir being the major type of reservoir. Combinations of multiple other trap elements developed with various lithology of trap cover, reservoir cover combination, and diverse occlusion conditions. The multi-stage filling and stacking is found to be the fundamental cause of the closure of fractured-vuggy diagenetic trap. The diagenetic filling caused by large-scale rapid settlement since the Neogene may be the direct cause of the closure of most fractured-vuggy diagenetic traps. These settlements simultaneously result in abnormal formation pressure in some parts of the reservoir.