准噶尔盆地车排子周缘地层超压特征及其与油气成藏的关系

Characteristics of formation overpressure and its relationship with hydrocarbon accumulation in Chepaizi and its surrounding area of Junggar Basin

以钻井、测井相关资料为基础,分析车排子周缘的超压分布特征及形成机制,研究超压对油气藏形成的影响,结合油气藏空间分布特征,探讨研究区超压分布与油气成藏的关系。研究结果表明:在纵向上,发育古近系安集海河组与侏罗系八道湾组—三工河组上下2套超压层,其主要形成机制分别为泥岩欠压实和有机质生烃;在平面上,超压主要分布在研究区南部,向北压力逐渐减小。超压对抑制成岩作用、减缓压实作用、产生微裂缝以提高储层储集性能、增强对油气的封盖能力以及促进油气的初次运移具有重要控制作用。超压与油气藏分布具有3种空间配置模式,即油气藏分布于超压层之上、油气藏分布于超压层内部以及油气藏分布于超压层之下。

Based on the drilling and logging information in Chepaizi and its surrounding area, the distribution characteristics and formation mechanisms of overpressure were analyzed. The impact of overpressure on the formation of hydrocarbon reservoirs was researched. Combined with the spatial distribution characteristics of reservoirs, the relationships between overpressure distributions and hydrocarbon accumulation were discussed. The results show that the overpressure systems are categorized into two sets in profile: the upper Paleogene Anjihaihe Formation and the Lower Jurassic Badaowan Formation-Sangonghe Formation, respectively. The main formation mechanisms of overpressure are mudstone undercompaction and hydrocarbon generation, respectively. On the plane, overpressure systems are mainly distributed in the south of the study area and the pressure decreases in the north. Overpressure plays an important role in restraining diagenesis, retarding compaction and producing micro-cracks in order to improve the reservoir bed physical properties, enhancing the sealing ability of cap rocks and promoting the primary migration of hydrocarbon. There are three spatial configuration modes between overpressure stratum and distributions of reservoirs, namely, reservoirslocated above the overpressure stratum, reservoirs located in the overpressure stratum and reservoirs located below the overpressure stratum.