沾化凹陷泥质岩储层中裂缝类型及其成因研究

对沾化凹陷沙三段泥质岩储层发育段及其围岩的岩石组分、结构、构造特征进行了研究,系统地描述了泥质岩储层的裂缝产状及其分布。研究结果表明,沾化凹陷泥质岩储集层为裂缝型储集层,它具有严重的非均质性,按其成因差异,泥质岩裂缝可进一步细分为构造缝、成岩缝、成烃缝3大类6小类。其中构造缝和成烃缝是泥质岩储集层的主要储油空间和渗流通道,断层消失端、断层交汇区以及断层外凸区是泥质岩储层的发育区。泥质岩储集层形成于呈拉伸状态的深湖半深湖相纹层状泥灰岩之中。较高的有机碳含量、适中的混层比和埋藏深度以及优越的地层组合是泥质岩裂缝形成和发育的内因,特定的构造环境是诱发泥质岩产生裂缝的重要外部因素。

Fracture pattern and genesis of mudstone reservoir in Zhanhua Depression

The composition, texture and structural features of rock in the mudstone reservoir and surrounding rock in Zhanhua Depression were investigated. The pattern and distribution of fractures in the mudstone reservoir of this area were described systematically. The results show that the mudstone reservoir in Zhanhua Depression is a fractured reservoir with extreme heterogeneity. According to the genetic difference of the fractures, the mudstone fractures can be further divided into three types of structural fracture, hydrocarbon generation fracture and compound fracture including six secondary types. The structural fracture and hydrocarbon generation fracture are the main space for oil accumulation and the percolation channel for mudstone reservoir. The disappeared edge, intersection zone and outside zone of faults are the growing areas for mudstone reservoir. The mudstone reservoir was formed in lacustrine facies of lamellar marl in the deep water or semi-deep water sediment with tensional state. The endogenetic action for forming and growing mudstone fractures includes high content of organic carbon, moderate mixing ratio of formations and burial depth, predominant formation combination. The ectogenetic action for forming mudstone reservoir is the special structural environment.