异常高压形成机理及对储集层物性的影响——以东濮凹陷文东油田沙三中油藏为例

Abnormal high pressure formation mechanism and its influence on reservoir properties: a case study of middle section of 3rd member of Shahejie formation in Wendong Oilfield,Dongpu sag

为研究油气藏储层异常高压的形成机理及对储集层物性的影响,以渤海湾盆地东濮凹陷文东油田沙河街组沙三中油藏为研究对象.通过镜质体反射率、显微镜下薄片、扫描电镜、X-衍射及实测压力等资料的分析表明:研究区储层异常高压形成的主要控制因素有生烃作用、膏盐岩封闭作用及断层的封闭性,油藏压力系数与储层物性参数具有较好的对应关系.异常高压对深部储集层物性的改善主要表现为:(1)减缓压实作用,有效保护原生孔隙;(2)促进溶解作用,形成大量的次生孔隙;(3)抑制黏土矿物的转化和后期成岩作用的持续进行;(4)致使储层岩石发生破裂,形成微裂缝.研究异常高压的形成机理及对深部低渗砂岩储集层物性的影响,对于深层油气勘探、开发具有重要意义.

In order to investigate the formation mechanism of abnormal high pressure in reservoirs and its effects on reservoir properties,we take the middle interval of the third member of Shahejie Formation in the Wendong Oilfield,Dongpu Sag,Bohai Bay Basin as the research object. It is shown by date from experiments such as vitrinite reflectance,microscopic thin-sections identification,scanning electron microscopy,X-ray diffraction and measured pressure that the main controlling factors of the formation of overpressure in the study area are hydrocarbon generation,closure effect of gypsum-salt rock and fault sealing ability. Besides,the relationship between reservoir pressure coefficient and reservoir physical parameters is significant. The improvements of physical properties in deep reservoirs resulted from abnormal high pressure mainly shows by：（1） compaction would be slow down and primary pores effectively would be preserved;（2） The dissolution would be promoted and a large number of secondary pores would be formed;（3） Clay minerals from conversion would be inhibited and subsequent diagenesis would be continued;（4） The reservoir rocks would be broken and microcracks would be formed. The study on the formation mechanism of abnormal high pressure and its effect on the physical properties of deep sandstone reservoirs lay a solid foundation for oil and gas exploration and development.