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莺歌海盆地异常地层压力的分布状况、异常地层压力条件下的流-岩相互作用以及其对储层成岩演化影响方面的研究尚未展开,综合应用岩石薄片鉴定、扫描电镜分析、稳定同位素分析、流体包裹体均一温度测试等技术,系统分析了莺歌海盆地LD区现今压力分布特征、超压环境下储层成岩作用特征及超压流体活动对储层成岩演化的影响.结果表明:(1)地层超压驱动深层热流体向上释放,富含碳酸盐类离子成分的热流体运移到超压顶界面附近时由于温压条件变化而重新沉淀,形成高含量的碳酸盐胶结物致密层;(2)地层超压通过抑制粘土矿物的转化来减少碳酸盐胶结物的生成和石英次生加大,使原生孔隙得以有效保存;(3)LD区块储层普遍富含CO2,在超压环境下CO2在流体中溶解度增大,会大量生成H+;另外一方面,超压增加了LD区块有机酸的释放空间和时间,促进溶蚀作用的产生.由此可知,造成研究区中深部超压储层具有较高的孔隙度的主要因素为超压抑制了胶结物的生成,其次为超压降低了机械压实作用及促进了次生孔隙的发育.
The distribution of anomalous formation pressure in Yinggehai Basin, the flow-rock interaction under abnormal formation pressure and its influence on the diagenetic evolution of the reservoir have not been studied yet. The comprehensive application of thin-slice identification, SEM, stable isotope analysis, Fluid inclusions and other uniform temperature test techniques to systematically analyze the pressure distribution characteristics of LD area in Yinggehai Basin, the characteristics of reservoir diagenesis overpressure and the influence of overpressure fluid on diagenetic evolution of reservoirs.The results show that: (1 ) Overpressure driven deep thermal fluid to release upward, the thermal fluid rich in carbonate ion components migrate to near the overpressure top interface due to changes in temperature and pressure conditions and re-precipitation, the formation of high levels of carbonate cements dense layer; (2) Formation overpressure can reduce the formation of carbonate cement and quartz secondary growth by inhibiting the conversion of clay minerals, so that the primary pores can be effectively preserved. (3) The LD block reservoir is generally rich in CO2, On the other hand, overpressure increases the release space and time of organic acids in the LD block and promotes the dissolution of CO2 It can be seen that the main factors contributing to the higher porosity of overpressured reservoirs in the study area are overpressure, which inhibits the formation of cements, followed by overpressure, which reduces mechanical compaction and promotes secondary porosity development.