硫酸盐还原作用对巴什托地区巴楚组生屑灰岩段储层的改造

Thermochemical sulfate reduction in bioclastic limestone section of Bachu formation in Bashentuo region

通过对巴什托地区巴楚组生屑灰岩段的地层特征、区域沉积相带和储层微观特征的研究,认为生屑灰岩段储层的发育是在有利的蒸发台地相带基础上,经历了早期准同生白云石化作用,进入埋藏阶段后又叠加了硫酸盐还原作用的结果。海西期和喜山期两期的油气充注,使得生屑灰岩段成为含烃储层,此后烃类作为弱还原剂参与了生屑灰岩段储层的成岩作用,可以根据成藏期次和地温变化具体分为早期有机酸溶蚀及微生物硫酸盐还原作用(BSR)和晚期热化学硫酸盐还原作用(TSR)两个阶段。与硫酸盐还原作用有关的H2S在溶于水后形成氢硫酸对生屑灰岩段顶部(含膏)粉晶白云岩产生了强烈的溶蚀作用,是后期改造生屑灰岩段顶部优质储层的关键。

From the research on macro- characteristics of stratum,region sedimentary facies and microscopic characteristics of reservoir of bioclastic limestone member of Bachu formation in Bashentuo region.Came to the conclusion that the reservoir of bioclastic limestone member was developed on beneficial sedimentary facies, which suffered penecontemporaneous dolomitization and sulfate reduction after burial.Hydrocarbon charging during Hercynian and Himalayan period,made bioclastic limestone member to be a hydrocarbon- bearing interval,hereafter,as a reductant,hydrocarbon participate the diagenesis process.We can divide it into two stages by hydrocarbon accumulation period and the temperature change in stratum,which include organic acid corrosion plus microbial sulfate reduction in early stage and thermochemical sulfate reduction（BSR）in advanced stage（TSR）.H2 S correlation with sulfate reduction was dissolved in water produced hydrosulfuric acid which made the dolomicrite on top of bioclastic limestone member be dissolution.The process is the key genetic mechanism of the top of bioclastic limestone member high quality reservoir.