博乐盆地石炭系阿克沙克组沉积演化及页岩气有利区预测

Sedimentary Evolution and Prediction of Favorable Shale Gas Areas about Carboniferous Akshak in the Bole Basin

基于优选博乐盆地石炭系阿克沙克组页岩气有利勘探区问题,通过41条野外露头剖面和35口探井砂(泥)岩厚度读取及特征识别,确定了研究区的物源、沉积环境、沉积相类型、烃源岩展布;通过23个岩心样品分析的TOC、Ro、有机质类型实验和镜下微观刻画,明确了研究区烃源岩的页岩气生成条件和储层的孔渗特征。分析认为博乐盆地石炭系阿克沙克组页岩主要发育于温泉凹陷及博乐隆起内,最大厚度达到500 m、TOC为0.36%~7.11%、Ro值为1.79%~2.03%,干酪根以Ⅲ型和Ⅱ2型为主,脆性矿物石英+长石含量为23%~86%,碳酸盐岩含量为0~36%。有机质含量变化较大、热演化程度较高,储层孔隙发育程度较差,为特低孔、特低渗,但脆性矿物含量较高有利于人工造缝。基于以上成果,划出了研究区页岩气的进一步勘探有利区。

Based on the selection of favorable exploration areas of Carboniferous Akshak formation shale gas in Bole Basin,41 field outcrop profiles and 35 exploratory sand(mud)rock thickness readouts and feature identification were used to determine the study area.Provenance,sedimentary environment,sedimentary facies type,and source rock distribution;through TOC,Ro,organic matter type experiments and microscopic characterization of 23 core samples,the conditions and conditions of shale gas generation in source rocks in the study area were clarified porosity characteristics of reservoirs.According to the analysis,Carboniferous Akshak formation shale in Bole Basin is mainly developed in the hot spring depression and Bole uplift,with a maximum thickness of 500 m,TOC of 0.36%~7.11%,and Ro value of 1.79%~2.03%,kerogen is mainly typeⅢand typeⅡ2.The content of brittle mineral quartz+feldspar is 23%~86%,and the content of carbonate rock is 0~36%.The organic matter content changes greatly,the degree of thermal evolution is high,and the degree of reservoir pore development is poor.It is extra-low porosity and extra-low permeability,but the higher content of brittle minerals is conducive to artificial fractures.Based on the above results,favorable areas for further exploration of shale gas in the study area are delineated.