川东北地区大安寨段页岩油气资源评价与有利区优选

Resource evaluation and favorable area optimization of shale oil and shale gas in the Da'anzhai member northeast Sichuan Basin, China

四川盆地是中国最具勘探潜力的非常规油气盆地之一,其中川东北地区的大安寨段地层发育富含机质并与薄层介壳灰岩互层的页岩,有生烃、含油含气的特征,具有页岩油气开发潜力。为明确四川盆地川东北地区大安寨段页岩储层的油气资源潜力,综合运用油气地球化学和地质学研究方法,对该地区的页岩油和页岩气的资源潜力进行评价,预测页岩油气的有利区。结果表明:大安寨段岩性主要为黑色页岩和介壳灰岩。其中,大二亚段为富含有机质的页岩层段;大安寨段累计厚度约为60~110m,埋藏深度约为1000~3600m;有机质类型以Ⅱ2型为主,有机碳含量介于0.42%~2.74%,平均值为1.18%;有机质成熟度为0.94%~1.84%,主要处于成熟—高成熟阶段;大安寨段页岩埋藏深度适中,有效厚度大,生烃潜力高,具备页岩油气成藏的基础条件;大安寨段页岩气和页岩油的有利区位于研究区西南部和东部,估算页岩气资源量为24543×10^(8)m^(3),页岩油资源量为10×10^(4)t。根据研究结果,分别优选研究区的页岩油气的Ⅰ类有利区带和Ⅱ类有利区带,可为大安寨段页岩油气勘探开发提供参考。

Sichuan Basin is one of the most potential unconventional oil and gas basins in China.The Da'anzhai formation in the northeastern Sichuan Basin has developed a set of shale rich in organic matter and interbedded with thin-layer shell limestone.It has the characteristics of hydrocarbon generation,oil and gas,and has great potential for shale oil and gas development.In order to clarify the oil and gas resource potential of shale reservoirs in the Da'anzhai section of the northeast Sichuan Basin,this paper comprehensively utilizes the methods of organic geochemistry and petroleum geology to evaluate the resource potential of shale oil and shale gas in the study area,to find out the direction of exploration as well as favorable zones for shale gas and oil.The results show that,the lithology of Da'anzhai section is mainly black shale and shell limestone,the thickness of shale in Da'anzhai section is about 60~110 m,and the depth of burial is about 1000~3600 m.The type of organic matter is mainly of typeⅡ2,and the content of organic carbon ranges from 0.42%to 2.74%,with an average of 1.18%.The vitrinite reflecance of organic matter is from 0.94%to 1.84%,which is in the mature to high-mature stage.The depth of shale in Da'anzhai section is moderate with large effective thickness and high hydrocarbon potential,therefore,the shale of Da'anzhai section has the basic conditions of shale oil and gas formation.The favorable areas of shale gas and shale oil in Da'anzhai section are located in the southwest and east of the study area with the estimated shale gas resources of 24543×10^(8) m^(3) and shale oil resources of 10×10^(4) t.According to the research results,this paper optimizes the Ⅰ-type favorable zone and Ⅱ-type favorable zone of shale oil and gas in the study area,which can provide reference for the exploration and development of shale oil and gas in the Da'anzhai section.