四川盆地及周缘地区牛蹄塘组页岩气概况及前景评价

General situation and prospect evaluation of the shale gas in Niutitang Formation of Sichuan Basin and its surrounding areas

探讨四川盆地及周缘地区下寒武统牛蹄塘组页岩的基础地质概况,并对牛蹄塘组页岩气前景进行评价。通过野外露头和盆地内的钻井资料分析,结果表明牛蹄塘组页岩除川西有剥蚀外,其他地区都有分布,且黑色页岩段厚度大,主要集中在下段;由川中地区向北、向东和向南3个方向分布,厚度一般在40m以上;有机碳含量高,多数地区有机碳的质量分数>2%;页岩已达成熟晚期—过成熟早期。该套页岩埋藏较深,演化时间长,保存条件复杂,因此勘探开发均有难度。四川盆地的西部、北部和东部,牛蹄塘组页岩埋深超过7km,只能作为页岩气勘探潜力区;勘探最有利的地区是川南地区,其次有利的地区为鄂西渝东地区。

In Sichuan Basin and its surrounding areas,the shale gas in Lower Cambrian Niutitang Formation is distributed over all areas except the corroded West Sichuan.And the effective thickness of the black shale is big,especially centralizes in the lower segment of Niutitang Formation.The thickness increases large from the central of Sichuan to the north,the east and the south and is generally above 40 m.The shale has high organic carbon content,more than 2% is in most areas of Sichuan Basin.The shale gas in Niutitang Formation has come to maturity or over maturity.This set of shales are deeply buried,evolved for a long time,and the preserved conditions complex,so,there are difficulties in exploration and development.The Niutitang Formation shale is buried deep over 7 km in the west,the north and the east of Sichuan Basin,therefore,these areas can only as the shale gas exploration potential areas.The most favorable exploration region is in the south of Sichuan Basin,and the second favorable areas are in West Hubei and East Chongqing.