川西地区上三叠统非常规天然气勘探潜力分析

川西地区上三叠统油气勘探经历了曲折复杂的过程，以砂岩地层为主，但砂岩储层表现为薄砂薄储，埋深大，物性差，勘探难度大，效益开发风险大，制约了川西油气勘探进程。川西须家河组主要为砂泥岩互层，泥页岩单层厚度和累计厚度均较大，有机质类型以Ⅲ型为主，有机碳量较高，有机质热演化程度较高，Ro在1.1%~2.3%，处于生烃高峰期，生成的天然气一部分运移到砂岩储层中，形成构造气藏及致密砂岩气藏，大部分天然气以游离和吸附状态存在于泥页岩中，为页岩气藏的形成奠定了基础。分析认为，川西地区须家河组具有致密砂岩气与页岩气共生的特点，致密砂岩气和页岩气的开发手段都以压裂造缝为改造工艺，具有相似性，为川西地区须家河组砂—泥岩一体化勘探提供了条件。研究得出，对川西须家河组非常规气勘探不能“单打一”，应有针对性地对砂岩、泥页岩实行“组合拳”式的综合勘探，从而发现更多的天然气资源。

Analysis of potential of unconventional gas exploration in upper Triassic in Western Sichuan

The upper Triassic oil and gas exploration in Western Sichuan has experienced a tortuous and complex process，mainly in sandstone formation，but the sandstone reservoir is characterized by thin sand and thin reservoir，large buried depth，poor physical property，great exploration difficulty and high benefit development risk，which restricts the process of oil and gas exploration in western Sichuan.The Xujiahe Formation in Western Sichuan is mainly composed of sand shale interbedding.The thickness of single shale layer and cumulative thickness are large.The type of organic matter is mainly type Ⅲ.The organic carbon content is high.The thermal evolution degree of organic matter is high.Ro is in the range of 1.1%~2.3%.It is in the peak period of hydrocarbon generation.Part of the generated natural gas is transported to the sandstone reservoir to form structural gas reservoir and tight sandstone gas reservoir.Most of the natural gas is free gas，and adsorption state exists in shale，which lays the foundation for the formation of shale gas reservoir.The analysis showed that the Xujiahe Formation in Western Sichuan has the characteristics of tight sandstone gas and shale gas symbiosis，and the development means of tight sandstone gas and shale gas all take fracturing as the transformation process，which has similarity，providing conditions for the integrated exploration of sand and shale in Xujiahe Formation in Western Sichuan.It was concluded that the unconventional gas exploration of Xujiahe Formation in Western Sichuan can not be carried out alone，but should be carried out in combination with sandstone and shale，so as to find more natural gas resources.