摘要
与北美页岩气区块页岩储层相比,昭通国家级页岩气示范区下志留统龙马溪组页岩表现埋藏深、成熟度高、孔渗低、地层压力系数高的特点。以页岩气钻井、测井资料解释及试井、试气数据为依据,着重对龙马溪组页岩气储层超压的分布规律和形成机制进行分析,以探索储层超压与页岩气高产的关系。研究表明,页岩储层超压与保存条件关系密切,随储层埋深与向斜宽度的增大、离通天断层与剥蚀区的距离增加,储层压力系数增大;而有机质生烃、剥蚀卸载、地应力挤压以及致密封隔层,是页岩储层超压形成的主要原因。分析认为,页岩储层超压是页岩气高产的重要因素,反映出处于有机质过成熟演化阶段的昭通示范区页岩储层,天然微裂缝发育,游离气所占比例较高。总体认为,昭通示范区龙马溪组页岩储层具有典型超压特征,是页岩气开发的甜点区,同时加强页岩储层超压预测研究有利于指导页岩气勘探。
Compared with North America,shale gas in the Zhaotong Demonstration Area is characterized by deep burial depth（2 000m）,excessively high thermal maturity（R_O=2.5%~3.2%）,low porosity and permeability,high pore pressure gradient（1.0~2.05）.The data of drilling,well logging,well testing verified the overpressure in Longmaxi Formation of Zhaotong area.The paper analyzed the distribution characteristics,formation mechanism of overpressure,and discussed the relationship between overpressure and enrichment of shale gas.The result shows that there are close connections among the overpressure distributions and burial depths,structural location,preservation condition of shale reservoirs;hydrocarbon-generation,rocks denudation,tectonic compression and tight surrounding rock are main formation mechanisms of shale reservoirs overpressure.The overpressure indicated over maturity of source rock,enrichment of micro-fractures and high component of free gas,which is thought as a major factor of the high-production of shale gas in this region.In all,the overpressure of Longmaxi Formation in Zhaotong is interiorly typical,meanwhile,it is the sweet spot of shale gas development,and the study of overpressure has important and directive effects for shale gas exploration in this region.
出处
《天然气地球科学》
EI
CAS
CSCD
北大核心
2016年第3期442-448,共7页
Natural Gas Geoscience
基金
中国石油天然气集团公司重大专项"页岩气钻采工程现场试验"(编号:2012F-47-02)
国家科技重大专项"云南昭通页岩气开采试验"(编号:2012ZX05018-006)联合资助
关键词
昭通国家级示范区
页岩储层超压
页岩气高产
游离气
龙马溪组
Zhaotong Demonstration Area
Shale reservoirs overpressure
High yield of shale gas
Free gas
Longmaxi Formation
