海相页岩有利储集条件分析-以四川盆地长宁区块龙马溪组为例

四川盆地长宁示范区志留系龙马溪组泥页岩层段是川东南地区重要的烃源岩和页岩气重点勘探层位。为综合评价其有利储层发育特性及影响因素,在单井岩心观察、矿物组分分析、有机地球化学特征和地球物理测井等分析的基础上,根据该地区沉积环境演化特征,比较分析龙马溪组龙一段和龙二段的的沉积环境、岩相组合、矿物组分、孔隙空间、储层压力等特性对储层发育的影响。研究表明:研究区龙一段和龙二段由于沉积环境不同导致其地层发育、岩性组合、矿物组分、孔隙空间及有机质富集程度上具有很强的差异性。与龙一段相比,龙二段具有成岩作用强、热演化程度高、游离气含量大等特性;并且主要发育有机孔储集空间。对研究区页岩气储集最有贡献的主要是有机质含量,其与孔隙度和含气量成正相关性。证明页岩的不同沉积环境发育不同岩相组合、矿物组分、有机质含量,其共同影响页岩储层储集性能;并且可根据其组合特性综合预测海相页岩气有利储层。

The Analysis for Sichuan Basin Changning Block Longmaxi shale reservoirs favorable conditions

Favorable Longmaxi formation shale reservoir in Changning area is the important hydrocarbon source rock and stratum for shale gas exploration in Southeast of Sichuan Basin. In order to evaluate its reservoir characteristics and influence factors comprehensively, the sedimentary environment,lithologic association and mineral composition of the first and second member of Longmaxi formation are compared and analyzed based on the core observation, organic geochemical characteristics, geophysical well logging, and the characteristics of sedimentary environment evolution, etc. Research shows that due to different sedimentary environment, the formation development, lithologic association, mineral composition and organic matter enrichment of the first and second member of Longmaxi formation are quite different. The latter experienced strong diagenesis and high thermal evolution and mainly developed organic pore and had big free gas content. Organic matter content makes the most contribution to gas reservoir in the studied area, which has positively correlation with porosity and gas content. It turns out that the lithologic association, mineral composition and organic matter content developed in different sedimentary environment comprehensively influence the shale reserving property. And their combined characteristics help to predict Marine shale gas favorable reservoir.