64 / 2023-07-06 21:45:32

川西坳陷中部须家河组陆相页岩储层特征及控制因素研究

陆相页岩；须家河组；储层特征；控制因素；天府气区

摘要：经过多年的实践证实，赋存在暗色富有机质页岩地层中的页岩油气藏是具有巨大勘探潜力的一种非常规油气藏，已成为油气勘探开发领域中的热点。川西坳陷须家河组须三段和须五段富有机质页岩发育，近期在川西坳陷中部须五段页岩层段获气，显示其具有较好的页岩气潜力。为了厘清川西坳陷中部须五段页岩的地质特征，利用岩心、薄片和X射线衍射等资料，对须五段页岩的岩石学特征、物性特征、储集空间类型以及TOC等有机地球化学特征进行研究。研究表明：天府气区须五段页岩厚度大，分布稳定，石英、长石等脆性矿物含量高，平均可达70%，为后期压裂开发提供有利条件；发育黏土质页岩相、硅质页岩相、混合质页岩相，以硅质页岩相占主体；孔隙度总体位于2%-4%之间，渗透率介于0.001mD-0.1mD，为一套致密页岩储层，主要发育剩余粒间孔、黏土矿物晶间微孔、黄铁矿粒间孔、溶蚀孔，有机质孔极少发育，镜下多见微裂缝；有机质丰度高，TOC介于2~2.5%，生烃潜力好，均达到成熟阶段，有机质类型以Ⅲ型为主。储层物性主要受到成岩作用及裂缝发育程度的控制，微裂缝的发育有效的提高了储层渗透性，有利于油气运移，黏土矿物的转化和有机质热演化可为泥页岩提供大量储集空间。有机质类型、有机质成熟度、泥页岩厚度控制着页岩气潜力，对后期页岩气的开发起到决定性作用。

关键词：陆相页岩；须家河组；储层特征；控制因素；天府气区

Abstract: After years of practice, it has been proved that shale oil and gas reservoir which in black organic-rich shale is an unconventional reservoir with great exploration potential. It has become a hot spot in the field of oil and gas exploration and development. The organic-rich shale is developed in the 3th Member of Upper Triassic Xujiahe Fm(T₃x³) and in the 5th Member of Upper Triassic Xujiahe Fm(T₃x⁵), Western Sichuan Depression, Sichuan Basin. Recently, natural gas has been obtained from organic-rich shale in the T₃x⁵ formation, indicating that it has a good shale gas potential. Based on the core, thin section and X-ray diffraction data, the petrological characteristics, physical properties, reservoir space types and TOC and other organic geochemical characteristics of the T₃x⁵ formation shale were studied, to clarify the geological characteristics of the T₃x⁵ formation shale, central part of the western Sichuan depression. The results show that the shale of the T₃x⁵ Formation shale in Tianfu gas area has a large and the thickness and stable distribution. Quartz, feldspar and other brittle minerals have a high content, up to 70% on average, which provides favorable conditions for later fracturing development. Argillaceous shale facies, siliceous shale facies and mixed shale facies are developed, mainly siliceous shale facies. Mainly developing the residual intergranular pores, clay mineral intergranular micropores, pyrite intergranular pores, dissolution pores, organic matter pores are rarely developed, microfractures are more common under the microscope. The abundance of organic matter is high, the content of TOC is between 2 to 2.5%, the hydrocarbon generation potential is respectable, all of which have reached the mature stage, and the organic matter type is mainly type III. Reservoir physical properties are mainly controlled by diagenesis and fractures. The development of micro-fractures effectively improves reservoir permeability, which is conducive to oil and gas migration. The transformation of clay minerals and the thermal evolution of organic matter can provide a lot of storage space for shale. Organic matter type, organic matter maturity and shale thickness control shale gas potential. This plays a decisive role in the development of shale gas in the later period.

Keyword: continental shale; Xujiahe formation; reservoir characteristics; controlling factor; Tianfu gas area.