豫西地区山西组—太原组页岩孔隙结构及其影响因素——以ZXY1井为例

Pore structure of shale in Taiyuan Formation and Shanxi Formation in Western Henan Province and the influence factors——A case study of drill hole ZXY-1

页岩孔隙结构是储层评价的关键,对页岩气的勘探、开发以及页岩储层改造等都具有十分重要的意义。本文以ZXY1井太原组—山西组页岩为例,利用低温氮吸—脱附实验、X衍射、扫描电镜等实验手段研究页岩孔隙结构及其影响因素。结果表明,太原组—山西组页岩孔隙复杂,发育有机孔、微裂缝和多种无机孔;孔隙孔径主要为2~50nm,以介孔为主,其次为微孔;孔容和比表面几乎全部由微孔和介孔提供。有机质、黏土矿物及其组合对孔隙结构影响分析表明,孔容与TOC含量、孔容与黏土矿物含量、比表面积与TOC含量、比表面积与黏土矿物含量均具有较为显著的正线性相关关系;TOC含量和黏土矿物含量数值乘积与孔容、比表面积表现为非常显著的正线性相关关系;TOC含量和黏土矿物含量双参数回归孔容与比表面积,相关系数高,误差较小。综合分析认为,有机质和黏土矿物对孔隙结构的影响并非简单正线性相关关系,而是复杂的正向关系。

Pore structure of shale is the key to reservoir evaluation. It is very important for shale gas ex ploration and development and shale reservoir reformation. This paper studied the pore structure of shale and its influencing factors by means of low temperature nitrogen absorption desorption experiments, X ray diffraction and scanning electron microscopy. The results show that in Taiyuan Formation and Shanxi Formation pore structure of the shale is complex, including organic pore, micro cracks and various inorganic pore. The pore size is mainly2～50 nm dominated bymesopore thancific surface area of the rock are almost all supplied by microporores and m of the whole organic materials and clay minerals on pore structure shows esopore. Ana olume and spe sis of influence that very clear positive linear correlation exists between the pore volume and the content of TOC, the pore volume and clay mineral con tent, specific surface area and TOC content, product of TOC content and clay mineral content and pore volume and product of TOC content and clay mineral content and specific surface area. The double parameter regression of TOC content and clay mineral content shows high correlation coefficient for pore volume and specific surface area smaller error. Comprehensive analysis shows that the influence of organic matter and clay minerals on pore structure is not a simple positive linear correlation, but a complex positive relationship.