高压压汞法和氮气吸附法分析页岩孔隙结构

Pore Structure of Shales from High Pressure Mercury Injection and Nitrogen Adsorption Method

页岩储层的孔隙结构对页岩含气性评价和勘探开发具有重要意义,但目前国内对于页岩孔隙结构的研究相对较少。为此,采用高压压汞实验和低温氮气吸附实验对页岩的孔隙结构进行了研究,计算了页岩的孔隙结构参数,并结合微观孔隙结构图片分析了页岩孔隙结构对气体吸附和渗流的意义。研究表明,页岩孔隙以微孔和过渡孔为主,微孔和过渡孔提供了大部分孔体积。有机质中的微孔是页岩比表面积的主要贡献者,构成了页岩气体的主要吸附空间。页岩的孔隙类型复杂,孔隙形态多样,存在一端封闭的不透气性孔、开放性的透气性孔和墨水瓶孔等多种孔隙,且孔隙之间的连通性较差。较高的微孔和过渡孔保证了页岩储层具有很高的吸附聚气能力,但中孔和大孔发育较差,不利于气体渗流和页岩气藏的开发。

The pore structure of shales plays an important role in the evaluation of hydrocarbon content,gas exploration and development. However,there is little study on the pore structure of shales at home. High- pressure mercury injection and nitrogen adsorption experiments are employed to study the pore structure of shales and the pore structure parameters are also obtained. The effect of pore structure on gas adsorption and movement is analyzed. The results show that micropores and transitional pores are the main pore in shales,which provide the vast majority of pore volume. Micropore in the organic matter is the primary con- tributor to specific surface area and functions as the main adsorption space. The pore types are complicated and the pore morphology is diverse. There are airtight pores with a close end, air pores, and ink-bottle pores in shales and the pore connectivity is poor. The high content of micropore and transitional pore is beneficial for gas adsorption in shales, but the mesopore and macropore are backward, which goes against for shale gas seepage and production.