盖层全孔隙结构测定方法

DETERMINATION OF THE TOTAL PORE TEXTURE OF CAPROCK

承秋泉 陈红宇 范明 王强 陈伟钧

Cheng Qiuquan Chen Hongyu Fan Ming Wang Qiang Chen Weijun

中国石油化工股份有限公司, 石油勘探开发研究院, 无锡石油地质研究所, 江苏, 无锡, 214151

Wuxi Research Institute of Petroleum Geology, SINOPEC, Wuxi, Jiangsu 214151, China

目前测定岩石孔隙结构的方法有压汞法、气体吸附法等,但压汞法测不到岩石中最小的孔隙,气体吸附法测不到岩石中较大的孔隙,测定结果均不能得到完整的岩石全孔隙结构。将压汞法和气体吸附法2种测定结果换算相衔接可得到完整的盖层全孔隙结构孔径分布图及其毛细管压力曲线,结合全驱岩样饱和水模拟实验即可直接测定岩样突破压力。研究结果表明,泥岩、灰岩、白云岩、粉砂质泥岩等的突破饱和度在19%～37%之间,平均26%,而细砂岩、粉砂岩、含砾泥质砂岩等的突破饱和度在41%～49%,平均44%。根据岩样的岩性,结合其毛细管压力曲线和孔径分布图选择合适的饱和度值,该饱和度值所对应的毛细管压力可以近似地看作该岩样在地层条件下的突破压力。

Based on the results of mecury injection and gas absorption analytical methods of caprock,the complete pore diameter distribution diagram of caprock and the capillary pressure curve can be obtained.The breakthrough pressure of a rock sample can be calculated directly by the simulated test of gas driving saturated rock water.Research shows that the breakthrough saturation values are different in different rock types.The values are from 19% to 37% with average value being 26% in mudstone,limestone,dolomite,siltymudstone,etc.,and 41% to 49% with average value being 44% in fine sandstone,siltystone,muddy-conglomeratic sandstone,etc.Combining the capillary pressure curve,the pore diameter distribution diagram and the lithology of a rock sample,a reasonable saturation value can be determined.The capillary pressure value corresponding to the saturation can be approximately taken as the breakthrough pressure of the rock sample under the fomation conditions.

https://doi.org/10.11781/sysydz200606604