四川盆地J区块五峰组页岩储层及吸附气特征研究

中国页岩气资源丰富,借助美国页岩气勘探开发经验,中石油、中石化两大石油巨头在四川盆地率先取得突破,中石化在J区块已建成10×108m3/年页岩气产能。为深化认识J区块五峰组页岩储层特征与吸附气特征,通过岩心显微图像、CT扫描和3D FIB图像观察、矿物成分分析、压汞测试、解吸气和吸附气量测量实验及测录井资料进行分析研究。结果表明,页岩代表岩性为灰黑色富含有机质硅质炭质页岩,黏土矿物以伊蒙混层(I/S)为主,脆性矿物以石英、长石为主,含量介于67.5%~85.0%;孔隙度分布在2.0%~7.1%之间,水平渗透率介于0.005~0.545 m D,孔喉半径主要集中分布于4~16 nm;TOC介于1.3%~5.9%,Ro介于2.2%~2.8%;页岩解析气量不低于3.0 m3/t,甲烷饱和吸附体积为2.77 m3/t,总解析气以吸附为主,散失气校正量偏小。研究结果为今后在四川盆地及中上扬子地区寻找页岩气勘探有利区块提供了借鉴。

Research on Shale Reservoir and absorbed gas characteristics of Wufeng Formation in J Block of Sichuan Basin

The shale gas resource is rich in China. Taking example by the exploration and development experience of shale gas in American, the two oil giantscompanies Petrochina and Sinopec both made a breakthrough in Sichuan Basin, and Sinopec has gotten 10*108m3/a of shale gas capacity. For deepening the understanding of shale reservoir and absorbed gas characteristics of Wufeng Formation in J Block, we use core microscopic image, CT scanning, 3D FIB image observation, mineral composition analysis, mercury intrusion porosimetry, desorbed gas and absorbed gas content measurement experiment and logging data to analyse and research. It turns out that the main shale is gray black siliceous carbonaceous shale with rich organic matter, the primary clay mineral is illite(I/S), the main brittle mineral are quartz and feldspar, the content is between 67.5%-85.0%, the porosity is distributed between 2.0%-7.1%, and the horizontal permeability is among 0.005mD-0.545mD, the pore throat radius is mainly distributed in 4nm-16nm, TOC is between 1.3%-5.9%, Ro is between 2.2%-2.8%, and the shale desorbed gas content is less than 3.0m3/t, the methane saturation adsorption volume is 2.77m3/t, the total desorbed gas is main absorption, and correcting value of free gas is small. The research result provides a reference for looking for favorable block of shale gas in Sichuan Basin or Upper and middle Yangtze region.