页岩等温吸附曲线SLD-PR模拟方法及应用

SLD-PR simulation method for shale adsorption isotherm and its application

胡志明 郭为 熊伟 左罗 沈瑞 高树生 杨发荣 苗雪

Hu Zhiming Guo Wei Xiong Wei Zuo Luo Shen Rui Gao Shusheng Yang Farong Miao Xue

页岩气主要由吸附气和游离气组成，吸附气体的含量直接影响页岩气藏的地质储量和页岩气井的产量。为了准确得到页岩的吸附气含量，以川南地区龙马溪组页岩为研究对象，设计了实验测量了温度在25～45 ℃，压力在0～8 MPa范围内页岩吸附甲烷的等温吸附曲线，发现页岩的吸附气量随着温度的升高而减少。通过简化局部密度函数（SLD-PR）理论计算了不同温度下页岩的等温吸附曲线并且与实验结果作对比，结果表明该方法可以用来计算页岩等温吸附曲线。利用SLD-PR方法预测了页岩气藏储层温度和压力条件下等温吸附曲线，弥补了高温高压下实验测量页岩等温吸附曲线误差大的不足。同时对比了利用SLD-PR方法和Langmuir方法计算的吸附气量，发现利用Langmuir方程计算得到的吸附气含量偏大，利用SLD-PR方法计算得到的页岩吸附气含量更加可靠。

Shale gas is mainly composed of adsorption gas and free gas.Adsorption gas content directly affects the geolo-gical reserves and well production for a shale gas reservoir.In order to accurately measure adsorption gas content, isothermal adsorption experiments were performed within temperature range of 25-45 ℃ and pressure range of 0-8 MPa on the Longmaxi Fm shale in South Sichuan Basin.Results indicate that shale adsorption capacity decreases as temperature increases.In addition, shale adsorption isotherms at different temperatures were calculated by using the simplified local density (SLD-PR) method and compared with the experimental results.The comparison shows that this method can be used to calculate shale adsorption isotherm.The SLD-PR method can be used to predict shale adsorption isotherm under reservoir pressure and temperature conditions, thus overcoming the disadvantage that the errors of isotherm experimental measurements under high temperature and pressure are large.Comparison between the calculated adsorption gas content by the SLD-PR method and that by the Langmuir method indicates that the former is more accurate and reliable than the latter.

10.11743/ogg20150121