不同温度条件下页岩储层吸附能力预测模型

1.延长石油(集团)有限责任公司研究院,陕西 西安 710075; 2.中国石油大学(北京)石油工程教育部重点实验室,北京 昌平 102249

页岩; 吸附; 温度; 预测模型

A new model for adsorption curves prediction at different temperatures in shale gas reservoir
AN Shu-ping1,LI Jing2,YU Peng-liang2,BAI Yan-gai2

(1. Research Institute of Shaanxi Yanchang Petroleum(Group)Co.,Ltd.,Xi'an 710075,China; 2. Key Laboratory for Petroleum Engineering of the Ministry of Education,China University of Petroleum(Beijing),Beijing 102249,China)

shale; adsorption; temperatures; prediction model

DOI: 10.13800/j.cnki.xakjdxxb.2016.0214

备注

吸附特征曲线函数是预测不同温度吸附曲线的重要参数,主要依靠“拟合”得到,缺乏严格理论推导,且需要多个温度下的吸附数据确保拟合精度,不能达到高效预测的目的 。基于Polanyi吸附势理论与Langmuir吸附理论,推导了吸附特征曲线函数式,揭示了温度对吸附曲线的影响规律,并且建立了“仅利用一条等温吸附曲线预测其他温度吸附曲线”的方法。实验表明:利用页岩样品低温(38 ℃)条件下吸附曲线,预测得到的高温(65~150 ℃)条件下吸附曲线误差小于5%,具有较高精度。同时,在考虑实际储层压力梯度、地温梯度基础上,耦合温度与压力的共同影响,量化了页岩吸附能力与储层埋深关系曲线。结果 表明:在埋深较浅的情况下(<750 m),页岩储层吸附能力随埋深增大而迅速增强; 随后吸附能力随埋深变化缓慢,达到峰值后,存在下降趋势; 样品吸附能力峰值对应的埋深约2 200~2 400 m.

Prediction of adsorption isotherms under different temperatures is significant to reserve estimation of shale gas reservoir.Based on the Polanyi's adsorption potential theory and Langmuir adsorption theory,a method was presented to predict adsorption isotherms with different temperatures only by one isotherm.By utilizing this method,we predicted shale adsorption isotherms of high temperature from 65 ℃ to 150 ℃ according to experiment data under low temperature(38 ℃).Result shows that,the adsorption data predicted by our method is in accord with experimental data and the error coefficient is less than 5%.By considering the pressure and temperature gradients in actual conditions,the relationship between the adsorption capacity and the depth was also quantified.The results indicated that the adsorption capacity increases sharply with depth for shallow case(<750 m).Then the adsorption capacity increases slightly until it reaches a peak,and it will reveal a downward trend.In our study,the depth corresponding to the adsorption capacity peak was about 2 200~2 400 m.Therefore,our study will provide a theoretical foundation for the efficient evaluation of shale adsorbed gas content under reservoir conditions.