页岩吸附气含量测井计算模型及其在昭通A井的应用

Log Calculation Model of Shale Adsorption Gas Content and Its Application in Well Zhaotong A

页岩气大部分以吸附状态赋存于有机质和黏土矿物颗粒表面(20%~85%)。通过Langmuir方程计算吸附气含量的测井剖面,进行温度和吸附比表面积校正。实际在页岩储层中,有机质孔隙表面和黏土矿物孔隙表面是页岩内气体吸附的主要空间。气体吸附的比表面可以表达为TOC和黏土矿物含量的函数。函数的系数随页岩储层类型的不同,呈规律性的变化。从昭通A井计算结果看,计算吸附气量与实验测得结果吻合较好。通过测井信息进一步计算了昭通A井的黏土矿物剖面、TOC剖面以及吸附气量剖面。昭通A井龙马溪组下部吸附气量与总含气量同步降低,这与实际解析实验的认识一致。

Most of the shale gas is adsorbed on the surface of organic matter and clay mineral particles (20%-85%).In this paper,the log profile of the adsorbed gas content is calculated by the Langmuir equation,and were corrected by the temperature and specific surface area of adsorption.For actual shale reservoirs,the pore surface of organic matter and the pore surface of clay minerals are the main spaces for gas adsorption in shale.The specific surface of the gas adsorption can be expressed as a function of TOC and clay mineral content.The coefficient of the function changes regularly with the type of shale reservoir.From the calculation results of well Zhaotong A,the calculated adsorption gas is in good agreement with the experimental results.In addition,the clay mineral profile,TOC and adsorption gas content of well Zhaotong A were further calculated by logging data.Result shown that the content of adsorbed gas in the lower part of the Longmaxi Formation in well Zhaotong A is synchronously reduced with the TOC, which is consistent with the actual desorption experiments.