A new method for evaluating favorable shale gas exploration areas based on multi-linear regression analysis: A case study of marine shales of Wufeng-Longmaxi Formations, Upper Yangtze Region

This paper has summarized the plane distribution characteristics of shale gas reservoir parameters, preservation parameters and pressure coefficient parameters of Wufeng-Longmaxi Formations in Sichuan Basin and its periphery. The ichnography of key-controlling parameters has been mapped and converted into data set. The multiple linear regression analysis has been applied to calculate the weight of each parameter and establish the corresponding multi-parameter weighted equation:Favorable area=-0.317+0.75×Buried depth+0.285×TOC+ 0.148×R_O+0.093×Porosity-0.128×Permeability+0.201×Brittle minerals-0.199×Pressure coefficient,to quantitatively screen, the favorable areas for shale gas exploration. The results show that the weights of parameters ranking from large to small are buried depth, TOC, brittle minerals, pressure coefficient, R_O, porosity and permeability, which represent the influence on shale gas bearing property. The quantitatively selected favorable areas are mainly concentrated in the Sichuan Basin, including the Weiyuan-Zigong, Yibin-Luzhou-Fuling and Eastern Sichuan area, while the Zhaotong, Jinsha, Daozhen and Qianjiang areas outside the basin are relatively favorable areas. The results are consistent with industrial exploration of Sichuan basin and its periphery. Compared to traditional methods, this quantitative screening method in this study is clearer and more intuitive.