元坝地区大安寨段二亚段页岩气储层有机碳含量计算方法

Calculation method of the organic carbon content of shale gas reservoir in the second sub-member of the Daanzhai section in the Yuanba area

元坝地区大安寨段二亚段是该区页岩气勘探的新层系,如何提高其有机碳含量计算精度是靶窗优选的关键。在对前期理论方法继承发展的基础上,首次建立了“铀体积法”计算页岩有机碳含量,通过对其它技术方法的适用性分析和应用效果对比研究,认为研究区“拟合模型法”难以建立模型,“岩性扫描测井技术”、“ΔLog R技术”、“ANN技术”、“KNN算法”、“密度体积法”和“铀体积法”计算有机碳含量与实验分析相比,相对误差分别是11.74%、37.28%、5.54%、10.52%、14.09%和1.13%,其中“铀体积法”计算结果误差最小,解释精度最高。结合各方法原理分析认为,“铀体积法”是目前大安寨段二亚段页岩气储层有机碳含量计算最适合的方法。研究成果推动了元坝地区大安寨段二亚段陆相页岩气的勘探部署。

The second sub-member of Daanzhai section in Yuanba area is a new formation for shale gas exploration in this area.How improve the calculation accuracy of its organic carbon content is the key to target window optimization.Based on the inheritance and development of the previous theoretical methods,the“uranium volume method”was established for the first time to calculate the carbon content of shale.Through the applicability analysis and comparative study of application effects of other technical methods,it is concluded that the“fitting model method”is difficult to establish the model in the study area.Compared with the experimental analysis,the relative errors of“lithological scanning logging technique”,“ΔLogR technology”,“ANN technology”,“KNN algorithm”,“density volume method”and“uranium volume method”in calculating the organic carbon content are 11.74%,37.28%,5.54%,10.52%,14.09%,and 1.13%,respectively.Among them,the“uranium volume method”has the smallest error and the highest interpretation accuracy.According to the principle analysis of each method,the“uranium volume method”is the most suitable method for calculating the organic carbon content of the shale gas reservoir in the second sub-member of the Daanzhai section.The research results promote the exploration and deployment of continental shale gas in the second sub-member of the Daanzhai section in the Yuanba area.