川东南焦石坝地区海相泥页岩含气量预测方法探讨

泥页岩的含气量反映了页岩气是否高产富集,是页岩气勘探选区及评价的关键参数之一。国内外学者在单井页岩含气量的测定和预测方面进行了大量的研究,但是综合利用地球物理技术进行页岩气含气量纵向及平面预测及评价的研究较少。以四川盆地东南缘志留系海相页岩气勘探井为基础,统计分析认为有机碳含量(C_TOC)及压力系数是影响页岩含气量的关键指标,建立了页岩含气量多元计算模型。首先基于岩性密度与总有机碳预测模型,采用高精度叠前密度反演技术,实现C_TOC的地震定量预测;其次通过叠前速度反演技术,利用改进的Fillippone地层压力系数计算公式进行压力系数的预测;最后综合C_TOC及压力系数进行页岩总含气量的预测。该方法较C_TOC单参数模型预测精度明显提高,且在构造复杂、压力系数差异明显的地区具有很好的推广应用前景。

The gas content of mud shale is the reflection of shale gas enrichment,which is an important parameter of acreage selection and evaluation for shale gas exploration,At present,the domestic and foreign scholars has done a lot of research on the prediction of shale gas content for single well.However,little research is carried out on the comprehensive geophysical exploration technologies for the prediction and evaluation of shale gas content.On the basis of marine shale gas exploratory wells in southeastern margin of Sichuan Basin,the statistical results reveal that C_TOC and pressure coefficient is the key parameters of shale gas content,and the multi-element calculation model of shale gas content is built.Firstly,based on the density logs and the total organic carbon prediction model,the high precision prestack density inversion technology is adopted to realize the seismic quantitative prediction of C_TOC.Secondly,the prestack velocity inversion technology is applied to predict the pressure coefficient using the Fillippone formula.Finally,the total shale gas content is predicted by integrating the C_TOC and pressure coefficient.The method can obviously improve the prediction accuracy compared with C_TOC single-parameter model,and can be well promoted in the area with complex structures and variable pressure coefficient.

国家科技重大专项(2011CX05005-003)和中国地质调查局油气资源调查中心油气专项(12120114020201)共同资助。