“存滞系数”法在页岩气资源评价中的应用——以川东南上奥陶统五峰组—下志留统龙马溪组页岩气为例

Application of“retention coefficiency”method in shale gas resource evaluation:a case study of Upper Ordovician Wufeng Formation to Lower Silurian Longmaxi Formation,southeastern Sichuan Basin

资源评价除提供结果数据外,更重要的是要对有利区优选和勘探部署提供依据。针对传统页岩气资评方法存在的不足,结合地层孔隙热压模拟实验和最新盆地模拟技术,提出了采用“存滞系数”法开展页岩气资源评价的流程,并指出泥页岩生—排—滞留烃演化模式和页岩气“存滞系数”是两项最关键的参数。以目前我国页岩气勘探开发程度最高的川东南上奥陶统五峰组—下志留统龙马溪组泥页岩为例,详细阐述了新方法的应用过程,结果显示“存滞系数”法具有较好的适用性和可行性。与传统方法相比,“存滞系数”法既考虑到页岩气的动态演化过程,又考虑到晚期保存条件对页岩气富集的影响,并能刻画页岩气资源的空间展布特征,在页岩气资源评价和有利区优选方面具有广阔的应用前景。

Besides providing resulting data,the evaluation of resource abundance is more important to provide evidence for the optimization of favorable areas and the deployment of exploration.In view of the drawbacks of traditional methods,combined with the newly developed thermal-pressure simulation method of formation porosity and basin simulation method,this paper puts forward the process of shale gas resource evaluation using the“retention coefficiency”method.It is pointed out that the model of hydrocarbon generation-expulsion-retention and the“retention coefficiency”are the two most critical parameters in this new method.The Upper Ordovician Wufeng Formation to Lower Silurian Longmaxi Formation,which are the most highly explored shale in China,are taken as targets to illustrate the application process of the new method.Results show that the new method has good applicability and feasibility in shale gas resource evaluation.Compared with traditional methods,the“retention coefficiency”method not only considers the dynamic evolution process of shale gas,but also considers the influence of late preservation conditions on shale gas enrichment.In addition,the new method can describe the spatial distribution characteristics of shale gas resources,with a broad application prospect in shale gas resource evaluation and favorable area optimization.