海相页岩储层纳米级孔隙精细表征与定量评价

The study on the sophisticated characterization and quantitative evaluation of shale reservoir porosity is a key problem in shale gas resources calculation, accumulation mechanism study and exploration. Using the Wufeng-Longmaxi Formation marine shale in Southeast Sichuan Basin as an example, the characteristics of reservoir pores, such as the type, distribution, morphology, proportion, connectivity, are characterized by qualitative, quantitative experimental methods and modeling methods. On consideration of the nonmatrix pores (such as graptolite rich horizontal bedding pores), heterogeneity, pore connectivity and effectiveness, the nano scale pore reservoir development types and proportions were full-scale studied and quantitatively clarified. On this basis, the influence of micro-nano scale pore structure on the occurrence and migration of gas in reservoir is quantitatively studied by mathematical model and computer simulation in combination with physical properties such as adsorption and seepage test, thus, the key geological factors of micro scale permeability are summed up. Based on the data of well logging modeling and gas bearing test, physical properties test and productivity, the relationship between reservoir porosity and log response, gas bearing capacity and high quality physical properties is analyzed and scheme of porosity evaluation and productivity prediction from the production point of view is established. The research results will provide theoretical basis for the calculation of shale gas resources, reservoir evaluation and block selection, exploration technology, gas bearing prediction and for solving the problems of pore structure quantification and gas content prediction.

页岩储层孔隙精细表征与量化研究，是页岩气资源量计算、页岩气成藏机理、页岩气勘探开发的关键问题之一。以四川盆地东南部五峰组-龙马溪组海相页岩储层研究对象，通过定性、定量实验测试结合建模等研究手段，对页岩储层的纳米级孔隙类型、分布、形貌、比例、连通性等进行综合精细表征，在充分考虑非基质孔隙（如笔石、层理孔隙）、非均质性、孔隙有效性等的基础上，全尺度、定量化厘清储层纳米级孔隙的发育类型及所占比例；以此为基础，通过吸附、渗流等物性测试结合建模模拟，定量研究微纳米孔隙结构对储层气体赋存、运移的影响，探究微观尺度渗透性特征的关键地质控因；结合测井建模、含气性、物性及产能数据，理清储层孔隙与测井响应、含气性、优质储层物性等之间的关系，构建可以服务于生产实践的孔隙评价与含气性预测方案，为页岩气资源量计算、储层评价与区块优选等提供理论基础，为解决孔隙结构量化与含气量预测等问题提供理论依据。

纳米尺度孔隙结构是页岩储层研究的重点，也是难点。受限于现有表征技术体系的制约，其结构特点本身的精细表征、量化及其对储层气体赋存、运移的影响仍然存在进一步深化研究。本项目以四川盆地五峰组-龙马溪组海相页岩储层样品为例，综合运用多种手段与综合技术体系精细量化表征了优质页岩储层孔隙结构。首先，通过对页岩储层的纳米级孔隙类型、分布、形貌、比例、连通性等精细量化表征方法及组合的系统研究，形成了具备以5nm为单位逐级、全尺度、定量化厘清储层纳米级孔隙的发育类型及所占比例能力的新技术体系；进而深入探究页岩非直观孔隙结构特点、孔隙系统特征、页岩气微观赋存运移机理以及孔隙与测井响应、含气性、产能等的联系，精细分类不同品质储层的孔隙系统及对应结构的特点，探讨了页岩储层孔隙结构特点对气体赋存、运移的影响及其定量评价；在此基础上，综合分析具备优质孔隙系统储层的复杂控制影响因素及机制，综合精细孔隙结构特征、测井、产能等数据反映的储层特点，形成了基于优质页岩储层纳米孔隙结构量化的评价与产能预测方案。本研究形成了针对储层孔隙表征技术难点的创新技术与方法，以及对孔隙结构连通性、非均质性、系统性等方面新的表征技术与思路，为加深对纳米孔隙系统的认识、形成机制研究的地质工程应用等提供基础和依据。项目资助发表研究论文20篇，毕业博士研究生3名，硕士研究生5名。