页岩储层全直径及覆压校正研究——以焦石坝页岩气田五峰组——龙马溪组为例

A Correction Research for Full Diameter and Overburden Pressure of Shale-reservoir:a Case from Wufeng and Longmaxi Formations in Jiaoshiba Shale Gas Field

低孔、特低渗非常规页岩储层的全直径校正与覆压校正仍处于探索阶段,其校正模型有待进一步研究。通过开展焦石坝地区五峰组—龙马溪组页岩岩心的全直径和覆压实验资料分析,明确变化规律,并利用数理分析方法建立校正模型。分析表明,页岩储层小岩样较全直径样品孔隙度低、渗透率高,覆压后孔隙度、渗透率值均降低;页岩岩心孔隙度与覆压值呈多项式关系,渗透率与覆压值呈幂律关系,且关系式中各项系数均与地面无压孔隙度、渗透率值密切相关。校正模型计算的孔隙度值与覆压实验测定孔隙度值吻合性高,说明本校正方法适用于焦石坝地区五峰组—龙马溪组页岩储层,能为页岩储层的全直径校正、覆压校正及储量参数研究提供技术支撑。

The correction model of full-diameter correction and overburden pressure correction is still in the exploratory stage in low porosity and extra-low permeability unconventional shale-reservoir, which needs further research. By analyzing the core of full-diameter and overburden pressure experiment date of the Wufeng-longmaxi formation in Jiaoshiba area, clearing the change rule, then establishing calibration model through mathematical analysis, the results shows that small and in full-diameter rock samples are in low porosity and high permeability, Both the porosity and permeability values are decreased after the overburden pressure. There is a polynomial relationship between porosity and overburden pressure, and the relationship between permeability and overburden pressure is power law. All the coefficients are closely related to the surface porosity and permeability. The porosity values calculated by the correction model are in agreement with the experimental results. It shows that this method can be applied to the shale-reservoir of Wufeng-longmaxi formation in Jiaoshiba area, and the method can provide technical support for the research of the whole diameter correction, overburden pressure correction and reserve parameters evaluation.