基于地化参数的页岩油储层孔隙度解释模型研究

Study on porosity interpretation model of shale oil reservoir based on geochemical parameters

针对陆相页岩储层核磁共振(NMR)测井和密度测井解释难以有效反馈干酪根内部孔隙度的问题,提出了一种基于地化参数的孔隙度测井解释方法。通过利用测井资料与岩心分析资料,确定有机质类型和成熟度来动态求取地化参数,进而得到页岩储层孔隙度解释模型,并用实测值验证模型准确性。结果表明:TOC为1.5%~3.5%,R0为0.90%~1.07%,研究区主要为低成熟、成熟阶段的Ⅱ_(1)型有机质,与岩心分析结果吻合;基于该模型的页岩油储层孔隙度为2.5%~6.5%,与该区域孔隙度的实测值(2.5%~5.5%)吻合度较好,两者平均相对误差为22.26%,小于30%,符合行业规定标准;该区核磁共振测井的φ_(NMR)为7.5%~15.0%,φ_(CBW)为8%~12%,两者与岩心实测值均不吻合,因此孔隙度解释模型比核磁共振测井计算值的精度高。该研究的模型对求取陆相页岩油储层的孔隙度具有一定的指导意义。

Aiming at the problem that NMR and density logging interpretation of continental shale reservoir cannot effectively feedback the internal porosity of kerogen, a porosity logging interpretation method based on geochemical parameters was proposed. By using logging data and core analysis data to determine the type and maturity of organic matter to dynamically obtain geochemical parameters, and then obtain the shale reservoir porosity interpretation model, and verify the accuracy of the model with the measured values. The results show that TOC ranges is 1.5%~3.5% and R0 ranges is 0.90%~1.07%. The study area is mainly composed of Ⅱ_(1) type organic matter of low maturity and mature stage, which is consistent with the results of core analysis. The porosity of shale oil reservoir based on this model is 2.5%~6.5%, which is in good agreement with the measured value of porosity in this region(2.5%~5.5%). The average relative error between the two is 22.26%, which is less than 30% in line with the industry standard. In this area, the φ_(NMR) and φ_(CBW) are 7.5%~15.0% and 8%~12% respectively, which are not consistent with the measured values of the core. Therefore, the accuracy of the porosity interpretation model is higher than that of the calculated values of the NMR logging. Based on the above results, the model has a certain guiding significance for calculating the porosity of continental shale oil reservoir.