沧东凹陷陆相页岩油电性各向异性分析及计算

Electrical Anisotropy Analysis and Calculation of Continental Shale Oil in Cangdong Sag

近年来水平井钻完井技术和分段分簇大型体积压裂技术大量应用于沧东凹陷Ek_(2)段陆相页岩油的开发,由于水平井的电性响应特征与垂直井存在明显差异,以往基于垂直井的页岩油测井评价技术的应用受到限制。通过方岩样不同方向和不同地层角度的柱塞样电阻率测量发现,Ek_(2)段陆相页岩油具有非常强的电性各向异性。分析发现,纹层和层间微裂缝高度发育,是Ek_(2)段陆相页岩油整体呈现强电性各向异性的主要因素。且岩性、物性、含油性均影响电性各向异性的强弱,泥质含量、铁磁矿物含量、含油性增加,储层电性各向异性增强;物性变好,电性各向异性降低。在综合考虑纹层以及层间微裂缝影响基础上,提出了基于岩性、物性、含油性加权融合的电性各向异性系数计算方法,为页岩油水平井电阻率校正提供技术手段。

In recent years,drilling and completion technology of horizontal well and multistage and cluster large volume fracturing technology have been largely applied in development and utilization in Ek_(2) formation of continental shale oil in Cangdong sag.Because of the electrical response characteristics of horizontal well are obviously different from those of vertical well,the past application of shale oil logging evaluation technology based on vertical wells is limited.By measuring the resistivity of cubic rock samples in different directions and formation angles,it is found that Ek_(2) formation of shale oil has very strong electrical anisotropy.Analysis suggests that lamina and interbedded micro-fracture being high growth is the main factor for the strong electrical anisotropy of continental shale oil in Ek_(2) formation.And lithologic,physical properties and oil-bearing are all affect the strength of electrical anisotropy.The reservoir electrical anisotropy is enhanced with the increase of shale content,ferromagnetic mineral content and oil saturation.The reservoir electrical anisotropy is decreased with the better physical properties.On the basis of the influence of unified laminae and interbedded micro-fracture,a weighted fusion method for calculating electrical anisotropy coefficients is proposed based on lithology,physical properties and oil-bearing.This method provides technical means for resistivity correction of shale oil horizontal wells.