低孔低渗储层裂缝常规测井识别技术——以川东北地区须家河组为例

Application of Conventional Logging Identifying Technique for Identifying Fractures in Low Porosity and Low Permeability Reservoirs——A Case Study of Xujiahe Formation in Northeastern Sichuan Basin

摘要: 低孔、低渗储层物性差，大多依靠储层中存在的裂缝来改善储集能力和渗流能力。目前低孔、低渗储层中常用的裂缝识别方法有取心特征描述和成像测井识别，受取心和成像测井资料采集限制。川东北地区须家河组(T3x)裂缝主要以构造缝和层面缝为主，倾角为斜交-低角度，方向以北东向为主。通过岩心观察和常规测井曲线对比发现，致密地层中的裂缝会在伽马测井、声波测井和电阻率测井上造成异常响应。针对上述异常响应，利用成像测井刻度常规测井的方法，建立了研究区裂缝的常规测井响应模型。通过该模型，识别并明确了T3x裂缝主要发育在断层附近，且上盘密度大于下盘密度。

Abstract: The reservoir with low porosity and low permeability had poor physical property and it mostly depended on the fractures to improve its reservoir capacity and flowing ability. Now the coring characteristic description methods and the imaging logging identifying methods were commonly used in fracture identification for the reservoirs with low porosity and low permeability, which were limited by data collection of coring and imaging logging. By taking Xujiahe Formation (T3x) in Northeastern Sichuan Basin as an example, its main fractures were structural fractures and interface fractures with an inclination of skew angle-low angle, whose direction was mainly northeast. By observation of cores and correlation of conventional logs, it is found out that fractures in tight strata would cause abnormal response in gamma ray logging, sonic logging and resistivity logging, which can be used to build a conventional logging response model for fractures by using imaging calibration conventional logging methods. By identification, fractures in T3x are mainly developed near the faults, where the density of hanging wall is larger than that of footwall.