基于地质模式约束的天然裂缝测井识别方法研究

低序级断层及其诱导裂缝的识别是目前研究热点及难点.本文针对大芦湖油田樊162块低序级断层诱导裂缝识别难度大的问题,在地质模式的约束下,开展了低序级断层诱导裂缝的测井识别研究.结合岩心、薄片等资料将低序级断层内部到相邻储层划分为断层核、诱导裂缝带及原状地层三个部分,其相应的岩性特征主要发育断层核的白云岩、诱导裂缝带的白云质砂岩及原状地层的细—中砂岩.在此基础上,通过常规测井、正交偶极子声波等资料对天然裂缝进行了识别研究,建立了常规测井资料定性、定量识别图版、正交偶极子声波识别图版;在常规测井识别图版中利用声波时差曲线、微电极曲线、双感应-聚焦测井曲线、龟裂系数法等综合识别了裂缝;在正交偶极子声波图版中,利用纵波、横波、斯通滤波时差、泊松比、弹性模量及裂缝指数等对高角度裂缝进行了综合识别研究.结果表明,正交偶极子声波测井结合常规测井可以有效的识别发育在断层核部及诱导裂缝带处的天然裂缝,识别结果与岩心、薄片数据匹配较好,为下一步的油水解释及测井储层评价奠定了基础.

Research on natural fracture logging identification method based on geological model constraints

The identification of low-order faults and their induced fractures is a hot topic and difficulty in current research.This paper is aimed at the difficulty of identifying cracks in the low-order faults of Fan 162 block in Daluhu Oilfield.Under the constraints of the geological model,Logging identification research on low-order fault induced cracks was carried out.Combining cores,thin slices and other data,the interior of the low-order fault is divided into three parts:the fault core,the induced fracture zone and the undisturbed stratum.The corresponding lithological features are mainly dolomite in the fault core,dolomitic sandstone in the induced fracture zone,and fine-middle sandstone in the undisturbed stratum.On this basis,the natural fractures were identified by conventional logging,orthogonal dipole acoustic waves,etc.The qualitative and quantitative identification plates and orthogonal dipole acoustic recognition plates of conventional logging data were established.In the conventional logging identification plate,the acoustic wave time difference curve,the microelectrode curve,the double induction-focusing logging curve,the crack coefficient method,etc.are used to comprehensively identify the crack.In the orthogonal dipole acoustic wave plate,the comprehensive identification of high-angle cracks is studied by using longitudinal wave,transverse wave,Stone filtering time difference,Poisson’s ratio,elastic modulus and crack index.The results show that the orthogonal dipole acoustic logging combined with conventional logging can effectively identify the natural cracks developed in the fault core and the induced fracture zone,and match the core and slice data well.Laid the foundation for the next explanation of oil and logging reservoir evaluation.