摘要
Because of the constraint mode of the inversion objective function in the traditional resistivity-inversion method of electromagnetic-propagation resistivity logging while drilling(EPR-LWD),obvious differences appear in the radial and vertical investigation characteristics between the amplitude-ratio and phase difference,which affect the practical application of EPR-LWD data.In this paper,according to the EPR-LWD data,a self-adaptive constraint resistivity-inversion method,which adopts a self-adaptive constraint weighted expression in the objective function to balance the contributions of the phase difference and amplitude attenuation,is proposed.A particle swarm optimization algorithm is also introduced to eliminate the dependence of the accuracy and convergence on the initial value of the inversion.According to the inversion results of multiple classical formation models for EPR-LWD,the differences between the adaptive constraint inversion-resistivity logs with the traditional amplitude-ratio and the phase difference of the resistivity logs are discussed in detail.The results demonstrate that the adaptive resistivity logs take into account the advantages of the amplitude-ratio logs in the radial investigation and phase difference logs in the vertical resolution.Further,it is superior in thin-layer identification and invasion-effect appraisal compared with the single-amplitude-ratio and phase difference logs.The inversion results can provide a theoretical reference for research on the resistivity-inversion method of electromagnetic wave LWD.
随钻电磁波测井传统电阻率反演方法受反演目标函数约束方式影响,随钻电磁波测井幅度比电阻率曲线及相位差电阻率曲线径向及纵向探测特性存在明显差异,从而影响了随钻电磁波测井数据实际应用效果。本文提出了一种基于随钻电磁波电阻率测井数据的地层电阻率自适应约束反演方法,该方法通过在随钻电磁波测井电阻率反演目标函数中引入一个自适应加权表达式平衡了相位差和幅度比数据的相对贡献,并引入粒子群算法来消除反演精度及收敛性对反演初始值的依赖性。基于多组理论地层模型的随钻电磁波测井电阻率反演结果,详细讨论了文中自适应约束反演电阻率曲线与传统幅度比电阻率曲线及相位差电阻率曲线探测特性的差异。反演结果表明,文中自适应电阻率曲线兼顾了传统幅度比电阻率曲线径向探测深度及相位差电阻率曲线纵向分辨率两方面的优势,在应用于划分纵向薄层及评价径向侵入特征时明显优于单一的幅度比电阻率曲线及相位差电阻率曲线,可为随钻电磁波测井电阻率反演新方法研究提供理论参考。
基金
supported by the Foundation of Key Laboratory of Exploration Technology for Oil and Gas Resources of the Ministry of Education, Yangtze University, Wuhan (No. K201812)
the Foundation of State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing (No. PRP/open-1704)
the Foundation of Education of Hubei Province, China (No. Q20171304)。
