基于自适应hp-FEM的过套管电阻率测井仪器响应数值模拟

Numerical simulation of TCRT based on self-adaptive hp-FEM

过套管电阻率测井技术对于解决老井和套管井重新评价以及油藏动态监测和剩余油评价具有重要的意义,因此开展过套管电阻率测井理论及新方法研究将十分必要.本文依据自适应hp有限元算法模拟并分析了电极结构、地层倾角、泥浆侵入以及水泥环等影响因素对过套管电阻率测井仪器响应和测量结果的影响;同时,利用HERMES有限元软件包与VC++开发平台建立模型,可以对仪器发射电极产生的电场在套管及地层中的分布情况进行显示,进而可以为套管检测提供有用信息.数值实验表明,自适应hp有限元算法收敛速度快且计算精度高,适合于对过套管电阻率测井仪器响应进行数值模拟计算.

The logging technology of formation resistivity through casing can be used to old well and casing well re-evaluate, reservoir dynamic monitoring and remaining oil evaluation, so it is very important to study the through casing resistivity logging theory and new methods. In this paper, self-adaptive hp-FEM method is used to simulate and analyze the electrode structure, dip angles of formations, mud invasion and cement sheath, which can influence the instrument response and the measurement results of through casing resistivity tool （TCRT）. Meanwhile, the hp-FEM analysis software HERMES and VC＋＋ development platform are combined as a tool can reflect the electric field distribution in casing and formations, which can provide the effective information for casing inspection. Numerical simulation results show that electrode structure can influence on the detection depth of TCRT, mud invasion can influence on the resolution of tool, cement sheath can strongly affect the detection accuracy of low resistivity formation. Meanwhile the self-adaptive hp-FEM has the ability of fast convergence and high compute accuracy. Thus, self-adaptive hp-FEM arithmetic is an effective method which can be applied to TCRT numerical simulation.