侵入条件下的双侧向测井影响因素分析

基于有限元方法分析了侵入条件下多种因素(围岩、层厚、侵入带等)对双侧向测井响应的影响,并在电热耦合场条件下,详细分析和模拟了井径对测井响应的影响.结果表明:目的层厚度较小时,仪器响应受上下围岩影响较大;当围岩电阻率与目的层电阻率相差较大,并且目的层厚度等于仪器电极距时,视电阻率曲线产生一个明显的反冲;侵入浅时曲线受侵入带和原状地层的综合影响,侵入的加深使曲线趋近于无侵高阻地层响应;随井径增大,仪器响应受井眼影响加重,井壁温度减小使仪器响应更易受井径变化影响.对测井曲线影响因素的分析可以指导在现场测井中应用曲线的形态特征进行储层评价,同时也为分析测井响应提供了理论基础.

Analysis of the influence factors on the dual-lateral logging response under the condition of invasion

Based on the FEM,the influence of the factors such as surrounding rock,formation thickness,invasion zone,etc. on the dual-lateral logging response under the condition of invasion is analyzed,and the influence of well diameter on the dual-lateral logging response in the electric and thermal coupled field is simulated and analyzed in detail. It is shown that: the resistivity of surrounding rocks has greater influence on the logging response in thin formation; there is a significant recoil in the apparent resistivity curve when there is a great deference between the surrounding rock resistivity and target formation resistivity and the thickness of the target formation is equal to the distance between the instrument electrodes; when invasion is shallow,the logging response trends to the response of the high-resistivity formation without invasion with the increase of invasion depth,which is because of the combined influence of invasion zone with original formation; the influence of borehole on the logging response will increase with well diameter increasing because the decrease of borehole wall temperature makes instrument response more easily influenced by well diameter. The analysis results of the dual-lateral logging response influencing factors can guide reservoir evaluation in the field logging,and can provide the theory basis for the analysis of logging responses.