泥浆侵入影响的电阻率测井校正方法对比研究

Study on comparison of correction methods for resistivity value of electric log affected by mud-invaded zone

测井视电阻率曲线不可避免地要受到泥浆侵入带的影响,以致造成视电阻率与地层真电阻率有很明显的差别。为了准确校正地层的真电阻率,在不分析泥浆侵入规律的情况下,提出一种利用常规孔、渗构造连续的毛管压力曲线,通过构造的毛管压力曲线计算油藏的含水饱和度,再利用导电模型正演得到地层真电阻率的新校正方法。同时利用新方法、基于双侧向电阻率校正图版的计算机处理校正方法和双侧向电阻率测井动态响应(DRRL)的试错法,对C油田4口井的资料进行了处理,并对处理结果进行了对比分析。结果表明,在不分析泥浆侵入动态响应的情况下,可利用常规孔、渗资料计算得到地层真电阻率,与试错法计算结果相比,图版法计算结果较差,新方法计算结果与试错法计算结果比较吻合。相对于试错法,新方法简单、可靠,且可达到连续校正地层真电阻率的目的。

The well logging apparent resistivity curves are inevitably affected by the mud-invaded zone, which results in an obvious difference between the apparent resistivity and true formation resistivity. To adjust the true resistivity accurately, a new correction method was presented when not analyzing the mud invasion regularities ,which involves using the conventional porosity and permeability to con- struct continual capillary pressure curves,which can be used to calculate water saturation in the reservior, and using the electric conduc- tion forward model to obtain true formation resistivity. Simultaneously, the new method, computer processing adjustment method based on dual-lateral resistivity correction chart, and trial-and-error method of dynamic resistivity response of dual-lateral logging （DRRL）, have been carried on to process the well log data of 4 wells in C oil field. The contrastive and comparative analysis of the results indicates that conventional porosity and permeability can be used to calculate the true formation resistivity when not analyzing the dynamic response of the mud invasion, and that compared with the result of the trial-and-error method, the result of chart correction method is bad, and the result of the new method tallies with that of the trial-and-error method. Compared with the trial-and-error method, the new method is simple, reliable, and can achieve the purpose of continuously adjusting the true formation resistivity.