Preprocessing and Application of Resistivity Logging After Casing Data

Resistivity Logging after Casing (RLAC) can measure formation resistivity in cased wells, which shows unique advantages in reservoir monitoring and residual oil and gas resource evaluation, however, the original measurements of this logging tool are discrete, multi-value, and unequal depth spacing, it is necessary to preprocess it to achieve single-value and equal-depth spacing data for subsequent processing, so as to be used with other logging data. In this paper, a preprocessing method for raw data of RLAC is proposed, which first uses the box plot method to remove possible abnormal measurements, and then uses Akima interpolation to form equal-depth interval and increase the density of data points. Finally, the pretreated cased hole formation resistivity data combined with the resistivity logging data of open-hole wells were used to process and interpret the actual well data. The results show that the preprocessing method proposed in this paper is effective and feasible, and the box plot method can effectively remove abnormal measurement values, avoid the influence of human factors in manual point selection, and improve work efficiency. Akima interpolation ensures the smoothness of the resistivity curve and avoid the swaying situation. The depletion index method is feasible and effective in the evaluation of flood level.