Research On The Interpretation Method Of Through Casing Resistivity Logging

Trough Casing Resistivity logging can measure variations of formation resistivity through casing, which has important significance and wide application prospect for solution of reevaluation and analysis of the old wells , cased wells reservoir monitoring in oilfield development process and evaluation of remaining oil. Russia cased-hole resistivity logging was introduced at 2006, based on which basic measurement theories and numerical simulations, this paper studied the method of correction of influence factors and log data processing and interpretation, and the corresponding software has been worked out. It provided whole solution for the processing and application of Trough Casing Resistivity.Through casing Resistivity can be influenced by many factors in the well. It can cause skip of resistivity by casing heterogeneity, this paper used chart and smoothing filtering to correct its influence. Numerical simulation result indicate that the resolution of Russia through casing resistivity logging tool is 1.0m, so thin reservoirs which thickness is between 0.5~1.0m should be corrected by surrounding rock correction chart. The paper has done core electricity experiment on cementing concrete, according to cement formulation which was provided by LiaoHe oilfield, 18 cement columns was made for porosity and resistivity measurement, which was saturated in 3 typical formation water salinities. Then'm'was obtained to calculate cement resistivity in software. With cement sheath correction chart of different casing sizes, software was programmed for correcting its influence. Instrument calibration coefficient (K factor) was influenced by formation Resistivity,casing size and unit longitudinal conductivity, we obtained K factor varying with formation and casing characteristics by curve coincidence between through casing resistivity and open hole resistivity and K factor correction chart. The influence of perforation and casing shoe can be neglected according to instrument measurement principle and traits.Original measurement data of Russia through casing resistivity is *.dbf database file, which should be formed WIS data for processing in FORWARD platform by the software which was developed with C# language in the Visual studio.Net platform. It can implement data point sort, depth correction and scattered data interpolation. We also made software on the FORWARD platform to correct influence factors according to the method we studied in this paper, and made software to calculate reservoir parameters to evaluate remaining oil saturation and water flooding degree.Using the software, we processed 3 wells through casing resistivity logging data of LiaoHe oilfield, and compared them with Schlumberger through casing resistivity data. The result indicates that two kinds of through casing resistivity data coincided at non infiltration layers, datum have good reliability and repeatability. The interpretation result obtained by the software was also essentially consistent with Schlumberger provided, which shows easy use and robustness of the software, and value of application in field.