Research on Wellbore Correction Charts for Array Laterolog in Small Boreholes Based on Numerical Modeling

Resistivity logging data play a crucial role in the qualitative delineation of oil and gas layers and the calculation of oil saturation. However, in practical operations, the resistivity variation curves are easily affected by borehole environmental factors, which in turn impacts their accuracy. Existing research lacks studies on the response characteristics of small borehole array laterolog tools and their correction charts for borehole effects. This paper optimizes the design of a small borehole array laterolog tool (featuring four detection depth curves) as the research subject. Through numerical modeling and finite element method simulations, we investigate the impact of boreholes and create environmental correction charts. Simulation results show that an increase in borehole diameter significantly reduces the response values of RLA1 to RLA3, while excessively high mud resistivity leads to severe distortion of the resistivity curves. For the correction charts corresponding to RLA1-RLA4, when the ratio of apparent resistivity to mud resistivity is greater than 1, the correction coefficient increases with borehole diameter. However, RLA1 and RLA2 are more significantly affected than RLA3 and RLA4. This study uses forward modeling to enhance the response analysis of small borehole array laterolog tools under various borehole conditions, filling a gap in the numerical theoretical research foundation in this field and providing important guidance for the future development of logging technology.