套管井电阻率测井方法及其影响因素分析

Casing-well resistivety logging method and its influencing factors

根据电磁场理论和中场区电场分布特点,建立套管井地层电阻率测井(CHFR)测井响应方程,用传输线理论分析了套管井测井数值计算的可行性,分析了水泥环、地层电阻率、套管厚度等因素对测井响应的影响.结果表明,低阻地层水泥环对测量结果的影响较大,电位二阶微商与地层电阻率成反比,随套管厚度的增大下降较快,特别是小于4mm时下降更快.

The numerical calculation and influencing factors of casing well resistivity logging are studied.The response equation of resistivity logging is established based on the electromagnetic field theory and the distribution characteristics of the electric field in the intermediate zone.The feasibility of the numerical calculation of casing well logging is analyzed according to transmission-line theory,and the influences of cement sheath,formation resistivity,casing thickness on the logging response are also analyzed.The results show that the cement sheath has greater influence on the logging response of low resistivity formation;the second-order derivative of potential is inversely proportional to the formation resistivity,and it rapidly declines with the increase of the casing thickness,especially when the casing thickness is less than 4 mm.