【作者】 张绍亮；

【导师】 孟凡顺；

【作者基本信息】 中国海洋大学 ， 地球探测与信息技术， 2005， 硕士

【摘要】 在套管井中实现井间地层电阻率的测量具有很广阔的应用前景,但该技术在国内外仍处于研究和开发阶段。在过金属套管井地层电阻率测井中,接收线圈收到的是金属套管和水泥环及地层耦合后的总信号,既包括套管产生的信号,也包括水泥环和地层产生的信号。由于套管与固结水泥环和地层之间的耦合作用,它们对地层信号的影响是复杂的。为了得到更精确更趋于实际的测井数据,研究套管和水泥环等对井问电磁测井的影响规律具有非常重要的意义。 本文以电磁场理论为基础,假设地下非均匀介质是关于发射器所在的井轴对称,发射源为垂直于井轴放置的通以交流电的多匝线圈,充分考虑套管、水泥环对地层信号的影响因素,建立了井液、套管、水泥环、地层四层媒质模型低频电磁场的求解方法。根据金属套管井井间电磁测井问题的原理,推导了以发射井为固有水泥环的金属套管井,接收井为裸眼井的井间电磁测井问题的理论公式,并应用该理论,分别对发射频率和地层电导率、磁导率以及井间距对接收信号的影响规律;套管的几何参数、电导率及磁导率对接收信号的影响规律;水泥环的几何参数、电导率及磁导率对接收信号的影响规律等进行了系统研究。分析结果表明本文所建立的电磁场测井理论及其方法是可行的、有效的。该方法不仅可以用来研究套管井低频电流及其特性,而且还可以用来确定过套管地层电阻率测量方法和套管、水泥环等对测井的影响及其校正方法。更多还原

【Abstract】 The cross-well logging technique of measuring electric resistivity of stratum through metal casing has wide foreground, but it is still in the primary stage of investigation and exploiture. During the logging of measuring electric resistivity of stratum through metal casing, the receiving coil receives the coupled signals of metal casing and cement sheath and stratum. The influence to the signal of stratum is complicated, because of the coupled function of metal casing and cement sheath and stratum. In order to get more accurate logging data, it is very important to do research on the influence rule of metal casing and cement sheath to cross-well electromagnetic logging.Based on the theory of electromagnetic field, assuming the subsurface inhomogeneous medium is axially symmetrical in respect of the bole axis where the transmitter is located and the transmitter source is the n-loop winding with indirect current in it which is vertical to the bole axis, full considered the casing and the cement wreath to the influence factor of the signal of stratum, built up the method of low-frequency electromagnetic fields to resolve four layers medium model with drilling fluid, casing, cement wreath and stratum geologic strata. In this paper, according to the principle of cross-well electromagnetic logging through metal casing, the theoretical formula is derived when the transmitting hole is metal casing of concretion cement wreath and the receiving well is naked hole. With this theory, this paper numerically simulates the relationship of the transmitting frequency and the well-to-well distance with the receiving signal. And the thickness, the magnetic conductance, and the electrical conductance of metal casing, analyzed the influencing rules of the casing and cement wreath, transmitting frequency andwell-to-well distance on cross-well electromagnetic logging by the numbers. The analysis and study shows the principle and method of cross-well electromagnetic logging established in this paper is feasible and valid. The method can not only research low-frequency current and its character of logging through metal casing but also confirm the method of measuring electric resistivity of stratum through metal casing.更多还原