The calculation results demonstrate the effective eccentricity and the lifting force of the upper drill string are the major influential factors. 计算结果表明，有效偏心距和上部钻柱的提升力是影响近井口套管偏磨的主要因素。
A transmitter toroid induces a low-frequency current in the drillstring, which flows out of the bit and returns farther up the string. 发射线圈在钻柱内感应出低频电流，从钻头流出，在钻柱上部返回。
