A Study Of Electromagnetic Logging Theory And Method For Production Well

With the development of oil and gas exploration,most of oil fields in China are in the middle and late stage of production.The technology based on Transient Electromagnetic Method(TEM)can help to detect the damage of casing,and understand the distribution of the reservoir behind casing of production well,which is of great importance in the field of production well logging.This paper mainly studies the TEM forward model correction,the fast numerical computational method of borehole TEM response,and the correction of logging speed and eccentricity.The principle of TEM logging is presented firstly.The borehole multi-cylindrical model including iron core probe is established,where the primary field in first layer and secondary field in each layer that excited by bipolar step current are also solved.Then,the expression of induction electromotive force both in the frequency domain and time domain of the probe are obtained and we also studied the fast numerical computational method for time-domain response.Moreover,characteristics of borehole time-domain response are studied.Based on this,the relationship between parameters of the iron core probe and the electromagnetic response is analyzed by considering the influence of casing parameters on receive signal.This paper also studied the electromagnetic response with continuous motion measurement,and a modified method of different logging speed is presented.In addition,the problem of eccentricity is also corrected and a modified receive signal model is proposed.Finally,field experiments are conducted based on correction model and modified method.It is proved that the detection performance of TEM well logging can be improved,and the accuracy of casing damage detection can be increased effectively.