Depth Correction Of Array Induction Logging

The depth is an important parameter in the well logging data. With the development ofpetroleum industry and logging tool, the requirement of the more accurate correction is putforward. The present method can not accurately identify the downhole stuck interval,especially the multiple stucks and corresponding depth corerction. The measurement of ArrayInduction Logging otfen becomes abnormal. In the dissertation, the stuck identiifcation andspeed correction are studied in detail and a new method is put forward. The results are veryimportant for the stuck identification and the depth correction of array induction logging.Firstly, the methods of depth measurement and the pirnciple of array induction loggingarc discussed. Factors which make the depth measurements inaccurate are analyzed‘Depthcorrection is divided into strctch correction, relative depth correction and speed correction.The three corrections are studied.Secondly, the downhole stuck interval is identified using accelerometer or cable tensionmeasurements separately. The shotrcomings of the two methods arc pointed out. Then a newmethod is put forward. It uses accelerometer and cable tension measurements simultaneouslyto indentify the stuck intervals.Thirdly, the motion state of downhole tool is studied‘The speed and depth correction oflog are calculated under the deterministic circumstance. The random error is taken intoaccount in the log speed and depth correction, combining the cable depth, the true tool depthcan be indentified.Finally, the depth correction of array induction logging is analyzed and studied in detail.The depth correction procedure is divided into the stuck-indentified module and thedepth-correction module. Using the array induction logging data, the true tool depth iscalculated. The ten curves of the array induction logging are resampled. The effectiveness ofthis method is veirifed. In addition，data resampling and time window during depthcorrection are discussed as well.