Research on a Calculation Model of Cable Tension and Pumping Displacement of a Logging Tool String of Horizontal-Well Drillpipes

Abstract

Summary With the vigorous development of unconventional oil and gas reservoirs, logging technology of horizontal-well drillpipes has become increasingly important. The improper selection of displacement during the pumping of drilling rods into horizontal wells can lead to accidents such as cable entanglement or tool-string pump detachment. Based on a comprehensive consideration of multiple factors such as drillpipe joints, small gap flow, pressure loss along the pipe, temperature, pressure, tool-string passability, and waterhole diameter variation, a cable tension analysis model for a logging tool string of a horizontal-well drillpipe is established. This model can predict a reasonable pumping displacement by analyzing the tension in the entire wellbore section, thereby avoiding cable entanglement or even tool-string pump detachment accidents during downhole operation. To verify the effectiveness of the model, we analyzed the cable tension during logging operations in Wells M1 and M2 using on-site test data and compared them with the measured tension data. The determination coefficient (R2), mean absolute error (MAE), and root mean square error (RMSE) were used to evaluate the degree of fit and accuracy of the model. The experimental results showed that the model can accurately predict the pumping displacement range before logging operations, ensuring that the cable does not entangle and the tool string is not pumped out during the downhole operation, thus providing effective methods and theoretical guidance for on-site drilling rod-pumping logging operations.