Surface Torque/Tension Measurements Used To Detect and Calculate Stick/Slip

Abstract

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 170624, “Stick/Slip Detection and Friction-Factor Testing Using Surface- Based Torque and Tension Measurements,” by Stephen W. Lai, SPE, Mitch Wood, Aaron Eddy, SPE, and Trevor Holt, Pason Systems, and Matthew Bloom, SPE, Nexen, prepared for the 2014 SPE Annual Technical Conference and Exhibition, Amsterdam, 27–29 October. The paper has not been peer reviewed. A surface-based torque and tension sub (TTS) was used to perform measurements while drilling several extended-reach horizontal wells. A filtered version of surface torque was used to calculate a stick/slip metric, which was compared with stick/slip measurements from a downhole tool. The results show that there is reasonable correlation between surface and downhole metrics. A comparison was also made between hookload measured with a deadline sensor and tension measurement from the surface sub. The results show a systematic discrepancy of approximately 5% that is likely caused by sheave friction. Torque- and Tension-Measurement Tool A commercially available TTS was used to perform accurate measurements of surface torque and tension for this study. The TTS measures torque and tension at 50 Hz and transmits the readings to the surface system by a wireless link. The surface electronic-drilling-recorder (EDR) system is used to display the readings to the driller and to store the raw 50-Hz data for post-processing. The TTS is shown in Fig. 1. The main body consists of a stainless-steel core on which several strain-gauge sensors are mounted. Measurements of mechanical strain in tangential and axial directions are used to calculate the magnitude of rotational torque and axial force being applied to the sub. A circular housing surrounds the middle of the core and contains the sub electronics including sampling circuits, radio transceivers, and replaceable batteries. Data are transmitted with two omnidirectional antennas that are directed downward toward the doghouse. A remote antenna radio module is placed in the doghouse or near the rig floor to receive the transmitted data. The TTS is powered by two disposable lithium batteries, which have an operational life of 40 days per battery. In this study, the TTS was installed in the topdrive assembly directly below the mudsaver valve (Fig. 1).