Optimization With Real-Time Monitoring Results in Enhanced Drilling Performance

Abstract

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 205152, “Offset Data Analysis and Seamless Execution Through Real-Time Monitoring Results in Step Change in Drilling Performance,” by Anurag Singh Yadav and Muhammad Imran Chohan, Weatherford, prepared for the 2021 SPE Europec featured at the 82nd EAGE Conference and Exhibition, Amsterdam, 18–21 October. The paper has not been peer reviewed. This project drilled horizontal wells with bottomhole assemblies (BHAs) with a topdrive as the primary drive mechanism. The rig in question was struggling to provide not only the required rotational speed but also to deliver consistent necessary torque. The complete paper analyzes how severe rig limitations were overcome through an optimization plan in which the optimal BHA was designed, and drilling practices were customized, for safe and successful execution of wells. Challenge The project involved drilling multiple re-entry wells for oil and gas production. A typical well design in this operation featured a whipstock set in a 9⅝-in. casing, followed by drilling of 8½-in. hole through the whipstock; the well was completed in a production hole of 6 in. The wells were drilled with a rotary steerable tool in the BHA. Most of the rigs used to drill these re-entry wells had limited capacity with respect to rotational speed and torque limits on the topdrives. This topdrive limitation was proving to be a major impediment to achieving optimal drilling performance. Offset Well Analysis To fully comprehend these challenges with topdrive capabilities, offset wells were studied. Typically, weight on bit (WOB) appeared to play a key role in determining behavior of drilling dynamics. WOB typically had to be varied in order to mitigate stick/slip. For example, with elevated levels of WOB (greater than 20,000 lbf), stick/slip levels were always severe, whereas stick/slip levels were lower when WOB was reduced. Furthermore, it was observed that, with variation of stick/slip, not only stick levels were being elevated but also torque behavior was becoming erratic. This analysis revealed that the degree of erratic behavior with regard to torque differed between bits. When comparing a bit with a 47-cutter count of 16-mm size with another bit that was slightly less aggressive with a six-cutter count of 13 mm on the face, the torque behavior did not change in terms of erratic behavior; however, it was possible to drill with higher WOB with the latter. Further analysis revealed that behavior of stick/slip also depended upon type of formation drilled (i.e., whenever a well was drilled through a denser formation, elevated levels of stick/slip were encountered). In addition, one rig had issues with rotational speed from the topdrive. Surface rotation speed was approximately 90–100 rev/min, resulting in severe levels of stick along with high and erratic torque.