New Rotary-Steerable System Delivers High Dogleg Severity, Improves Penetration Rate

Abstract

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 177836, “New Rotary-Steerable Drilling System Introduction in the UAE for ADCO Delivers High DLS Capabilities While Improving ROP and Providing Extensive Formation-Evaluation Data,” by Imran Tipu, Shurooq Abdulla Mohamed Al Jasmi, Juma Sulaiman Al Shamsi, Ali M. Danche, and Muhammad Javid, Abu Dhabi Company for Onshore Petroleum Operations, and Jehanzeb Nurzai, SPE, Enrico Biscaro, SPE, and Nour Shat, Baker Hughes, prepared for the 2015 Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, 9–12 November. The paper has not been peer reviewed. A new rotary-steerable system (RSS) was designed to give geometrically greater dogleg-severity (DLS) capability while still being able to withstand the increased bending stresses. This high-build-rate RSS was able to eliminate controlled rate of penetration (ROP) as a limiter, which resulted in 39% ROP improvement. In addition, the development of a high-build-rate RSS provided multiple benefits, including elimination of ROP and logging-while-drilling limitations, increased curvature capabilities, and higher reliability of the system with respect to high-bending-related issues. Introduction Directional-Drilling Methods. In the early days of directional drilling, the process involved jetting and the use of bent subs as the main methods for deviating a wellbore. These methods largely have been superseded by the use of engineered bottomhole assemblies (BHAs) for inclination-only control and motor or rotary-steerable BHAs for complete 3D control. Simple BHAs (Inclination Control). In simple BHAs, placement of stabilizer elements determines the net force on the bit and results in either a building or a dropping tendency of the BHA. A stabilizer placed close to the bit acts as a fulcrum, with one side being forced down by the weight of drill collars. Because of this, the bit will drill along a path of increasing inclination and the BHA will have a tendency to build angle. On the other hand, a stabilizer placed significantly away from the bit will cause the collars below to sink to the low side of the borehole, pushing the bit to drill a path of decreasing inclination. This BHA will have a tendency to drop angle. A BHA designed to maintain direction will have stabilizers placed so as to create a rigid BHA, which will not bend in any direction with the force of gravity, causing the bit to drill along a straight path.