Development of a Low-Cost Rotary Steerable Drilling System

Abstract

The project had the goal to develop and commercialize a low-cost rotary steerable system (LCRSS) capable of operating downhole at conventional pressures and temperatures to reduce operating costs by a minimum of 50% and lost-in-hole charges by at least 50% over the currently offered systems. The LCRSS system developed under this project does reduce operating costs by 55% and lost-in-hole charges by at least 50%. The developed product is not commercializable in its current form. The overall objective was to develop and commercialize a low cost rotary steerable system (LCRSS) capable of operating downhole at conventional pressures and temperatures (20,000 psi/150 C) while reducing the operating costs by 50% and the lost-in-hole charges by 50% over the currently available systems. The proposed reduction in costs were to be realized through the significant reduction in tool complexity, a corresponding increase in tool reliability as expressed in the mean-time between failure (MTBF), and a reduction in the time and costs required to service tools after each field operation. Ultimately, the LCRSS system was to be capable of drilling 7 7/8 in. to 9 5/8 in. borehole diameters. The project was divided into three Phases, of which Phases I & II were previously completed and reported on, and are part of the case file. Therefore, the previously reported information is not repeated herein. Phase III included the fabrication of two field ready prototypes that were to be subjected to a series of drilling tests at GTI Catoosa, DOE RMOTC, and at customer partnering wells, if possible, as appropriate in the timing of the field test objectives to fully exercise all elements of the LCRSS. These tests were conducted in an iterative process based on a performance/reliability improvement cycle with the goal of demonstrating the system met all aspects required for commercial viability. These tests were conducted to achieve continuous runs of 100+ hours with well trajectories that fully exercised the tool's build/turn/drop/hold target capabilities and its higher end ratings for bit weight, torque and rotary speed. The tool teardowns were rigorously analyzed at the conclusion of each field run to assess component wear rates and to fully document any detrimental behavior(s) observed.