New Bit Optimization Method Proves Superior Drilling Performance and Reliability Showcased by Lab Data and Record ROP in North-America Land

Abstract

The oil and gas industry pushes for longer, faster, and more reliable well construction. Predicting and optimizing drill bit performance offers tremendous potential to achieve high rate-of-penetrations. Torsional and lateral vibrations are detrimental to bits and drilling tools. Specifically, High-Frequency Torsional Oscillations (HFTO) can lead to electronic failures, body cracks and twist-offs of drilling tools. A recently upgraded full-scale drilling rig enables the analysis of drilling speed and generated high frequency vibrations under laboratory conditions. This paper presents new methods to optimize bit performance and stability fast, at low costs and low risks for performance and stability in a controlled environment. The results are validated by field operations in North America Land. Four bit designs were used to drill rocks under realistic downhole pressure and WOB and RPMs in the lab. High-frequency sensors at the rig and in the bit capture the rate-of-penetration and the dynamic response at multiple combinations of operative parameters. The data allow a full assessment of the performance, efficiency and lateral and torsional stability of bits using stability-maps, Rate of Penetration (ROP)-maps, MSE maps and Depth-of-Cut (DOC)-WOB curves. The lab tests are supported by 3D full bit simulations. The lab results are compared to field operations in vibration prone rocks in North America. The field runs were drilled in comparable well paths, formations and BHAs enabling a direct comparison. The bottom-hole-assemblies (BHA) were simulated and compared to high-frequency downhole data, surface data and offset-wells. Recommendations for choice and operation of the drill bits are deduced to reduce loads on the BHA while increasing drilling performance. The best bit design showed a 33% higher ROP while increasing the torsional stability. Stability maps revealed stable regions of RPM-WOB combinations free of torsional vibrations. HFTO can be mitigated by increasing the rotational speed above an RPM threshold. The range of HFTO free operative parameters was enlarged by 40% through bit design optimization. The best bit design also showed superior performance in the field achieving instantaneous ROP of more than 1,000 ft/h. Multiple record runs have been achieved with this frame including the most recent of drilling greater than 12,000 ft in a 24-hour period and drilling more than 25,000 feet in a single run. The new bit optimization methods enable to improve bit designs, develop operational recommendations quicker, minimize costs, and deliver more precise and reliable solutions compared to optimizations in field operations. Improvements of the performance and the torsional stability simultaneously are made possible through the upgraded drilling rig. The suppression of HFTO by bit design and cutter configuration combined with expanded stable operating parameters will lead to increased tool reliability, less NPT and higher drilling performance.