Improvements in Drilling Performance and Reduced Tool Loads in Challenging Vibration Prone Applications with Solutions from Lab and Field Testing

Abstract The oil and gas industry pushes for longer, faster, and more reliable drilling operations. Predicting and optimizing drilling 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 vibrations under laboratory conditions. This paper presents methods to generate heat maps to optimize drilling parameters to increase ROP while simultaneously mitigating harmful vibration dysfunctions. The method is validated by full-scale laboratory tests and field operations. Three bit designs were used to drill rocks under realistic downhole pressure and weight-on-bit (WOB) and revolutions-per-minute (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-maps (ROP-maps), mechanical-specific-energy-maps (MSE maps) and depth-of-cut-weight-on-bit (DOC-WOB) curves. The lab tests are supported by 3D full bit simulations. The lab results are compared to commercial field tests in vibration prone rocks the middle east. 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. The new procedure covers a wider range of parameters and the resulting stability maps are used to deduce recommendations for choice and operation of the drill bits to reduce loads on the BHA while increasing drilling performance. The laboratory tests identified differences in ROP, torsional and lateral stability between the tested bit designs. 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. Applying the new operative procedure in field operations shows that the stability maps are very comparable to the lab results despite differences in the BHA setup. Learnings generated in the laboratory are translatable to improvements in the field. Certain rock types provide less vibration excitation leading to a larger vibration free-zone identified through the stability maps. The new testing procedure and evaluation method enables to improve bit designs, develop operational recommendations quicker, minimize costs, and deliver more precise and reliable solutions. Improvements of the performance and the torsional stability simultaneously are made possible through the new testing methods. The suppression of HFTO by optimized bit and BHA design combined with expanded stable operating parameters will lead to increased tool reliability, less NPT and higher drilling performance.