Development and Deployment of a High- Frequency Torsional Vibration Suppressor Based on Downhole Measurements and Scientific Modeling

This paper presents development of a system to test the origins of high-frequency torsional oscillation (HFTO) and identify the physical cause that allow for building information, which will alleviate this damaging dysfunction. It will present field data where the actual amplitude of HFTO is a complex function of many parameters in which both drill-bit speed and weight on the bit are extremely significant. The HFTO amplitude will increase with both parameters to a peak and then a further increase will reduce the actual vibration. To characterize these relations, a facility was built in our Research Centre in Cambridge, UK, to test HFTO in a laboratory environment. A torsional equivalent to a mass spring resonator was used. The facility allows for drilling under identical drilling conditions with HFTO enabled or disabled. It will be shown that the origin of HFTO is at the actual cutting structure contact with the formation. The HFTO is not driven by the broadband bit drilling noise but by the actual bit cutter's interaction with the formation rock. It is these interactions that drive the speed and weight on bit (WOB) characteristics observed in downhole operations. The characteristics and scale of the dysfunction are dependent upon the formation, the cutting structure, as well as the cutter profiles. This new knowledge will enable bits to be built that will alleviate HFTO rather than drive it.

Mitigating Drilling Dysfunction: Stopping HFTO Where it Starts

Johnson,

Panayirci,

Scott

et al. 2024

Effectiveness of HFTO-Damper Assembly Proven by Extensive Case Study in Permian Basin

Hohl,

Herbig,

Reckmann

et al. 2024

High-frequency torsional oscillation (HFTO) is a particularly damaging vibration phenomenon that occurs while drilling HFTO-prone rocks with Polycrystalline Diamond Compact (PDC) bits and aggressive drilling parameters. Mitigation or load reduction strategies are based on weight on bit or bit rotary speed reduction and are associated with lower rate of penetration and therefore limit the drilling efficiency. This paper discusses the suppression of HFTO with a 4.75-inch tool size damper assembly that is placed above the bottom-hole assembly (BHA) and typically below the mud motor. The efficiency of the damper assembly is discussed in a case study with more than 40 runs in Permian Basin targeting different applications, environments, and formations, giving further evidence that providing damping to the BHA can completely mitigate HFTO. The damper tool is designed for the purpose of mitigating HFTO. Inputs for the design of the inertia-based damper elements are the required damping identified from high-frequency downhole measurement data, laboratory testing and modeling to analyze and optimize the damping principle incorporated in the tool, and numerical simulations to analyze the achievable damping in different BHAs. The tool design is robust as proven in a standard process of tool reliability tests including rotating bending, vibration, temperature, and pressure, and not limiting the drilling parameters. The deployment is preceded by a step that maximizes achievable damping in the deployed BHA enabled by an optimization algorithm and numerical modeling. Herein, the damper elements are optimally placed for the identified critical modes of HFTO, targeting a placement in antinodes of the mode shapes with high vibration amplitudes guaranteeing a high damping effect. The case study incorporates more than 40 runs in NAL showing that the occurrence of HFTO is reduced significantly in different applications. The case study includes back-to-back runs with similar BHAs with and without the damper assembly in different HFTO prone applications proving the efficiency of the tool in mitigating HFTO. Consecutive runs in the same well and formation using other vibration mitigation tools show a significantly higher HFTO-suppression rate with the damper assembly. The overall performance gain by use of the damper is further proven by a statistical evaluation and in comparison to the second and third best performing vibration mitigation tool, showing significant increase in all relevant performance metrics, including, but not limited to, Mean Distance Between Failure (MDBF) and Mean Time Between Failure (MTBF). BHAs with the new damper tools outperform BHAs with industries currently preferred commercial vibration mitigation tools by as much as +100% in MDBF and +100% in MTBF. The case study shows that HFTO can be mitigated by use of the new 4.75-inch damper assembly. The damaging HFTO that held back the drilling parameters is suppressed which enables a step change in drilling efficiency and reliability, which ultimately leads to a significant decrease in drilling cost.

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

Kueck,

Goodman,

Hayes

et al. 2024

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.