| Title | Maximizing Rate of Penetration in Deep Geothermal Wells using a Novel Downhole Actuator |
|---|---|
| Authors | Pradeepkumar Ashok |
| Year | 2026 |
| Conference | World Geothermal Congress |
| Keywords | maximizing ROP, drillstring dynamics, drilling optimization, vibration control, downhole actuator |
| Abstract | Mitigating drillstring vibration remains a challenge in deep geothermal well drilling, where greater depths, larger wellbore diameters, and harder, more abrasive formations amplify drilling dysfunctions. This study presents a novel downhole actuator design that enables the control of coupled axial, torsional, and lateral vibrations in deep geothermal wells leveraging a lumped-parameter modeling framework. The actuator and its controller utilizes a dynamics model that discretizes the drillstring into multiple mass-spring-damper elements, comprehensively capturing critical geothermal-specific conditions such as elevated formation strength, increased frictional interactions, larger drillstring dimensions, and variations in drilling fluid properties. The simulation of a 15,000 ft deviated geothermal well drilling through hard, abrasive rock is presented in this paper, and reveal that in deep geothermal wells, vibration amplitudes can be significantly higher, with a narrower operating window for adjusting the WOB (weight on bit) and RPM (rotary speed) to avoid system resonance. Whirling and stick-slip regions are superposed over a WOB-RPM drilling map to predict optimal drilling parameters for vibration-free high ROP (rate-of-penetration) drilling. Additionally, the study further evaluated vibration mitigation strategies for the 15,000 ft geothermal well scenario, including drillstring design optimization (e.g., varying drillpipe dimensions and material properties), adding passive vibration damping tools, and proactive downhole actuation systems. Simulation results reveal the distinct dynamic responses of each approach, highlighting their underlying mechanisms for enhancing system stability and drilling efficiency. The downhole actuator design presented in this paper shows significant potential to improve ROP over all other approaches. |