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The Potential of Hybrid Drillstrings for Vibration Mitigation for Deep Geothermal Wells
Fidan IBRAHIMOVA, Roman SHOR
[Texas A&M University, USA]
Severe downhole vibrations have been observed while drilling extended-reach geothermal wells in high-temperature and hard-rock environments. These vibrations reduce the efficiency of drilling and wear out components of the bottom-hole assemblies. Steel is currently the most common drillstring material; however, alloys like titanium and aluminum can help to decrease the severity of vibration, as they are less dense and have different damping characteristics. In this study, Utah FORGE drilling data is used in the DrillScan simulations to analyze the vibration behavior of both conventional and hybrid drillstrings. The base case assumes all steel configuration, with hybrid models substituting sections of the drillstring with titanium or aluminum drill pipe. Findings indicate that partial replacement has the potential to decrease the levels of lateral and torsional vibration without affecting mechanical integrity due to increased damping. Additionally, the thermal properties of titanium (half the thermal conductivity of steel) allow its use as a partial replacement for insulated drill pipe. The presented results indicate the potential of hybrid drillstring designs as an effective and cost-efficient tool to address the problem of vibration in geothermal drilling, thereby enhancing the life of the tools used and overall drilling characteristics.
Topic: Drilling