A drill pipe Continuous Circulation Device (CCD) system was used by a geothermal operator in Indonesia, with this paper's scope as follows:

  • Demonstrate CCD system performance used to successfully drill two wells to section Total Depth (TD) with reduced Non Productive Time (NPT) related to stuck pipe events;

  • Highlight the engineering design modifications of the CCD system to cope with the harsh and challenging geothermal drilling environment, through the application of lessons learnt and the use of statistical data. These design enhancements to the CCD, provided a robust method for reducing drilling risks and improved operational performance.

The CCD system was used to successfully drill two wells: a total of seven hole sections were drilled from 17 ½" to 7 7/8" in diameter at two geothermal well sites in the same field, onshore Java. The use of the CCD system allowed the rig to maintain constant flow rate of drilling fluid down the drillstring during drill pipe connections. This is paramount to prevent stuck pipe events when total drilling fluid losses are experienced especially in geothermal wells due to their inherent subsurface geological complexity coupled with the risks of formation breakout collapse typical of geothermal well down hole environments. Maintaining dynamic wellbore conditions through circulation and maintaining constant hole cleaning prevents pack offs due to cuttings and formation breakout cavings, settling, and dropout.

The harsh geothermal drilling environment required the CCD system to be modified to operate with higher circulating flow rates and high levels of Lost Circulation Material (LCM) in a total mud losses scenario. The CCD system was developed accordingly through lessons learnt analysis and application, root cause identification, and management of change processes to provide engineered solutions, which were then field tested. The application of this technology improved project economics by reducing NPT related to stuck pipe events and helped in the avoidance of stuck pipe events escalation, resulting in expensive fishing jobs and, potentially, Bottom Hole Assemblies (BHA) lost in hole with consequent sidetracks and associated cost impact.

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