Perpustakaan Digital ITB

Geothermal drilling is recognized to take up an average of 40% of geothermal total field development cost, which number could surge higher as remedial-associated expenses and additional daily rig rate often made to solve unexpected occurrences of drilling problems such as a stuck pipe. Stuck pipe, a situation in which the movement or/and rotation of tubular (drill string or casing) is suddenly unable to move or restricted, is one the most significant Non-Productive Time (NPT) event during geothermal drilling resulted from two primary causes: formation challenges and drilling practice challenges. Despite sometimes being unavoidable, early detection of the pipe restrictions as well as knowing the causes is therefore crucial in the process of preventing the occurrences of stuck pipe. This study analyzes the stuck pipe occurrences as one of the most significant NPT events in a geothermal field through a series of qualitative and quantitative analyses. Three wells are selected through data availability check and quality control to proceed to formation lithology analysis and drilling practice analysis. Formation lithology analysis results in the andesite complex, with microdiorite intrusion being the zone where the majority of pipe sticking occurs due to formation hardness and abrasive characteristics. Drilling practice analysis further confirms stuck pipe occurrences through evaluations of the leading indicators: drilling parameters, hole cleaning, tight spots, and loss circulations, resulting in mechanical sticking as the type of sticking most likely to occur in the geothermal field. Recommendations of practices on stuck pipe prevention are also provided based on the analyses to improve future drilling campaigns in the respective field to minimize the potential financial loss due to remedial operations and additional daily rig time as a response to stuck pipe incidents.