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Lwd Acquisition of Calliper and Drilling Mechanics As A New Approach On Geothermal Drilling Operation, A Case Study In Sorik Marapi Field – Indonesia
The geothermal drilling environment presents many obstacles that limits the use of directional-drilling and logging-while-drilling (LWD) technologies, such as borehole washout, mud losses, severe vibration, and high temperature. The case study presented in this paper demonstrates a novel practice to enhance data logging in geothermal drilling by deploying advanced telemetry and LWD technologies. This operation aims for continuous improvement in geothermal drilling operations. The case study covers 12.25-in. hole section of well XX-05 at the Sorik Marapi Geothermal Field. LWD string consisted of electromagnetic (EM) telemetry, pressure while drilling (PWD), vibration (DDSr), and acoustic calliper (ACAL). Through this tool configuration, the operator acquired drilling mechanics and calliper logs in real-time and recorded mode, enabling effective monitoring and evaluation of wellbore stability. Throughout the real-time acquisition, EM-PPM telemetry had provided three times faster data rate to surface unit compared to conventional tools. Furthermore, with the integration of Calliper and Drilling mechanics data (vibration and equivalent circulating density), the borehole conditions became more visible to the directional driller, allowing better control of drilling parameters to minimize vibration and achieve optimum hole cleaning in washed-out or tight formation sequences. The recorded data from the calliper sensor indicated an average of 8.6% washout for the entire 12.25-in. interval. Washout intervals were compared with loss occurrence during drilling and the presence of paleosol-smectite bearing, showing that the washout zones associate with the later one and it supports the paleosol-smectite bearing model in explaining the cause of stuck pipe incidents at Sorik Marapi field. In addition, the measurements of hole ovality were compared with the interpreted fault trend, providing actual insight towards the existing model. In general, this LWD case study has given added value through geothermal borehole characterization, from drilling hazard identification to subsurface analysis. Identified challenges while running LWD in this geothermal environment were addressed for future improvements, such as effect of tool eccentricity and impact of vibration. Perusal of both real-time and recorded of calliper and drilling-mechanics data has opened various possibilities for maximizing the sensor usage in future wells.