Publications

CPK-1 and NWR-1 are vertical exploration wells located in South Sumatra, Indonesia, with a total depth (TD) of around 5,000 ft MD. Based on offset well data (GRN-1), an unplanned inclination occurred when drilling the 12-1/4� hole, causing additional time and cost to rectify the problem. As a part of the lesson learned and optimization process, a way to enhance vertical drilling efficiencies will be explained in this paper. Comprehensive and fit-for-purpose are the two appropriate words that describe the optimization method applied in both wells. In the planning phase, a comprehensive Bottomhole Assembly (BHA) tendencies analysis was conducted. In this analysis, a case study from the GRN-1 well was analyzed to obtain an effective BHA by considering the number and type of drill collar(s), stabilizer(s) and drilling parameter. In the execution phase, a novel fit-for-purpose real time survey system was utilized to respond and adjust the drilling parameters accordingly to the BHA tendencies. This real-time survey tool is a simpler and cheaper version of Measurement While Drilling (MWD) tool. By combining a comprehensive engineering study of BHA tendencies analysis and a fit-for-purpose technology of real-time survey, both of the wells were successfully drilled through the designated target with the final inclination at 12-1/4� TD for CPK-1 and NWR-1 Well respectively are 0.4� and 1.4�. The BHA tendencies analysis has given a robust drilling assembly for drilling a vertical well, while the real-time survey tool provides excellent and reliable continuous monitoring of inclination and azimuth. This whole process and procedures generally increase the drilling economics of the well and become one of the company; benchmarks for the next vertical well(s) drilling campaign. This paper presents a systematic process of BHA design for vertical wells by analyzing the previous offset well BHA design and its relation to the problems, up to proposing a new optimum BHA design.