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Mubadala Petroleum planned to drill a complex Extended Reach Well (ERD) from an existing platform. To reach the required geological targets, the preferred wellpath was required to pass within close proximity of an adjacent oil producer that had a resultant separation factor (SF) of 0.70. A SF of less than 1.0 presents a mathematical possibility of well collision due to overlapping Elipses of Uncertainties (EOU). As such there was the likelihood of the inability to drill the well with a consequencial impact to the Mubadala business plan. A novel solution was by implemented by utilizing High Inclination Drilling with Gyro (HIDWG) tool to safely manage and mitigate the risk of well collision. The Jasmine field is a mature, complex oil field containing multiple stacked sandstone reservoirs, largely having individual oil and gas water contacts that have been on production since 2005. One of the major challenges is safely and economically accessing the remaining bypassed oil. Wellpath collision is an ever increasing risk as the ageing assets become more congested, which could lead to property damage and losses of production. Collision avoidance is gauged with a SF that takes into account the well depth, toolface, and the error model of the electronic survey tool. A conventional Bottom hole Assembly (BHA) with Measurement While Drilling (MWD) tool was initially considered, however the proximity calcuations yielded a SF of 0.7, and the well could not be drilled according to the company's drilling standard. To manage the risk and safely drill the well, the survey error uncertainty needed improvement. Instead of a conventional MWD, a High Inclination Drilling with Gyro (HIDWG) tool was utilized to reduce the survey error uncertainty to yield higher precision drilling control at depth in excess of 10,000 feet and at an inclination higher than 70 degrees. As a result of the BHA upgrade, the SF was instantly improved from 0.70 to 1.0, the collision risk was reduced to an acceptable level, and the well design was compliant with the drilling standard. Furthermore, the HIDWG was utilized for the first time in the Gulf of Thailand. Mubadala Petroleum successfully executed the ERD well utilizing the HIDWG, in combination with an Advance Hybrid Rotary Steerable System (RSS). The HIDWG tool provided an all-inclusive real-time surveying solution that delivered highly accurate surveys and with the Advance Hybrid Rotary Steerable System (RSS)'s precise drilling control throughout the intervals of close proximity with other wells. This paper explains how the HIDWG tool provided an inclusive surveying solution that could deliver both high accuracy surveys and precision drilling control throughout the zones of anti-collision concern of the ERD well. The chosen solution enabled the ERD well to be drilled to the required target successfully and allowed production to be established as planned.

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This paper highlights the top quartile performance well delivery of Yetagun In-fill Phase 6 drilling campaign in Yetagun gas field, offshore Myanmar. Drag, Torque, Hook load and Stand Pipe Pressure that occur in an ERD well is typically higher than conventional well due to long horizontal displacement and high lateral inclination angle. Hence, the importance of planning process, execution, drilling practices and lesson learnt which essentially resulting in a successful drilling operation were discussed in the paper. PETRONAS Carigali Myanmar Limited (PCML) successfully drilled three in-fill wells: YA-01, YA-05, and YA-12ST1 which were classified as ERD based on extended reach industry experience plot with the objective to maintain the gas production rate. Excellent planning process and good teamwork among the project team members were required to tackle all the technical issues as well the environmental and logistical challenges. The unique and challenging design for YA-05 as compared to others where it has the longest tangent length which fall within 70-80° sail angle. YA-01 and YA-12ST1 were classified as ERD medium reach class design, thus require specific ERD drilling, hole cleaning, ECD monitoring, tripping and backreaming practices to ensure success of the well. The challenges in designing ERD wells were multiple such as high torque and drag, loss circulation, well collision, differential sticking, borehole instability, hole cleaning, longer open hole interval, high stand pipe pressure and high temperature. YA-12ST1 well was planned with sidetracking design utilizing whipstock and hence, tortuous wellpath which leads to high dogleg at the sidetrack point need to be considered. Losses of circulation were observed from historical development campaign of the field. Thus it was essential that extra precautions have been prepared for efficient hole cleaning and consistent penetration control. Other challenges attached with the recommended practices to overcome them including wellbore instability, differential sticking, drag and friction factors were analyzed further in this paper. In conclusion, this paper serves as a reference for future ERD well planning and execution as the overall drilling campaign achieved excellent well delivery performance in term of cost and time. This campaign has been successfully completed with remarkable achievements such as the first semi-submersible tender-assisted drilling rig used by PETRONAS group, huge total cost saving, zero lost-time injury, and successfully secured the reservoir target and meet the gas volume target. The novelty of the successful Yetagun Phase VI development wells project yielded good practices, technology used and excellent project planning that can be applied in future projects. This paper also can be a reference for future ERD well drilling in Myanmar.