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Summary Continous improvement of technology and operating procedures is a key to the oil and gas industry. One of the ultimate goals of such improvement is to reduce drilling time and, consequently, save well construction costs. Drilling multilaterals in one run, using rotary steerable systems (without pulling out of hole for changing BHA for kick-off proceduce) has become the first step change enabling shorter drilling cycles. In 2018, a project was designed to drill both horizontal and transport sections of a multilateral well in one run. According to this methodology, one 146mm casing is run instead of two: 178 mm and 114 mm casings. In case of succefull implelemtation, this project will reduce well construction time by more than 15 days.

The objective of pilot testing was to optimize horizontal well construction cycle by decreasing the number of casing strings. The testing involved drilling of 13 wells, in which only production casing was run in hole instead of intermediate casing and a liner. The key issue during drilling was failure of measurement tools due to high vibration. This paper covers decisions and actions being made to get a well with new casing design successfully drilled. To mitigate the issues, the bottom hole assembly (BHA) behavior was modeled using a proprietary software for static and vibration analysis. Relevant diameters of stabilizers and drilling modes were selected. The interpreted computations were successfully used for drilling further wells. For comprehensive approach, an optimal bit design was selected vibration mitigation wise. Three-axis vibration sensors installed in the BHA enabled selecting of optimal drilling modes in real time. Drilling of triple casing wells showed reduction in actual well construction time compared to quadruple casing by 20% on the average. The record-setting well was drilled in 8.6 less days compared to a similar 4-string well. Furthermore, BHA with mud motor was used, which is less expensive compared to a BHA with Rotary Steerable System (RSS). The three-string design was used at the fields in question for the first time. The accumulated experience makes it possible to use this technology at other fields, where horizontal wells are drilled.