Publications

Well A, drilled by KN, an oil & gas operator in Indonesia, is a deepwater vertical exploration well located offshore Bali. The high cost of a deepwater operation demanded all drilling components to be as efficient as possible. One of the optimizations performed was a single-trip hole-enlargement-while-drilling (HEWD) and rathole elimination (RHE) operation, in which drilling the pilot hole, opening the hole, and eliminating the rat hole were all executed in one run. The key component of the single-trip HEWD and RHE was the on-demand hydraulically actuated reamer, an underreamer with advanced technology by which activation based on flow index is utilized instead of a conventional ball-drop system, this enables the tool to be positioned below measurement- and logging-while-drilling (M/LWD) tools, closer to the bit. This advanced technology, however, required extensive preplanning activities, especially for bottomhole assembly (BHA) vibration and hydraulics modeling. Multiple BHA alternatives were evaluated using simulation based on finite element analysis (FEA) in terms of stability, and the most stable BHA was selected. In terms of hydraulics, sufficient pressure drop below the reamer and RSS tool needed to be achieved to ensure the full cutter-block opening capability as well as the RSS functionality. The integrated BHA design and modeling successfully delivered an excellent single-trip HEWD and RHE operation in two different hole sections. The 12 1/4-in.  14 1/2-in. BHA utilized a rotary steerable system (RSS) to drill a 1400-ft interval in HEWD mode and eliminated 157 ft of rathole using the on-demand reamer. The 10 5/8-in.  12 1/4-in. BHA drilled 1418 ft with HEWD, and eliminated 182 ft of rathole. A savings of 57 operating hours (equal to USD 1,425,000 cost) was realized as a result of eliminating a dedicated RHE run. The 11 3/4-in. liner and 9 5/8-in. casing were smoothly run to bottom indicating a good hole quality produced by a stable HEWD and RHE system.