Dual-reamer technology eliminates cleanout trips: A new drilling system saves money in deepwater drilling operations

摘要

Deepwater reservoirs hold a wealth of resources for a hydrocarbon-thirsty world, but they are complex, risky, and expensive to produce. Specialized drilling operations that are necessary to enhance production in this growing sector also can impact the economics and efficiency of the well construction process. In deepwater Gulf of Mexico (GoM) wells operators frequently use hole enlargement while drilling (HEWD) to use larger casing sizes and increase the diameter of the production string, minimize hole-opening trips, enable better equivalent circulating density (ECD) management, and improve borehole quality. These are typically achieved through the use of a concentric expandable underreamer in a conventional bottom-hole assembly (BHA) design. The underreamer is positioned above the long, complex LWD suing so that the enlarged borehole will not degrade the accuracy of formation evaluation measurements and to account for stabilization of the MWD/LWD tools, realtime communication of the MWD/LWD tools, and the ball-drop requirements of reamers. The rathole is a result of the underreamer being placed high in the BHA and is the unenlarged portion of the hole from the reamer to the bit. To open the long rathole to the larger borehole size to accommodate the liner suing, the drilling BHA must be tripped back to surface to allow for a dedicated cleanout - or hole-opening-run, which adds time and cost to the entire operation. Ratholes can create various issues for operators such as causing difficulties in selecting a casing point, having negative effects on liner hanger setting depth, increasing ECD concerns while cementing if the casing is set in the rathole, and causing flat time between redrilling the interval between the shoe depth and the total depth.