Rib-Steered Motor as Solution for Demanding Multi-Lateral Coiled Tubing Drilling Challenges

This paper presents the unique synergy is essential for achieving optimal dogleg severity (DLS) capability, allowing for a single bottom-hole assembly (BHA) that can directionally drill in multiple sections all in a single run. This approach enhances the existing Rib-Steered Motor (RSM) technology by optimizing the wellbore profile with minimal tortuosity. Conventionally, a positive displacement motor (PDM) is used as the drive type in two different bent configurations to achieve the required DLS in hard carbonate applications. During the drilling process, a high adjustable kick-off (AKO) motor was employed at the beginning of the first lateral, just below the whipstock window or the 4.5-inch liner, to achieve a high DLS of approximately 25 degrees per 100 feet during the build-up section. After this phase, the operation involved pulling out of the hole (POOH) to change the motor for a medium AKO, which was necessary to drill the lateral section with a significantly lower DLS requirement. After reaching the total depth (TD) of the first lateral, the medium AKO motor BHA was POOH to the second lateral side-tracking depth. Due to the lower DLS expected from this lateral section BHA, side-tracking process took a longer period, and in the worst-case scenario, it failed to initiate the next lateral. This resulted in an additional trip required to use a high AKO motor to provide a higher DLS for sidetracking. Historically, first-generation RSM was used in the same application but only in the lateral section, with a DLS ranging from 5 to 10 deg/100ft. However, in response to current challenges and application requirements, RSM has been enhanced to achieve a higher DLS capability, targeting 25 deg/100ft. Prior to the field test, finite element analysis (FEA) was conducted on the second-generation RSM (RSM2) in conjunction with the existing 3.625-inch fixed cutter drill bit design. Multiple iterations of the bit features were simulated to identify the most effective configuration. During the field test, the RSM2 with the optimized drill bit design successfully achieved a DLS of 19.5 deg/100ft while utilizing 60% of the steering force on the ribs. Calculations indicate that it can deliver a DLS of 32 deg/100ft when using 100% of the steering force. This concludes that the RSM2 in combination with an appropriate drill bit design, capable of providing a single solution for delivering the required directional response while managing tool availability and flexibility across multiple BHA designs. Consequently, the number of trips could be reduced, which helps minimize flat time in drilling progress. This novel synergy between drill bit design and RSM technology demonstrates a unique capability that helps achieve all drilling objectives with fewer trips, reduces flat time, manages the tool fleet, and delivers a wellbore with minimal tortuosity.