Development and Field Testing of a Novel Multifunctional Drilling Enhancement Tool in a Middle East Field

Abstract

Well drilling and wellbore conditioning typically involve multiple specialized drilling tools. Systematic application of such tools can be a challenge from a logistics and maintenance perspective, which eventually has an impact on the efficiency of the drilling process as well as the resulting wellbore condition. This paper presents a new multifunctional drilling tool developed to address such operational challenges. The tool’s effect on the drilling and logging process is illustrated through a field case study. The CRS is a multifunctional drilling tool able to Cut, Ream and Stabilize when installing in a BHA. It is envisioned as an integral bottom hole assembly (BHA) component replacing the uppermost stabilizer while selectively acting as a fixed blade cutter, roller-reamer, lateral vibration damper, friction reducer, stabilizer and/or key-seat wiper. The specific function is dependent on wellbore conditions and is passively activated or engaged during operation. The CRS was successfully field-tested in a middle east field late 2018. Offset well data were used to validate the effectiveness of the tool and provide recommendations for future development. An offset well was used as a benchmark for comparison to characterize CRS performance. The CRS replaced the stabilizer directly above the measurement while drilling (MWD) tools as part of the BHA used for drilling the interval from 1800 to 2520 meters. When compared to the offset well, the tool had no negative effect on trajectory or dogleg severity. Tight spots required significant back-reaming in the offset well during pull-out-of-hole (POOH). Using the CRS saved 63 hours of rig time when POOH due to the tool’s effective tight spot cutting capability. High torque fluctuations ranging between 2 to 13 klbs-ft were observed in the offset well while drilling formations mainly composed of sticky claystone and limestone. The resulting poor wellbore quality rendered significant logging challenges. The CRS’s ability to damp lateral vibration while engaging in its reaming function resulted in the mitigation of these challenges. Another innovative feature of the CRS’s reaming function is the complete elimination of cutter loss risk. The CRS body is, by far, the industry’s largest area bearing mounted reaming structure and its concentric design eliminates the possibility of it being lost in the hole. The CRS body rotates in response to lateral vibration and drill string whirl when in a vertical or deviated wellbore, effectively contributing to the damping of both vibration modes. The body acts as friction reducer at high deviations. The rotating body also translates on the tool mandrel when faced with a tight spot or pack-off. This translation is opposed by a unique spring assembly that can deliver full top drive torque to the body to cut through the formation.