Abstract
Abstract
Drilling the 12.25-in. landing section in one of the Middle East fields had been a challenge in terms of drilling performance due to combined downhole severe drilling dynamic mechanics effects and borehole instabilities. These complications eventually lead to downhole tool failures and a low rate of penetration (ROP). This manuscript describes the solution to introduce tandem downhole dynamic recording tools in the Bottom Hole Assembly (BHA) which provides a better understanding of the downhole dynamics and mechanics effects guiding to optimum BHA design and leading to better performance.
Drilling the curve and landing section is challenging due to extreme stick & slip (S&S) and shocks & vibrations (S&V) phenomena resulting in low performance and difficulties in achieving the directional requirement. The 12.25-in. landing section is drilled with a full set of Rotary Steerable System (RSS) drive, Positive Displacement Mud Motor (PDM), Measurement While Drilling (MWD) and Logging While Drilling (LWD) tools, making the BHA very rigid. Nevertheless, many initiatives have been carried out to enhance the BHA and bit design with limited improvement. After performing a detailed risk analysis, tandem downhole dynamic recording tools were introduced to understand the downhole dynamics behavior and the interaction between the bit, the drilling BHA components, and the different formations drilled.
The downhole dynamic recording tool is powered by batteries and records the data in memory mode for post-run analysis. It measures downhole drilling mechanics with its three-axis accelerometers, gyro, and temperature electronics along with other measurements. The downhole recording tools was installed tandemly across the 12.25-in. motorized RSS BHA where one tool was positioned inside the bit and another one in a sub above the mud motor. After the run, all the data from the two downhole recording tools were downloaded and then analyzed. From the recording tool at the bit, it can be concluded that the PDC bit used in the analyzed run, generated low-to-medium stick & slip, hence, a new bit design with more aggressive features could be used safely to enhance the ROP. From the recording tool in the sub above the mud motor, it was concluded that the BHA components and mainly the LWD tool created high-to-severe stick & slip due to its stabilizers, and action should be taken to minimize this effect. In addition, the drilling fluid lubricity needs to be enhanced to reduce the stick & slip and shocks & vibrations effects on the tools. All the presented solutions and lessons learned of the downhole dynamic recording tools utilization can be used for future run enhancement and to be replicated worldwide as applicable.