Abstract
Modern drill bits designs have become more efficient using static modelling, and in more advanced cases, time-based dynamic modelling. These methods have created improved cutting structures that fail rock more effectively, however, at-bit vibrations are difficult to estimate because of the high-frequency nature of the vibration and its proximity to typical vibration sensors. In conventional applications, vibration is not measured near the bit. A solution to capture this data on conventional assemblies and use the data in an actual bit design is presented in this paper with subsequent performance and vibration results. The relative efficiency, bit dull grading, and vibration performance are compared across these designs and explored in depth.
This new generation of vibration tool fits inside the bit pin, enabling accurate at-bit vibration measurements by a suite of sensors. The tool includes a tri-axis accelerometer that measures lateral and axial acceleration, and gyro sensors to measure rpm and torsional acceleration. Together, these outputs combine with the rig surface data to have time- and depth-based vibration data in the context of the run. When used to quantify the dynamic model, this represents a modelling calibration that improves bit design performance. The lower-vibration environment created by the new bit design enables the operator to run increased parameters with a lower likelihood for measurement-while-drilling (MWD) failures, motor failures, and premature catastrophic bit failures leading to faster run times and less nonproductive time (NPT). These results also prove that meaningful bit design changes can take place more frequently than through traditional means, translating value to the operator in the form more successful BHA improvements and less drilling time.
Using the new in-bit sensor in a baseline design to start the design cycle, a baseline mechanical specific energy (MSE) and vibration model was developed foot-by-foot. The worst areas of vibration were seen as the bit became dull in the lower section of the drilling interval. A new dull bit model was created in parallel to capture this section of data. A new design was proposed to Whiting Petroleum to improve both sharp and dull efficiency and vibration, and subsequently run with sensor in an offset well.
Missing sensor data restoration for vibration sensors on a jet aircraft engine
