Auto Driller Improvements and Open Source Modeling Reduce Drilling Time and Trips

Abstract

Abstract The objective of the auto driller is to maintain stable control of drilling parameters to reduce the time per stand and increase single run sections when possible. Large variation in rate of penetration, weight on bit, differential pressure, torque, and rotary speed have been found to damage the bit, motor, and bottomhole assembly (BHA), reducing the performance and life of these tools. During operations it was found that some instability in drilling parameters was introduced by the auto driller. The first attempt was to find the best set point combination to improve stability and net rate of penetration (ROP). This helped, but the system still tended to be unstable with changes in formation. The next step was to adjust the auto driller tuning parameters to improve system stability. The tuning was modified so that the system could be stabilized over the range of formations being drilled and were sent to the real-time centers and recorded to become part of the drilling roadmap. The net rate of penetration, or minutes per stand, was used as a key metric for real time performance. Variation in rate of penetration, weight on bit, differential pressure, torque, and rotary speed were used as leading indicators of BHA stress and thus life expectancy. Manually tuning these systems on the rig, with intensive support from the operator’s and contractors subject matter experts, and real time centers resulted in a reduction in drilling time and stress on downhole motors and tools. The drilling time was improved from 30-50 minutes per stand to 18-25 minutes per stand in the fast drilling part of the lateral interval (about 1500 meters). Furthermore, the fluctuation of the drilling parameters were reduced to two-thirds compared to previous wells. The drilling team completed its first shoe-to-TD single run in two years in the 8-1/2" section, typically requiring three BHAs. This was drilled in about half the time compared to the prior single run and was followed by another 3000-meter single run lateral. The downhole temperature in this section exceeded the motor vendor’s specifications and reducing the stress on the BHA due to parameter variation was critical in improving performance. Key performance indicators were developed to measure the health and function of the auto driller system. These were shown to be useful as real time and leading indicators of performance. A case study demonstrates how to use these KPIs to manually tune the system while drilling. Finally an example is shown on how to use source code from the Open Source Drilling Community to help tune the system offline and make it more robust to formation changes.