Design and Optimization of an Autonomous Laboratory-Scale Drilling Rig and Bit Design for Directional Drilling

Abstract

This report documents the work that has gone into the design and optimization of a laboratory-scale drilling rig and bit design for the purpose of directional drilling and to participate in the Drillbotics competition. Drillbotics is an international competition organized by SPE's Drilling Systems Automation Technical Section (DSATS) that challenges university teams to build an autonomous laboratory-scale drilling rig. Each year a different challenge is introduced and autonomous directional drilling, steering and downhole measurements are the main focus for this year's competition. A brand new Bottom Hole Assembly (BHA) was designed and manufactured at the University of Stavanger to accommodate the improvements identi ed during the 2019 Drillbotics competition. One of the recognized challenges was the pneumatic motor in the BHA breaking at the connection point. The addition of bushing, bearings, a motor shaft and motor sleeve provided the pneumatic motor with the necessary protection, and no motors broke during this year's testing. A proprietary bit design has been 3D-printed at the University and designed with the assistance from Lyng Drilling, a Schlumberger company. The UiS bit is optimized for directional drilling and was made to enhance performance and ensure good borehole quality. The results from the tests performed show great potential for the UiS bit, and compared with the other drill bits it had the greatest horizontal displacement built, reduced vibrations and excellent hole quality. The implementation of a 9-axis Inertial Measurement Unit (IMU) on a custom

exible Printed Circuit Board (PCB) allowed the team to t the sensor closer to the bit, providing more accurate data regarding the current bit position. The testing of the downhole sensor was limited due to unforeseen incidents, however the sensor has been assembled, calibrated and debugged. The results from the limited testing showed great potential and the position of the IMU in the x-, y- and z-axis could be measured. The code will be handed over to the team competing in the 2021 competition for further development. Limited time for testing and a complicated BHA design resulted in countless hours spent on making slight adjustments to overcome challenges and practicalities to ensure a functional drilling assembly. The challenges, lessons learned and future recommendations for the 2021 competition are thoroughly explained in the nal chapter of the report. The competition day for the 2020 competition should have been on June 24th in Celle, Germany. Unfortunately, the competition was cancelled due to the global pandemic and this report could not include the rig performance at the competition.