The 2017 Drillbotics design report by the team at the Norwegian University of Science and Technology (NTNU) in Trondheim, Norway has been updated to include test results and analyses. The work was presented as the team’s master’s thesis. It was added to the permanent collection of the university and is available at http://hdl.handle.net/11250/2458492
Summary
As stated in the introduction, the aim of this master project was to ”design a drilling rig and related
equipment to autonomously drill a vertical well as quickly as possible while maintaining borehole
quality and integrity of the drilling rig and drillstring.” The rig was designed during the fall semester of 2016 based on the guidelines provided by the Drillbotics competition committee and on research about drilling dysfunctions, dysfunction mitigation and automation. Economic considerations also largely determined the projects desirability and dictated how it should be carried out having the rig maximum allowable expenditures constrained to US$ 10,000 or its equivalent. During the spring semester of 2017 the rig was constructed and the control architecture was developed.
After having set up the system, it was possible to start the testing phase. Experiments were carried
out on different rock samples to analyze the reaction of the drill string and the rest of the rig to
various operating conditions, directly related to WOB and RPM. This very quickly gave a much
better understanding of the main problems that would be encountered, of the weaknesses of the
design, of the areas to improve and of initial operations that required a re-design. It became clear
that vibrations could potentially damage the equipment and reduce the drilling efficiency.
One of the main ideas in the project was to pressurize the drill pipe to increase the geometrical
stiffness, which in turn would reduce the tendencies of buckling and thereby allowing greater WOB.
To minimize the risk of bit walking and wobbling, and mitigate the chance of destructive vibrations,
several stabilizers were implemented in the mechanical design. A fixed stabilizer in the drill deck
floor, a stabilizer designed as a landing module for the riser, and the conventional integral spiral
blade stabilizers on the BHA were all used to reduce the risk of any drilling dysfunctions.
The performance of the rig design and control algorithms were demonstrated on the on-site test
day 8th of June 2017 by drilling the block sample witnessed by DSATS members.
