Uncertainty quantification on the control of oil well drilling process

• Grant number: 22/11381-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: October 01, 2022
• End date: September 30, 2023
• Field of knowledge: Engineering - Mechanical Engineering - Mechanics of Solids
• Principal Investigator: Marcelo Areias Trindade
• Grantee: Pedro Augusto Pereira Magalhães
• Host Institution: Escola de Engenharia de São Carlos (EESC). Universidade de São Paulo (USP). São Carlos , SP, Brazil

Abstract

In the oil well drilling process, torsional vibrations due to the stick-slip phenomenon lead to high amplitude oscillations of the drilling angular velocity which, in its turn, has the potential to damage the drillstring and/or drill-bit. The usual strategy to reduce these oscillations is to diminish the weight-on-bit and/or augment the drilling velocity. The first reduces the drilling rate and, thus, diminishes the process efficiency. The second tends to lead to lateral vibrations that may damage the drillstring and the oil well. Since the drilling cost is of the order of hundreds of thousands of dollars per day, any occurrences of reduction in the drilling rate and/or interruptions in the process due to drill-bit and/or drillstring failures must be avoided. Therefore, there is great interest on the development of control strategies for the drilling process that minimize these torsional vibrations. The main challenge is due to the fact that the actuation is done through the application of a control torque at surface with the objective of controlling the angular velocity of the drill-bit, which is subject to a resisting torque due to its interaction with the rock formation, while the torque transmission is performed by a drillstring with diameters of the order of a dozen centimeters and lengths of the order of a few kilometers. The large flexibility of the drillstring combined to the lack of knowledge in real-time about the interaction between drill-bit and rock formation makes that a simple and usual velocity control strategy at the surface may induce the stick-slip phenomenon. The objective of this project is to study the performance of some drilling control strategies and their dependencies on uncertainties associated with the interaction between drill-bit and rock formation. It is expected to establish performance criteria in nominal and robustness terms for each strategy and design methodologies to improve the performance.