Thursday 17th February at 14:00, both physically in Salle du Conseil (4th floor), Bât. Breguet, and online via Microsoft Teams
Salle du Conseil (4th floor), Bât. Breguet, CentraleSupélec
3 rue Joliot Curie
91190 Gif-sur-Yvette, France
Speaker: Jean Auriol, CNRS researcher at L2S, Paris-Saclay University
Title: Sitck slip vibrations in drilling: modeling, estimation, avoidance
Abstract: Extraction of resources in the earth’s subsurface – oil, gas, minerals, and thermal energy – necessitates drilling long slender boreholes from the surface to the subsurface target. The diameters of the wells required to extract these resources range from 10 to 50 cm, and lengths can frequently exceed 10,000 m, leading to mechanical systems with extreme aspect ratios. These systems are the source of complex dynamic behaviors as many dynamic phenomena are involved, such as vibrations, bending and twisting quasi-static motion, and bit-rock interactions. In particular, the drillstring interaction with the borehole gives rise to a wide variety of undesired oscillations, which can be classified depending on the direction they appear. Among these oscillations, torsional vibrations can appear due to downhole conditions (such as significant drag, tight annular clearances, or formation characteristics, for instance) or due to side forces induced by Coulomb friction terms. These oscillations are known as stick-slip and are considered to be the most destructive as they may cause fatigue of the equipment, a deterioration of the performance of the process, or a premature failing of the bit. This may result in catastrophic damages and at least wear to expensive components of the drillstring. These oscillations are characterized by a series of stick (a cessation of bit rotation) and slip (a sudden release of energy) cycles.
In this talk, we will present some recent developments for estimating and controlling the torsional motion of a drilling device. We will introduce first the stick-slip phenomenology and explain its physical causes. We will present a mathematical distributed model that can accurately describe the torsional motion of the drilling device. We will then focus on the case of a drilling system with the bit off-bottom, which represents the system at the start-up of a drilling operation, e.g., after a connection. We will design and test an algorithm for estimating the bit angular velocity and side forces on a drill string using only topside measurements fed into an adaptive observer. The proposed approach combines a high fidelity model with recent theoretical developments on observer design for hyperbolic PDEs to find appropriate feedback gains to ensure a fast and robust tuning. The estimates produced by the algorithm can be displayed to a driller in real-time in an advisory system, and the result can be built on to help optimize the drilling operation and improve directional drilling control. We will finish this presentation by comparing recent advanced control strategies to eliminate stick-slip oscillations. The different results will be illustrated by simulation with field scenarios and tests against field data.
Bio: Jean Auriol received his M. Sc. degree in civil engineering (major in applied mathematics) from MINES ParisTech, PSL Research University in 2015. In 2018, he obtained his Ph.D. degree (control theory and applied mathematics) from the same university. In 2019, he was a post-doctoral associate at the Department of Petroleum Engineering, University of Calgary, AB, Canada, where he worked on the attenuation of mechanical vibrations in drilling systems.
Since December 2019, Jean is a researcher at CNRS, L2S, CentraleSupelec, Université Paris-Saclay, in France. His research interests include Partial Differential Equations, infinite-dimensional systems robust control of hyperbolic systems, neutral systems, networks, and interconnected systems, mechanical vibrations.