Robust optimization of horizontal drillstring rate of penetration through a nonlinear stochastic dynamic model

Americo Cunha Jr (1, 2, 3) , Christian Soize (1) , Rubens Sampaio (2)

1 MSME - Laboratoire de Modélisation et Simulation Multi Echelle
2 Departamento de Eng. Mecânica
3 UERJ - Universidade do Estado do Rio de Janeiro [Brasil] = Rio de Janeiro State University [Brazil] = Université d'État de Rio de Janeiro [Brésil]

A drillstring is a long column under rotation, composed by a sequence of connected drill-pipes and auxiliary equipment, which is used to drill the soil in oil prospecting. During its operation, this column presents a three-dimensional dynamics, subjected to longitudinal, lateral, and torsional vibrations, besides the effects of friction, shock, and bit-rock interaction. The study of the dynamics of this equipment is very important in many engineering applications, especially to reduce costs in the oil exploration process. In this sense, this work aims to formulate and solve a robust optimization problem that seeks to maximize horizontal drillstrings rate of penetration into of the soil, subjected to the restriction imposed by the structural limits of the column. To analyze the nonlinear dynamics of drillstrings in horizontal configuration, a computational model, which uses a nonlinear beam theory of Timoshenko type is considered. This model also takes into account the effects of friction and shock, induced by the lateral impacts between the drill-string and borehole wall, as well as bit-rock interaction effects. The uncertainties of the bit-rock interaction model are taken into account using a parametric probabilistic approach. Two optimizations problems (one deterministic and one robust), where the objective is to maximize the drillstring rate of penetration (ROP) into the soil, respecting its structural limits, are formulated and solved. In order to optimize the ROP, it is possible to vary the drillstring velocities of translation and rotation. The solutions of these optimization problems provided two different strategies to maximize the ROP.

Mots clés: drillstring dynamics; horizontal drillstring; parametric probabilistic approach; robust optimization

Domaines: Mécanique [physics.med-ph]; Probabilités [math.PR]; Statistiques [math.ST]

Americo Cunha Jr, Christian Soize, Rubens Sampaio. Robust optimization of horizontal drillstring rate of penetration through a nonlinear stochastic dynamic model. Biennial International Conference on Engineering Vibration (ICoEV-2015), Sep 2015, Ljubljana, Slovenia. pp.1-11. ⟨hal-01169135⟩