Eventos Anais de eventos
ENCIT 2018
Brazilian Congress of Thermal Sciences and Engineering
A New Constitutive Equation to Represent Drilling Fluids
Submission Author:
Tainan Gabardo , PR
Co-Authors:
Tainan Gabardo, Cezar Otaviano Ribeiro Negrao
Presenter: Tainan Gabardo
doi://10.26678/ABCM.ENCIT2018.CIT18-0697
Abstract
Drilling fluids present thixotropic behavior and normally gel at rest. The sol-gel transition is important in order to prevent the deposition of rock cuts generated by the drill bit in eventual stops during the process. When the gel is formed, a pressure higher than the usual is required to restart the flow. It is important to control the pressure level, as a high pressure may damage the formation and a low pressure can cause a kick. In the first case, drilling fluid can be lost to the formation. In the second case, if the kick is not controlled, a blowout may occur. Both cases represent environmental and financial problems. Therefore it is imperative to understand better the behavior of these fluids. So the objective of this paper is to propose a new constitutive equation for time-dependent materials and use the rheological data of a drilling fluid to fit the model. In order to show the model potential, a modified Jeffreys model coupled with a regularized Herschel-Bulkley equation and an unbalance equation for the viscosity are going to be used. Next the model is fitted to rheological data of a drilling fluid. The preliminary results show agreement with the literature regarding shear stress and shear rate controlled tests.
Keywords
drilling fluid, Constitutive equation, mathematical model, Thixotropy
