Evaluating the transport of solids generated by shale instabilities in ERW drilling

The problem of cuttings transport in the inclined sections of extended reach wells (ERW) is a major concern in the oil-well drilling industry. This article presents an innovative time-dependent mathematical model, along with a computer implementation of it, which is based on the well-known two-layer model approach. An innovative feature of this model consists in the consideration of the added amount of solids that comes from the crumbling and cave-in of the wellbore. The unstable effects of this added amount of solids is taken into account through a variable representing-the added volume of cuttings per unit time and length. A finite volume approach is used to solve the system of differential equations. The paper represents a first step on the integrated analysis of cuttings, transport and wellbore stability problems.