Author(s): Tarasevich Vladimir
Linked Author(s): Vladimir Tarasevich
Keywords: Coaxial pipe system; Water hammer; Wave propagation; Computation method
Abstract: Pressure surges in the coaxial pipe systems differ significantly from the water hammer in a single pipe due to interaction through the inner pipe wall. An example of such kind of transients could be the pressure surge triggered in the borehole by inserting the bypass plug at the bottom of the casing string. The present paper discusses the process of pressure surge propagation for the cases when this surge is caused by closing the hole in the wellbore-casing string system with a divider. The basic principles of the Joukowsky water hammer theory have been used to describe this process. The system of four partial differential equations, describing coupled propagation of surge waves inside the drill string and in the annular space, has been obtained. Unlike the case of the “classic” tube, the case of the concentric pipes produces four waves of disturbances (instead of two ones) with various velocities. The problem formulation in terms of the Riemann invariants is given. A computation method based on the explicit finite-difference scheme of running calculation was elaborated. Computation results are demonstrated.
Year: 2013