Abstract
Cement displacement plays a key role in the well construction and completion. The displacement of drilling fluids with cement to support, protect casing and seal reservoir formation has been a required process in oil industry for years. Also plug cementing has been applied in the abandoned wells for the environmental concerns. In all these cases, poor cement displacements such as cement channeling and bad zonal isolation will result in a subsequent remedial squeeze cementing, which is both expensive and time consuming. Currently, the cement displacement process relies very often on field engineer's experience. So far, in the literature, cement displacement phenomenon has been qualitatively described by lubrication theory on the basis of the macro-scale consideration.
In order to understand the fluid transport behavior, we propose a new approach to simulate the cement displacement process in this paper. From the micro-scale viewpoints, this new approach is using a Lattice-Boltzmann method to describe quantitatively the fluid flow's behavior in the tubular and annulus during the displacement operation. The traditional approaches such as finite-difference, finite-element or finite volume methods of computational fluid dynamics have serious problems: like long computational times, poor convergence and numerical instabilities. However, the Lattice-Boltzmann method is another computational approach that is more efficient and it is based on a more rigorous description of the transport phenomena, the Boltzmann equation.
The velocity distribution profiles with mud and slurry in the annuli will be obtained from the fluid dynamics computation. The effects of slurry properties, inlet flow rate on the displacement's velocity profiles are investigated. The chances of cement channeling also are discussed with the Lattice-Boltzmann's simulation results. This study will provide insight in the mechanism of miscible fluid transport properties and a guidance of cement displacement's job design.
