Computer Simulation Research On Displacement Efficiency Under Different Flow State

In order to looking for oil and gas, the exploratory development is gradually carried through, and the wells which have particular casing program become more and more. It challenges drilling and cementing engineering. Cementing displacement efficiency directly influences the cementing quality, and it affects the life and the recovery of the well. There are many factors that can affect displacing efficiency. However, study on this aspect is limit. Therefore, it is very significant to study the displacing efficiency under different condition and different flow pattern, and it is also very important to study the fluid properties which influence the displacement efficiency.In the paper, it is investigated that how the properties of non-Newtonian fluid(cement slurry, spacer fluid, drilling fluid) which flows in different patterns (stopper flow, laminar flow, turbulent flow) affect the displacing efficiency in different types of well (vertical well, horizontal well, directional well). And the conclusions consist of displacing efficiency in stopper and turbulent flow is higher than that in laminar flow, the law which the fluid influence displacement efficiency in different patterns is similar, flow pattern is more important than fluid properties to displacing efficiency and so on. And optimal fluid properties which include viscosity, shear force, consistency coefficient and liquidity index of drilling fluid and cement slurry are found. And the study that the borehole condition affect the displacing efficiency is completed, the conclusions include displacement efficiency is decreasing when annular size is reducing, or borehole roughness is serious, or casing eccentricity is increasing, and or calabash borehole. In addition, the displacing turbulence model is modified while the parameters can't be directly inputted in turbulence flow. And the mathematical model of the relationship between the behaviors of drilling fluid and cement slurry is established by computer simulation study. The study in this paper can contribute to improving displacement efficiency and cementing quality and is significant.