Abstract
A successful primary cementing job requires an efficient fluid displacement process in order to place cement in the annulus between a casing or liner and the formation around the wellbore. This operation is a critical part of the well construction and due to the hardening properties of cement there will be no second chance with this operation. Once hardened, the cement should provide zonal isolation and pressure containment and should do so through the lifetime of the well. Furthermore, the cement shall anchor and support the casing string and protect it against corrosion due to formation fluids. A good quality cement job is important both from an environmental and from an economical perspective.
In order to improve recommended cementing practices, and thus also the quality of cementing process, it is necessary to develop cementing simulation software for proper engineering. Detailed data on the displacement efficiency from practical operations are difficult or impossible to obtain. Furthermore, field operations do not allow for a systematic change in fluid properties. To be able to validate the engineering tools it is therefore necessary to perform laboratory measurements with fluids with relevant properties. It is also important to perform these experiments in laboratory equipment of sufficient diameter dimensions to facilitate scale up of the results.
The purpose of the present article is to give an overview of cement displacement experiments which were conducted using a large diameter annular flow loop using model fluids with relevant rheological properties. While some results from these experiments have been presented in previous articles, this article is intended to give an overview of all the experiments, including the setup and experimental approach, and provides in more detail results not presented previously. In particular we show results from video recordings which confirm previous conclusions based on conductivity measurements.
It is found that eccentricity affects the displacement physics significantly. In washout sections the effects of eccentricity are different and generally smaller since the eccentricity is also reduced. Drill string rotation improves displacement efficiency in all tested cases both within and outside the washout cavity.
Since the amount of publicly available experimental data of this type is very limited, the detailed information presented here should be of great interest and relevance for the development and validation of industrial cementing simulation software.
