Cement Placement in Irregular Wellbores

In drilling industry, one of the most important operations performed as part of well construction is primary cementing. The quality of the annular cement barrier affects wellbore integrity. Poor cement quality can result in operational challenges and difficult remedial operations and can prevent cost-efficient abandonment operations of the well. Most importantly, it can lead to devastating environmental consequences with little chance for rectification and possibly irreversible damages to the environment and the society.

The purpose of this project is to study the effect of irregular wellbore features on both the bulk annular displacement and removal of mud layers left on the annulus walls. An important motivation for this project is the availability of a new Impulse Radar Caliper tool, or 4D Caliper tool, that can be run behind the bit on drill strings, enabling high-resolution imaging of the open-hole section as it is drilled, and while tripping out.

Reviewing the substantial amount of research executed to improve the displacement efficiency, it appears that little emphasis has been placed on fluid displacement in wellbores with irregular geometric features. Since perfectly regular wellbores would never exist, geometric irregularities may be one of the major reasons for why the industry still struggles with achieving effective cementing jobs in both onshore and offshore wells.

The project aims to improve the methods, both mathematical and practical, implemented in primary cementing operations in wellbores with irregularities. A combination of mathematical (both analytical and CFD) and experimental work will be conducted.

The ultimate goal is to contribute to more effective cementing jobs, thereby reducing the risk of environmental consequences, and ensuring safety and wellbore integrity. The outcome of the project shall propose improvements to current modelling approaches, complementing the models developed for fluid displacement in regular wellbore geometries.