Potential well control incidents at Top of Liners (TOL) may take place after cement placement. Typically, liners are run and cemented. After liner hanger is set, reverse circulation takes place. Positive and negative tests might be conducted to ensure integrity at TOL position. Then a clean out run is conducted, and well fluids is displaced to lower fluid density to conduct a flow check after displacement. Potential well control incidents could be indicated from the previous flow tests (positive test, negative test, or flow check test). If potential well control incidents are detected, a proper well control procedure followed by remedial cementing operation will be conducted.

The objective of this study is to detail proper cement formulations that is suitable for liner primary cementing, to resist any potentials for possible well control incidents. To mitigate potential well control incidents, cementing practices should be optimized. The cementing practices include cement composition, drilling fluids composition, spacer composition and operations such as pumping procedure and pressure testing. As cement slurry sets, hydrostatic pressure is reduced on the formation. During this transition, gases or fluids can travel up through the cement column resulting in potential kicks.

Spacers, cements, and drilling fluids should be designed and tested for compatibility for good displacements and bonding. Different types of spacer are required for each type of drilling fluid, such as salted drilling fluid or oil-based fluids. Testing should include running rheology tests, thickening time tests, and compressive strength development tests.

Cement shrinkage is another factor that can lead to potential well control incidents. Expansion additives are usually added to overcome this shrinkage. However, attention should be made to optimize the concentration and type used to avoid over expansion behavior. The study also evaluates the performance of the improved cement formulation against a conventional one. This is achieved by first measuring the relevant mechanical properties of both cement samples using tri-axial loading equipment. The measured properties are then used to populate a numerical model with the required input data. The numerical model is aimed to simulate the performance of each cement formulation within the context of a common and challenging operational scenario that could result in potential wellbore integrity and potential well control incidents.

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