Cementing design and placement methods to optimize seal integrity and lower cost for deepwater wells drilled with non-aqueous drilling fluid

The challenges of both primary and remedial cementing in Non-Aqueous Drilling Fluid (NAF) are well known in the deepwater industry. NAFs allow for stable drilling in high pressure high temperature (HPHT) and ultra-deepwater environments. However, mud properties that were beneficial for drilling become detrimental to completions. Fluid incompatibilities resulting from contamination, residue, fluid swapping and other fluid interactions can result in reduced compressive strength, channeling, downhole gelation and a poor cement bond. Incompatibility and incomplete hole cleaning can result in safety and environmental risks including job failure, future operational issues and loss of zonal isolation. Commercially available products are available to assist with mud displacement, however, there is a need for a fundamental characterization of mud-cement interactions on a chemical level to improve the knowledge of related technical risks and the technology required for risk reduction and long-term well integrity. The objectives of this project are to develop fundamental knowledge of mud-cement compatibility issues related specifically to deepwater cementing, to quantify risks associated with cementing in NAF and to develop best practices and derive recommendations in order to reduce the recognized risks.