Application of Innovative Resin System to Improve Wellbore Integrity: Case Studies from Saudi Arabia

Abstract

Abstract A significant challenge occasionally faced during the well's lifecycle is the pressure buildup between the cemented annuli, also known as sustained casing pressure (SCP). The presence of SCP indicates a path of flow of formation fluids to the surface. Compromise of cement sheath integrity is one of the primary reasons for such a pressure buildup. This challenge prompted the development of such an isolation material that should enhance the mechanical properties of cement to prevent the SCP. In parallel, another isolation material was required to remediate the wells suffering from SCP. After some research, a specialized resin system was developed that could be deployed to prevent and eliminate the SCP in the situations mentioned above. This paper presents the lab testing and application of the innovative resin system. This system can be used as a standalone product and blended with cement, depending upon the nature of the application and zonal isolation objective. While using the resin as a standalone product, its solids-free nature and low yield point enable it to flow freely into micron-sized leaks or channels. Pure resin is mainly used for remedial applications. When the resin is added to the cement during primary cementing operations, it forms a dense and highly cross-linked matrix with improved mechanical properties that helps to provide a dependable barrier to maintain long-term zonal isolation. Engineered solutions ultimately deliver the optimal asset value of the reservoir. During the last few decades, several laboratory investigations and field studies have been conducted to find answers to the problem of SCP, which appears after primary or remedial cement jobs. Almost all these studies unanimously conclude that conventional cement does not always endure the mechanical stresses imposed by the wellbore conditions, and it often falls short in providing permanent isolation beyond the well's production life. This paper illustrates two case studies to validate this. The first case study is related to primary cementing, where the resin-cement blend was successfully utilized to prevent the expected high-pressure influx across a water-bearing formation. The resin-cement system was designed to be placed as a tail slurry to provide enhanced mechanical properties compared to a conventional slurry. The combined mixture of resin and cement slurry provided the desired product's necessary properties. The cement treatment was performed as designed and met all zonal isolation objectives. The second case study relates to remedial cementing, where the resin system was utilized to remediate the three annuli on an offshore oil well. Reliable and effective annular barriers are critical to well management for safety and performance. Conventional Cement slurries have been the industry's typical means of creating these barriers. However, the cement alone is inadequate to meet the industry needs; hence, combined solutions deliver improved well integrity.