Enhancing Well Integrity Self-Healing Cement as a Solution for Sustained Casing Pressure in Middle East Field

The major operator managing the field has encountered Sustained Casing Pressure (SCP), a challenge that arises when fluid migrates through compromised well barriers, causing annular pressures at the wellhead that reaccumulate after being bled off. Despite enhanced placement techniques using conventional cement, SCP persists, highlighting the need for an alternative cement system capable of withstanding anticipated stresses and resolving this issue. To address this challenge, a self-healing cement system was developed, which autonomously restores the integrity of the cement sheath when cracks or microannuli form and hydrocarbons come into contact with the cement. The cement is placed in the annulus using conventional methods, either across or above the hydrocarbon-bearing formation. Once in place, it acts as a dynamic pressure seal, expanding to accommodate downhole changes and healing upon exposure to hydrocarbons. This technology has been successfully tested in four wells within the field, delivering exceptional results. The self-healing cement was used as a single cement slurry, effectively creating an impermeable cap over the hydrocarbon-bearing zones. The cement formulation was specifically designed with a low Young's modulus, enhancing its mechanical flexibility and reducing susceptibility to fractures or the formation of microannuli. To mitigate the risks associated with cement integrity failure due to microannuli or microdebonding from chemical shrinkage post-setting, the formulation incorporated controlled linear expansion of up to 1.2%. This ensures a robust and resilient seal under varying downhole conditions. Following placement, the wells underwent high-pressure testing, designed to induce significant annular pressures. Despite these demanding conditions, the cement's self-healing properties enabled it to autonomously repair and restore wellbore isolation and structural integrity within 1 to 2 weeks, all without requiring external intervention. As a result, the self-healing cement system has been adopted as the standard for all future wells in the field, with plans to extend its use to other reservoirs facing similar well integrity challenges. This paper provides a detailed demonstration of successful casing pressure remediation through the application of a flexible, engineered self-healing cement system. The design methodology, material selection, cement formulation, execution process, and performance evaluation are thoroughly analyzed, with particular emphasis on the engineering principles behind the cement's self-healing capabilities. These principles include the use of low Young's modulus for enhanced flexibility and the incorporation of linear expansion properties to counteract microannuli formation. The results offer valuable insights and establish a technical framework that will inform future well integrity management strategies, engineering practices, and operational procedures in similar subsurface environments across the global oil and gas industry.