Improvement in Well Integrity by Mitigating Casing to Cement Debonding Using Advanced Technique

Abstract This paper addresses the deployment of an external protective coating with a rough surface profile on wells identified as susceptible to common well cementing issues. It presents the associated challenges and highlights the distinctive benefits and robustness of the solution in effectively enhancing the well integrity. Initially, experimental investigations were conducted to assess the impact of casing surface profile on casing/cement bond quality. Subsequently, candidate wells were selected where additional cementing requirements was required to reinforce well integrity. Coated casings with rough surface profiles were deployed, followed by Cement Bond Logs (CBL) to evaluate the quality of casing/cement bond. The CBL responses of the selected wells were then compared to wells utilizing bare casings. The results indicated that the casing surface roughness due to external protective coating serves a dual purpose of corrosion protection and establishing a robust bond with cement. The corrosion logs provided a positive indication of good corrosion prevention. The findings from the CBL-VDL logs were aligned with the presence of a sturdy casing/cement bond. Cement bond logs from the wells, in which casing surface roughness is high, revealed the establishment of a solid cement/casing bond. The study indicated that an increase in surface roughness contributed to shear bond strength. The protective coating reinforced with special quartz, to provide high surface roughness, created a robust and rough surface that not only prevented corrosion initiation/propagation but also fostered a strong bond between the casing and cement. The outcomes indicated that the implementation of this innovative technique does not only provide corrosion protection but also enhanced casing-cement bond. Thus, it lowered the risk of fluid migration, consequently, mitigating sustained casing pressure. Therefore, it extended the lifespan of producing wells, resulting in notable cost reductions by eliminating frequent shut-in and costly workovers.