Real-time monitoring of cement sheath integrity under high-angle HPHT wellbore conditions.

Wilcox, Lawrence B.

Abstract

The lengthy time span over which the cemented well needs to retain its integrity is a massive challenge today. The cement plugs in abandoned wells, in conjunction with the annular cement sheath, need to prevent leakages well beyond the life of the wellbore. The results of a recent engineering study of 15,500 wellbores in the Gulf of Mexico show that, as a wellbore turns fifteen years of age, it develops a fifty percent chance of being adversely affected by sustained casing pressure. Even though a high percentage of the results are for wells in the Gulf of Mexico, similar numbers have been reported for the North Sea. This research project investigated the mechanical behaviour of the cement sheath over the entire life cycle of the wellbore by applying analytical and numerical methods. Analytical and numerical models were developed and applied to explain wellbore phenomena - such as cement failure and sand production - by ascertaining the eligibility of elastic and non-elastic approaches. In addition, a three-dimensional, geomechanical model was developed to predict the effect of a ductile formation on stress loading in the wellbore. The results of the numerical and analytical models provided definitive results for casing-cement-formation deformation as a function of time under downhole operating conditions. The results show that wellbore pressure, wellbore temperature variation, and the Young's modulus of cement have a stronger influence on shear failure than other parameters.

Citation

WILCOX, L.B. 2023. Real-time monitoring of cement sheath integrity under high-angle HPHT wellbore conditions. Robert Gordon University, PhD thesis. Hosted on OpenAIR [online]. Available from: https://doi.org/10.48526/rgu-wt-2071847

• Thesis Type: Thesis
• Deposit Date: Sep 6, 2023
• Publicly Available Date: Sep 6, 2023
• DOI: https://doi.org/10.48526/rgu-wt-2071847
• Keywords: Well integrity; Wellbore lifespan; Cement sheaths; Materials engineering; Geomechanics; Offshore engineering
• Public URL: https://rgu-repository.worktribe.com/output/2071847
• Award Date: Mar 31, 2023