Establishment and Application of T-H-M Coupling Model of Casing-Cement Ring-Formation in Thermal Recovery Wells

With the gradual increase of thick oil extraction in petroleum resources around the world, the well wall sealing integrity problem caused by thick oil extraction is becoming more and more prominent. In order to prevent the seal failure of the casing-cement ring-formation combination, this paper establishes a T-H-M coupled mathematical model of a hot recovery well to analyze the seal integrity of the cement ring. In response to the problem that the existing finite element model for thermal recovery wells ignores the mechanical parameters of cementite that change with temperature when studying the integrity of cement ring seal, this paper couples the heat conduction model and the H-M coupling model in turn to establish a T-H-M coupled finite element model, and introduces the failure factor of cementite body to make the analysis more comprehensive. The model was used to simulate the form of seal integrity failure in well FHW3057P, proving the reasonableness of the model while giving countermeasures to effectively prevent the casing-cement ring interface from detaching due to thermal expansion by simulation optimization, requiring the thermal expansion coefficient of the casing to be less than 1.3 × 10^–5 K⁻¹ and the thermal expansion coefficient of the cement ring to be greater than 0.95 × 10^–5 K⁻¹. The model can be used to simulate and analyze the possible failure forms of cement rings so that targeted measures can be proposed to improve the integrity of cementing seals and provide theoretical guidance for the safe and orderly production of hot recovery wells in oil fields.