Numerical Study on the Influence of Saltwater Seepage in High-Pressure Salt-Gypsum Layers on Wellbore Integrity

The salt layer serves as an excellent caprock for oil and gas resources, with its underlying strata often containing abundant hydrocarbon reserves. However, the strong creep characteristics of the salt layer frequently lead to damage issues. Therefore, research on the wellbore integrity of salt layers holds significant practical value. This study focuses on the wellbore integrity of high-pressure salt layers. Based on the Heard time-hardening creep model, a numerical simulation model of composite salt-layered wellbores incorporating a saline water seepage field was established. This study analyzed the mechanical influence of factors such as well inclination angle, azimuth angle, brine density, and liquid column density on the wellbore. The results indicate that high formation pressure, salt creep, and saline water seepage in high-pressure salt layers are the main causes of wellbore stress and deformation. These conditions pose a high risk of damage to the casing and cement sheath. When designing directional well trajectories within high-pressure salt layers, the inclination angle should be controlled between 45° and 60°, and the azimuth angle should be kept below 30°.