NEW METHODOLOGY FOR GAS MIGRATION PREDICTION BEFORE OILWELL CEMENTING

Many challenges have been presented in the oil well drilling Many challenges have been presented in oil well drilling including preventing gas migration after cementing operations. This phenomenon is potentially dangerous since the gas can migrate to the surface causing the annular pressurization or lead to a blowout with catastrophic results that may include the loss of the well. If the hydrostatic pressure in front of the gas zone becomes lower than the pressure in this zone, the gas will invade the well. This work presents a comprehensive methodology to evaluate gas migration after cementing operations taking into account the critical static gel strength concept associated with time dependent viscosity behavior. A mechanistic model based on a force balance acting on gas bubble was proposed to predict the bubble displacement through the cement slurry while it gels and evaluate if the hydraulic isolation will be affected allowing project operation changes to ensure well construction safely.