Rock mechanics aspects of blowout self-containment

摘要

A blowout is an uncontrolled flow of reservoir fluids into the wellbore to the surface,causing serious, sometimes catastrophic, problems in different types of petroleumengineering operations. If the formation's strength is low and the pore pressure is high,bridging can be a very effective method for blowout containment. In this method, theformation caves into the open hole or onto the casing and stops the flow of theformation's fluid, either naturally or intentionally. This method can be effective indeepwater blowouts where the formation has high pore pressure and considerable shaleintervals with low strength.In this research, wellbore stability and fluid flow performance subroutines havebeen developed with Visual Basic for Applications (VBA) programming. By integratingthe subroutines together, we made a simulation tool to predict wellbore stability duringblowouts and, consequently, predict wellbore bridging during normal and blowoutsituations. Then we used a real case in the country of Brunei to investigate a field case ofa bridged wellbore to validate the simulator. In addition to the field case, we used GMISFIB 5.02, a wellbore stability software, to provide validation.In the final part of this research we studied the effect of water depth in bridgingtendency during blowout for the deepwater Gulf of Mexico (GOM). Since we could notfind any real data in this area, we used general trends and correlations related to theGOM. The results of our study showed that water depth delays the occurrences ofbreakout in the wellbore during blowouts (i.e. for greater depth of water, wellbore collapse occurs farther below the mudline). However, the depth in which collapse occursis different for different maximum horizontal stress amounts.