This paper presents the preliminary results of a research project on ultra deepwater blowouts. This research is a part of a comprehensive study currently conducted by Petrobras, the Brazilian oil company, aiming at drilling and producing safely, in terms of well control, in water depths as deep as 10000 feet (approximately 3000 meters). Firstly, the paper presents a mathematical procedure that predicts wellbore pressures and flow properties during a gas blowout using an unsteady state model that considers the multiphase nature of the flow. Coupled to this procedure, there is a gas reservoir model that calculates gas flow rates entering the well during the unloading part of the process and later on during the blowout itself. The mathematical procedure was implemented in a FORTRAN computer program and several simulation runs were performed to analyze the effect of some drilling variables and reservoir properties on blowout flow rates including the effect of the high backpressure generated by the seawater hydrostatic head. Afterwards, the paper shows the modifications implemented in the computer program to make possible simulations of the dynamic kill technique using a relief well drilled by a dynamically positioned vessel. Finally, the results of the simulations are discussed and analyzed and, when pertinent, recommendations for field application are suggested.

You can access this article if you purchase or spend a download.