A Study To Determine Necessity of Pilot Holes When Drilling Shallow Gas Zones Using Top Hole Dual Gradient Drilling Technology

摘要

When drilling offshore, shallow gas hazards are a major concern because of theirpotential to cause a major blowout. This is a special concern when drilling in shallowerwater, where the gas influx reaches the rig sooner. A common practice used to avoid thepotential dangers of shallow gas is to drill a pilot hole through the shallow gas zone withthe hope that the smaller diameter hole will prevent such a large influx. The use of dual-gradienttop hole drilling technology would allow for a larger hole to be drilled and thepossible gas influx to be killed dynamically, which I have simulated with the use of atop hole dual-gradient simulator.