Numerical Simulation Research Of Character For New Supercritical Carbon Dioxide Drilling Fluid

In recent years, with progress of gas drilling technology and coiled tubing drilling technology, new demands have been put forward for drilling fluid system. Supercritical carbon dioxide drilling fluid not only has low viscosity and high diffusibility coefficient as gas, but also has high density and good dissolving feature as liquid, which can satisfy extreme demands for coiled tubing and small hole drilling. Supercritical carbon dioxide drilling fluid has been paid many attentions in the world as a sort of advanced technology recently.This paper made use of numerical simulation means and the simulation experiment. The basic change law of the characteristic for supercritical carbon dioxide drilling fluid with pressure and temperature was researched.With fluent soft system, drilling fluid the liquid variation law for drilling fluid in the drilling string and annulus space was numerical simulated. The research indicated that the pressure and temperature were increased and the density and viscosity were declined with the well depth.The numerical simulation analysis was consistent with theoretical results.With circulating simulating experimental equipment manufactured newly of the supercritical carbon dioxide drilling fluid, the feature of carrying cutting in different inclined angle were researched. In some condition, the simulating experiment indicated that the low carrying cuttings velocity was reduced with the adding of pressure and increased with the increasing of temperature.In addition, simulation experiment studied stability of carbon dioxide hydrate and solubility.