Abstract:

HTHPUnder the condition of HT and HP, the density of water base drilling fluid will not be a constant. Too narrow range of safe fluid density is not the biggest problems in drilling HT and HP well. The apparatus for testing stastic density at HT and HP and the property of conventional drilling fluid are used to research the rule that stastic density of running water, low density , medium density and high density water base drilling fluid changes as temperature and pressure, and a regression relationship is set up, the mathematic model of the stastic density of drilling fluid change as temperature and pressure established, the factors affecting water base drilling fluid density under HT and HP analyzed. It is concluded that temperature impacts the waterbase drilling fluid density more than pressure does. Based upon the experimental data, pressure impacts the change of drilling fluid density more as temperature increases.

Key words: water base drilling fluid, high temperature, high pressure, density, mathematic model