Prediction Model Of Surge Pressure At High Temperature And High Pressure

With the increasing difficulty of exploration and development, our country in deepwater drilling, HPHT drilling and drilling thrust belt safety issues narrow mud weight window conditions have become increasingly prominent, drilling facing severe technical challenges. At its core, is that accurate measurement and control of the entire wellbore pressure and downhole drilling parameters.During drilling, the presence of temperature gradient and pressure gradient, the deeper the borehole temperature and pressure in the wellbore becomes higher. The density of the drilling mud is no longer a constant, but as the temperature and pressure changes. Temperature and pressure also affect the rheological properties of drilling mud, drilling mud and thus affecting the equivalent circulating density. Therefore, this paper theoretical model derived circulating wellbore temperature field, and then launched a high-temperature high-pressure drilling mud density experiments and experimental study of high temperature and pressure of drilling mud rheology, and the establishment of a high-temperature high-pressure drilling method using multiple linear regression analysis on an experimental basis mud ESD, apparent viscosity, plastic viscosity and dynamic shear force prediction model. Consider the downhole temperature and pressure, the drilling mud rheology, density, and annulus fluid state, borehole size, and other factors displacement cycle, iterative numerical methods ECD model was established, and the preparation of the ECD prediction software. For from the drilling, casing and other conditions, to stabilize the flow state theory, the establishment of a steady-state pressure fluctuation model, through amendments to the drilling mud density and rheological parameters, improved pressure fluctuations predicted steady-state model accuracy. Pressure fluctuations on various factors were analyzed that flow index, hole size, column maximum speed, the impact is more significant consistency coefficient, followed by the drilling mud density from column run under acceleration and position depth. The model system for the maintenance of the well pressure balance, reduce blowout, lost circulation, well caving underground complex situations and accidents, shorten the drilling cycle, reduce drilling costs, are of great significance.