Research On Calculation Of Wellbore Pressure In Horizontal Well

Horizontal drilling technology has been rapidly developed and popularized, but the research of well control technology for horizontal well is not enough as vertical well in the most of cases, particularly in the aspect of gas cut issue. Based on the theory of gas-liquid two-phase flow and the general principle of well control of horizontal well, one-dimensional transient theory model of the annular two-phase flow during well gas influx which couples the flow in wellbore with the formation percolation is established. The model gives priority to the drift flux model and assisted by the separated flow model and the homogeneous flow model. The finite difference method is employed to solve the theoretical model. Through numerical simulation calculation, this paper analyses the variation of the wellbore pressure distribution when two-phase flow moves up along the horizontal well as time passes by. The factors of influencing the wellbore pressure in horizontal wells such as overflow level, build-up rate, hole angle, the horizontal section length, drilling fluid displacement is discussed.The example shows that the mathematical model of annular two-phase flow is credible, and it provides a basis for the further theory research and well control design of horizontal wells.