Error analysis of stand-pipe pressure control and prediction of . surface casing pressure for horizontal well killing process

Key words:  horizontal well  well killing  circulating pressure  error analysis  surface casing pressure

Abstract:

Considering the calculation errors brought by annular friction and fluid flow pattern，the compared errors of standpipe pressure control for horizontal and vertical wells killing process were anzlyzed on the basis of the principle of horizontal well killing. Based on the theory of multiphase transient flow and the general principle of well control of vertical well, a comprehensive theoretical model dealing with dynamic well control for horizontal well was developed. The finite difference method was adopted for solving mathematical equations. The results show that errors can be found not only at initial circulating pressure point and final circulating pressure point but also at kick-off point and hold angle point in horizontal well killing process. For horizontal well, the surface casing pressure gradually increases until kick removed from horizontal section. The annulus space is reduced by cuttings bed so that the velocity of the fluid and the surface casing pressure increase. The curvature radius, horizontal section length, slight horizontal inclined angle, and multi-buildup rates have little effect on surface casing pressure while other parameters such as the well bore size, killing rate and kick size have considerable influence on surface casing pressure.