Patent ID: 6484816
Filing Date: 2002-11-26
Classification: E21B

Abstract:
A system for maintaining fluid pressure control of a well bore drilled through a subterranean formation using a drilling rig and a drill string having a through bore and positioned at least partially within the well bore, the system comprising:a BOP to contain an annulus fluid pressure within an annulus of the well bore; a drilling fluid choke in fluid communication with the annulus of the well bore; a fluid pump for pumping the selected fluid at a benchmark selected fluid circulation rate through the drill string, then through the annulus of the well bore and substantially back to the drilling rig; a drill pipe pressure sensor to sense a fluid pressure within the drill string; and a programmable controller responsive to the drill pipe pressure sensor to control at least one of (a) the fluid pump to effect the fluid circulation rate, (b) the drilling fluid choke to control pressure in the annulus of the well bore, and (c) the BOP to control pressure in the annulus of the well bore, such that while pumping the selected fluid a bottom hole circulating fluid pressure remains substantially constant and at least as great as the bottom hole kick pressure, while also controlling an axial position of the drill string relative to the well bore.