US Patent 7296624 Pressure control apparatus and method

Pressure control in an isolated lower wellbore annulus, defined by a conduit sealably positioned within an isolated lower wellbore segment, is achieved while gravel packing by sensing the pressure within the isolated lower annulus while gravel packing and admitting fluid from the isolated lower annulus into the conduit at one or more discrete locations along the conduit when the sensed pressure corresponds to one or more threshold pressure conditions. The annulus pressure is sensed while gravel packing using a pressure-sensitive device disposed in the annulus, e.g., positioned by the conduit at a high-pressure location. The pressure-sensitive device actuates one or more valves carried along the conduit to admit fluid from the annulus into the conduit at one or more of the discrete locations, and thereby control the pressure in the isolated lower annulus.