Reservoir communication with a wellbore

Abstract

A method and apparatus for improving reservoir communication includes, in one arrangement, use of one or more chambers to create an underbalance condition and/or a fluid surge in the wellbore. In another arrangement, a tool string comprises a packer, a circulating valve, and an atmospheric chamber, in which the circulating valve, when open, is adapted to vent a lower wellbore region below the packer when the packer is set, and the atmospheric chamber is capable of being operated to create an underbalance condition below the packer. In yet another arrangement, an apparatus comprises a subsea wellhead equipment including a blow-out preventer, choke line filled with a low density fluid, and a kill line filled with a heavy fluid. The choke line is adapted to be opened to create an underbalance condition in the wellbore. In yet another arrangement, a method of creating an underbalance condition comprises controlling wellbore pressure at least in a perforating interval to achieve a target level, configuring a perforating gun to achieve a target detonation pressure in the perforating gun upon detonation, and creating an underbalance condition in the perforating interval of the wellbore when the perforating gun is shot. In yet another arrangement, a tool string for use in a wellbore extending from a well surface comprises a closure member adapted to be positioned below the well surface, and a chamber defined at least in part by the closure member. The tool string further comprises at least a port selectively openable to enable communication between the chamber and a wellbore region. The port when open creates a fluid surging to the chamber to provide a low pressure condition in the wellbore region. A tool in the tool string is adapted to perform an operation in the low pressure condition.