Apparatus and method for fracturing a well

摘要

An apparatus and method is provided for fracturing a well in a hydrocarbon bearing formation. The apparatus can include a valve subassembly that is assembled with sections of casing pipe to form a well casing for the well. The valve subassembly includes a sliding piston that is pinned in place to seal off ports that provide communication between the interior of the well casing and a production zone of the formation. A dart can be inserted into the well casing and propelled by pressurized fracturing fluid until the dart reaches the valve subassembly to plug off the well casing below the valve subassembly. The force of the fracturing fluid against the dart forces the piston downwards to shear off the pins and open the ports. The fracturing fluid can then exit the ports to fracture the production zone of the formation.

主权项

1. A method for fracturing a well in a formation, the method comprising the steps of:
a) providing an apparatus having at least two valves, each valve having a key profile disposed thereon, wherein the key profile of each of the at least two valves is different from the key profile of the other of the at least two valves and a piston that is slidable between an open position and a closed position; b) placing the apparatus in a casing string disposed in the well, the apparatus located near a production zone in the formation; c) placing a dart into the casing string, the dart having a dart profile disposed thereon, wherein the dart profile matches the key profile on only one of the at least two valves; and d) injecting pressurized fracturing fluid into the casing string wherein the fracturing fluid moves the dart through the casing string into the apparatus until it reaches one of the at least two valves with the key profile which matches the dart profile and thereby engages the key profile disposed on an interior sidewall of a tubular piston disposed within the apparatus, to place a downward force on the piston to move the piston from the closed position to an the open position wherein the fracturing fluid can pass through at least one port of the apparatus to fracture the formation.