Patent attributes
Apparatus and methods are provided for fracturing a well in a hydrocarbon bearing formation. The apparatus can include one or more valve sub-assemblies assembled into a tubing string inserted into an unlined well. The valve sub-assembly can include a sliding piston initially pinned in place to seal off ports that provide communication between the interior of the tubing string and a production zone of the formation. A ball can be inserted into a tubing string and moved along the tubing string by injected pressurized fracturing fluid until the ball sits on a valve seat of a valve sub-assembly coupled to the sliding piston to close off the tubing string below the valve. The force of the fluid forces the piston downwards to shear off the pins and open the ports. Fracturing fluid can then exit the ports to fracture the production zone of the formation.
