Dual-stage valve straddle packer for selective stimulation of wells

• US 20090159299A1
• Filed: 12/21/2007
• Published: 06/25/2009
• Est. Priority Date: 12/21/2007
• Status: Active Grant

• Current Assignee: Extreme Energy Solutions, Inc.
• Original Assignee: Extreme Energy Solutions, Inc.
• Inventors: Schofield, Dan, Kratochvil, Robert, Kirk, Scott, Smolcic, Darko
• Granted Patent: US 7,789,163 B2
• Time in Patent Office: Days
• US Class Current: 166/387
• CPC Class Codes: E21B 33/124 Units with longitudinally-spaced plugs for isolating the intermediate space
• CPC Class Codes: E21B 33/1265 with mechanical slips
• CPC Class Codes: E21B 33/12955 using drag blocks frictionally engaging the inner wall of the well
• CPC Class Codes: E21B 43/26 by forming crevices or fractures

Abstract

A straddle packer which, when in place during a fracing or well stimulation service, isolates the fracing zone from zones in the wellbore above and below the fracing zone, and which when run into the wellbore provides an open passageway from below the packer to the tubing string, relieving built up fluid pressure below the tool and permitting insertion at relatively high speeds.

Claims

1. A straddle packer with a dual stage valve which opens and closes, the packer, comprising:

a. a drag body connected to a hollow mandrel;

b. the hollow mandrel, open at one end to the wellbore below the straddle packer, with an outer surface;

c. slideably fit into a matching cavity in the straddle packer'"'"'s lower body;

d. the cavity configured to be operatively sealed with the outer surface of the hollow mandrel, and with a port which, when the packer is open, communicates between the mandrel'"'"'s hollow to the wellbore below the tool and through the cavity and then the body to the annulus between the packer and the wellbore, and which, when the packer is closed, is configured such that the port is sealed by the sealed interface between the outer surface of the hollow mandrel and the inner surface of the body'"'"'s cavity.

e. the sliding motion between the opening and closing positions of the port being motivated by force exerted by friction between the drag body and the wellbore'"'"'s casing when the packer is moved, such that a downward movement of the packer slides the mandrel and opens the port, while an upward movement of the packer closes the port, the valve being pressure balanced.

2. A dual-stage valve straddle packer for insertion into a wellbore and delivery of fracing and stimulation service to a particular zone of the wellbore comprising:

a. a body operatively connected to a tubing string, with fluid communication to the inner bore of the tubing;

b. the body having an upper cup-seal for isolation of fluid delivered under pressure through fracing ports in the body below that seal by sealing the annulus between the body and the wellbore'"'"'s casing;

c. the body having a set of lower cup-seals for isolation, by a top lower cup-seal of the fracing ports from the wellbore below the top lower seal, and by a bottom lower cup-seal of the wellbore below the bottom lower seal from the fracing ports, the cup-seals being essentially one-way seals sealing a higher pressure side from a lower pressure side, the seals deployed to seal the annulus between the body and the wellbore'"'"'s casing;

d. a passageway from the wellbore below the bottom lower seal through the body and a pressure balanced valve to ports in the body in fluid communication when the valve is open with the annulus between the body and the wellbore'"'"'s casing at a point above the bottom lower seal and below the upper seal;

e. the valve being capable of opening and closing, responsive to a movement of the body in the wellbore, where an upward movement will close the valve and a downward movement will open the valve.

3. A method of inserting a straddle packer for isolation of a fracing service in a zone from zones in a wellbore above and below the fracing zone, comprising the steps:

a. where the straddle packer has three unidirectional seals, sealing flow from high pressure side to low pressure side, the uppermost seal sealing the low pressure wellbore zone above the tool from a high pressure fracing zone below the uppermost seal;

a middle seal sealing the high pressure fracing zone above the middle seal from a low pressure wellbore zone below the seal, and a lowermost seal sealing a high pressure wellbore zone below the lowermost seal from a low pressure fracing zone, the seals being seals when the relative pressures are as stated, otherwise a seal will not act as a seal;

b. inserting the straddle packer into a wellbore, and applying a downhole force;

c. which causes a valve in the body to open;

d. opening a passageway between the wellbore below the packer'"'"'s body through the body and through a port to the annulus between the body and the wellbore'"'"'s casing between an the lowermost and the middle seal;

e. which passageway is then in fluid communication through a fracing port to the tubing string,

permitting the packer to be inserted through a fluid at a higher speed than if the passageway was not open or not there.

4. The method of claim 3 where the valve is caused to close by movement of the packer uphole, isolating the wellbore below the packer from the fracing zone between the uppermost and middle seals for fracing.