Hydrostatically insensitive testing and injection plug

A plug for use in a wellbore, the plug comprising:

• a body having a head and a tail, the body defining a passage extending from a port toward the tail to an opening toward the head;
• a piston housing movably disposed on the tail of the body from a first position to a second position and enclosing a piston chamber therewith;
• a control valve disposed in communication with the piston chamber and having an opened state and a closed state, the control valve in the opened state permitting pressure communication between the wellbore and the piston chamber, the control valve in the closed state preventing the pressure communication between the wellbore and the piston chamber;
• a low-pressure volume disposed in communication with the control valve and configured to urge the control valve to the opened state;
• a rupturable barrier separating the low-pressure volume from the wellbore and being rupturable in response to a predetermined pressure level in the wellbore, the control valve being configured to transition from the opened state to the closed state in response to the rupture of the rupturable barrier, the piston housing being urged from the first position to the second position in response to a pressure differential between chamber pressure in the pressure chamber and wellbore pressure in the wellbore;
• a closure being movable from a closed condition to an opened condition relative to the port, the closure in the closed condition preventing fluid communication through the passage, the closure in the opened condition permitting fluid communication through the passage;
• a biasing element disposed between the piston housing and the closure, the biasing element biasing the closure toward the opened condition and biasing the piston housing toward the second position;
• and
• a fixture releasably affixing the closure to the piston housing, the fixture initially holding the closure in the closed condition and preventing the movement of the piston housing from the first position to the second position, the fixture being configured to release in response to the movement of the piston housing from the first position to the second position due to the pressure differential increased above an initial level.

A plug for use in a wellbore, the plug comprising:

• a body having a head and a tail, the body defining a passage extending from a port toward the tail to an opening at the head;
• a piston movably disposed on the tail of the body, the piston having a closure portion and a housing portion, the housing portion defining a piston chamber with a portion of the body, the closure portion being movable from a closed condition to an opened condition relative to the port, the closure portion in the closed condition preventing fluid communication through the passage, the closure portion in the opened condition permitting fluid communication through the passage;
• a control valve disposed in communication with the piston chamber and having an opened state and a closed state, the control valve in the opened state permitting pressure communication between the wellbore and the piston chamber, the control valve in the closed state preventing the pressure communication between the wellbore and the piston chamber, the control valve being configured to transition from the opened state to the closed state in response to a predetermined pressure level in the wellbore;
• a low-pressure volume disposed in communication with the control valve and configured to urge the control valve to the opened state;
• a rupturable barrier separating the low-pressure volume from the wellbore and being rupturable in response to a predetermined pressure level in the wellbore, the control valve being configured to transition from the opened state to the closed state in response to the rupture of the rupturable barrier, the closure portion of the piston being urged from the closed condition to the opened condition in response to a pressure differential between chamber pressure in the pressure chamber and wellbore pressure in the wellbore;
• a biasing element disposed between the piston and the body, the biasing element biasing the closure portion toward the opened condition;
• and
• a fixture releasably affixing the piston to the body with the closure portion initially held in the closed condition, the fixture being configured to release in response to the movement of the piston due the pressure differential increased above an initial level.

A method of cementing tubing in a wellbore during a cementing operation, the method comprising:

• landing a plug in the tubing during the cementing operation, the plug having a closure, a pressure chamber, and a fixture;
• performing a pressure test by increasing tubing pressure in the tubing behind the landed plug and preventing, with the closure in a closed condition, communication through a passage in the landed plug;
• controlling communication of the tubing pressure to the pressure chamber on the plug;
• releasing a fixture in response to movement of the pressure chamber from a first position to a second position due to an increased pressure level in the pressure chamber;
• and
• permitting communication through the passage in the plug by permitting the closure to move from the closed condition to an opened condition in response to the release of the fixture.

A wiper plug for use in a wellbore, the wiper plug comprising:

• a body having a head and a tail and having a wiper fin disposed thereabout, the body defining an opening toward the head and defining a port toward the tail, the body defining a passage extending between the port and the opening;
• a piston being movable on the body from a first position to a second position, the piston defining a piston chamber;
• a control valve disposed in communication between the wellbore and the piston chamber and being configured to capture wellbore pressure in the piston chamber as captured chamber pressure;
• a closure disposed on the body and being configured to transition from a closed condition to an opened condition relative to the port in response to the movement of the piston, the closure in the closed condition preventing fluid communication through the port, the closure in the opened condition permitting fluid communication through the port;
• and
• a fixture releasably holding the closure in the closed condition on the body, the fixture being configured to release in response an increased pressure differential on the piston above an initial pressure differential between the captured chamber pressure and the wellbore pressure.