Casing float tool

An apparatus for forming a buoyant chamber in a well, the apparatus comprising:

• (a) a first length of tubing operable to be positioned in the well and having an up-hole end and a downhole end, the downhole end operable for connection to a second length of tubing, said second length of tubing comprising an apparatus operable for forming a lower boundary of a buoyant chamber;
• (b) a rupture disc assembly disposed within the first length of tubing and operable for forming an upper boundary of the buoyant chamber, the rupture disc assembly comprising a rupture disc operable to be supported in a first position within the first length of tubing by a support structure;
• said rupture disc assembly operable to provide said upper boundary of said buoyant chamber when said rupture disc is in said supported position within the first length of tubing;
• wherein the support structure is operable to release in response to the upper surface of the rupture disc being subjected to a hydraulic pressure that is of a magnitude is at least as high as a threshold hydraulic pressure;
• wherein in operation, in response to the upper surface of the rupture disc being subjected to a hydraulic pressure of a magnitude that is at least as high as the threshold hydraulic pressure and said magnitude being less than a rupture burst pressure of the rupture disc, the support structure releases causing the rupture disc to move from the first position within the first length of tubing and break within the first length of tubing.

An apparatus for forming a buoyant chamber in a well, the apparatus comprising:

• (a) a first length of tubing operable to be positioned in the well and having an up-hole end and a downhole end, the downhole end operable for connection to a second length of tubing that comprises an apparatus operable for forming a lower boundary of a buoyant chamber;
• (b) a rupture disc assembly disposed within the first length of tubing operable for forming an upper boundary of the buoyant chamber during deployment of the buoyant chamber into the well, the rupture disc assembly comprising a rupture disc held in a held position within the first length of tubing by a securing mechanism;
• said rupture disc assembly operable to form and maintain a seal within said first length of tubing when said rupture disc is in said held position and when an upper surface of the rupture disc is subjected to a hydraulic pressure of a magnitude that is less than a threshold hydraulic pressure;
• wherein the securing mechanism is operable to release in response to the upper surface of the rupture disc being subjected to a hydraulic pressure of a magnitude that is at least as large as the threshold hydraulic pressure;
• wherein an internal surface of the first length of tubing has a larger diameter than an internal surface of the second length of tubing;
• wherein in operation, in response to the upper surface of the rupture disc being subjected to a hydraulic pressure of a magnitude that is at least as large as the threshold hydraulic pressure, the securing mechanism releases causing the rupture disc to break within the first length of tubing.

An apparatus for forming a buoyant chamber in a well, the apparatus comprising:

• (a) a first length of tubing operable to be positioned in the well and having an up-hole end and a downhole end, the downhole end operable for connection to a second length of tubing, said second length of tubing comprising a device operable for forming a lower boundary of a buoyant chamber;
• and
• (b) a rupture disc disposed within the first length of tubing operable for forming an upper boundary of the buoyant chamber;
• wherein the rupture disc is movable in an axial direction of the first length of tubing between:
• a first position, and
• a second position axially downhole from the first position and within the first length of tubing,
• wherein the rupture disc is supported by a support structure operable to support the rupture disc in the first position,
• wherein the support structure is operable to release in response to hydraulic pressure being applied to an upper surface of the rupture disc of a magnitude that is at least as great as a threshold hydraulic pressure, and
• wherein the rupture disc is operable to break upon moving from the first position and reaching the second position.