Patent Application
20150315873
The field of the invention is pressure operated ported subs opened with sleeve movement and more particularly where the sleeve is actuated with a delay to allow a pressure test of a string followed by sleeve actuation at a far lower pressure than the string test pressure.
In the past, pressure actuated sleeves have been protected from setting pressures with a rupture disc that is set at a higher pressure than the string test pressure, as described in U.S. Pat. No. 8,555,960. US Publication 2014/0102703 uses pressure cycles and an indexing device with Belleville washers to selectively open a sliding sleeve. U.S. application Ser. No. 14/080544 discusses using timers or sensors to operate a ported sleeve without any detailed description as to how this is to be accomplished.
Timers and signal devices add complexity and expense and the present invention accomplishes a time delay economically and reliably. A disintegrating plug is first exposed to well fluids during the pressure test of the string. After a time the plug disintegrates sufficiently to allow tubing pressure access to a second rupture disc mounted in a pressure balanced chamber. Then when it is desired to shift the sleeve the second rupture disc is deliberately broken at a lower pressure level than the test pressure to allow entry of tubing pressure to a piston that is referenced to a low pressure such as atmospheric. The large differential pressure on the piston then shifts the sleeve. The opening of the ports provides formation access for a variety of operations such as fracturing, acidizing, injecting or conditioning. These and other aspects of the present invention will be more readily apparent to those skilled in the arts from a review of the description of the preferred embodiment and the associated drawings while recognizing that the full scope of the invention is to be determined by the appended claims.
A ported sub is operated with a pressure actuated shifting sleeve. A first rupture disc is set at a lower pressure than the test pressure for the tubing string that houses the ported sub. The first rupture disc breaks at a lower pressure than the string test pressure to expose well fluids to a disintegrating plug. The plug disintegrates over time to then expose tubing pressure to a chamber and a second rupture disc with the chamber configured to have no effect on moving the sliding sleeve. When the tubing pressure is then raised to a predetermined pressure below the test pressure for the string, the second disc breaks exposing a piston to tubing pressure on one side and trapped low pressure being the opposite side of the string. The differential moves the sleeve to open a port to let tools be pumped into position without a need to perforate.
a is a closer view of the rupture discs and plug of
a is a closer view of parts of the sliding sleeve of
Referring to
The operation of the tool begins with
An application of the pressure operated sleeve is in a cemented casing where circulation needs to be established to allow pumping down equipment particularly in a horizontal portion of a borehole. Perforation is not needed to open up such a circulation path. The pressure actuated sleeve can be placed just above a cement shoe so that pressure can be built up to the string test pressure and on the way to that pressure the first rupture disc breaks and starts the clock in a sense on the disintegration of the plug. The plug can be made of different materials depending on the time needed to conduct the pressure test to conclusion and then reduce the tubing pressure. One such material is a controlled electrolytic material (CEM) that has been described in US Publication 2011/0136707 and related applications filed the same day. US Publication 2011/0136707 and the related applications are incorporated by reference herein as though fully set forth. Other materials that disintegrate or otherwise fail from exposure to well fluids, heat or fluids added to a well can also be employed to get the desired delay time. After the delay with the tubing pressure lowered a decision can be made to actuate the sleeve 18 by raising the tubing pressure above the burst pressure of the second rupture disc. This pressurizes chamber 40 to push sleeve 18 against minimal resistance from chamber 24. The use of low pressure chamber 24 allows the sleeve to be made thicker with no loss of drift dimension represented by its inner wall 46 because the required piston area is diminished by the large pressure differential between chambers 40 and 24. The sleeve is then less likely to distort because it has a heavier wall with little to no loss of drift dimension through the sleeve 18.
The above description is illustrative of the preferred embodiment and many modifications may be made by those skilled in the art without departing from the invention whose scope is to be determined from the literal and equivalent scope of the claims below:
