SELECTIVE PRESSURE RELIEF DEVICE
Publication Date: 2016-Aug-17
The IP.com Prior Art Database
A wellhead assembly and method are presented herein comprising a string of at least two tubulars disposed in a subterranean formation, wherein an outer tubular and an inner tubular define an annulus therebetween. The wellhead assembly includes a pressure relief device set in the outer tubular and configurable in a sealed position to seal pressure between the annulus and the formation, and in an open position to vent pressure between the annulus and the formation. The wellhead assembly also includes an isolation sleeve mounted on the outer tubular and configurable in a protective arrangement to isolate the pressure relief device from a pressure load, and in an exposure arrangement to expose the pressure relief device to the pressure load.
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SELECTIVE PRESSURE RELIEF DEVICE
The present disclosure relates generally to the integrity of an oil and gas well, and more particularly, to controlling pressure build-up within an annulus of a wellhead assembly.
Systems for producing oil and gas from subsea wellbores typically include a wellhead assembly that includes a wellhead housing attached at a wellbore opening, where the wellbore extends through one or more hydrocarbon producing formations. Casing and a tubing hanger are landed within the housing for supporting casing and production tubing inserted into the wellbore. The wellhead assembly may include strings of concentrically arranged casing, such as conductor pipe, surface casing, and an inner casing. Generally, the inner casing goes deeper than the conductor pipe and surface casing and lines the wellbore to isolate the wellbore from the surrounding formation. Tubing typically lies concentric within the inner casing and provides a conduit for producing the hydrocarbons entrained within the formation. Annuli are defined between each pair of adjacent concentric tubulars, where each annulus is sealed from pressure communication with any of the other annuli. If an annulus becomes unexpectedly pressurized, such as from a leak or thermal expansion of fluids contained and constrained within the annuli, a pressure differential will develop across a tubular wall adjacent the pressurized annulus.
Pressure relief devices, such as rupture discs, are rarely, but sometimes, used as an annular pressure build-up protection device in well construction. These devices can protect casing strings from collapsing and compromising the integrity of the well.
Pressure relief devices, such as rupture discs, have a predetermined activation pressure and have proven to have high reliability. The activation pressure naturally impacts the pressure rating of the casing since the pressure relief device is designed to protect that casing from catastrophic failure. Activation of the pressure relief device is only acceptable after a casing string is covered by a subsequent string and no longer needed for pressure integrity. However, prior to the installation of the subsequent string, the reduced pressure rating can have an unacceptable impact on well design and often disallows the application of a pressure relief device. The present disclosure is intended to address the above-
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identified problem(s) by presenting an apparatus, method and/or system for isolating the pressure relief device until the time it is needed for its intended protective purpose.
In accordance with at least one aspect of the present disclosure, there is provided a wellhead assembly having a string of at least two tubulars disposed in a subterranean formation, wherein an outer tubular and an inner tubular define an annulus therebetween. The wellhead assembly includes a...