LOCKING SYSTEM FOR A BLOWOUT PREVENTER FUNCTION

Abstract

A hydraulic locking system for a blowout preventer function is provide. The locking system enables implementation and practical engagement as part of the routine functioning of the blowout preventer. The locking system may be adapted to fluidly interconnect a control system port and a function port so as to trap and release hydraulic actuation pressure against the function port and any blowout preventer function fluidly communicating thereto.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority of U.S. provisional application No. 62/024,560, filed 15 Jul. 2014, the contents of which are herein incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates to blowout preventers and, more particularly, to a hydraulic locking system for a blowout preventer function, wherein the locking system enables implementation and practical engagement as part of the routine functioning of the blowout preventer.

A blowout preventer is a large, specialized valve or similar mechanical device, usually installed redundantly in stacks, used to seal, control and monitor oil and gas wells. Blowout preventers were developed to cope with extreme erratic pressures and uncontrolled flow emanating from a well reservoir during drilling that can lead to a potentially catastrophic event known as a blowout. The term BOP (pronounced B-O-P, not “bop”) is used in oilfield vernacular to refer to blowout preventers. As used herein, unless specified otherwise the terms “blowout preventer,” “BOP,” “blowout preventer function,” “blowout preventer stack,” “blowout preventer system,” “BOP stack” are to be given their broadest possible meaning manner to describe an assembly of several stacked blowout preventers of varying type and function, as well as auxiliary components.

Practically all commonly available BOP hydraulic actuation systems use the continuous application of hydraulic pressure to an actuated function as the primary means of ensuring that the actuated BOP function is sustained. As a result, if the pressure integrity of said BOP hydraulic actuation system is lost, the sustaining pressure of the actuated BOP function is also lost.

Currently, devices based on mechanical locking methods are used to lock BOP functions. Such devices are commonly based on manually actuated screws which take time to actuate and require direct access by personnel to the BOP stack. Moreover, such devices are normally impractical to engage mechanical BOP function locking systems as a routine precaution for situations when and where hydraulic actuation pressure loss.

As can be seen, there is a need for a hydraulic locking system for a blowout preventer function, wherein the locking system enables implementation and practical engagement as part of the routine functioning.

SUMMARY OF THE INVENTION

In one aspect of the present invention, a system for locking actuation pressure in a BOP function includes a control system configured to control a hydraulic pressure therein; a control line fluidly communicating the BOP function to the control system; and a hydraulic locking apparatus disposed along the control line, wherein the hydraulic locking apparatus having a function port adapted to fluidly communicate to a portion of the control line connected to the BOP function; a control system port adapted to fluidly communicate to a portion of the control line connected to the control system; and a locking mechanism movable from an unlocked configuration to a locked configuration, locking the actuation pressure against the function port.

These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an exemplary embodiment of the present invention;

FIG. 2 is detail view of an exemplary embodiment of the present invention; and

FIG. 3 is a detail view of an exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description is of the best currently contemplated modes of carrying out exemplary embodiments of the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims.

Broadly, an embodiment of the present invention provides a hydraulic locking system for a blowout preventer function, wherein the locking system enables implementation and practical engagement as part of the routine functioning of the blowout preventer. The locking system may be adapted to fluidly interconnect a control system port and a function port so as to trap and release hydraulic actuation pressure against the function port and any blowout preventer function fluidly communicating thereto.

Referring to FIGS. 1 through 3, the present invention may include a hydraulic locking system 20 for a blowout preventer function, wherein the locking system enables implementation and practical engagement as part of the routine functioning. The locking system 20 may embody a plurality of apparatuses and methods thereof for hydraulically locking BOP functions.

Typically, a BOP includes a control system 3 fluidly communicating to the BOP function by way of a control line 18, as illustrated in FIG. 1. The locking system 20 may be disposed along the control line 18 so as to fluidly interconnect the BOP function and the control line 18. The locking system 20 may include a function port 6 and a control system port 7 fluidly communicating to the BOP function and a control system 3, respectively, as illustrated in FIG. 2. In certain embodiments, an accumulator 5 may be connected in series to the portion of the control line 18 interconnecting the BOP function and locking system 20. For example, the locking system 20 may be fluidly connected to the function port 6.

The locking system 20 may include a check valve 1 and a two-way valve 2 connected in parallel to the control line 18, as illustrated in FIG. 1. The check valve 1 may include a passage cavity fluidly communicating the function port 6 to the control system port 7, as illustrated in FIG. 2. In certain embodiments, a check-spring 12 may operably engage a ball check 8 dimensioned and adapted to operatively block an esophagus, preventing the passage of actuation and/or hydraulic fluid flowing therethrough, whereby the resulting actuation pressure may be trapped against the function port 6. In certain embodiments, a bleed valve 14 may be disposed in the passive cavity between the function port 6 and the esophagus, wherein the bleed valve 14 may be adapted to allow a predetermined amount of actuation fluid and/or hydraulic pressure to flow therethrough. The check valve 1 may be adapted so that the ball check 8 may be urged away from the esophagus, allowing the flow of actuation and/or hydraulic fluid. In certain embodiments, a pneumatically operated stem 9 may be disposed in the check valve 1 for urging said ball check 9 (locking mechanism). The operated stem 9 may be adapted to be movable from an unlocked configuration to a locked configuration, operatively hydraulically locking the actuation pressure against the function port 6. The unlocked configuration of this ball check and stem assembly may result from controlled pneumatic pressure by a pneumatic cylinder assembly 10 communicating to a pneumatic port 13, and the locked configuration is urged by a return spring 11, as illustrated in FIG. 2.

In an alternative embodiment, the check valve 1 locking mechanism may include a poppet 15 for trapping the actuation pressure against the function port 6, wherein the poppet may be dimensioned and adapted to operatively block the esophagus, as illustrated in FIG. 3. The poppet 15 may be operatively urged by a long stem 16 biased by a poppet spring 17, whereby this poppet and stem assembly may be movable from the unlocked configuration to the locked configuration, operatively hydraulically locking the actuation pressure against the function port 6.

A method of using the present invention may include the following. The hydraulic locking system 20 disclosed above may be provided. The hydraulic locking system 20 may be adapted to allow pressurized actuation fluid to flow to the BOP function being activated. Once a predetermined maximum actuation pressure delivered through the control line 18 is realized, the hydraulic locking system 20 may be adapted to trap actuation fluid within the function port 6 so as to hold and sustain the activated BOP function. Optionally, the hydraulic locking system 20 may trap actuation pressure in the accumulator 5. Alternatively, if the hydraulic locking system 20 may be adapted to equalize actuation pressure across the control system and function ports 7, 6, respectively. The hydraulic locking system 20 may be adapted to allow fluid to flow from the activated BOP function when it is deactivated.

When the BOP function is activated, the check valve 1 may be either opened or already opened so that hydraulic actuation pressure and flow may be allowed to pass through the check valve 1 to actuate the BOP function 4. Once the actuation pressure from the control system 3 through the check valve 1 remains constant or begins to decline, the hydraulic locking system 20 may be closed to trap actuation pressure against the function port 6. If the pressure on the control system 1/control system port 7 of the valve ever exceeds the trapped pressure at or near the function port 6, the check valve 1 may be opened (the ball check 8 and/or poppet 15 is urged from the esophagus) and pressure on the BOP function may be equalized to the higher control system pressure and then closed again.

By opening the hydraulic locking system 20 only when it is possible to increase the pressure at or near the function port 6, a loss in BOP control system pressure would not result in a loss of actuation pressure on the BOP function, as is the case for a vast majority of BOP control systems in use today.

In an alternative embodiment, the hydraulic locking system 20 could further be enhanced by connecting the accumulator 5 to the control line 5 on the BOP function portion of the locking system 20. The accumulator 5 may be adapted to store actuation pressure to help sustain actuation pressure on the BOP function even if leaks were present in the control lines 18 and/or BOP function hydraulic seals.

Prior to deactivating the hydraulically locked BOP function, the pressure across the hydraulic locking system 20 would preferably be equalized to reduce valve wear, and then the hydraulic locking system 20 could opened. The pressure in the actuated BOP function could then be vented through the control line 18 by the BOP control system 3, allowing the opposing BOP function to be actuated.

The present invention may be manually or computer implements based in part on predetermined actuation pressures.

Initially the opposing BOP function may be actuated and there is little or no pressure in control system port 7 and the function port 6. In this initial depressurized condition the two-way valve 2 may be in the close position. If the BOP control system 3 vents the actuation pressure on the opposing BOP function and pressurizes BOP control system port 7, fluid pressure is free to automatically by-pass the closed two-way valve 2 by flowing through the check-valve 1 and into the function port 6 to actuate the BOP function. If the accumulator 5 is installed, it may begin filling once its pre-charge pressure is exceeded in the function port 6. At this point the BOP function connected to the function port 6 is fully actuated and pressurized. If by some unintended cause the pressure drops or is vented from the control system port 7, the check-valve 1 may automatically close and trap actuation pressure in the function port 6 (along with accumulator pressure if present) thereby hydraulically locking the actuated BOP function connected to the function port 6.

It is possible for the locking pressure trapped in the function port 6 to drop in the event of leakage, for example through the bleed valve 14. If this occurs slowly enough, and hydraulic pressure may be restored to the control system port 7 quickly enough, the check-valve 1 may open and re-pressurize the BOP function via pressure through the function port 6. Installation of the accumulator 5 may allow a higher actuation pressure to be sustained for a longer periods of time for a given leak rate.

In order to actuate the opposing BOP function, it would be preferable, but not necessary, to ensure that the control system port 7 may be first pressurized to a predetermined full BOP control system pressure. This ensures that the control system port 7 may be pressurized to a predetermined pressure higher than or equal to the pressure trapped in the function port 6 and thereby would equalize the pressure across the two-way valve 2 through the check-valve 1. Equalizing the pressure across the two-way valve 2 may reduce erosion and wear on the two-way valve 2 when it is subsequently opened in preparation for venting the pressure from the function port 6 and the attached BOP function.

It should be understood, of course, that the foregoing relates to exemplary embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.

Claims

1. A system for locking actuation pressure in a BOP function, comprising:

a control system configured to control a hydraulic pressure therein;

a control line fluidly communicating the BOP function to the control system; and

a hydraulic locking apparatus disposed along the control line, wherein the hydraulic locking apparatus comprises: a function port adapted to fluidly communicate to a portion of the control line connected to the BOP function; a control system port adapted to fluidly communicate to a portion of the control line connected to the control system; and a locking mechanism movable from an unlocked configuration to a locked configuration, locking the actuation pressure against the function port.

2. The system of claim 1, further comprising an actuation fluid flowing through the control system under said hydraulic pressure.

3. The system of claim 1, wherein the hydraulic locking apparatus further comprises a check valve.

4. The system of claim 3, wherein the check valve further comprises a ball check and stem assembly.

5. The system of claim 3, wherein the check valve further comprises a poppet and stem assembly.

6. The system of claim 1, further comprising an accumulator fluidly interconnecting the locking mechanism and the function port.

7. The system of claim 3, further comprising a two-way valve connected in parallel with the check valve.

8. The system of claim 2, wherein the control system is configured to operatively move the locking mechanism to the locked configuration at a predetermined maximum actuation pressure.

9. The system of claim 8, wherein the control system is configured to operatively move the locking mechanism to the unlocked configuration if the hydraulic pressure at the control system port exceeds the hydraulic pressure at the function port.

10. The system of claim 6, wherein the accumulator is configured to store actuation pressure to help sustain actuation pressure when the locking mechanism is in the locked configuration.