Patent Application
20120234396
The present invention relates generally to pressure regulation within a system. More particularly, the present invention relates to a novel pressure-regulating device for such systems that exhibits improved sensitivity and deadband performance.
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the presently described embodiments. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present embodiments. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
As will be appreciated, supplies of oil and natural gas have a significant effect on modern economies and civilizations. Devices and systems that depend on oil and natural gas are ubiquitous. For instance, oil and natural gas are used for fuel in a wide variety of vehicles. Further, oil and natural gas are frequently used to heat homes during winter, to generate electricity, and to manufacture a wide array of everyday products.
In order to meet the demand for these resources, companies often spend a significant amount of time and money searching for and extracting oil, natural gas, and other subterranean resources from the earth. Particularly, once desired resources are discovered below the surface of the earth, drilling systems are often employed to access and extract the resource. These drilling systems may be located onshore or offshore depending on the location of a desired resource. Further, such systems include a wide array of components, such as valves, that control drilling or extraction operations. Often, some of these components are controlled through pressure variation, such as that provided by a hydraulic control system.
In some such systems, a hydraulic pressure regulator is used to provide a fluid at a regulated pressure to downstream components, such as solenoid valves. One common type of hydraulic pressure regulator has a control piston that moves back and forth to open and close both supply ports and vent ports of the regulator in response to the magnitude of pressure within the regulator. As the functionality of an entire drilling system may depend on proper operation of the hydraulic pressure regulator, it is generally desirable to employ a pressure regulator that is both durable and sensitive to changes in pressure. Further, when such a regulator is employed in a subsea application, halting production from the system to replace an underwater pressure regulator may be particularly undesirable. Additionally, many pressure regulators have excessive deadband that negatively impacts their ability to consistently provide an output pressure within a desired range, which may make such pressure regulators ill-suited for certain applications.
Certain aspects of some embodiments disclosed herein are set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of certain forms the invention might take and that these aspects are not intended to limit the scope of the invention. Indeed, the invention may encompass a variety of aspects that may not be set forth below.
Embodiments of the present invention generally relate to a novel pressure regulator exhibiting reduced deadband and improved sensitivity. In certain embodiments, the pressure regulator is a spring-loaded hydraulic pressure regulator configured for use in controlling components of a drilling system. In one embodiment, the pressure regulator includes a sensing piston and supply seal rings that operate to regulate flow of a control medium into the pressure regulator, and the ratio of the diameter of the piston to the sum of the diameters of the supply seal rings is greater than 0.50. The pressure regulator may also include one or more seal plates having an aperture that is partially shaped in accordance with the geometry of a respective portion of a mating seal ring to further improve sensitivity of the pressure regulator. Additional embodiments may also include various combinations of the features noted above.
Various refinements of the features noted above may exist in relation to various aspects of the present embodiments. Further features may also be incorporated in these various aspects as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to one or more of the illustrated embodiments may be incorporated into any of the above-described aspects of the present disclosure alone or in any combination. Again, the brief summary presented above is intended only to familiarize the reader with certain aspects and contexts of the some embodiments without limitation to the claimed subject matter.
These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
One or more specific embodiments of the present disclosure will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.
When introducing elements of various embodiments, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Moreover, any use of “top,” “bottom,” “above,” “below,” other directional terms, and variations of these terms is made for convenience, but does not require any particular orientation of the components.
Turning now to the present figures, a drilling system 10 is illustrated in
As will be appreciated, the surface equipment 14 may include a variety of devices and systems, such as pumps, power supplies, cable and hose reels, control units, a diverter, a gimbal, a spider, and the like. Similarly, the riser equipment 16 may also include a variety of components, such as riser joints, fill valves, control units, and a pressure-temperature transducer, to name but a few. The riser equipment 16 facilitates transmission of the extracted resource to the surface equipment 14 from the stack equipment 18 and the well 12.
The stack equipment 18 may also include a number of components, such as blowout preventers, production trees (also known as “Christmas” trees), and the like for extracting the desired resource from the wellhead 20 and transmitting it to the surface equipment 14 and the riser equipment 16. In the presently illustrated embodiment, operation of the stack equipment 18 is controlled by a control system 22. The control system 22 includes a pressure regulator 24 and a plurality of valves 26 that control flow through the system 10. The pressure regulator 24 may include a configuration that exhibits reduced deadband and improved sensitivity, as described in further detail below. Additionally, in some embodiments, one or more of the plurality of valves include a blowout preventer, compose a portion of a Christmas tree, or both.
Further, in one embodiment, the pressure regulator 24 is a hydraulic pressure regulator and the plurality of valves 26 includes solenoid valves. As will be appreciated, valves 26 may be configured with a specific pressure rating, such as 3000 psi. An initial supply pressure may be provided to the pressure regulator 24 from a source of pressurized fluid, such as from a bank of accumulator tanks of the control system 22, that is higher than the pressure rating of various other system components, such as valves 26, to facilitate maintenance of adequate pressure to the other system components even during periods of high usage. For example, in some embodiments, the supply pressure may be 3000 psi or 5000 psi. But in other embodiments, other supply pressures may be provided, such as a supply pressure of at least 1000 psi. Indeed, any desired supply pressure may be used in accordance with the presently disclosed techniques. In the system 10, the pressure regulator 24 enables management of the supply pressure to deliver a regulated pressure to downstream components, such as the valves 26. While the pressure regulator 24 of the presently illustrated embodiment is a component of the stack equipment 18, it will be appreciated that, in other embodiments, the pressure regulator 24 may be disposed in other portions of the system 10, such as a component of the surface equipment 14, in full accordance with the present techniques. Additionally, certain embodiments may include multiple pressure regulators 24, which may be configured to receive and transmit control fluid at the same respective pressure levels as each other or, alternatively, such that two pressure regulators 24 each receive or transmit fluids at pressure levels that are different between the two regulators 24.
An example of a pressure regulator 24 is illustrated in
The pressure regulator 24 also includes a pair of supply assemblies 44 disposed on opposite sides of the lower housing 34, and a pair of vent assemblies 46, which are also disposed on opposite sides of the lower housing 34 from one another. The supply and vent assemblies 44 and 46 may be secured to the lower housing 34 in any suitable fashion, such as by fasteners 42. While the presently depicted pressure regulator 24 includes a pair of both supply pressure assemblies 44 and vent pressure assemblies 46, it should be noted that a different number of such assemblies could instead be employed in full accordance with the present techniques.
During operation, a control medium at a first (supply) pressure, such as 5000 psi, may enter the pressure regulator 24 through the supply ports 48 of the supply assemblies 44, and the control medium may be output at a second, regulated pressure, such as 3000 psi, via a regulated pressure outlet port 50 disposed in a side of the lower housing 34. Additionally, if the pressure inside the regulator 24 exceeds a certain threshold, the control medium may be vented from the regulator 24 through the vent ports 52 of the vent assemblies 46.
In the presently illustrated embodiment, the pressure regulator 24 is a hydraulic pressure regulator and the control medium includes hydraulic fluid. In other embodiments, however, the control medium may be some other material, such as a pressurized gas. Consequently, while the instant description of the illustrated embodiments may refer to a control fluid, it will be appreciated that such description may apply to a control liquid in a hydraulic pressure regulator in accordance with one embodiment, and does not necessarily preclude the use of a gaseous control medium in an alternative embodiment.
The internal operation of the regulator 24 may be better understood with reference to
As discussed in greater detail below, pressure within the chamber 60 may apply a thrust force to the piston 62 that acts against the biasing force provided by springs 64 and 66 to control opening and closing of the supply ports 48 and vent ports 52. The biasing force supplied by springs 64 and 66 can be modified via a spring load adjustment mechanism 68 disposed at one end of the upper housing 32. The adjustment mechanism 68 includes a screw that may be rotated to cause axial movement of a plunger within the upper housing 32 to vary the biasing force, as illustrated in
The opening and closing of the supply ports 48 and vent ports 52 may be better understood with reference to the sectional views of
Similarly, in the present embodiment, vent shear seal rings 96 are disposed within one or more recesses 98 of the piston 62. The vent shear seal rings 96 are biased by a spring 100 against a pair of vent seal plates 102. The vent seal plates 102 also include first and second fluid passageways 104 and 106, respectively, which enable fluid to be vented from the chamber 60 through the vent ports 52. In the presently illustrated embodiment, the vent seal rings 96 are of a different size than the supply seal rings 84. Further, the various passageways of the seal plates 90 and 102, respectively, may also be of different sizes than one another based on the particular sizes and geometries of the seal rings 84 and 96, as discussed in greater detail below.
An initial operating state is depicted in
As the pressure downstream and within the regulator 24 increases and approaches the first pressure threshold, the hydraulic force on the piston 62 becomes sufficient to move the piston 62 in the direction indicated by arrow 108 and toward the closed position generally illustrated in
As may be appreciated, as the pressure within the pressure regulator 24 continues to increase beyond the first pressure threshold, the thrust applied to the piston 62 by the internal pressure also increases, causing the piston 62 to continue moving in the direction indicated by arrow 108. As the internal pressure reaches a second pressure threshold, the piston 62 and vent seal rings 96 are moved into an open position, as generally illustrated in
As previously noted, excessive deadband in a pressure regulator may negatively impact its ability to provide a reasonably steady desired output pressure. For example, a pressure regulator having a deadband of 400 psi would not operate effectively to provide a hydraulic fluid at a regulated output pressure of 300 psi—in such an instance the output pressure could drop to zero without the pressure regulator even responding due to its deadband limitations. In the field of resource exploration and procurement, there has long been a need in the art for a spring-loaded, hydraulic pressure regulator with the degree of sensitivity that would enable the regulator to effectively operate at lower pressure levels. For instance, there are occasions in which pressure to an annular blowout preventer is to be maintained at a level as low as 300 psi to 400 psi. The presently disclosed pressure regulator meets this long-felt need and exhibits increased sensitivity and decreased deadband. In some embodiments, the pressure regulator 24 has a maximum deadband of 200 psi or less when coupled to a source of pressurized fluid providing a supply pressure of at least 1000 psi. In other embodiments, the maximum deadband may instead be 180 psi or less, 160 psi or less, 150 psi or less, 130 psi or less, 120 psi or less, or some other amount. Indeed, in testing with a supply pressure of 3000 psi, one example of the presently disclosed pressure regulator demonstrated a maximum deadband significantly lower than 150 psi, the level specified in the American Petroleum Institute Specification 16D published Jul. 1, 2004, which is incorporated by reference herein.
Various features contributing to the improved deadband characteristics of the presently disclosed pressure regulator are depicted in
Additionally, in at least some embodiments, the supply seal plates 90 may be specifically configured based on the geometries of their respective seal rings 84 to further improve the sensitivity of the pressure regulator 24. For instance, in the embodiment illustrated in
Similarly, vent seal plates 102 (
In one embodiment, the pressure regulator 24 is a one-inch, spring-loaded, manually adjustable hydraulic pressure regulator. Test results of such a pressure regulator 24 are provided below in Tables 1 and Table 2. Table 1 provides data obtained for a supply pressure of 3000 psi to the regulator, and Table 2 provides data obtained for a supply pressure of 5000 psi to the regulator. Particularly, the tables provide data obtained in testing the pressure regulator over a range of spring loads (represented by the number of complete turns of the screw of adjustment mechanism 68).
It is noted that in both instances (supply pressures of 3000 psi and 5000 psi), the pressure regulator 24 has a maximum deadband of less than 200 psi. Further, at a supply pressure of 3000 psi, the maximum deadband of the pressure regulator 24 was less than 120 psi, and the average deadband was less than 100 psi. At a supply pressure of 5000 psi, the maximum deadband measured was no higher than 180 psi, and the average deadband of the pressure regulator 24 was less than 130 psi. Additionally, as indicated in the tables above, the screw of the adjustment mechanism 68 may be rotated through multiple revolutions. Due to the improved sensitivity and lower deadband, the response of the presently disclosed pressure regulator 24 may be substantially more linear than that of previous regulators in that the piston 62 may move, and the output pressure may change, during each revolution of the screw, as generally demonstrated by the tables above. This is in contrast with previous regulators that may require several revolutions of an adjustment screw before the piston responds.
While the aspects of the present disclosure may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. But it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the following appended claims.
