Pressure regulator arrangement and method

Abstract

An arrangement for precise pressure control using a mechanical regulator. The mechanical regulator comprises a supply line for providing high- pressure fluid and a drain line for fluid discharge. A pilot line is connected to the mechanical regulator for controlling a set-point pressure, while a pilot pressure control device adjusts the pilot pressure. A main surge bottle is fluidly connected to a main regulated line, with a pressure sensor measuring the pressure in this line. Additionally, an intermediate regulated line is connected to the mechanical regulator and linked to the main regulated line through an isolation valve. An intermediate surge bottle is fluidly connected to the intermediate regulated line via an intermediate branch line, with a pressure sensor configured to measure pressure in the intermediate branch line. This arrangement ensures accurate pressure regulation through interconnected components that provide real-time pressure monitoring and control.

Description

PRESSURE REGULATOR ARRANGEMENT AND METHODFIELD OF INVENTION

[0001] Aspects of the present disclosure relate to pressure regulation and control. Specifically, but not exclusively, aspects of the present disclosure are directed to pressure control using mechanical regulators. Specially, but not exclusively, aspects of the present disclosure are directed to an arrangement and methods for precise pressure control using a mechanical regulator.BACKGROUND

[0002] In the field of pressure regulation for hydraulic circuits, mechanical pressure regulators are well known. Such mechanical pressure regulators have many uses. One of these uses is to control the hydraulic pressure for drilling annulars, such as on Blow Out Preventers (BOP). They could also be used to regulate the closing pressure on annular sealing elements that allow rotation. These annular sealing elements could in principle be located anywhere between the drilling rig and the lowest casing in the well. For an offshore drilling operation, they will typically be located either in the BOP or in the riser between the BOP and the drilling rig. Surface back-pressure drilling is an example of where such annular elements that allow rotation will typically be used.

[0003] The basic principle of these mechanical regulators is to have a supply pressure (Supply), the pressure to be regulated (Regulated) and a drain (Drain), with Drain at a pressure lower than Supply and Regulated. Mechanical pressure regulators work on a principle offeree balance. Typically, there will be a piston within a cylinder, with the pilot pressure on one side of the piston and the Regulated pressure on the other side of the piston. In order to separate these pressures, there will be a sealing arrangement. In addition, there will be internal passages to allow the Supply pressure to pass to the Regulated side, as well as internal passages to allow the Regulated pressure to drain back to Drain whenever the Regulated pressure needs to be decreased. There are a number of ways to design these mechanical regulators, but common for all is that due to the design, where there are effects such as friction involved, there is always a pressure "deadband" associated with these mechanical regulators.

[0004] Within this deadband, the mechanical pressure regulator will not respond to pressure changes either on the Regulated or Pilot side. The magnitude of the deadband may not be a fixed figure, but could change with the magnitude of Supply, Regulated and Drain. It could also change over time as the mechanical pressure regulator gets worn as well as from other effects, such as temperature, fluid contamination or external pressure. For applications where precise pressure management is required, this deadband represents a challenge and needs to be accounted for in the operational planning when using such regulators.SUMMARY OF INVENTION

[0005] According to an aspect of the present disclosure, there is provided an arrangement for precise pressure control. The arrangement comprises a mechanical regulator configured to regulate pressure. The mechanical regulator includes a supply line for providing high-pressure fluid, a drain line for fluid discharge, and a pilot line connected to the mechanical regulator for controlling a set-point pressure. A pilot pressure control device is connected to the pilot line for adjusting the pilot pressure. The arrangement also includes a main surge bottle fluidly connected to a main regulated line and a pressure sensor configured to measure the pressure in the main regulated line. Additionally, an intermediate regulated line is connected to the mechanical regulator and linked to the main regulated line via an isolation valve. An intermediate surge bottle is fluidly connected to the intermediate regulated line via an intermediate branch line, and a pressure sensor is configured to measure the pressure in the intermediate branch line

[0006] According to an additional aspect of the present disclosure, the isolation valve is configured to selectively open and close, enabling incremental pressure adjustments in the main regulated line that are smaller than the deadband of the mechanical regulator for precise pressure control.

[0007] According to an additional aspect of the present disclosure, the intermediate surge bottle and the main surge bottle are pre-charged with a gas to create controlled volume expansion and contraction. This allows for fine-tuned pressure modulation independent of the inherent deadband limitations of the mechanical regulator.

[0008] According to an additional aspect of the present disclosure, the pilot pressure control device is configured to dynamically adjust the pilot pressure in the pilot line at a rate faster than the mechanical regulator can respond. This enables finer resolution of pressure regulation in the main regulated line by leveraging time-delay effects in the system.

[0009] According to an additional aspect of the present disclosure, the intermediate regulated line and the main regulated line form a staged pressure control system. The intermediate regulated line acts as a dosing chamber to allow stepwise pressure changes in the main regulated line without exceeding the deadband constraints of the mechanical regulator.

[0010] According to an additional aspect of the present disclosure, the pressure sensors provide continuous or near real-time feedback to a control system. This enables automated adjustments to the pilot pressure and isolation valve actuation, maintaining the main regulated pressure within a range smaller than the inherent deadband of the mechanical regulator.

[0011] According to an aspect of the present disclosure, there is provided a pressure control system. The system comprises an arrangement as described above, a control unit configured to receive data from the pressure sensors and automatically adjust the pilot pressure in the pilot line in response to detected pressure fluctuations, and a remote actuator configured to open and close the isolation valve based on control signals from the control unit. The control unit executes an algorithm to maintain the pressure in the main regulated line within a predefined threshold smaller than the deadband of the mechanical regulator.

[0012] According to an aspect of the present disclosure, there is provided a method for precise pressure control using a mechanical regulator with an isolation valve and an intermediate surge bottle to achieve incremental pressure adjustments smaller than the deadband of the mechanical regulator. The method comprises providing a mechanical regulator configured to regulate pressure in a regulated line. The mechanical regulator includes a supply line for high-pressure fluid and a drain line for fluid discharge. The method further includes incorporating an isolation valve into the regulated line to separate an intermediate regulated line, located between the mechanical regulator and the isolation valve, from a main regulated line downstream of the isolation valve. An intermediate surge bottle is connected to the intermediate regulated line via an intermediate branch line, and a pressure sensor is used to measure pressure in the intermediate regulated line. The method includes controlling the isolation valve to enable incremental pressure adjustments. This involves closing the isolation valve to allow the mechanical regulator to increase pressure in the intermediate regulated line beyond the deadband threshold and opening the isolation valve to transfer a controlled volume of pressurized fluid from the intermediate regulated line to the main regulated line. This increases the pressure in the main regulated line in increments smaller than the deadband of the mechanical regulator.

[0013] According to an additional aspect of the present disclosure, the intermediate surge bottle is pre-charged with a gas to act as a compressible volume, enabling finer pressure control by modulating the pressure transfer dynamics between the intermediate regulated line and the main regulated line.

[0014] According to an additional aspect of the present disclosure, the method further comprises dynamically adjusting the pilot pressure in a pilot line using a pilot pressure control device to precisely control the set-point pressure of the mechanical regulator. The pilot pressure is increased or decreased in a controlled manner to ensure the mechanical regulator does not actuate prematurely during pressure equalization.

[0015] According to an additional aspect of the present disclosure, the intermediate regulated line functions as a dosing chamber that enables stepwise pressure adjustments in the main regulated line, allowing pressure increments to be controlled within a precision range smaller than the deadband of the mechanical regulator.

[0016] According to an aspect of the present disclosure, there is provided a method for automated pressure control using the described arrangement. The method comprises receiving real-time pressure data from pressure sensors in the intermediate regulated line and the main regulated line and determining whether the pressure deviation in the main regulated line exceeds a predefined threshold smaller than the deadband of the mechanical regulator. If the pressure deviation exceeds the threshold, a control signal is generated to adjust the pilot pressure in the pilot line to initiate a pressure increase in the intermediate regulated line. The method further includes monitoring pressure stabilization in the intermediate regulated line before opening the isolation valve to equalize pressure in controlled increments and continuously adjusting the pilot pressure based on real-time feedback to maintain stable pressure within the predefined threshold.

[0017] According to an aspect of the present disclosure, the arrangement described above is used for controlling hydraulic pressure in an annular seal to maintain pressure within atolerance range smaller than the deadband of the mechanical regulator, thereby preventing pressure variations associated with operational instability.

[0018] According to an additional aspect of the present disclosure, the arrangement is used for controlling hydraulic pressure in a drilling annular seal to prevent gas influx into a riser while minimizing excess pressure associated with accelerated component wear.

[0019] According to an additional aspect of the present disclosure, the arrangement is used to improve the operation of a blowout preventer (BOP) by providing precise pressure control to ensure rapid and accurate sealing activation in response to well pressure changes.

[0020] Beneficially, the arrangement described herein provides a significant improvement over known mechanical regulators by addressing and minimizing the inherent deadband limitations that affect pressure control accuracy. Traditional mechanical regulators rely on a fixed deadband to function, which means that pressure fluctuations must exceed a certain threshold before the regulator can respond. This results in imprecise control, delayed responses, and potential overshooting or undershooting of the desired pressure. In contrast, the present arrangement introduces an intermediate regulated line, an isolation valve, and an intermediate surge bottle, which together enable incremental pressure adjustments smaller than the deadband of the mechanical regulator itself. By selectively isolating and controlling the pressure within the intermediate chamber, the arrangement allows for finer resolution in pressure regulation without requiring fundamental modifications to the mechanical regulator. Additionally, the use of real-time pressure feedback, dynamic pilot pressure adjustment, and staged pressure control ensures that pressure variations are corrected more quickly and accurately than in conventional systems. This level of precision is particularly advantageous in applications where maintaining stable pressure is critical, such as in drilling operations, fluid control in industrial systems, and hydraulic actuators. By overcoming the fundamental constraint of deadband-induced pressure variation, the present arrangement offers a novel and inventive solution that enhances the reliability, efficiency, and accuracy of mechanical pressure regulation.

[0021] The skilled person will understand that any above-described apparatus, process, system, and method is not limited to controlling hydraulic pressure in a drilling annular and may be applied to alternative contexts and usage scenarios. For example, the arrangement can be used in any system where precise pressure regulation is required despite the inherent deadband limitations of mechanical regulators. This includes, but is not limited to, hydraulic and pneumatic control systems in industrial automation, aerospace applications requiring fine pressure adjustments in flight control systems, medical devices where accurate pressure dosing is critical, and subsea operations where controlled pressure adjustments are necessary to mitigate environmental variations. The principles of reducing operational deadband and achieving fine-tuned pressure control can also be beneficial in fluid distribution networks, gas pipeline pressure regulation, and energy storage systems, ensuring stability, safety, and efficiency in processes where traditional mechanical regulators would otherwise impose limitations.BRIEF DESCRIPTION OF DRAWINGS

[0022] Embodiments of the invention will now be described, by way of example only, and with reference to the accompanying drawings, in which:

[0023] Figure 1 illustrates a system architecture diagram for a mechanical regulator with a pilot pressure;

[0024] Figure 2 illustrates a system architecture diagram for a pressure regulation arrangement modified with an intermediate chamber with an isolation valve and a surge bottle arrangement;

[0025] Figure 3 illustrates a graph that shows how a mechanical regulator will respond to changes in regulated pressure;

[0026] Figure 4 illustrates a graph that shows how pressure changes that appear by the process can be controlled to within the deadband;

[0027] Figure 5 illustrates a graph showing how the pressure can be changed in increments lower than the mechanical regulator deadband by manipulating the pilot pressure; and

[0028] Figure 6 shows a flowchart of a method for precise pressure control using a mechanical regulator with reduced operational deadband.

[0029] All illustrations of the drawings are for the purpose of describing selected versions of the present invention and are not intended to limit the scope of the present invention.

[0030] As a preliminary matter, it will readily be understood by one having ordinary skill in the relevant art that the present disclosure has broad utility and application. As should be understood, any embodiment may incorporate only one or a plurality of the above-disclosed aspects of the disclosure and may further incorporate only one or a plurality of the abovedisclosed features. Furthermore, any embodiment discussed and identified as being “preferred” is considered to be part of a best mode contemplated for carrying out the embodiments of the present disclosure.

[0031] Other embodiments also may be discussed for additional illustrative purposes in providing a full and enabling disclosure. Moreover, many embodiments, such as adaptations, variations, modifications, and equivalent arrangements, will be implicitly disclosed by the embodiments described herein and fall within the scope of the present disclosure. Accordingly, while embodiments are described herein in detail in relation to one or more embodiments, it is to be understood that this disclosure is illustrative and exemplary of the present disclosure and are made merely for the purposes of providing a full and enabling disclosure.

[0032] The detailed disclosure herein of one or more embodiments is not intended, nor is to be construed, to limit the scope of patent protection afforded in any claim of a patent issuing here from, which scope is to be defined by the claims and the equivalents thereof. It is not intended that the scope of patent protection be defined by reading into any claim a limitation found herein that does not explicitly appear in the claim itself. Additionally, it is important to note that each term used herein refers to that which an ordinary artisan would understand such term to mean based on the contextual use of such term herein. To the extent that the meaningof a term used herein — as understood by the ordinary artisan based on the contextual use of such term — differs in any way from any particular dictionary definition of such term, it is intended that the meaning of the term as understood by the ordinary artisan should prevail. Furthermore, it is important to note that, as used herein, “a” and “an” each generally denotes “at least one,” but does not exclude a plurality unless the contextual use dictates otherwise. When used herein to join a list of items, “or” denotes “at least one of the items,” but does not exclude a plurality of items of the list. Finally, when used herein to join a list of items, “and” denotes “all of the items of the list.”

[0033] The following detailed description refers to the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the following description to refer to the same or similar elements. While many embodiments of the disclosure may be described, modifications, adaptations, and other implementations are possible. For example, substitutions, additions, or modifications may be made to the elements illustrated in the drawings, and the methods described herein may be modified by substituting, reordering, or adding stages to the disclosed methods. Accordingly, the following detailed description does not limit the disclosure. Instead, the proper scope of the disclosure is defined by the appended claims.

[0034] The present disclosure contains headers. It should be understood that these headers are used as references and are not to be construed as limiting upon the subjected matter disclosed under the header. Other technical advantages may become readily apparent to one of ordinary skill in the art after review of the following figures and description. It should be understood at the outset that, although exemplary embodiments are illustrated in the figures and described below, the principles of the present disclosure may be implemented using any number of techniques, whether currently known or not. The present disclosure should in no way be limited to the exemplary implementations and techniques illustrated in the drawings and described below.

[0035] Unless otherwise indicated, the drawings are intended to be read together with the specification, and are to be considered a portion of the entire written description of this invention. As used in the following description, the terms “horizontal”, “vertical”, “left”, “right”, “up”, “down” and the like, as well as adjectival and adverbial derivatives thereof (e.g., “horizontally”, “rightwardly”, “upwardly”, “radially”, etc.), simply refer to the orientation of the illustrated structure as the particular drawing figure faces the reader. Similarly, the terms “inwardly,” “outwardly” and “radially” generally refer to the orientation of a surface relative to its axis of elongation, or axis of rotation, as appropriate.

[0036] When the term “pressure bottle” is used in the present specification, this should not be construed as limiting to a specific shape. The pressure bottle could be any type of enclosure that is capable of holding a pressure and which can be fluidly coupled to a line to exert the pressure in the enclosure into the line. The enclosure could for instance be a chamber inside a larger item.

[0037] The present disclosure includes many aspects and features. Moreover, while many aspects and features relate to, and are described in the context of a pressure control system, embodiments of the present disclosure are not limited to use only in this context.DETAILED DESCRIPTION

[0038] Embodiments of the present disclosure will now be described with reference to the attached figures. It is to be noted that the following description is merely used for enabling the skilled person to understand the present disclosure, without any intention to limit the applicability of the present disclosure to other embodiments which could be readily understood and / or envisaged by the reader. While the present disclosure is primarily directed to precise pressure control in drilling annular applications, the skilled person will appreciate that the apparatus, processes, methods, and systems described herein are applicable to any scenario requiring fine pressure regulation beyond the inherent deadband limitations of mechanical regulators. For example, the disclosed arrangement can be used in industrial fluid control systems, aerospace applications requiring high-precision actuation, medical devices necessitating controlled fluid or gas pressure adjustments, subsea pressure management systems, and gas pipeline pressure stabilization. These applications benefit from the ability to make incremental pressure adjustments smaller than the mechanical regulator’s deadband, ensuring improved accuracy, system stability, and operational safety.

[0039] As mechanical regulators necessitate presence of a deadband, even if it is limited, this results in a lower limit to the pressure control accuracy of any given mechanical regulator. For many applications, this limit to pressure control accuracy represents a challenge. An example could be a case where the regulator is used to control the hydraulic pressure on a drilling annular seal. Dropping below a certain pressure could allow gas to enter the riser above the annular seal, which in turn could lead to a blowout. Therefore, the pressure needs to be set higher than then minimum required pressure. This in turn will increase wear on the element. This is one example of why it would be desirable to reduce the operational deadband of a mechanical regulator.

[0040] It should be noted that, according to aspects of the present disclosure, the Regulated pressure controls a drilling annular seal, but it will be obvious to the person skilled in the art that the present invention can be used on any application where it is desired to have a more precise control of Regulated pressure than what can be offered by the mechanical regulator itself.

[0041] For simplicity, in the remainder of this document, when talking about pressure and volume changes in the various sub-sections of the system, a line, e.g. line 5, will be referred to, but it should be taken to include all the elements that are fluidly connected to and / or in pressure communication with the specified line.

[0042] A mechanical regulator regulated by a pilot pressure will have a pressure ratio between the Pilot pressure and the Regulated pressure. This pressure ratio is any value from 0 to infinity and is driven by the area ratio between the 2 sides. In the disclosure herein, a pressure ratio of 1:1 is assumed unless specified otherwise, e.g. the set-point for Regulated will be the same as the Pilot pressure, any pressure ratio is applicable.

[0043] The present disclosure is directed towards a mechanical regulator with a given deadband and a system that allows the Regulated pressure to be accurately controlled with an operational deadband that is lower than the deadband of the mechanical regulator itself. Two different methods are described to achieve an operational deadband that is lower than thedeadband of the mechanical regulator. While examples may focus on increasing the pressure on the Regulated side, this should be read as optionally including the concept of decreasing the pressure.

[0044] In order to better understand the improvements offered by the present disclosure, Figure 1 shows a typical layout of a mechanical regulator with an adjustable pilot pressure that controls an annular.

[0045] Figure 1 comprises a mechanical regulator 3, attached to a Supply line 2, a Drain line I as well as the process line where the pressure is to be regulated, line 11. The Supply line 2 will have pressure that is higher than that of the Regulated line 11.

[0046] The Regulated line 11 controls the hydraulic pressure on the annular seal 13. On the regulated line 11, there could be attached a main surge bottle 15, either directly onto line 11, or through a connection line 14. There is optionally also a pressure sensor 16 fluidly coupled to line 14.

[0047] The Pilot line 5 is fluidly connected to a pilot surge bottle 4 through a connection line 6, which has a pressure sensor 7 fluidly connected to it. The pressure sensor 7 is actively used in the control of the pressure on the pilot circuit. The pressure in Pilot line 5 can be either increased or decreased by a pilot pressure control device 8, which is connected to a high-pressure pilot supply 9 and a low-pressure pilot drain 10.

[0048] By increasing the pressure on the pilot line 5, the set-point of the mechanical regulator 3 will increase. Once the set-point passes the pressure in regulated line 11 plus the deadband, the pressure in line 11 will start to be increased.

[0049] If the pressure on Regulated line 11 drops to below the set-point less the deadband, the mechanical regulator 3 will open and allow high-pressure fluid from Supply line 2 to be pumped into regulated line 11, thus increasing the pressure.

[0050] When the pressure regulator 3 starts to regulate the pressure in line 11 , it will take some time before the set-point pressure in line 11 is reached. This is both due to the frictional pressure drop from Supply line 2, through the mechanical pressure regulator 3 and in regulated line 11 , as well as the volume change required in the gas-filled main surge bottle 15.

[0051] The arrangement shown in Figure 1 is optionally used to control the hydraulic pressure of the annular seal according to the method of the second aspect of this invention, where the pilot pressure is actively manipulated in a rapid and controlled manner. This method makes use of the time-delay associated with pressure changes when operating the pressure regulator and makes changes to the pilot pressure on line 5 faster than the pressure on Regulated line I I will change. The method of pressure manipulation according to the second aspect of the invention is shown schematically and described in figure 4.

[0052] Figure 2 illustrates a schematic architecture diagram showing a pressure regulation arrangement modified with an intermediate chamber with an isolation valve and a surge bottle arrangement.

[0053] One advantage of the arrangement described in Figure 2 is its ability to provide fine pressure adjustments without the need for an entirely new mechanical regulator design.Traditional mechanical regulators are constrained by their internal components, which inherently define their deadband. Reducing the deadband in a conventional mechanical regulator typically requires either tighter tolerances on mechanical seals and springs or an entirely new regulator architecture. These approaches are costly and may introduce operational instability. In contrast, the present disclosure achieves finer pressure control by utilizing an intermediate surge bottle, an isolation valve, and dynamic pilot pressure adjustments. This allows an operator to make pressure changes within a tolerance range smaller than the inherent deadband of the mechanical regulator, thereby increasing accuracy while maintaining the robustness of a standard mechanical regulator.

[0054] Figure 2 comprises components shown in Figure 1, e.g. the pilot circuit and the pressure regulator 3 with Supply line 2 and Drain line 1. Between the pressure regulator 3 and the outlet to line 14 to the main surge bottle 15, an isolation valve 34 is added. Line 11 in figure 1 has now been split into an Intermediate Regulated line 111 and a Main Regulated line 112. Between the isolation valve 34 and the annular seal 13, there is a Main Regulated line 112, as well as the same main surge bottle 15, main pressure sensor 16 and main branch line 14 as on figure 1.

[0055] On the Intermediate Regulated line 111, between the pressure regulator 3 and the isolation valve 34, an intermediate surge bottle 31 is added. The intermediate surge bottle 31 is fluidly connected to the Intermediate Regulated line 111 through an intermediate branch line 33. The intermediate branch line 33 is also fitted with an intermediate pressure sensor 32 configured for calculating the volume added per cycle of operation. The intermediate pressure sensor is optionally a position sensor or other suitable sensor, e.g. a temperature sensor or a flow rate sensor, on the intermediate surge bottle 31, as its purpose is.

[0056] In an operating mode with isolation valve 34 open, the pressure in Main Regulated line 112 is equal to the set-point of the pressure regulator 3. The pressure on the annular seal 13, which is the pressure in Main Regulated line 112, is to be increased by a small increment, e.g. smaller than the deadband of the pressure regulator 3. First, the isolation valve 34 is closed. The isolation valve 34 is optionally remotely actuated. Then, pressure in the pilot line 5 is increased to increase the set-point of the pressure regulator 3. The set-point is increased by more than the deadband. The pressure regulator 3 opens and pressure in Intermediate Regulated line 111 increases to the new set-point. The pressure regulator 3 then closes. The pressure behaviour between (a) when the pressure regulator 3 opens, and (b) when it closes after a set-point change, varies depending on specific pressure regulators. For example, there can be under-shoots and / or over-shoots of pressure before it reaches the equilibrium.

[0057] After the pressure regulator 3 has closed, isolation valve 34 is opened and the pressure equalizes between Intermediate Regulated line 111 and Main Regulated Line 112. Upon opening isolation valve 34 at this stage, the pressure on Main Regulated line 112 will increase. When opening isolation valve 34, the pressure on Intermediate Regulated line 111 will drop. By knowing the volume and (e.g. Nitrogen) pre-charges of Intermediate Surge bottle 31 and Main Surge bottle 15, the person skilled in the art will be able to predict what the pressure will be on Main Regulated line 112 after opening isolation valve 34. Therefore, prior to opening isolation valve 34, the operator will optionally adjust the pilot pressure on pilot line 5 to be close to this predicted pressure, so that when isolation valve 34 is opened, and the pressure onIntermediate Regulated line 111 drops, the pressure regulator 3 does not open. When dropping the pilot pressure on pilot line 5, it should be obvious that the magnitude of this pressure drop must be lower than the deadband, in order for the pressure regulator 3 not to open and drain pressure to Drain line 1.

[0058] The magnitude of increase in pressure on Main Regulated line 112 after opening isolation valve 34 depends on the volumes and (e.g. Nitrogen) pre-charge pressures of Intermediate Surge bottle 31 and Main Surge Bottle 15. In principle, any component in the system optionally has a “surge-bottle” effect, as even steel tubing will expand with pressure, but the effect is preferably negligible for the operation of the system compared to the effect of Intermediate Surge bottle 31 and Main Surge bottle 15. For some applications, the actual element to be controlled, e.g. case annular 13, has a volume vs pressure effect that is relevant to include in the calculations.

[0059] This process of charging the Intermediate Surge bottle 31 and releasing volume into the Main Surge bottle 15 is preferably repeated until the desired pressure is reached, e.g. the pressure measured by sensor 16 is within a desired range. Optionally, the desired range is smaller than the deadband of the mechanical regulator s.

[0060] The above disclosure is directed towards changing the pressure on annular 13 from one value to another value. According to another operation of the system shown in Figure 2, the pressure on the annular seal 13, e.g. in Main Regulated Line 112, starts dropping or increasing. Without the isolation valve 34 and intermediate surge bottle 31, pressure needs to drop below or increase above the set-point less the deadband before pressure regulator 3 responds. With the arrangement in Figure 2, once the pressure starts e.g. dropping on Main Regulated line 112, as measured by main pressure sensor 16 or intermediate pressure sensor 32 if isolation valve 34 is open, the same steps of using the isolation valve 34 and intermediate surge bottle 31 as described above can be used to increase pressure back to the desired pressure well before it has dropped by the magnitude of the deadband.

[0061] For example, an isolation valve 34 and an intermediate surge bottle 31, such as a Nitrogen-filled piston accumulator with a pre-charge, are added to the regulated side of a mechanical regulator. The components are added between the mechanical regulator 3 and the element that is to be controlled, in our example an annular 13, to create an intermediate volume (e.g. the sum of intermediate regulated line 111, intermediate branch line 33, and intermediate surge bottle 31) that can be used as a dosing chamber to increase or decrease the pressure in small increments on the Regulated side. If the pressure on Regulated line 112 is to be increased by a small margin, isolation valve 34 is closed and the pilot pressure in line 5 is increased beyond the deadband. This will cause the mechanical regulator 3 to open and the pressure in line 111 will be increased to the new set-point. The pilot pressure in line 5 is then decreased, e.g. by a margin smaller than the deadband, so that the mechanical regulator 3 will not open when the pressure in intermediate regulated line 111 is decreased in the subsequent step. Isolation valve 34 is then opened. As intermediate regulated line 111 and main regulated line 112 equalize, the pressure on main regulated line 112 increases. The increased pressure level is lower than the original pressure in intermediate regulated line 111 before the isolation valve 34 was opened. This process is optionally repeated until the desired pressure is reached.

[0062] By proper sizing of the intermediate surge bottle 31 and main surge botte 15, both with regards to volume and pre-charge, as well as controlling the pilot pressure in pilot line 5 relative to the deadband, it is possible to adjust the pressure in intermediate regulated line 111 in increments that are much smaller than the deadband of the mechanical regulator 3.

[0063] According to another example, the pressure on the Regulated side is manipulated in increments lower than the deadband of the mechanical regulator 3 by momentarily increasing the pilot pressure in pilot line 5 to above the deadband. This causes the pressure in intermediate regulated line 111 to start increasing. The pilot pressure in pilot line 5 is then dropped back down to close the mechanical regulator 3. The pressure in intermediate regulated line 111 will consequently only build up by a fraction of the deadband. By doing this rapidly and successively the pressure can be adjusted rapidly with a pressure adjustment ability much finer than that of the mechanical regulator itself, e.g. without the isolation valve 34 and intermediate surge bottle 31.

[0064] It is understood that, in the arrangements using the present disclosure, there is optionally elevation differences involved. This entails slight gravity-induced pressure variations throughout the system. In order to not complicate the description, for the purposes of explaining this invention, it can be assumed that there are no gravity effects involved. The person skilled in the art will know how to account for such gravity effects.

[0065] The ability to momentarily increase the pilot pressure above the deadband and then reduce it in small increments allows the system to perform rapid pressure adjustments with higher resolution than a mechanical regulator alone. This approach is particularly beneficial in applications where immediate responsiveness is required, such as drilling operations where pressure fluctuations must be minimized to avoid gas influx or blowouts. The dynamic pilot pressure manipulation method enables fine-tuned control without necessitating the complete actuation of the mechanical regulator, which would otherwise introduce unwanted pressure fluctuations due to its deadband characteristics.

[0066] The system comprises the use of surge-bottles. These are optionally either piston or diaphragm accumulators with a pre-charge, e.g. a Nitrogen pre-charge. However, any other type of suitable gas could be used. Accumulator type surge bottles is also only example of how the surge-bottle effect can be achieved. In alternative implementations, the intermediate surge bottle and main surge bottle may be implemented as multiple smaller accumulators instead of single large ones. This modular approach allows for flexibility in system design, as the number and volume of accumulators can be tailored to specific pressure regulation requirements. Additionally, the surge bottles may be equipped with temperature compensation mechanisms to account for variations in environmental conditions that may affect gas compressibility. In some cases, alternative working fluids, such as inert gases or hydraulic oils, may be used instead of nitrogen to optimize system performance based on the operating environment.

[0067] A common issue in mechanical pressure regulation is the oscillatory behaviour that occurs when the regulator continuously opens and closes in response to pressure fluctuations near the activation threshold. This oscillation can lead to excessive wear on regulator components, energy inefficiencies, and instability in pressure-sensitive applications. The disclosed arrangement mitigates this issue by allowing pressure to be adjusted in controlled increments using the intermediate regulated line and surge bottle. This ensures that themechanical regulator operates within a narrower and more stable range, significantly reducing the likelihood of oscillatory behaviour while maintaining precise control of the regulated pressure.

[0068] Figure 3 illustrates a graph that shows the pressure behaviour of a typical pressure regulator.

[0069] A pressure set-point 303 is shown as a stable line. The graph also comprises a lower deadband 301 and an upper deadband 302, a lower activation pressure 305 and an upper activation pressure 306, and a regulated pressure 304.

[0070] At the start of the graph, the regulated pressure 304 is equal to the set-point 303. At point “A”, the regulated pressure 304 starts dropping.

[0071] At point “B”, the regulated pressure 305 reaches the lower activation pressure 305, and the pressure regulator 3 opens. There is some time delay, typically in the order of milliseconds, before the regulated pressure starts to increase at point “C”. It should be noted that the y-axis is not necessarily linear in time, this is an example to show an optional sequence. The pressure development between point “B” and “C” is not necessarily a straight line, and there is potentially a further under-shoot depending on the dynamics of the system.

[0072] After point “C”, the regulated pressure 304 starts increasing and continues to increase until it stops increasing at point “D”. At this point, the regulated pressure 304 is equal to or higher than the set-point pressure 303. If Regulated pressure 304 is higher than set-point pressure 303 at point “D”, at point “E” it will start dropping until it reaches the set-point pressure 303 at “F”. In practice, the regulated pressure 304 might oscillate several times around the set-point pressure 303 before settling.

[0073] Figure 4 is a continuation of the pressure behaviour shown in Figure 3, e.g. the pressure is changed as in Figure 3 up to and including point “F”.

[0074] At Point “G”, the regulated pressure 304 starts dropping. At point “H”, an operator, e.g. an automated control system, detects regulated pressure 304 has dropped. To prevent continued dropping, the pilot pressure 303 is increased. At point “I”, the difference between the pilot pressure 303, which is the same as the set-point for the pressure regulator 3, and the regulated pressure 304 is equal in value to the upper deadband 302, shown in the figure as 302a. Pressure ranges 302 and 302a are equal in magnitude. At this point the regulator 3 opens, and regulated pressure 304 starts to increase. At point “J” the operator has detected that the regulated pressure has responded and drops the pilot pressure, which reaches the desired set-point at point “K”. In this example, the set-point at point “K” is the same set-point as prior to point “H”, as the intention is to keep the regulated pressure 304 at a fixed value. The regulated pressure 304 continues to increase at least until it reaches the set-point pressure. It might over-shoot, as shown by the dotted line, but eventually settles on the setpoint pressure, equal to the pilot pressure 303 at “L”. The regulated pressure 304 might oscillate more around the set-point pressure 303 than what is shown in figure 4.

[0075] Figure 5 illustrates a graph showing pressure levels during operation of the arrangement of Figure 2. Specifically, Figure 5 shows the various pressure traces during a small increase in the pressure on annular seal 13.

[0076] At Point “AO”, an increase the pressure on the annular 13 is sought, e.g. by an operator or control system, and the set-point pressure 303 is increased. At point “A1”, the set-point pressure 303 crosses the upper activation pressure 306 and the intermediate pressure 315 starts increasing. The intermediate pressure 315 is the pressure in line 111 in Figure 2.

[0077] At point “B1”, the set-point pressure 303 is stabilised. At point “C1”, the intermediate pressure 315 has reached the set-point pressure 303 and stabilizes.

[0078] At point “D1” the set-point pressure 303 is dropped until point “E1”. Preferably, the setpoint pressure 303 does not drop below a lower activation threshold A 305a. The lower activation threshold A 305a is the current intermediate pressure 315 less the lower deadband 301. It represents the point at which the regulator 3 will open to regulate the pressure on intermediate line 111.

[0079] At Point “F1” isolation valve 34 (figure 2) is opened, and the intermediate pressure 315 and the main regulated pressure 314 start to equalize. These pressures are equalized at point “G1”.

[0080] Optionally, the set-point is dropped closer to the lower activation threshold A 305a than is necessary at point “D1 ”. A further increase to the pressure on the annular 13 is then required, and, at point “G2”, the set-point pressure 303 is increased and isolation valve 34 is closed.

[0081] At point “H1 ” the set-point pressure crosses the upper activation threshold A 306a and intermediate pressure 315 starts to increase. At point “11” the set-point pressure 303 reaches the desired level and stabilizes. At point “J1” the intermediate pressure 315 has reached the set-point pressure 303 and stabilizes.

[0082] At point “J2”, the set-point pressure 303 is dropped until it reaches the desired pressure at point “K1”. It can be seen that, in this example, the set-point pressure 303 was dropped less than in the previous cycle. Additionally, the set-point pressure 303 has a much higher margin to the lower activation threshold B 305b than it had to the lower activation threshold A 305a at point “E1”.

[0083] At point “L1 ”, isolation valve 34 is opened and the intermediate pressure 315 and the main regulated pressure 314 start to equalize. At point “M1” these pressures have equalized. They are not the same as the set-point pressure 303, but by a margin less than the upper deadband 302, so the pressure regulator 3 will not actuate.

[0084] At this stage, main regulated pressure is close enough to the desired pressure, and further adjustments are not required.

[0085] Optionally, isolation valve 34 is closed or, alternatively, left open. Further optionally, the set-point pressure 303 is maintained at the current level or dropped to be the same as the main regulated pressure 314. In a further example, the set-point pressure 303 is set to any pressure within the deadband at this stage. Preferably, the set-point pressure 303 is set close to the main regulated pressure 314, e.g. in case the main regulated pressure 314 or the pilot pressure in pilot line 5 starts to fluctuate.

[0086] It should be noted that in the description of figure 5, the upper and lower activation pressures change whenever the intermediate pressure 315 changes. Not all upper and loweractivation pressure changes have been shown on figure 5, only those relevant for the description.

[0087] Figure 6 shows a flowchart of method 600 for precise pressure control using a mechanical regulator with reduced operational deadband.

[0088] Method 600 begins with step 602, where the initial conditions are received, including opening the isolation valve 34 and setting the initial pilot pressure in line 5. In step 604, the pressure on the annular is increased by raising the set-point pressure 303 until it crosses the upper activation pressure 306, then stabilizing it and waiting for the intermediate pressure 315 to match the new set-point. Step 606 involves adjusting the set-point pressure 303 to a value above the lower activation threshold A 305a and ensuring it remains stable. In step 608, the isolation valve 34 is opened to equalize the intermediate pressure 315 and main regulated pressure 314. If further pressure increase is needed, optional step 610 is performed, where the isolation valve 34 is closed, the set-point pressure 303 is increased again, stabilized, and then decreased to a value above the lower activation threshold B 305b before reopening the isolation valve 34 to equalize the pressures. The process ensures precise control of the main regulated pressure 314 within the desired range.

[0089] Step 602 comprises obtaining the initial conditions, e.g. opening the isolation valve 34 and setting the initial pilot pressure in line 5. This step prepares the system for precise pressure adjustments. By opening the isolation valve 34, the system ensures that the intermediate regulated line 111 and the main regulated line 112 are initially equalized, providing a stable starting point for subsequent pressure adjustments. Setting the initial pilot pressure in line 5 ensures that the mechanical regulator 3 is ready to respond accurately to changes in the setpoint pressure.

[0090] Beneficially, step 602 comprises a more controlled and precise initialization process. In traditional systems, the absence of an isolation valve and intermediate surge bottle can lead to larger fluctuations and less precise control of the regulated pressure. By incorporating these components and actively managing the initial conditions, method 600 reduces the operational deadband and enhances the accuracy of pressure regulation, leading to improved performance and safety in applications where precise pressure control is critical.

[0091] Step 604 comprises increasing the pressure on the annular by raising the set-point pressure 303. This is done by increasing the set-point pressure until it crosses the upper activation pressure 306, e.g. incrementally. Once the set-point pressure 303 is increased, it is stabilized, and the system waits for the intermediate pressure 315 to reach and stabilize at the new set-point.

[0092] In conventional systems, the pressure adjustments are often less accurate due to the inherent deadband of the mechanical regulator. By using the apparatus described in Figure 2, the system can incrementally increase the pressure in a controlled manner, ensuring that the intermediate pressure 315 accurately matches the new set-point. This results in a more precise control of the pressure on the annular, reducing the risk of pressure fluctuations that could lead to operational issues or safety hazards.

[0093] Step 606 comprises adjusting the set-point pressure 303 to ensure it remains within a desired range. After the initial increase in pressure on the annular in step 604, the set-pointpressure 303 is decreased to a value above the lower activation threshold A 305a. This adjustment is crucial to prevent the mechanical regulator 3 from opening prematurely and to maintain the stability of the system. The set-point pressure 303 is carefully controlled to ensure it remains stable and does not drop below the lower activation threshold, which would trigger the regulator to open and cause unwanted pressure fluctuations.

[0094] A benefit of step 606 over traditional methods is the enhanced precision in maintaining the set-point pressure. In conventional systems, the deadband of the mechanical regulator can lead to larger pressure variations, making it difficult to achieve fine control. By actively adjusting the set-point pressure 303 and keeping it within a narrow range above the lower activation threshold, method 600 minimizes the impact of the deadband and allows for more accurate pressure regulation. This precise control is particularly important in applications where maintaining a stable pressure is critical for safety and performance, such as in hydraulic systems used in drilling operations.

[0095] Step 608 comprises equalizing the pressures between the intermediate regulated line 111 and the main regulated line 112. This is achieved by opening the isolation valve 34, which allows the intermediate pressure 315 and the main regulated pressure 314 to equalize. The equalization process ensures that the pressure on the main regulated line 112 is adjusted to the desired level, based on the previously set intermediate pressure. By using the isolation valve 34 to manage the equalization process, method 600 ensures that the pressure adjustments are smooth and precise.

[0096] Step 610 is an optional step that involves repeating the pressure increase process if further adjustments are needed. If the desired pressure has not been reached after the initial equalization in step 608, the isolation valve 34 is closed again. The set-point pressure 303 is then increased once more, crossing the upper activation threshold A 306a. The set-point pressure is stabilized, and the system waits for the intermediate pressure 315 to reach and stabilize at the new set-point. After stabilization, the set-point pressure 303 is decreased to a value above the lower activation threshold B 305b, ensuring it remains stable. The isolation valve 34 is then reopened to equalize the intermediate pressure 315 and the main regulated pressure 314.

[0097] In conventional systems, achieving fine pressure control is challenging due to the inherent deadband of the mechanical regulator. By repeating the pressure increase process as needed, method 600 allows for small, controlled adjustments that gradually bring the main regulated pressure 314 to the desired level. This iterative approach ensures that the pressure is adjusted accurately and consistently, reducing the risk of overshooting or undershooting the target pressure. This level of precision is particularly important in applications where maintaining exact pressure levels is crucial for safety and performance.

[0098] After completing the main steps of method 600, an additional optional step comprises fine-tuning the set-point pressure 303 to ensure it is as close as possible to the desired main regulated pressure 314. This can be done by making small adjustments to the pilot pressure in line 5, ensuring that the mechanical regulator 3 does not open or close unexpectedly. This fine-tuning helps maintain a stable pressure and further reduces the impact of the deadband.

[0099] Another optional step is to continuously monitor the stability of the system after the pressure adjustments have been made. This involves using pressure sensors to track any fluctuations in the main regulated pressure 314 and intermediate pressure 315. If any significant deviations are detected, additional adjustments can be made to the set-point pressure 303 or the pilot pressure in line 5 to maintain stability.

[0100] Depending on the specific application and system requirements, the settings of the isolation valve 34 can be adjusted to optimize the pressure equalization process. This may include changing the timing of when the valve is opened or closed, or modifying the actuation mechanism to ensure smoother transitions between pressure states.

[0101] To enhance the precision and efficiency of method 600, an automated control system can be implemented. This system can use real-time data from pressure sensors to automatically adjust the set-point pressure 303, pilot pressure in line 5, and the operation of the isolation valve 34. Automation reduces the potential for human error and ensures consistent and accurate pressure control.

[0102] In some applications, environmental factors such as temperature and elevation differences can affect pressure regulation. An optional step involves accounting for these factors by incorporating temperature sensors and elevation data into the control system. Adjustments can then be made to compensate for any environmental influences, ensuring more accurate pressure control.

[0103] Regular system diagnostics can be performed as an optional step to ensure all components are functioning correctly. This comprises checking the mechanical regulator 3, isolation valve 34, surge bottles, and / or pressure sensors for any signs of wear or malfunction. Performing diagnostics helps maintain the reliability and accuracy of the pressure control system.

[0104] The pressure control system and method described herein may be further enhanced by integrating an adaptive learning algorithm that continuously optimizes the pilot pressure adjustments based on real-time feedback. By utilizing machine learning techniques, the system can predict pressure fluctuations and pre-emptively adjust the set-point before the pressure deviation reaches the mechanical regulator’s deadband. This allows for proactive rather than reactive control, reducing response time and improving stability. The control unit may also incorporate a fail-safe mechanism that reverts the pilot pressure to a predefined safe level in the event of unexpected pressure drops, ensuring operational safety in critical applications such as drilling and subsea pressure regulation. Accordingly, method 600 is optionally at least partially automated, e.g. using one or more machine learning models.

[0105] The following statements encompass example embodiments of the systems and method described herein, and do not define the scope of the invention, which is instead defined in the appended claims.Statements of invention:1. A mechanical regulator arrangement for precise pressure control, comprising:a mechanical regulator unit (3);a supply line (2) for providing high-pressure fluid, coupled to the mechanical regulator unit (3);a drain line (1) for fluid discharge, coupled to the mechanical regulator unit (3);a pilot line (5) for controlling a set-point pressure, coupled to the mechanical regulator unit (3);an intermediate regulated line (111) coupled to the mechanical regulator unit (3); a main regulated line (112) coupled to the intermediate regulated line (11);a pilot pressure control device (8) coupled to the pilot line (5) for adjusting the pilot pressure;a main surge bottle (15) fluidly coupled to a main regulated line (112); anda pressure sensor (16) configured to measure the pressure in the main regulated line (112);an isolation valve (34) coupled between the main regulated line (112) and the intermediate regulated line;an intermediate surge bottle (31) fluidly coupled to the intermediate regulated line (111); anda pressure sensor (32) configured to measure the pressure in the intermediate regulated line (111).2. The arrangement of statement 1 , wherein the isolation valve (34) is configured to selectively open and close to enable incremental pressure adjustments in the main regulated line (112) that are smaller than the deadband of the mechanical regulator (3) for precise pressure control.3. The arrangement of statement 1 or 2, wherein the intermediate surge bottle (31) and the main surge bottle (15) are pre-charged with a gas to create controlled volume expansion and contraction, allowing for fine-tuned pressure modulation independent of inherent deadband limitations of the mechanical regulator (3).4. The arrangement of any of the statements 1 to 3, wherein the pilot pressure control device (8) is configured to dynamically adjust the pilot pressure in the pilot line (5) at a rate faster than the mechanical regulator (3) can respond, enabling finer resolution of pressure regulation in the main regulated line (112) by leveraging time-delay effects in the system.5. The arrangement of any of the statements 1 to 4, wherein the intermediate regulated line (111) and the main regulated line (112) form a staged pressure control system, wherein the intermediate regulated line (111) and the intermediate surge bottle (31) act as a dosing chamber to allow stepwise pressure changes in the main regulated line (112) without exceeding deadband constraints of the mechanical regulator (3).6. The arrangement of any of the statements 1 to 5, wherein the pressure sensors (32, 16) are coupled to a control system to provide continuous or near real-time feedback to the control system, and that the control system provide automated adjustments of the pilot pressure andactuation of the isolation valve (34), to maintain the main regulated pressure (112) within a range smaller than an inherent deadband of the mechanical regulator (3).7. A pressure control system comprising:an arrangement according to any of statements 1 to 6;a control unit configured to receive data from the pressure sensors (16, 32) and automatically adjust the pilot pressure in the pilot line (5) in response to detected pressure fluctuations; andan actuator configured to open and close the isolation valve (34) based on control signals from the control unit;wherein the control unit executes an algorithm to maintain the pressure in the main regulated line (112) within a predefined threshold smaller than the deadband of the mechanical regulator (3).8. A method for precise pressure control using a mechanical regulator (3) with an isolation valve (34) and an intermediate surge bottle (31) to achieve incremental pressure adjustments smaller than the deadband of the mechanical regulator (3), the method comprising:providing a mechanical regulator (3) configured to regulate pressure in a regulated line, the mechanical regulator (3) comprising a supply line (2) for high-pressure fluid and a drain line (1) for fluid discharge;incorporating an isolation valve (34) into the regulated line, the isolating valve (34) separating an intermediate regulated line (111), located between the mechanical regulator (3) and the isolation valve (34), from a main regulated line (112) downstream of the isolation valve (34);coupling an intermediate surge bottle (31) to the intermediate regulated line (111); measuring pressure in the intermediate regulated line (111) using a pressure sensor (32); andcontrolling the isolation valve (34) to enable incremental pressure adjustments, comprising:closing the isolation valve (34) to allow the mechanical regulator (3) to increase pressure in the intermediate regulated line (111) and the intermediate surge bottle (31) beyond the deadband threshold; andopening the isolation valve (34) to transfer a controlled volume of pressurized fluid from the intermediate regulated line (111) to the main regulated line (112), thereby increasing the pressure in the main regulated line (112) in increments smaller than the deadband of the mechanical regulator (3).9. The method of statement 8, wherein the intermediate surge bottle (31) is pre-charged with a gas to act as a compressible volume, enabling finer pressure control by modulating the pressure transfer dynamics between the intermediate regulated line (111) and the main regulated line (112).10. The method of statement 8 or 9, further comprising dynamically adjusting the pilot pressure in a pilot line (5) using a pilot pressure control device (8) to precisely control the set-point pressure of the mechanical regulator (3), wherein the pilot pressure is increased or decreased in a controlled manner to ensure the mechanical regulator (3) does not actuate prematurely during pressure equalization.11. The method of any of the statements 8 to 10, wherein the intermediate regulated line (111) functions as a dosing chamber that enables stepwise pressure adjustments in the main regulated line (112), allowing pressure increments to be controlled within a precision range smaller than the deadband of the mechanical regulator (3).12. A method for automated pressure control using the arrangement of any of the statements 1 to 6, the method comprising:receiving real-time pressure data from pressure sensors (16, 32) in the intermediate regulated line (111) and the main regulated line (112);determining whether the pressure deviation in the main regulated line (112) exceeds a predefined threshold smaller than the deadband of the mechanical regulator (3); if the pressure deviation exceeds the threshold, generating a control signal to adjust the pilot pressure in the pilot line (5) to initiate a pressure increase in the intermediate regulated line (111);monitoring pressure stabilization in the intermediate regulated line (111) before opening an isolation valve (34) to equalize pressure in controlled increments; and continuously adjusting the pilot pressure based on real-time feedback to maintain stable pressure within the predefined threshold.13. Use of the arrangement of any of the statements 1 to 6 for controlling hydraulic pressure in an annular seal (13) to maintain pressure within a tolerance range smaller than the deadband of the mechanical regulator (3), thereby preventing pressure variations associated with operational instability.14. The use of statement 13, wherein the arrangement is used for controlling hydraulic pressure in a drilling annular (13) to prevent gas influx into a riser while minimizing excess pressure associated with accelerated component wear.15. The use of any of the statements 13 or 14, wherein the arrangement is used to improve the operation of a blowout preventer (BOP) by providing precise pressure control to ensure rapid and accurate sealing activation in response to well pressure changes.

[0106] Any of the above statements can be combined and the skilled person would understand such examples do not limit the potential embodiments of the present disclosure. Components referenced in parenthesis are non-limiting illustrative examples, and suitable alternative components may be used.

[0107] The skilled person will also understand that any use of “or” throughout the statements of invention or description herein encompasses use of “or”, “and / or”, and “and”. For example, the term "or" within the discourse is construed to encompass both "and" and "and / or" owing toits inherent inclusivity. Within linguistic reasoning, "or" denotes an inclusive disjunction, allowing for the consideration of scenarios wherein either one condition holds true, the other condition holds true, or both conditions hold true concurrently. This interpretation inherently incorporates the conjunction "and", permitting the acknowledgment of scenarios wherein multiple conditions coexist. Additionally, the term "and / or" explicitly acknowledges the possibility of either condition being singularly true or both conditions being true simultaneously, thus aligning with the broader meaning of "or" within the context of this disclosure. Consequently, "or" functions as a flexible connector within the statements of invention, accommodating both exclusive and inclusive interpretations to suit the nuanced requirements of embodiments described herein.

Claims

PATENT CL IMS1. A mechanical regulator arrangement for precise pressure control, comprising:a mechanical regulator unit (3);a supply line (2) for providing high-pressure fluid, coupled to the mechanical regulator unit (3);a drain line (1) for fluid discharge, coupled to the mechanical regulator unit (3);a pilot line (5) for controlling a set-point pressure, coupled to the mechanical regulator unit (3);an intermediate regulated line (111) coupled to the mechanical regulator unit (3); a main regulated line (112) coupled to the intermediate regulated line (111);a pilot pressure control device (8) coupled to the pilot line (5) for adjusting the pilot pressure;a main surge bottle (15) fluidly coupled to a main regulated line (112);a pressure sensor (16) configured to measure the pressure in the main regulated line (112);an isolation valve (34) coupled between the main regulated line (112) and the intermediate regulated line;an intermediate surge bottle (31) fluidly coupled to the intermediate regulated line (111); anda pressure sensor (32) configured to measure the pressure in the intermediate regulated line (111).

2. The arrangement of claim 1 , wherein the isolation valve (34) is configured to selectively open and close to enable incremental pressure adjustments in the main regulated line (112) that are smaller than the deadband of the mechanical regulator (3) for precise pressure control.

3. The arrangement of claim 1 or 2, wherein the intermediate surge bottle (31) and the main surge bottle (15) are pre-charged with a gas to create controlled volume expansion and contraction, allowing for fine-tuned pressure modulation independent of inherent deadband limitations of the mechanical regulator (3).

4. The arrangement of any of the claims 1 to 3, wherein the pilot pressure control device (8) is configured to dynamically adjust the pilot pressure in the pilot line (5) at a rate faster than the mechanical regulator (3) can respond, enabling finer resolution of pressure regulation in the main regulated line (112) by leveraging time-delay effects in the system.

5. The arrangement of any of the claims 1 to 4, wherein the intermediate regulated line (111) and the main regulated line (112) form a staged pressure control system, wherein the intermediate regulated line (111) and the intermediate surge bottle (31) act as a dosing chamber to allow stepwise pressure changes in the main regulated line (112) without exceeding deadband constraints of the mechanical regulator (3).

6. The arrangement of any of the claims 1 to 5, wherein the pressure sensors (32, 16) are coupled to a control system to provide continuous or near real-time feedback to the control system, and that the control system provide automated adjustments of the pilot pressure and actuation of the isolation valve (34), to maintain the main regulated pressure (112) within a range smaller than an inherent deadband of the mechanical regulator (3).

7. A pressure control system comprising:an arrangement according to any of claims 1 to 6;a control unit configured to receive data from the pressure sensors (16, 32) and automatically adjust the pilot pressure in the pilot line (5) in response to detected pressure fluctuations; andan actuator configured to open and close the isolation valve (34) based on control signals from the control unit;wherein the control unit executes an algorithm to maintain the pressure in the main regulated line (112) within a predefined threshold smaller than the deadband of the mechanical regulator (3).

8. The Pressure control system of claim 7, configured to:receive real-time pressure data from pressure sensors (16, 32) in the intermediate regulated line (111) and the main regulated line (112);determine whether the pressure deviation in the main regulated line (112) exceeds a predefined threshold smaller than the deadband of the mechanical regulator (3);if the pressure deviation exceeds the threshold, generate a control signal to adjust the pilot pressure in the pilot line (5) to initiate a pressure increase in the intermediate regulated line (111);monitor pressure stabilization in the intermediate regulated line (111) before opening an isolation valve (34) to equalize pressure in controlled increments; andadjust the pilot pressure based on real-time feedback to maintain stable pressure within the predefined threshold.

9. A method for precise pressure control using a mechanical regulator (3) with an isolation valve (34) and an intermediate surge bottle (31) to achieve incremental pressure adjustments smaller than the deadband of the mechanical regulator (3), the method comprising:providing a mechanical regulator (3) configured to regulate pressure in a regulated line, the mechanical regulator (3) comprising a supply line (2) for high-pressure fluid and a drain line (1) for fluid discharge;incorporating an isolation valve (34) into the regulated line, the isolating valve (34) separating an intermediate regulated line (111), located between the mechanical regulator (3) and the isolation valve (34), from a main regulated line (112) downstream of the isolation valve (34);coupling an intermediate surge bottle (31) to the intermediate regulated line (111); measuring pressure in the intermediate regulated line (111) using a pressure sensor (32); andcontrolling the isolation valve (34) to enable incremental pressure adjustments, comprising:closing the isolation valve (34) to allow the mechanical regulator (3) to increase pressure in the intermediate regulated line (111) and the intermediate surge bottle (31) beyond the deadband threshold; andopening the isolation valve (34) to transfer a controlled volume of pressurized fluid from the intermediate regulated line (111) to the main regulated line (112), thereby increasing the pressure in the main regulated line (112) in increments smaller than the deadband of the mechanical regulator (3).

10. The method of claim 9, wherein the intermediate surge bottle (31) is pre-charged with a gas to act as a compressible volume, enabling finer pressure control by modulating thepressure transfer dynamics between the intermediate regulated line (111) and the main regulated line (112).

11. The method of claim 9 or 10, further comprising dynamically adjusting the pilot pressure in a pilot line (5) using a pilot pressure control device (8) to precisely control the set-point pressure of the mechanical regulator (3), wherein the pilot pressure is increased or decreased in a controlled manner to ensure the mechanical regulator (3) does not actuate prematurely during pressure equalization.

12. The method of any of the claims 9 to 11, wherein the intermediate regulated line (111) functions as a dosing chamber that enables stepwise pressure adjustments in the main regulated line (112), allowing pressure increments to be controlled within a precision range smaller than the deadband of the mechanical regulator (3).

13. Use of the arrangement of any of the claims 1 to 6 for controlling hydraulic pressure in an annular seal (13) to maintain pressure within a tolerance range smaller than the deadband of the mechanical regulator (3), thereby preventing pressure variations associated with operational instability.

14. The use of claim 13, wherein the arrangement is used for controlling hydraulic pressure in a drilling annular (13) to prevent gas influx into a riser while minimizing excess pressure associated with accelerated component wear.

15. The use of any of the claims 13 or 14, wherein the arrangement is used to improve the operation of a blowout preventer (BOP) by providing precise pressure control to ensure rapid and accurate sealing activation in response to well pressure changes.

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