Patent Description:
Fluid pathways and conduits employ a variety of devices in order to control fluid flow. One illustrative device is a valve that is used to block fluid flow across a fluid path way upon occurrence of a specified condition. These valves may sometimes be referred to as flow stop valves. In some configurations, a flow stop valve may be set to remain open to allow fluid flow during normal operation, but close when operation is interrupted. Such interruptions of fluid flow may cause transient conditions, e.g., pressure waves, which may damage the flow stop valve or may hinder the closing of the flow stop valve. Conventional flow stop valves use dampening arrangements to reduce cyclical impact between the valve cone and seat (or "chattering") during such transient conditions. From <CIT> check valve comprising a housing, fluid flow openings, a valve seat on a plug, a ball, and a spring in said housing is known. The check valve eliminates excessive wear on the valve member when the fluid under pressure enters the valve. Further, from <CIT> a pressure relief valve with a housing is known. In the housing a valve seat is formed. A valve body can be moved in the housing between a position in contact with the valve seat, and a position raised from the valve seat, which corresponds to an open state of the pressure relief valve. <CIT> refers to a valve which briefly interrupts the flow of fluid to bit jets to reduce the effective hydrostatic pressure at the drilling face. The valve comprises a piston, an upstream and downstream end, a sealing surface on said piston, and an annular surface, and at least one spring arranged to urge said piston toward a peripheral seat. <CIT> refers to a valve structure which is not liable to become clogged by material carried in suspension by the fluid flowing through a pipe. The valve comprises a chamber, a valve head and an annular valve seat at its upper end. <CIT> describes a valve apparatus which comprises a valve plunger in a valve body with the plunger opening against spring means. The plunger further comprises an elastomeric collar intermediately located on the plunger shaft for allowing to fill up a pipe string above a predetermined differential pressure. <CIT> refers to a casing filling and circulating apparatus which includes a flow passage therethrough and a check valve disposed within the flow passage for preventing spillage and for preventing fluid back-flow through the apparatus. Additionally, the apparatus includes a pressure relief seal means. From <CIT> valve is known comprising a closure member and a deformable seal member, which makes wiping contact with an annular wall of the seat member.

The present disclosure provides a different approach to protecting valve components under such conditions.

Disclosed is an apparatus for controlling flow of a fluid in a fluid conduit and a method for controlling flow of a fluid from a first section to a second section in a conduit as set forth in the independent claims.

In aspects, the present disclosure provides an apparatus for controlling flow of a fluid in a fluid conduit. The apparatus includes a closure member having a cone body comprising a nose and a base, wherein the nose has an outer circumferential surface defined by a geometry different from a geometry defining an outer circumferential surface of the base; a biasing member applying a biasing force to the closure member; and a sealing member receiving the closure member, a fluid seal being formed in the fluid conduit when the biasing member presses the closure member against the sealing member, wherein the geometry of the outer circumferential surface of the cone body is designed to reduce a rate at which an annular flow space between the sealing member and the closure member increases while the closure member disengages and slides away from the sealing member, so that a pressure equalization is delayed, wherein the apparatus is configured to prevent the closure member from chattering.

In aspects, the present disclosure further provides a method for controlling flow of a fluid from a first section to a second section in a conduit. The method includes enclosing the first section and the second section in an enclosure; forming a flow path conveying the fluid from the first section to the second section; positioning a sealing member, a biasing member, and a closure member in the second section and along a flow path of the flowing fluid; forming a fluid seal in the flow path when the biasing member presses the closure member against the sealing member, wherein the fluid seal blocks fluid flowing along the flow path from the first section to the second section; and applying a compressive force on the sealing member using a biasing member, wherein the closure member has a cone body comprising a nose and a base, wherein the nose has an outer circumferential surface defined by a geometry different from a geometry defining an outer circumferential surface of the base, wherein the geometry of the outer circumferential surface of the cone body is designed to reduce a rate at which an annular flow space between the sealing member and the closure member increases while the closure member disengages and slides away from the sealing member, so that a pressure equalization is delayed, wherein chattering of the closure member is prevented.

For a detailed understanding of the present disclosure, reference should be made to the following detailed description of the embodiments, taken in conjunction with the accompanying drawings, in which like elements have been given like numerals, wherein:.

In aspects, the present disclosure provides a flow control device for use in oil and gas well applications. One illustrative use of the flow control device is to stop the flow of a fluid, e.g., a drilling fluid, when a fluid mover (e.g., surface pumps) is stopped or deactivated. This may be a desirable function in dual gradient drilling (DGD) applications because such a flow control device can minimize a "u-tube" effect caused by equalizing the mud pressure between the inside of the drilling tubular and the return line. It may also be useful for keeping the drilling tubular filled with drilling fluid during connections in applications known as dynamic kill drilling (DKD) or riserless mud recovery (RMR). Illustrative embodiments of the present disclosure reduce the dynamic pressure loss across the flow control device by controlling the rate at which fluid passes between a valve cone and valve seat. Controlling this flow rate can delay pressure equalization across the flow control device and thereby prevent minimize valve cone chatter.

Referring to <FIG>there is shown one embodiment of a flow control device <NUM> for controlling fluid flow along a conduit having an upper section <NUM> (<FIG>) and a lower section <NUM> (<FIG>). The flow control device may include an enclosure <NUM> that connects with the upper section <NUM> (<FIG>) and the lower section <NUM> (<FIG>); e.g., a threaded connection. In one arrangement, a fluid <NUM> flows from the upper section <NUM> to the lower section <NUM>. The flow control device <NUM> may be configured to block this fluid flow upon the occurrence of one or more conditions. As used herein, the term "flow control device" may be a valve, choke, flow restrictor or other such device that can partially or completely block fluid flow along a path way. As used herein, the term fluid refers to liquids and mixtures that are mostly liquid (i.e., more than fifty percent liquid).

The flow control device <NUM> may include a flow path <NUM> providing fluid communication between the upper section <NUM> and the lower section <NUM>, a sealing member <NUM>, a closure member <NUM>, and a biasing member <NUM>. In one embodiment, the biasing member <NUM> may include spring members <NUM> (e.g., disk springs, leaf springs, coil springs, etc.) that surround and are supported on a mandrel <NUM>. The springs members <NUM> may be disposed between a retaining wall <NUM> and a piston <NUM> that is connected to the mandrel <NUM>. Optionally, the flow control device <NUM> may include a dampener <NUM> that is operatively connected to and controls the movement of the closure member <NUM> during seating with or unseating from the sealing member <NUM>.

The advantages of the present teachings may be illustrated by first describing a conventional closure member <NUM>, such as that shown in <FIG>. The conventional closure member <NUM> may be a cone having an outer surface <NUM> defined by a straight line; i.e., a linear surface. Initially, an area <NUM> upstream of the closure member <NUM> has a pressure higher than a pressure at an area <NUM> downstream of the closure member <NUM>. When this differential pressure reaches a threshold value, the spring force of a biasing member (e.g., biasing member <NUM> of <FIG>) is overcome and the closure member <NUM> unseats by moving axially away from a valve seat <NUM>.

When the conventional closure member <NUM> separates from the valve seat <NUM>, an annular flow area <NUM> between the conventional closure member <NUM> and the valve seat <NUM> increases in size. This size increase allows a corresponding increase in fluid flow from the upstream area <NUM> to the downstream area <NUM>. This fluid flow can be sufficiently high enough to allow pressure equalization between the upstream area <NUM> and downstream area <NUM>, which then can cause the conventional closure member <NUM> to reseat due to the spring force.

Closure members, or valve cones, according to the present disclosure may be sized and shaped to control the rate at which the pressure differential across a flow control device decreases while the closure member disengages and slides away from a sealing member, such as a valve seat.

Referring to <FIG>closure members <NUM> according to the present disclosure have a cone body defined by one or more surfaces configured to reduce the rate at which an annular flow space increases, which then delays pressure equalization. In these embodiments, the closure member <NUM> seats against the sealing member <NUM>, which may be formed as a sleeve or ring-like member that has a valve seat <NUM>. A fluid-tight seal, which may be a metal-to-metal seal, may be formed between the closure member <NUM> and the sealing member <NUM>.

<FIG> shows a closure member <NUM> having a body with an outer surface <NUM> defined by a composite geometry that includes linear and curved surfaces. The outer surface <NUM> extends around a circumference of the closure member <NUM>. The closure member has a nose <NUM> and a base <NUM>. The base <NUM> may have a linear surface aligned to seat against the valve seat <NUM>.

The nose <NUM> may be formed using a geometry that allows the annular flow space <NUM> to increase in size slowly relative to the <FIG> closure member <NUM>. In one non-limiting embodiment, an outer surface <NUM> of the nose <NUM> follows a curve having a first end point at a juncture <NUM> with the base <NUM> and a second end point at or proximate to an apex <NUM> of the nose <NUM>. The outer surface <NUM> may be described as concave dome that projects from a straight line (not shown) that connects the juncture <NUM> and the apex <NUM>. In some embodiments, the outer surface <NUM> may be defined by a mathematical formula. It should be noted that the projecting curved surface <NUM> creates a smaller cross-sectional flow area with the adjacent valve seat <NUM> between the juncture <NUM> and the apex <NUM> as compared to the <FIG> closure member <NUM>. That is, the surface <NUM> of the prior art valve cone <NUM> would not project from such a straight line.

It should be noted that the composite geometry is used principally along the surfaces of the closure member <NUM> that defines the annular flow area. Thus, the surfaces defining this annular flow area are circumferential. Axially, this area is generally bounded at one end by a line of physical contact between the closure member <NUM> and the valve seat <NUM> and at the other end by the apex <NUM>.

<FIG> shows another closure member <NUM> having a body with an outer surface <NUM> defined by a composite geometry having two straight lines with different slopes. The closure member has a nose <NUM> and a base <NUM>. The base <NUM> may be configured as the base <NUM> of <FIG>.

The nose <NUM> also uses a geometry that allows the annular flow space <NUM> to increase in size slowly relative to the <FIG> closure member <NUM>. In one non-limiting embodiment, an outer surface <NUM> of the nose <NUM> follows a straight line having a first end point at a juncture <NUM> with the base <NUM> and a second end point at or proximate to a face <NUM> of the nose <NUM>. The slope of the line defining the outer surface <NUM> is less than the slope of the line defining the outer surface of the base <NUM>. The slopes are with reference to a longitudinal axis <NUM>. It should be noted that, due to the relatively shallower slope, the outer surface <NUM> creates a smaller cross-sectional flow area between the juncture <NUM> and the face <NUM> as compared to the <FIG> closure member <NUM>.

<FIG> shows still another closure member <NUM> having a body with an outer surface <NUM> defined by a composite geometry having one sloped line and one line parallel with the longitudinal axis <NUM>. The closure member has a nose <NUM> and a base <NUM>. The base <NUM> may be configured as the base <NUM> of <FIG>.

The nose <NUM> uses a geometry that varies the distance the fluid travels in an annular flow path in order to delay the loss of a pressure differential across the flow control device <NUM>. The nose <NUM> is formed as a cylinder that is separated from an inner surface <NUM> of the valve seat <NUM> by an annular flow space <NUM>. In this arrangement, axial displacement of the closure member <NUM> away from the valve seat <NUM> reduces the axial distance the fluid travels through the annular flow space <NUM>. Thus, while the size of the annular flow space does not substantially vary, flow resistance decreases as the distance the fluid travels decreases.

Referring now to <FIG>, there is shown another non-limiting embodiment of a closure member <NUM> that may be used in conjunction with a flow control device <NUM>. The <FIG> closure member <NUM> has a body <NUM> with an outer surface <NUM> defined by a composite geometry. The outer surface <NUM> extends along the circumference of the body <NUM>. The closure member has a nose <NUM> and a base <NUM>. The base <NUM> may have a linear surface aligned to seat along a contact line with an edge of a valve seat <NUM>. In one aspect, the linear surface is circumferential to provide a contiguous line of contact. A fluid-tight seal, which may be a metal-to-metal seal, occurs along such a contact line.

The nose <NUM> may be formed using a geometry that allows the annular flow space <NUM> to increase in size slowly relative to the <FIG> closure member <NUM>. In one non-limiting embodiment, the nose <NUM> has a juncture <NUM> with the base <NUM>, an end face <NUM>, and a concave outer surface <NUM> that connects the base <NUM> to the end face <NUM>. It should be noted that by extending from the juncture <NUM> and terminating at the end face <NUM>, the concave outer surface <NUM> from the majority, i.e., more than fifty percent, of the surface on the closure member <NUM> that defines an annular flow path <NUM>. The concave outer surface <NUM> may follow a curve that forms a dome-like projection on the nose <NUM>. Thus, in one aspect, the outer surface <NUM> is circumferential.

The geometry of the curve defining the concave outer surface <NUM> may depend on a number of factors including, but not limited to, the dimensions of the components of the flow control device <NUM>, the expected operating parameters, and properties of the flowing fluid. Generally speaking, the geometry may be selected to gradually increase an annular flow area <NUM> between the closure member <NUM> and the valve seat <NUM>. For some embodiments, the x, y coordinates of a curve defining the outer surface <NUM> may be defined by the formula: y = m xn.

The variable "m" may be a value between <NUM> and <NUM>, a value between <NUM> and <NUM>, or a value between <NUM> and <NUM>. The value "n" may be a value between <NUM> and <NUM>, a value between <NUM> and <NUM>, or a value between <NUM> and <NUM>.

Referring to <FIG>in one mode of operation, the flow parameter (e.g., flow rate, pressure, etc.) of the fluid supplied to the upper section <NUM> reaches a value sufficient to generate a pressure against the closure member <NUM> that overcomes the biasing force of the biasing member <NUM>. This may sometimes be referred to as the "crack open" pressure of the flow control device <NUM>. Thus, the closure member <NUM> unseats and the fluid fills a cavity <NUM> next to the piston <NUM>. The fluid pressure in the cavity <NUM> displaces the piston <NUM> and compresses the spring members <NUM>. The movement of the piston <NUM> also activates the dampener <NUM>, if present, which also resists the unseating movement.

Referring to <FIG>, advantageously, the shape of the closure device <NUM>, and particularly the concave outer surface <NUM> controls the size of the annular flow space <NUM> such that the pressure differential across the flow control device <NUM> is high enough to prevent the closure member <NUM> from reversing the direction of axial movement and re-seating on the valve seat <NUM>.

It should be appreciated that the teachings of the present disclosure may be used in any number of situations wherein it is desired to form a fluid tight seal along a flow path in a controlled manner. Some of these situations involve an arrangement wherein the fluid flow is used to maintain a flow control device in an open position and the interruption of fluid flow is used to initiate the closing of the fluid flow device. Described below is one non-limiting mode of operation.

Referring now to <FIG>, there is a system <NUM> that may use a flow control device <NUM> for controlling flow during dual gradient drilling. In dual gradient applications, mud pumps on the sea floor may be used to supercharge the drilling fluid so that it returns against a higher geostatic pressure through the annulus/return lines to the surface (drilling platform or ship). This reduces the pressure gradient inside the well annulus, allowing very tight windows between formation fracture pressure and formation pore pressure to be used.

<FIG> schematically shows a surface platform <NUM> from which a drill string <NUM> may be deployed to drill a wellbore <NUM>. The drill string <NUM> may be disposed in a conduit formed of a riser <NUM> that extends from the platform <NUM> to the seabed <NUM>. The drill string <NUM> may include a tubular member <NUM> that carries a bottomhole assembly (BHA) <NUM> at a distal end. The tubular member, which may be jointed tubulars or coiled tubing, is configured for use in the wellbore <NUM> (a wellbore tubular) and may include power and/or data conductors such as wires for providing bidirectional communication and power transmission (e.g., wired pipe). The conductors may be optical, metal, etc. Communication signals may also be transmitted by pressure pulses, acoustic signals, EM waves, RF waves, etc. A top drive (not shown), or other suitable rotary power source, may be utilized to rotate the drill string <NUM>. A controller <NUM> may be placed at the surface for receiving and processing downhole data. The controller <NUM> may include a processor, a storage device for storing data and computer programs. The processor accesses the data and programs from the storage device and executes the instructions contained in the programs to control the drilling operations.

The system <NUM> may include a fluid circulation system <NUM> that flows a drilling fluid into a bore <NUM> of the drill string <NUM>. The fluid exits and returns to the riser <NUM> via an annulus <NUM>. The riser <NUM> may include a restriction device <NUM> that diverts the fluid flowing in the annulus <NUM> to a flow cross line or a diverter line <NUM>. A subsea pump <NUM> pumps the return fluid from the riser <NUM> to the surface via the diverter line <NUM>. <FIG> further illustrates a material <NUM> having a lower density than the fluid in the annulus <NUM> in the riser <NUM> uphole of restriction device <NUM>. The material <NUM> usually is seawater. However, a suitable fluid could have a density less or greater than seawater. The material <NUM> is used in providing a static pressure gradient to the wellbore that is less than the pressure gradient formed by the fluid downhole of the flow restriction device <NUM>.

During drilling, fluid circulation system <NUM> maintains a continuous flow of fluid for the system <NUM>. However, deactivating the fluid circulation system <NUM> does not immediately stop fluid circulation in the well because the density of the fluid in the bore <NUM> is greater than the density of the fluid in the annulus <NUM>. That is, fluid in the bore <NUM> will continue to flow downward and out to the annulus <NUM> until the hydrostatic pressure in the bore <NUM> and the annulus <NUM> are the same. This is sometimes referred to as a "u-tube" effect.

Claim 1:
An apparatus for controlling flow of a fluid in a fluid conduit, comprising:
- a closure member (<NUM>) having a cone body comprising a nose (<NUM>, <NUM>, <NUM>) and a base (<NUM>, <NUM>, <NUM>), wherein the nose (<NUM>, <NUM>, <NUM>) has an outer circumferential surface defined by a geometry different from a geometry defining an outer circumferential surface of the base (<NUM>, <NUM>, <NUM>);
- a biasing member (<NUM>) applying a biasing force to the closure member (<NUM>); and
- a sealing member (<NUM>) receiving the closure member (<NUM>), a fluid seal being formed in the fluid conduit when the biasing member (<NUM>) presses the closure member (<NUM>) against the sealing member (<NUM>);
wherein the geometry of the outer circumferential surface of the cone body is designed to reduce a rate at which an annular flow space between the sealing member (<NUM>) and the closure member (<NUM>) increases while the closure member (<NUM>) disengages and slides away from the sealing member (<NUM>), so that a pressure equalization is delayed, wherein the apparatus is configured to prevent the closure member from chattering.