GB2517959A

GB2517959A - Annular valve

Info

Publication number: GB2517959A
Application number: GB1315875.3A
Authority: GB
Inventors: Kurt Canfield
Original assignee: SAFETY CRITICAL ANALYSIS Ltd
Current assignee: SAFETY CRITICAL ANALYSIS Ltd
Priority date: 2013-09-06
Filing date: 2013-09-06
Publication date: 2015-03-11
Also published as: GB201315875D0; WO2015033112A3; WO2015033112A2

Abstract

An annular valve 1, for closing an annular bore between concentric pipes 11 and 12, comprises an annular housing 3, 4 located coaxially around outer pipe 12, means comprising an extrudable annular packing member 8, an electrical means operable to axially move means 8 to at least partially open/close the annular bore. Energising the electrical means in a first direction causes the annular packing member 8 to be moved in a first, essentially axial direction such that it is extruded through an annular hole 13 in pipe 12 into the annular bore between pipes 11 and 12 thus closing the bore. The electrical means may comprise an annular piston 5 or coil 14.

Description

ANNULAR VALVE

This specification relates to annular valves, It is particularly relevant to apphcations on S hydrocarbon drilling rigs, where such valves are used to control the flow of mud during drilling operations and to control the flow of hydrocarbon during production operations but has other applications, particularly in the chemical and process industries.

The search for hydrocarbons commenced on land, thence in to shallow waters and has now moved into deep water. Nowadays, drilling in depths of over 1000 or 2000+ metres of water (3-6000+ feet) are common. In such deep water, a considerable quantity of equipment has to be located on, or near, the seabed to control the drilling and production operations. Of necessity, much of this equipment has to be operated by remotely, e.g. by hydraulic means. One particular item of such equipment is the annular valve, which controls mud flow during drilling and hydrocarbon flow during production. This valve is part of the blowout prevention measures.

Figs. 1 and 2 show the principle of operation of the current design of such annular valves (prior art). Annular valve 1 is located around, and is fast with, drilling means 2. It consists of upper 3 and lower 4 housings fast with annular mud return pipe 12. Annular valve I consists of an annular piston 5, encircling pipe 12, with an integral annular skirt 6. Skirt 6 forms an annular piston 6 in annular cylinder 7 and is operable by hydraulic fluid 9. The reservoir of fluid 9 is annular in nature so that uniform pressure is exertable all round the circumferential end of skirt piston 6, causing it to move in cylinder 7 so that piston 5 will move normally upwards 23 or downwards 24 with skirt piston 6, as shown.

Drilling means 2 consists of an inner pipe 11, down which the drill string (not shown) passes. Drilling mud also passes 25 down inner pipe 11. Annular pipe 12 is the return pipe, taking the mud and rock debris back 26 up to the sea surface.

Annular valve I is formed by an annular polymeric donut-shaped packing member 8, fast with annular piston 5, which can be forced upwards 23, by annular piston 5 (driven by the operation of hydraulic means 6, 7 and 9). As it is forced upwards 23, member 8 is forced radially inwards by the inside curvature 3A of housing 3so that part of member 8 is extruded through annular hole 13 into the annular return flow pipe 12 until it is blocked 8A (Fig. 2).

To open valve 8A, hydraulic fluid 9 is removed from cylinder 7, lowering piston 5A, withdrawing polymer member 8A and allowing flow 28 to resume. Piston 5 (5A) may be moved to positions intermediate between 8 and 8A to restrict flow 26, without actually stopping it. Single acting hydraulics is shown but double acting means may be provided.

S

Pipe 10, secured to the outside of pipe 12, is provided for actuating hydraulic means 6, 7 and 9, and this is where problems arise. Annular valve 1 is part of the blow out prevention system and, as such, is required to operate as quickly as possible, ideally, essentially instantaneously; the DNV requirement is full closure within 45 seconds. Unfortunately, when rigs are operating in deep water, the time taken to close valve 1, i.e. to pump hydraulic fluid 9 from the sea surface, down pipe 10 into cylinder 7, can take a considerable time, e.g. up to 2 minutes. The reason for this is that a considerable volume of fluid 9 has to be pumped into cylinder 7 (compare annular volumes 9 in Figs. 1 and 2) and friction between fluid 9 and the inside wall of pipe 10 opposes the fluid flow. For its length, pipe 10 is is of relatively small bore and pumping a large volume of fluid 9 quickly down a long, relatively small bore pipe is difficult. Even if a powerful pump and / or a large pressurised accumulator is used, it takes a significant period of time to move the requisite volume of fluid 9 to close valve 1.

Further, the physical volume of the pump and accumulator, present problems in the confines of a drilling rig, and the costs of the installation, and keeping it running 24/7 while drilling is taking place, are additional drawbacks.

When merely controlling the mud flow 26, the slow operation may not be critical but when a blow-out occurs, time is vital. Consider that a volume V of gas escapes at a depth of, say, 10,000ft. By the time it has risen to 5000ft, the volume is 2V (Boyle's law, P.V = constant), 4V at 2500ft and over 8000V at the surface. If the blow out continues for a period, this violent expansion is likely to cause damage, or worse. The Deep Water Horizon Rig was lost in the Gulf of Mexico due to a blow-out, explosion and fire with several people being killed.

There is thus an urgent need for a quick-acting, highly reliable annular valve operable within seconds of a blow-out being detected.

According to the invention, there is provided an annular valve for controlling the flow in a pipe, comprising:-I) an annular housing; ii) a pipe, located coaxially in the annular housing, said pipe having an annular hole in the circumference I outer circumference; iii) a means to close, partly close or fully open the bore of the pipe thus stopping, partly stopping or fully opening the bore for fluid or slurry flow through the pipe, said means comprising an extrudable annular packing member, fast with an annular member movable in the axial direction of the pipe; and iv) an electrical means operable when energised to close, partly close or open the means to stop, restrict or permit flow in the pipe by causing the annular member to move in either a first direction in the axial direction of the pipe or to move or in a second direction opposite to first direction according to the direction of flow of the energising current; characteilsed in that the energising of the electrical means in a first direction causes the annular member to move in a first, essentially, axial direction urging the annular packing member, or a part thereof, to be extruded through the annular hole so wholly, or partly, closing the bore of the pipe and thus stopping or restricting flow in the pipe and when the electrical means is energised in the second opposite direction, the annular member is caused to move in the opposite direction withdrawing or partially withdrawing the extruded part of the annular packing member from the bore of the pipe through the annular hole thus fully, or partially, re-establishing the flow in the pipe.

According to a first variation of the apparatus of the invention, the annular housing is provided with internal contours which co-operate with the means to close, partly close or fully open the bore of the pipe.

According to a second variation of the apparatus of the invention, the pipe has a single coaxial bore or has an annular coaxial bore.

According to a third variation of the apparatus of the invention, the means to close, partly close or fully open the bore of the pipe incudes a packing member.

According to a fourth variation of the apparatus of the invention, the packing member is extrudable.

According to a fifth variation of the apparatus of the invention, the electrical means employs high power linear motor technology.

According to a sixth variation of the apparatus of the invention, the electrical means is a coil S wound around a ferromagnetic member, which is urged to move when a magnetic field is generated by a current flowing around the coil.

According to a seventh variation of the apparatus of the invention, the ferromagnetic member moves in opposite directions according to the direction of the current flowing in the

coil and the polarity of the field thus generated.

According to an eighth variation of the apparatus of the invention, the ferromagnetic member has the form of an annular member surrounding the pipe.

According to a ninth variation of the apparatus of the invention, the ferromagnetic member is fast with, or connected to, an intermediate member(s) which operates, or engages with, the means to close, partly close or fully open the bore of the pipe.

According to a tenth variation of the apparatus of the invention, the means to close, partly close or fully open the bore of the pipe includes an annular hole in the circumference I outer circumference of the pipe.

According to an eleventh variation of the apparatus of the invention, the means to close or partly close the bore of the pipe includes urging the ferromagnetic member, either directly / indirectly via the intermediate member, against the packing member extruding it through the annular hole in the circumference / outer circumference of the pipe into the bore of the pipe fully or partly blocking it.

According to a twelfth variation of the apparatus of the invention, the means to open or partly open the bore of the pipe includes withdrawing the ferromagnetic member thus withdrawing the extruded part of the packing member wholly, or partially from the bore of the pipe.

According to a thirteenth variation of the apparatus of the invention, the extrudable packing member is fast with the ferromagnetic member or intermediate member.

According to a fourteenth variation of the apparatus of the invention, sensors are provided to monitor the movement and I or position of the ferromagnetic member or intermediate member so that, when calibrated, real time information of the degree of closure of the valve is known.

S

According to a fifteenth variation of the apparatus of the invention, fail safe locking means are provided.

According to a sixteenth variation of the apparatus of the invention, the locking means provides fail open, fail closed or failure in the last position.

According to a seventeenth variation of the apparatus of the invention, the locking means includes urging a piston into a locking recess.

According to an eighteenth variation of the apparatus of the invention, the means of urging the piston into I out of the recess includes either or both of an electromagnetic means or a spring.

In a preferred application of the invention, the apparatus consists of an annular housing fast with the outer circumference of an underwater drilling pipe. Usually, such a pipe has a concentric inner pipe containing the drill string and mud downflow and an outer annular sleeve up which the mud and rock debris returns to the surface. One purpose of the invention is to control the return flow in the sleeve. Another is to provide an essentially instantaneously-reacting blow-out shut off valve during drilling or production operations. In the housing, an annular electromagnetic solenoid arrangement is provided to bear on, and fast with, an elastomeric packing member, which is urged, via co-operating contours of the inside shell of the housing, to be extruded through an annular hole in the circumference of the sleeve, thus wholly, or partially blocking the bore of the sleeve. Reversing the direction of the current in the solenoid withdraws the extruded portion of the packing member from the bore of the sleeve.

A fail safe locking means is taught, again employing electromagnetic principles in which the valve may be locked in the fail open, fail closed or fail last positions.

For a clearer understanding of the invention and to show how it may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings in which:-Figure 1 is a part sectional elevation of apparatus showing the principle of the operation of the hydraulic annular valve, showing it in the open position (Prior art); Figure 2 is a part sectional elevation of the valve of Figure 1 showing it in the closed

position (Prior art);

Figure 3 is a part sectional elevation of one form of the apparatus of the invention, showing the annular valve in the open position; Figure 4 is a part sectional elevation of the valve in Figure 3 showing it in the open position; Figure 5 is a part sectional elevation showing the principle of the failsafe locking mechanism in the unlocked position; and Figure 6 is a part sectional elevation of the failsafe locking mechanism of Figure 5 shown in the locked position.

In the following description, the same reference numeral is used for the same component in different Figures and I or for different components fulfilling identical functions.

Referring to Figs. 3 and 4, the annular valve IA of the invention consist of annular housings 3 and 4, through which coaxial pipes 11 and 12 pass. Extensions of pipes 11 and 12 extend above and below valve IA and are shown by dashed lines. Pipe 11 takes drilling mud down 25 to the drill bit (not shown) and annular pipe 12 is the return, taking 26 mud and rock debris back to the surface; it is the retum flow 26 that is controlled by valve 1A.

(For simplicity, reference numerals 11 and 12 refer to both the walls and bores of the pipes.) Annular piston 5 is located around pipe 12 and bears on polymeric packing 8. Packing 8 is fast with piston 5 or an intermediate member (not shown) fast with piston 5. Also fast with piston 5 is ferromagnetic, annular skirt 6, which is surrounded by an electric coil 14, wound round a former 14. (Reference numeral 14 is used for both the coil and former to avoid additional, confusing detail.) Coil 14 receives power via cable 15, attached to the outside of pipe 12. Though basic solenoid technology could be used in the operation of coil 14, high power linear motor technology is preferred as it is substantially more reliable. It is a more modern technology and much belier able to overcome minor frictions or stickyness' in the operation of the mechanism, which could well cause a solenoid system to fail. As valve I is on the seabed, it is effectively inaccessible and, thus, extremely high reliability is required.

Energising 15 coil 14 with the current passing in a first direction, generates a magnetic field inside former 14, which acts on ferromagnetic skirt 6 to urge it upwards 23, causing piston to compress packing 8 and force it, via a reaction with the curved inner wall 3A of housing 3, through annular hole 13 in the wall of pipe 12 to close off BA (Fig. 4) flow 26 in pipe 12. Reversing the direction of the current in coil 14 reverses the direction of the magnetic field and draws skirt 6 and piston 5A downwards 24, pulling the packing BA back through annular hole 13, allowing flow 26 in pipe 12 to resume.

As electrical power travels effectively at the speed of light, operation of the switch to admit power to cable 15 immediately starts the movement of piston 5 and the stopping of flow 26 in pipe 11. Ideally, the power would be applied slowly to avoid rupturing packing B and the valve 8 would close, say, over a second or two. However, in a blow-out situation, full power would be applied immediately and the valve B closed equally quickly. This is a major safety improvement over the operation of the hydraulic system.

Operating electrical means 14 to close the valve 8 may be done rapidly, as the packing member B will be in compression. However, re-opening valve B would always be done slowly and progressively as the connection between piston 5A and packing member B would be in tension and excessive tension could result in tearing member B. The pressure in pipe 12 would assist re-opening closed valve BA (Fig. 4) by helping to force packing B back into its closed position B (Fig. 3).

Appropriate control of the electrical current and the time of its operation permit part closure of valve 1A, i.e. only moving piston 5 and packing 8 to an intermediate position(s) (not shown). This allows drilling or production operations to be controlled as required.

Positional sensors (not shown) provide instant (real time) feedback to the control panel in the drilling rig to confirm what has happened in valve IA. This is a further improvement over the current hydraulic system, where the operator cannot be sure what has happened on the seabed until the new flowrate 26 can be measured on the surface.

Electrical control is much more sensitive than hydraulic control, particularly when it has to act through a thousand, or more, metres of small bore piping. Fine control (modulation), in realtime, of electrical signals to affect accurate positioning of piston 5 (and hence valve 1) is readily achieved, e.g. by the use of inverters with bi-directional sensory feedback. When a the well is in production accurate control of gas or oil flows is essential. Similarly, while the well is being drilled, accurate control of the mud is necessary. It is not unknown for pressure surges to occur as the hydrocarbons enter the riser and quick reaction times are essential to operate the recovery process safely. This dictates the need for electrical control and the reliability of linear motor technology.

The skilled person will know that, for all valves in critical locations, fail safe measures are essential, e.g. in the event of power failure. Preferred safety locks 16 are shown in Figs. 5 (locks withdrawn) and 6 (locks in place), teaching the basic principle. As taught above, skirt 6 moves relative to coil former 14. A plurality of blind recesses 21 are provided in skirt 6 and another plurality of blind recesses 16 are provided in former 14. In recesses 18, spring-loaded 19 ferromagnetic pistons 17 are provided. Electrical coils 20 surround each recess 18 and control the movement of pistons 17. Fig. 5 shows coils 20 activated, moving piston 17 to the left against springs 19, allowing skirt 6 (and piston 5 and packing 8) to move 22 in either direction. Fig. 6 shows the coils de-energised and pistons 17 driven to the right by springs 19 to engage with recesses 21, preventing skirt 6 from moving either up or down.

As before, electrical power may be passed in either direction through coils 20, urging pistons 17 either to the right of to the left, as required. Thus, the combination of bi-directional current in coils 20 and springs 19 permits operation of safety locks 16 to make valve 1A fail open, fail closed or fail in its last position (fail last), as required. If total electrical failure occurs and valve 1A has to be moved, e.g. from the open to the closed position, battery power (not shown) would be provided and would be activated automatically.

The skilled person will appreciate the applications of the control methods taught above, allied with linear motor technology, to the operation of valve 1A and safety locking means 16 and the greater reliability and real time feedback monitoring that it will provide adding significant extra levels of safety to the drilling and recovery of hydrocarbons.

Though the above description has been directed to drilling for hydrocarbons, the principle of the invention has many other applications, e.g. in chemical and process plants. The extrudable-packing type of valve 8, BA is ideal for hydrocarbon drilling and recovery operations as flow 26 may be a slurry with rock debris in the mud but may also be useful in handling slurries and non-Newtonian fluids in the chemical processing field.

The annular valve I of the invention would probably have an axial length of between a half and one metre in length. This is considerably smaller than and lighter than currently available equipment. Though there is not usually any restriction on the size of wellhead equipment on the seabed, reducing the size and mass of such items is desirable as S reduced weight and height above the seabed is beneficial as it minimises loads on the foundations and bending forces due to tides and currents.

Claims

Claims:- 1. An annular valve for controlling the flow in a pipe, comprising:-I) an annular housing; S ii) a pipe, located coaxially in the annular housing, said pipe having an annular hole in the circumference I outer circumference; iii) a means to close, partly close or fully open the bore of the pipe thus stopping, partly stopping or fully opening the bore for fluid or slurry flow through the pipe, said means comprising an extrudable annular packing member, fast with an annular member movable in the axial direction of the pipe; and iv) an electrical means operable when energised to close, partly close or open the means to stop, restrict or permit flow in the pipe by causing the annular member to move in either a first direction in the axial direction of the pipe or to move or in a second direction opposite to first direction according to the direction of flow of the energising current; characterised in that the energising of the electrical means in a first direction causes the annular member to move in a first, essentially, axial direction urging the annular packing member, or a part thereof, to be extruded through the annular hole so wholly, or partly, closing the bore of the pipe and thus stopping or restricting flow in the pipe and when the electrical means is energised in the second opposite direction, the annular member is caused to move in the opposite direction withdrawing or partially withdrawing the extruded part of the annular packing member from the bore of the pipe through the annular hole thus fully, or partially, re-establishing the flow in the pipe.
2. An annular valve, as claimed in claim 1, wherein the annular housing is provided with internal contours which co-operate with the means to close, partly close or fully open the bore of the pipe.
3. An annular valve, as claimed in any preceding claim, wherein the pipe has a single coaxial bore or has an annular coaxial bore.
4. An annular valve, as claimed in any preceding claim, wherein the means to close, partly close or fully open the bore of the pipe incudes a packing member.
5. An annular valve, as claimed in claim 4, wherein the packing member is extrudable.
6. An annular valve, as claimed in any preceding claim, wherein the electrical means employs high power linear motor technology.
7. An annular valve, as claimed in claim 6, wherein the electrical means is a coil S wound around a ferromagnetic member, which is urged to move when a magnetic field is generated by a current flowing around the coil.
8. An annular valve, as claimed in claim 7, wherein the ferromagnetic member moves in opposite directions according to the direction of the current flowing in the coil and thepolarity of the field thus generated.
9. An annular valve, as claimed in claims 7 or 8, wherein the ferromagnetic member has the form of an annular member surrounding the pipe.
10. An annular valve, as claimed in claim 9, wherein the ferromagnetic member is fast with, or connected to, an intermediate member(s) which operates, or engages with, the means to close, partly close or fully open the bore of the pipe.
11. An annular valve, as claimed in any preceding claim, wherein the means to close, partly close or fully open the bore of the pipe includes an annular hole in the circumference I outer circumference of the pipe.
12. An annular valve, as claimed in claims 4-11, wherein the means to close or partly close the bore of the pipe includes urging the ferromagnetic member, either directly / indirectly via the intermediate member, against the packing member extruding it through the annular hole in the circumference / outer circumference of the pipe into the bore of the pipe fully or partly blocking it.
13. An annular valve, as claimed in claim 12, wherein the means to open or partly open the bore of the pipe includes withdrawing the ferromagnetic member thus withdrawing the extruded part of the packing member wholly, or partially from the bore of the pipe.
14. An annular valve, as claimed in claims 12 or 13, wherein the extrudable packing member is fast with the ferromagnetic member or intermediate member.
15. An annular valve, as claimed in any preceding claim, wherein sensors are provided to monitor the movement and / or position of the ferromagnetic member or intermediate member so that, when calibrated, real time information of the degree of closure of the valve is known.
16. An annular valve, as claimed in any preceding claim, wherein fail safe locking means are provided.
17. An annular valve, as claimed in claim 16, wherein the locking means provides fail open, fail closed or failure in the last position.
18. An annular valve, as claimed in claims 16 or 17, wherein the locking means includes urging a piston into a locking recess.
19. An annular valve, as claimed in claim 18, wherein the means of urging the piston into I out of the recess includes either or both of an electromagnetic means or a spring.
20. An annular valve, as described in and by the above description, with reference to the accompanying Figures 3-6.