MX2008010072A - Fluid injection device - Google Patents

Abstract

The present invention regards a device designed for injection of fluids in a well bore, typically an offshore well bore for petroleum production and gas injection / gas lift system for fluid injection. The device comprises a outer hollow housing (1) with an internal body (2) moveable within the outer housing (1) with an internal bore(3) which in a first closed position is closed with a metal to metal seal system between the outer housing (1) and the internal body (2), which internal body (2) is operated by pressure differential across the internal body (2), where the internal body (2) is designed with slots (4) forming outlets of the internal bore (3) which in an open position of the device leads to the outside of the outer housing (1).

Description

FLUID INJECTION DEVICE FIELD OF THE INVENTION The present invention relates to a device for injecting fluid into a borehole, typically an overseas borehole for oil production and a gas injection / gas lift system.

BACKGROUND OF THE INVENTION Several different principles for operating a gas injection valve are known, one of these is based on the venturi principle, for example described in the O 2004/092537 Al. Another method has a central stem with a surface of external sealing and a flow passage between an external housing and the central stem through the sealing surface, for example described in CA 02461485 Al. After a period of time, known gas lift valves will have a tendency to not work as expected One problem may be the erosion of the sealing surface of the valve device, which leads to leakage through the valve seat and reduced performance and reduced life time for the valve devices. This creates a problem for the development of the well with increased downtime, maintenance time and increased safety risk.

THE INVENTION A main purpose of the present invention is to minimize and possibly alleviate those problems. It is also a primary purpose to provide a device with a reliable metal-to-metal seal of the device. The metal-to-metal seal in a preferred embodiment is understood as a single seal between two metal surfaces without any secondary seal, soft seal or a combination thereof. It is also an objective to provide a device with a reduced erosion rate of the sealing surface. Another purpose is to provide a device with an increased flow area compared to similar known valves. There is an additional objective providing a device with restrictions and minimal flow disturbances in the injection flow, giving reduced pressure losses through the device. There is also the purpose of providing a device with a low operating pressure difference. These objectives are achieved by a device according to the following claims and alternative modalities given in the description. The present invention relates to the device designed for the injection of fluids into a borehole, typically an offshore borehole for oil production and a gas injection / gas lift system for fluid injection. The device can also be used for injection of other constituents such as well stimulation fluid, injection cutting, water injection etc. The device comprises an external hollow housing with an internal body (called a dart) movable within the external housing. The housing can be manufactured in a unit, or it can alternatively comprise several parts, such as a main part and a corresponding tip. According to the invention, the internal body comprises an internal orifice, which in a first closed position is closed with a metal-to-metal seal system between the external housing and the internal body. In motion the internal body is operated by the pressure difference through the internal body. This pressure difference can be a fluid pressure that operates on the surfaces of the internal body, surfaces which can be exposed to different fluids. These fluids may be well fluids on one or more surfaces to operate the device or injection fluids on one surface and well fluids on another surface or combinations. According to one aspect, the pressure difference across the Internal body can be aided by at least one elastic element balanced by a predetermined pressure to open and close the device. According to the invention, the internal body comprises at least one slot between the hole and the outside of the internal body. Those grooves in the internal body, in an open position of the device, they lead towards the outside of the external housing. According to one aspect of the invention the outer housing may comprise grooves between an inner surface of the outer housing and an external surface of the outer housing. Those grooves in the outer housing correspond to the grooves in the inner body in an open position of the device. According to another aspect, the slots can be longitudinal and distributed over the circumference of the internal body and the external housing of the device. The distribution can be uniformly around the circumference of the internal body. The shape of the groove can be uniform or non-uniform around the circumference of the body. The grooves can be longitudinal with a main longitudinal direction, mainly parallel with a longitudinal axis of the internal body. The grooves can be longitudinal with a principal direction at an angle with respect to the axis longitudinal of the inner body or spiral shape around an axis. longitudinal, or be formed with another form. According to another aspect the grooves in the internal body and / or external housing can be beveled and angled from an internal surface to an external surface of the internal body and / or external housing to obtain the linear flow of the internal orifice and the outside of the device. According to another aspect of the invention, the grooves in the inner body and / or the outer housing can be placed in such a way as to prevent the linear flow of the current from hitting the sealing surfaces. According to another aspect of the invention, the internal body comprises a hole placed at an opposite end of the grooves observed in a longitudinal direction of the device and connected to the internal hole, where the hole is formed to obtain the rotation of the injected fluid when the fluid injected between the internal orifice. According to another aspect of the invention, the external housing comprises at least one through outlet. These outlets may be longitudinal and parallel to the longitudinal axis of the outer housing as they are uniformly housed around a circumference of the housing. external hosting. The outputs can also be longitudinal and angled with respect to the longitudinal axis of the external housing. In addition, the outputs can be connected to the slots in the external housing or they can be arranged as separate outputs in the external housing. Its function is proportional in the injected fluid to the ability to penetrate the production flow in the pipeline, thus damaging the best incorporation of the fluid injected into the flow. According to another aspect of the invention the seal system comprises a valve seat in the outer housing and a sealing surface in the valve element on the internal body, which in an open position of the device are placed mainly outside the injection fluid stream. With the open position, a position in which the grooves of the internal body are at least partially superposed to the grooves of the external housing observed in a direction transverse to the longitudinal axis of the device should be understood in this description. According to another aspect of the invention, the valve seat and the sealing surface of the valve element in an open or partially open position are placed on opposite sides of a groove observed in a longitudinal direction of the device. The The sealing surface of the valve element is placed mainly outside the flow of injection fluid through the device, since in one embodiment it is partially covered by a part of the external housing. The valve seat is positioned outside the fluid flow of the injection through the device, at least partially covered with the internal body. This causes the grooves that form the flow path of the injection fluid to be placed between the valve seat and the sealing surface of the valve member. The shape and size of the grooves in the inner body and the outer housing may be the same or different. The valve seat arranged in the outer housing is arranged at a distance from the slot in the outer housing, and in the valve surface trimmed over the inner body is arranged at a distance from the slot in the inner body. It causes the sealing surfaces of the valve seat in the sealing element to experience that the injected fluid forms a complete flow pattern in contact with those surfaces. According to another aspect of the invention the valve seat may comprise a low pressure guide to obtain optimum guide seal coupling.

According to another aspect, the internal body comprises a stop surface which in a completely open position of the device is connected to a corresponding surface (the tip) in the external housing. This stop surface can be placed on one end of the inner body near the output of the device, preferably on an opposite side of the grooves in comparison with an inlet for the injection fluid towards the preferred orifice and therefore avoiding vibration in the internal body of the injection fluid, in an open position of the device. According to another aspect of the invention, the internal body comprises a pressure surface exposed to the well fluid in an open position of the device, which deviates the device to a closed position. According to another aspect of the invention, the internal body and the external housing can comprise corresponding parts of at least one guide element that predefines a displacement between a closed and an open position of the device. In addition, or alternatively, the inner body may comprise at least one of the fins or the fluid-balanced deflectors or the additional grooves in the internal surface of the internal body exposed to the injection fluid to guide the internal body at a predetermined displacement between the open and closed position of the device. This predefined path can be linear, rotational or a combination of these. According to another aspect of the invention, the device may further comprise at least one element for canceling and / or controlling the open and closed position of the device. According to another aspect of the invention, the outer housing may comprise a cleaning element positioned for splicing against and cleaning the sealing surface during closure of the device. This is favorable in the case when the injection fluid contains particles prone to bond to the sealing surface. According to another aspect of the invention, the elastic element may comprise a spring element enclosed in a chamber, which chamber is filled with a fluid separated from both the well and the injection fluid.

Those features of the invention will provide a device where the flow path of the injection fluid is substantially less tortuous than in other known gas injection valves due to the more direct flow through the orifice in the internal body and directly outwardly through the valves. grooves This also gives less pressure loss to through the valves. Designing the entrances, orifices, exits and slots of the device could achieve the desired effect with respect to the flow pattern and cavitations. The present invention is also a simplified device with few elements compared to most other known injection valves. This gives a more reliable device too. The present invention also has a relatively large flow area through the devices as compared to most other known injection valves of similar size.

BRIEF DESCRIPTION OF THE DRAWINGS Next, a non-limiting description of an embodiment of the invention will be given with reference to the accompanying drawings, wherein Figure 1 shows a cross section of a first embodiment of the present invention. Figure 2 shows a cross section along the line II of the embodiment shown in figure 1. Figure 3 shows a cross section along the line II-II of the embodiment shown in figure 1. The figure 4 shows a front view of the first embodiment of the present invention in FIG. 1, and Figure 5 shows a cross section of the front part of the device of a second embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED MODALITIES OF THE INVENTION In figure 1 a first embodiment of a device according to the invention is shown. This mode is a gas lift valve to be placed in the flow of a well. An expert will understand how to do this and therefore is not described in this application. In Figure 1 the device, normally used as a gas lift valve, but initially can be used for another type of injection valves, comprises an external housing 1 with an internal body 2 mobile inside the outer housing 1 between two positions. As can be seen, in the figure, the external housing in this embodiment comprises two parts, that is, the main part 1 and the tip 34. The tip 34 is connected to the main part 1 with suitable means, such as a threaded joint . An open position is shown in Figure 1. The inner body 2 moves in the longitudinal direction of the body "internal 2 and the outer housing 1. The outer housing 1 comprises injections of injection fluids 7 near one end of the body. external housing 1. These inlets 7 are in contact with the injection fluid source (not shown). From the inlets 7 the injection fluid is transferred through an internal hollow of the external housing 1 through the hole 8 (only indicated) towards an internal hole 3 of the internal body 2. The hole 8 is located at one end of the internal body 2, and forms part of the internal hole 3. Furthermore the orifice is designed to create a rotational flow in the injected fluid when it enters the orifice 3. The hole 3 is seen in the longitudinal direction of the inner body 2 from one end of the inner body 2 and almost to the other end of the inner body 2. The injection fluid subsequently in an open position of the valve will flow through the slots 4 leading from the inner hole 3 to the outside of the inner body 2. In the example shown four slots are shown 4, of course there may be fewer or more grooves around the circumference of the device. In an open position of the valve, these grooves 4 of the inner body v2 cooperate with the grooves 5 in the outer housing 1, the injection fluid leading the outward flow in the process fluid, where the device is placed. This gives a flow pattern in an open position of the valve for the injection fluid which with a minimum amount of folds gives minimum pressure losses through the valve. To improve the flow pattern a surface 9 of the grooves 4 between an inner side to an outer side of the inner body 2 and a similar surface 12 of the grooves 5 in the outer housing 1 can be angled with different angles to 90 degrees with the longitudinal axis Of the device. The surfaces 9 and / or 12 can also be formed with different dependent angles around the groove 4, 5 the part of the surfaces 9, 12. The angles of the surfaces 9, 12 of the grooves 4 of the inner body 2 and the grooves 5 of the external housing 1 may also be different. In one embodiment, the devices are formed with four small slots and four large slots 33.5 around the circumference of the device, thereby deflecting upwards the flow in droplets or jets. An inner bottom 37 of the inner body 2 near the end, where the slots 4 are placed, are formed as a flat bottom (cone is shown in Figure 1) or a countersunk bottom. When large particles (larger than 20 micrometers) collide with the flat bottom of the inner body 2, they will lose all their energy and therefore will flow towards the outward flow of the valve. The inner bottom of the inner body 2 can also be covered by an elastic material, such as rubber. Also forming a bottom of the inner body 2 as a countersunk bottom, the direction in which the particles leave the slots 4, 5 could also be influenced. The valve shown also comprises an elastic element 6 arranged between a rim of the outer housing 1 and a rim of the inner body 2 by diverting the inner body 2 to a position closed valve (not shown). When the pressure difference through the inner body 2 reaches a fixed limit this pressure difference will move the inner body 2 against the elastic element to an open position, or the pressure of the elastic element will move the inner body 2 to a closed position of the valve. The internal body 2 comprises a sealing surface of valve element, annular 11, with a surface of mainly conical shape. This surface 11 is arranged near one end of the inner body 2 with the end of the conical shaped surface 11 with the larger diameter, farther from the grooves 4 of the inner body 2. The grooves 4 are arranged near one end of the body. inner body 2, and the surface 11 closer to the same end of the inner body 2. The sealing surface 11 of the inner body cooperates with the seat of the valve 10 arranged in the outer housing 1. The seat of the valve 10 in the housing external 1 is arranged on the center relative to the other side of the slot 4, 5, when aligned in an open position, in comparison with the sealing surface 11 with the body 2, observed in a longitudinal direction of the device. In a closed position, the inner body 2 moves relative to the outer housing 1, so that the sealing surface 11 is connected to the seat of the valve 10, giving a metal-to-metal seal, sealed for the valve. In this closed position, the slots 4 of the inner body 2 will be positioned within the valve device and the slots 5 of the outer housing on the other side of the interaction between the sealing surface 11 and the seat of the valve 10. There is a connection with the valve seat 10 in the outer housing 1 arranged to a low pressure guide 15, at the end of the seat of the valve 10 with the largest diameter. This gives a guide of the surface of the valve member 11 towards the valve seat 10, to make good contact and a sealing connection. The low pressure guide 15 can also have a sealing function. The sealing surface on the inner body 2 and the seat of the valve 10 in the outer housing 1 will be in an open position of the device at least partially covered by another device element, the outer housing and the inner body respectively. At the end of the inner body 2 near the slots 4, there is also arranged a stop surface 21, whose abutment surface 21 is connected to the corresponding abutment surface 20 in the external housing 1, which limits the movement and displacement of the internal body 2 relative to the external housing 1 of a completely open position of the valve, wherein the slots 4 and the slots 5 are completely aligned. In this way, the stop surface 20, 21 and its interactions will also limit the vibration of the inner body 2 in an open position of the device being arranged on an opposite end of the inner body 2 as compared to the elastic element 6, relative to the grooves , giving two points of contact between the inner body 2 and the outer housing 1 in an open position of the device. The external body is further arranged with a pressure inlet 24 at the end of the device. This pressure inlet 24 opens between the process fluid around the valve and a pressure surface 25 of the inner body 2. The pressure surface 24 affected by the pressure in the process fluid, together with a back pressure surface 23 arranged in one end of the inner bore of the inner body 2, which gives a pressure difference across these two surfaces, will assist the movement of the inner body 2 relative to the outer housing 1. In the embodiment shown here it is also shown a guide element 30 as a groove in the outer housing 1 and a projection (not shown in Figure 1, but in Figure 2) of the inner body 2 cooperating with the groove as best seen in Figure 2. The element guide 30 limits or controls the rotational movement of the inner body 2 relative to the outer housing 1 when the inner body 2 moves in the longitudinal direction relative to the outer housing 1, giving the inner body 2 a linear or predetermined rotational displacement or even a combination, linear in one direction and rotating in the opposite direction. Another possible solution is to influence or control this rotational movement as also shown in Figure 1 and Figure 2 and again arrange balance fins inside the internal hole 3 of the inner body 2. The injection fluid flowing through the Internal orifice will affect the movement of the inner body 2. There may be one or more of those arranged elements around inside the circumference of the inner hole or inside the outer housing. As can be seen in Figure 3, there are arranged grooves 32 in the outer housing 1, where these grooves 32 form a channel between the inner body 2 and the outer housing 1. The grooves 32 extend from the internal flange 36 of the outer housing and longitudinally with a longitudinal axis of a housing 1, where the slots 32 can run towards the slots 5 of the external housing 1. The slots 32 will allow any fluid present in the slots 32 to move freely when the elastic element 6 is compressed, avoiding for thus a "lock" of the internal body 2, between the external housing 1, the elastic element 6 and the internal body 2. In figure 4 a cross section of the first embodiment of the present invention is shown, where four grooves are arranged 5 around the circumference of the outer housing 1; in this embodiment the grooves are positioned directly opposite each other, and cooperate as mentioned at the beginning, with the grooves 4 of the internal body 2. Figure 5 is a cross section of the front part of a device, a second embodiment of the present invention showing the area around the slot 5 of the outer housing 1 where one or more through holes 33 are arranged around the circumference of the outer housing. The outlets 33 are longitudinal, circular in shape and mainly parallel to the longitudinal axis of the external housing 1. The outlets 33 are further connected to the slots 5 and their functions are to bring forward the injected fluid and have the ability to penetrate the production flow in the pipe, thus gaining a better incorporation of the fluid injected into the flow. Only the elements related to the invention are described and a person skilled in the art will understand that an external housing or internal body can be formed in a unit or can be comprised of several connected elements, and that the inputs have to be connected to a source of the fluid to be injected, the appropriate connection devices to connect the valve within a process fluid flow, and which will of course be arranged for example sealing elements between elements as a standard. The skilled person will also understand that various alterations or modifications may be made to the described and shown embodiment that are within the scope of the invention as defined in the following claims.

Claims (21)

1. CLAIMS 1. Device for injecting fluids into a process fluid, typically for use in an overseas well bore characterized in that the device comprises an external hollow housing with at least one inlet and one outlet, a pressure inlet and a mobile internal body inside the external housing and a longitudinal direction of the external hollow housing, where the internal body comprises an inlet and at least one slot that is connected by a mainly internal longitudinal orifice for the flow of injection fluid from the inlet to the outlet, exit the which in a closed position is closed with a seal system between the outer hollow housing and the inner body, the injection fluid having a mainly linear flow through the orifice in an open position of the device, the movement of the inner body to close or Open the outlet that is operated by the pressure difference through the internal body. Device according to claim 1, characterized in that the external housing comprises at least one slot corresponding to at least one slot of the internal body in an open position of the device. Device according to claim 2, characterized in that at least one output is arranged around the circumference of the external hollow housing, where the outlet is further connected to the grooves. Device according to claim 2, characterized in that the pressure difference through the internal body is assisted by at least one elastic element balanced by predetermined pressure to open and close the device, superimposing the slots. Device according to claim 2, characterized in that the grooves are longitudinal and are distributed on the circumference of the internal body and the external housing of the device. Device according to claim 2 or 4, characterized in that the grooves in the internal body and or the external housing are leveled and angled from an internal surface to an external surface of the internal body and the external housing to obtain a linear flow of current. Device according to claim 4, characterized in that the longitudinal grooves in the inner body and or the outer hollow housing are parallel to a longitudinal direction of the device or twisted or bent about the longitudinal axis. Device according to claim 4, 5 or 6, characterized in that the grooves in the internal body and / or the external hollow housing are placed between the sealing surfaces, in a way to prevent the linear flow of the current from colliding with the sealing surfaces. Device according to claim 1 or 2, characterized in that the sealing system comprises a valve seat in the outer housing and a sealing surface of the valve element on the internal body, where the sealing surface in an open position of the device they are placed outside the injection fluid flow in a closed position together with the metal-to-metal sealing valve seat. Device according to claim 7, characterized in that the seat of the valve and the sealing surface of the valve element in an open or partially open position are placed on opposite sides of a groove observed in a longitudinal direction of the device. Device according to claim 7 or 8, characterized in that the valve seat arranged in the outer housing is arranged at a distance from the groove in the outer housing, and the surface of the valve element arranged on the internal body is arranged to a distance from the groove of the inner body, where the valve seat and the surface of the valve element are arranged on different ends of the grooves observed in the longitudinal direction of the valve. device . 12. Device according to claim 7, characterized in that the valve seat comprises a low pressure guide for obtaining an optimum sealing coupling. Device according to claim 7, characterized in that the internal body comprises a stop surface which in a completely open position of the device is connected to the corresponding surface of the external housing. Device according to claim 2, characterized in that the internal body comprises a pressure surface exposed to the process fluid in an open position of the device by diverting the device to a closed position. Device according to claim 1, characterized in that the internal body and the external housing can comprise corresponding guiding elements which predefine a movement between an open and a closed position of the device. Device according to claim 1, characterized in that the internal body comprises fins or baffles balanced with fluid and or additional grooves in the internal surface of the internal orifice exposed to the injection fluid to guide the internal body in a Default displacement between an open and a closed position of the device. Device according to claim 1, characterized in that the internal body comprises an orifice placed on the opposite side of the slots, where the orifice is designed to obtain a rotation of the injected fluid. 18. Device according to claim 1, characterized in that the device further comprises elements for canceling and / or controlling the open or closed position of the device. 19. Device according to claim 9, characterized in that the external housing comprises a cleaning element positioned for splicing against and cleaning the sealing surface during closing of the device. Device according to claim 1, characterized in that the elastic element comprises a spring element inserted in a chamber, which chamber is filled with a fluid separated from both the well fluid and injection. Device according to claim 1, characterized in that the inner bottom of the internal body at the end of the grooves is formed as a flat or countersunk bottom.