RU2049226C1 - Subsurface safety valve - Google Patents

Abstract

FIELD: oil field equipment. SUBSTANCE: subsurface safety valve has body 1 in which movable rod is installed. Movable rod 2 is engageable with compression string 3. Axial channel 4 of rod 2 accommodates main seat 5 made in form of spring split ring engageable with balls 7, and additional seat 9 engageable with balls 11. Balls 7 are engageable with inner surface of body 1 and main seat 5, and balls 11 are engageable with inner surface of body 1, and additional seat 9 that is responsible for formation of, either, gap which provides for expansion of seats 5 and 9 between balls 7 and 11 and seats 5 and 9, respectively, or they prevent seats 5 and 9 from expanding. Seats 5 and 9 have flexible seal 13 which protects spaces of grooves 6 and 10 of holes 8 from formation fluid. Installed in bore 4 is spring-loaded stepped bushing 15 whose outer diameter of lower step 17 is larger than outer diameter of upper step 18. Located in central channel 19 of bushing 15 is seat 20 similar in design with seats 5 and 9. To change over the safety valve to the CLOSED position, shutoff member 33 is dropped to build up pressure above it. Shutoff member 33 is made in form of ball and is alternately engageable with seats 20, 5 and 9. To open the safety valve, shutoff member-ball 33 is forced through seat 9 to drop into accumulator. EFFECT: higher operate reliability, extended operation capabilities and reduced maintenance costs. 4 dwg

Description

 The invention relates to oilfield equipment, specifically to deep shutoff devices used in the repair of wells.

 A device for blocking a wellbore [1] is known, comprising a body with a central channel in which a saddle is provided for a locking element in the form of a ball, an input and output cavity, between which a side pocket is made in the body, and in the open state of the device, the ball is placed in the side pocket.

 A disadvantage of the known device is the low reliability of operation, due to the fact that the side pocket of the housing can be filled with solid inclusions that precipitate from the flow of produced fluid. Silt and sand, being cemented with paraffin-bitumen deposits, will prevent the ball from entering the central channel when closing. For the same reason, it will be impossible to place the ball in the side pocket when opening. In both cases, the device will be inoperative.

 A device for blocking a well [2] is known, comprising a body with a central channel blocked by a poppet valve, a saddle for a locking element made in the form of a ball, and a side chamber for accommodating the locking element.

 A disadvantage of the known device is the low reliability of operation, due to the presence in the design of many cavities in which precipitation of sand, silt and paraffin-bitumen deposits is possible, as a result of which jammed moving parts and device failure can occur.

 In addition, when the flow rate of the reservoir fluid is more critical, the devices are tuned, their autonomy is possible idle, without the need for closing operation, which requires the costs of the subsequent operation to open the devices and put the well into operation. In addition, a simple well during these operations leads to a loss of oil production.

 Known downhole shutter company "Page Oil Tools" [3] containing a housing in which a movable rod with an axial channel and a seat for a locking element in the form of a ball placed in the open position of the cutter in the side pocket of the housing, the node fixing the rod in the open position of the cutter, made in the form of a sealed cavity of the housing, communicating by pipeline with the ground control unit in the form of a hydraulic station, and in the stem wall under the village there is a through longitudinal groove for interaction with the locking element.

 The known cutter does not provide sufficient reliability, since remote control from the surface provides only the operation of forcibly switching the cutter to the open position. Closing the shut-off device is carried out autonomously from the flow of produced fluid, for a certain critical value of which the design of the parts is provided.

 Thus, random, unnecessarily, switching of the cutter to the closed position is possible, associated with short-term pulsation of the fluid flow of a more critical value, which entails an increase in the cost of the subsequent transfer of the cutter to the open position and putting the well into operation.

 However, a reverse situation is also possible when the cutter must be closed, for example, when changing the wellhead equipment, repairing the submersible pump, etc., and the oil flow is not enough to carry out this operation, since the well production rate has decreased during operation. In this regard, weighted fluid will have to be pumped into the well, which leads to an increase in operating costs.

 In addition, the known cutter has a limited range of applications, since it must be lowered on the tubing string with the obligatory equipping of the latter with an additional control pipeline and a ground station.

 Due to the eccentric placement of the locking element and the control pipe relative to the longitudinal axis, it is necessary to either reduce the passage channel or increase the diameter of the production string. In the first case, the hydraulic resistance to the flow of the produced fluid and the speed of the flow through the channel increase, which increases the loss of reservoir energy on the cutter and contributes to its rapid failure due to abrasion from solid inclusions in the fluid composition. In the second case, operating costs increase, since for launching a larger diameter string, it is necessary to drill a well with a large diameter, the cost of which will be more expensive.

 The aim of the invention is to increase reliability, expand operational capabilities and reduce costs from the use of downhole cutter.

 In a downhole cutter containing a housing, a movable rod located in the housing with an axial channel and a main seat mounted to interact with a locking element made in the form of a ball, a rod fixing unit in the housing in the open and closed positions of the cutter, a switchover unit for the cutter from open to closed position, equipped with a node for fixing the rod in an intermediate position when the cutter is switched from open to closed position, the diameter of the axial channel of the rod exceeds the outer diameter of the locking element, axial stem channel formed annular grooves in the wall of the rod through holes, the rod is spring loaded relative to the housing and has an additional seat disposed under the main seat for interaction with the locking member in the closed position; the seats have elastic seals and balls placed in the through holes of the stem wall and are made in the form of spring split rings installed in the annular grooves of the stem with the ability to interact with the balls, and in the open and closed positions of the cutter, the balls of the main saddle have the ability to interact with the inner surface of the housing and the balls of the additional seat with the lower annular groove made on the inner surface of the housing, and in the intermediate position of the rod when switching the cutter from rytogo the closed position of the main seat balls have the opportunity to interact with the lower annular housing groove and the additional seat balls with the inner surface of the housing; the cutter switching unit from the open to the closed position is made in the form of a movable step sleeve with a central channel, spring-loaded relative to the rod and placed in its axial channel above the main seat, the diameter of which exceeds the diameter of the locking element, and the outer diameter of the lower step of the sleeve exceeds the diameter of the upper stage; an annular groove is made in the central channel of the sleeve, and through holes in the wall of the lower stage of the sleeve; the sleeve has a saddle for the locking element, made in the form of a spring split ring with an elastic seal, and balls placed in the through holes of the sleeve; wherein the spring split ring is installed in the annular groove of the sleeve with the possibility of interaction with the balls; moreover, in the open and closed positions of the cutter, the balls are able to interact with the inner surface of the axial channel of the rod, and in the intermediate position, when the cutter is switched from open to closed position, the balls are able to interact with the annular groove of the rod; the rod fixing unit in the housing in the open and closed positions of the shutter is made in the form of balls installed in the through holes of the stem wall with the possibility of interaction in the open and closed positions of the shutter with the outer surface of the lower stage of the sleeve and with the upper annular groove made on the inner surface of the housing, and in the intermediate position of the rod, when the cutter is switched from open to closed position, with the possibility of interaction with the outer surface of the upper stage of the sleeve and the inner erhnostyu body.

 The set of distinctive features of the inventive cutter provides, in comparison with the prototype, the following advantages.

 Forced, only upon a command from the surface, switching of the cutter from open to closed position and vice versa, which guarantees the independence of the cutter from the flow rate of the well, thereby eliminating accidental closure operations during flow pulsations and ensuring closure either downward or downward side of the increase, deviation of the flow rate from the nominal.

 The absence of cavities in the passage channel in which accumulation of solid inclusions precipitated from the formation fluid flow is possible, which prevents jamming of moving parts during switching.

 The absence of a side pocket and a remote control pipe eccentrically located relative to the longitudinal axis, which, all other things being equal, can significantly increase the channel for the passage of the produced fluid, and therefore, reduce the flow rate through the cutter and increase the wear resistance of the parts forming the transition channel for the fluid flow, if last abrasive particles. At the same time, the loss of reservoir energy is reduced due to a decrease in hydraulic resistance to the fluid flow and the possibility of descent of downhole equipment, devices, etc., through the cutter into the interval of the reservoir is provided.

 The possibility of autonomous, without suspension on the tubing, placement in the production casing ensures the use of the inventive cutter in wells with any method of operation (fountain or pumping) or operating multiple layers.

 Lack of remote control pipeline and ground hydroelectric station.

 The ability to install during operation at any depth: from the wellhead to the perforation interval of the reservoir.

 Together, the above provides increased reliability, enhanced operational capabilities and reduced costs from the use of the inventive cutter compared with the prototype.

 In FIG. 1 shows a cutter, a cut, an open position; figure 2 the initial phase of switching to the closed position; figure 3 intermediate phase switching to the closed position; figure 4 is a closed position.

 The cutter (figure 1) contains a housing 1, in the bore of which, with the possibility of longitudinal movement, a rod 2 is installed, interacting with the compression spring 3. In the axial channel 4 of the rod 2 there is a main saddle 5 made in the form of a spring split ring installed in an annular groove 6 made in the channel 4 and interacting with balls 7 installed in through holes 8 made in the wall of the rod 2. Under the saddle 5 an additional saddle 9 is placed, made in the form of a spring split ring installed in an annular groove 10 made in the channel 4 and interacting with balls 11 installed in the through holes 8 made in the stem wall 2. In open and closed the positions of the cutoff, the balls 7 interact with the inner surface of the housing 1 and with the saddle 5, not allowing the latter to expand, and the balls 11 interact with the lower annular groove 12 made inside the housing 1, so that a gap is formed between the balls 11 and the saddle 9, which allows the saddle to expand 9.

 The saddles 5 and 9 are equipped with an elastic seal 13, which protects the cavities of the grooves 6 and 10, the openings 8 from the formation fluid.

 Above the seat 5 in the stem 2, a bore 14 is made, in which a step sleeve 15 is installed, which interacts with the spring 16. The outer diameter of the lower stage 17 of the sleeve 15 is larger than the outer diameter of the upper stage 18. A seat 20 is placed in the central channel 19 of the sleeve 15, similar to saddles 5 and 9 in the form of a spring split ring installed in an annular groove 21 made in the channel 19 and interacting with balls 22 installed in the through holes 23 made in the wall of the lower stage 17. In the open and closed positions balls 22 interact with the surface of the bore 14 of the rod 2, not allowing the seat 20 to expand, which is equipped with an elastic seal 24. Under the seat 20, an annular groove 25 is made in the bore 14, and an annular groove 26 is made over the seat 20 on the lower stage 17 balls 27 installed in through holes 28 made in the wall of the rod 2 and interacting in the open and closed positions of the cutter with the inner surface of the housing 1. Under the holes 28 in the housing 1 an intermediate annular groove 29 is made, and above the holes 28 in the rod 2, through holes 30 are made, in which balls 31 are installed, in the open and closed positions of the cutter interacting with the outer surface of the lower stage 17 and with the upper annular groove 32 made in the housing 1.

 With the saddles 20, 5 and 9 interacts with the locking element 33, made in the form of a ball, and the diameters of the channels 19 and 4 are larger than the outer diameter of the ball 33.

 Downhole cutter operates as follows.

 In the arrangement with the packer 34, the shut-off device in the open position (Fig. 1) without ball 33 is lowered into the production casing 35 and installed in the necessary interval with packing, hermetically separating the cavity 36 of the casing 35. In this case, the packer-cut-off arrangement can be suspended on the pump compressor pipes (tubing) or be autonomously mounted in column 35 after disconnecting and lifting the tubing string.

 In the position shown in figure 1, the reservoir fluid through the channels 4 and 19 and the channel of the packer 34 enters from the under-packer zone to the over-packer, where it is sampled to the surface by any of the oil production methods. With sufficient reservoir pressure, fluid can flow to the surface by gravity and in this case, the discharge of the ball 33 into the column 35 is carried out only if it is necessary to close the cutter. In the pump operation method, when the gaps between the pump and the walls of the column 35 are insufficient for the ball 33 to pass, the latter is placed in a special seating socket under the pump, from where it is forced out into the column 35 if it is necessary to close the shut-off device.

 The cutter will be in the open position (figure 1) regardless of the flow rate of the well, which can fluctuate or smoothly change both upward and downward due to the fact that the rod 2 is fixed by balls 31, step 17 of the sleeve 15 and the upper annular groove 32. In turn, the sleeve 15 cannot move down and release the stem 2 even when the ball 33 is seated on the seat 20 until the flow of formation fluid circulates through the channels 4 and 19, i.e. during well operation. If it is necessary to transfer the cutter to the closed position, the ball 33 is thrown into the column 35 and the output of the formation fluid to the surface is closed. The ball 33, under its own weight, lowers and sits on the saddle 20, after which formation fluid is pumped from the surface into the column 35.

 The tightness of the seating of the ball 33 on the seat 20 is provided by an elastic seal 24. The ball 33 cannot pass through the seat 20, since it retains its inner diameter less than the diameter of the ball 33 due to the balls 22, which interact with the bore 14, not allowing the seat 20 to expand.

 The force from increasing the pressure above the ball 33 and the sleeve 15, the latter is shifted down, compressing the spring 16 and unlocking the rod 2 at the moment when the upper stage 18 is shifted to the holes 30, ensuring the exit of the balls 31 from the upper groove 32. At the same time, the annular ledge of the groove 26 affect balls 27 and the pressure from the surface is transmitted through the ball 33, the seat 20, the sleeve 15, the ledge of the groove 26, the balls 27 and the holes 28 to the rod 2, which begins to move downward, compressing the spring 3 (the moment of release of the rod 2 is shown in figure 2 ) In this case, the balls 11 (Fig. 3) exit from the lower groove 12 onto the smooth surface of the housing 1 and, interacting with the latter and with the seat 9, fix the seat 9 with an inner diameter smaller than the diameter of the ball 33. At the end of the stroke of the rod 2 down into place balls 11 in the lower groove 12 go balls 7, allowing expansion of the saddle 5 to pass the ball 33. At the same time, the balls 27 go into the intermediate groove 29, unlocking the sleeve 15 relative to the rod 2, so that the sleeve 15 is shifted down to the stop in the end face of the bore 14. In this section the decomposition balls 22 enter into the groove 25, allowing the extension of the saddle 20 through which is able to pass the ball 33 (Figure 3, position A of the ball 33). The latter, passing through the saddle 20, sits on the saddle 5 (Fig. 3, position B of the ball 33) and, passing through it, sits on the saddle 9 (Fig. 3, position B of the ball 33), through which the ball 33 will not pass due to the interaction saddles 9 with balls 11, in turn interacting with the inner surface of the housing 1.

 After the ball 33 passes through the seat 20, the sleeve 15 will be unloaded from the downward force, and under the influence of the spring 16 and the pressure in the column 35 above the ball 33, which will affect the difference in the area of the steps 17 and 18, will be forced to move up.

 However, the return of the sleeve 15 to its original position is impossible due to the fact that the rod 2 is forced by pressure to move to the lowest position and the balls 31 will hold the sleeve 15 in an intermediate position in the rod 2. In this case, during the forced (pressure) movement of the ball 33 from saddles 20 to saddle 5, the rod 2 will not move upward, being fixed in the intermediate (lowermost) position by balls 27, which can exit the intermediate groove 29 only when the sleeve 15 is moved up and placed over the balls 27 of the groove 26 Due to the time delay, the ball 33 manages to sit on the saddle 5 and again create a force from the pressure on the rod 2 directed downward, preventing the latter from moving upward from the spring 3 and allowing the ball 33 to pass through the saddle 5, since the balls 7 are in the lower groove 12 , do not interfere with the expansion of the seat 5 for passing the ball 33, as a result of which the ball 33 is fixed between the seats 5 and 9. After the ball 33 is seated and stopped on the seat 9, due to the elastic seal 13, the cavities of the column 35 under and above the ball 33 are sealed. a ball 33 in the column 35 will begin to increase, which will be recorded on the surface by the pressure gauge of the injection pump. Together with the pressure jump when moving the ball 33 from the saddle 20 to the saddle 5, this information will indicate the operation of the shutoff nodes, after which the pump is turned off and the pressure in the column 35 above the ball 33 is reduced to zero. At the same time (Fig. 4), the spring 3 moves the rod 2 up to its initial position, in which the balls 11 again fall into the lower groove 12, allowing the saddle 9 to expand to pass the ball 33, and the balls 7 exit the lower groove 12 and interacting with saddle 5, fix the latter in a closed state, excluding the passage of the ball 33 through the saddle 5 up. Holding the ball 33 from falling down at this moment is due to the stiffness of the seat 9, for the expansion of which and the passage of the ball 33 it is necessary to apply force to the latter from the pressure of the fluid pumped into the column 35. The tightness of the ball 33 on the lower edge of the seat 5 is ensured by a seal 13.

 Simultaneously with the entry of balls 11 into the lower groove 12, the balls 31 go into the upper groove 32, ensuring the release of the sleeve 15, which, due to the action of the spring 16, moves upward, fixing the balls 31 in the upper groove 32 by the step 17.

 Thus, the rod 2 will be fixed from moving down and the shutter will be finally closed. As the pressure of the reservoir fluid under the ball 33 is restored, the upward force on it also increases the ball 33, compressing the seal 13 and being fixed from moving upward by the seat 5, will ensure the tightness of the overlap, which is controlled on the surface by the absence of pressure increase in the over-packer zone and the flow of the reservoir fluid.

 After the necessary work is performed, the shut-off device is opened by injecting formation fluid into the cavity of the column 35 above the ball 33. With increasing pressure, the force on the ball 33 increases and, having overcome the resistance of the seat 9, expands the latter and, passing through it, falls into the reservoir under the cut-off (not shown )

 The cutter will be open (figure 1 or 4 without ball 33). In this case, the rod 2 cannot move down due to the fact that it is fixed by the balls 31 in the upper groove 32, which are held in this position by the step 17 of the sleeve 15. The sleeve 15 also cannot move down and unlock the balls 31 due to the difference in the area of the steps 17 and 18, as a result, with increasing pressure above the ball 33 on the sleeve 15 there is a force directed upward. This eliminates the possibility of moving the rod 2 with the ball 33, located on the seat 9, down, which prevents the exit of the balls 11 from the lower groove 12, fixing the seat 9 in the closed state and the inability of the ball 33 to move the cutter from open to closed position.

 The use of the inventive cutter allows you to increase the reliability of operations on the overlap-opening of the wellbore for repair and maintenance work without first killing heavy fluid, since these operations are performed by force from a surface, regardless of the flow rate of the well being operated.

 This eliminates the additional communication channel of the cutter with the surface in the form of a pipeline and a ground control station, which reduces operating costs. In addition, the independence of the inventive cutter from the flow rate of the well expands its range of operational capabilities. The absence of local hydraulic resistances in the central channel in the form of fittings eliminates the loss of reservoir energy.

Claims (1)

 BOTTOM-BASED SHUT-OFF, comprising a housing, a movable rod located in the housing with an axial channel and a main seat mounted to interact with a locking element made in the form of a ball, a rod fixing unit in the housing in the open and closed position of the cutter, and a switching unit for switching the cutter from open to closed position, characterized in that it is equipped with a node for fixing the rod in an intermediate position when the cutter is switched from open to closed position, the diameter of the axial channel of the rod exceeds the outer diameter p of the locking element, annular grooves are made in the axial channel of the rod, through holes are provided in the rod wall, the rod is spring-loaded relative to the body and has an additional seat located under the main seat to interact with the locking element in the closed position, the seats have elastic seals and balls placed in through the holes of the stem wall, and are made in the form of split spring rings installed in the annular grooves of the rod with the possibility of interaction with the balls, moreover, in the open and closed positions of the compartment balls of the main saddle have the ability to interact with the inner surface of the casing, and the balls of the additional saddle with a lower annular groove made on the inner surface of the casing, and in the intermediate position of the rod when switching the cutter from open to closed position, the balls of the main saddle can interact with the lower annular groove the housing, and the balls of the additional saddle with the inner surface of the housing, the switching unit of the cutter from open to closed position is made in the form spring-loaded relative to the rod and placed in its axial channel above the main seat of the movable step sleeve with a central channel whose diameter exceeds the diameter of the locking element, the outer diameter of the lower step of the sleeve exceeds the diameter of the upper stage, an annular groove is made in the central channel of the sleeve, and in the wall of the lower stage bushings through holes, the sleeve has a seat for the locking element, made in the form of a spring split ring with an elastic seal, and balls placed in through holes the sleeve, with the spring split ring installed in the annular groove of the sleeve with the ability to interact with the balls, and in the open and closed positions of the cutter, the balls are able to interact with the inner surface of the axial channel of the rod, and in the intermediate position when switching the cutter from open to closed position, the balls have the ability to interact with the annular groove of the rod, the node for fixing the rod in the housing in the open and closed positions of the cutter is made in the form of balls, set in the through holes of the stem wall with the possibility of interaction in the open and closed positions of the cutter with the outer surface of the lower step of the sleeve and with the upper annular groove made on the inner surface of the housing, and in the intermediate position of the rod when switching the cutter from open to closed position with the possibility of interaction with the outer surface of the upper stage of the sleeve and the inner surface of the housing.

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