DE1583001A1 - Borehole tool - Google Patents

Description

description

to the patent application

from Schlumberger Technology Corp., 277 Park Avenue, New York

Concerning:

"Borehole Tool"

The invention relates generally to a downhole tool and, more particularly, to a downhole tool for use in the Packing and isolation of borehole sections.

About testing, sampling, stimulation or production operations To perform in a particular borehole zone, the zones can be separated from one another by downhole tools which are placed in the borehole above and below the particular zone. The lower tool, commonly referred to as a bridge plug, serves the Sealing the entire cross-section of the borehole to isolate the zone from fluids that are below the zone with a certain hydrostatic pressure. The top tool, commonly called the packer, serves sealing the annulus between a string of tubing connected to the packer and the well casing to isolate the zone from liquids that are above the

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Zone with a certain hydrostatic pressure exist. The tubing allows access to the isolated zone for fluid flow, for testing tools, or for wires or other instruments lowered through will like.

Purely the lower tools are generally two Types of bridge plugs in use. First, the so-called "permanent" bridge plug is used with two opposing sliders and a packer element; once this type of bridge plug is in place, it can only be removed again through destruction, that is by drilling away with a drilling device. Second, the so-called "retractable" bridge plug is used, the just like the permanent bridge plug forms a pressure bridge, but out of the borehole again after use can be pulled out. This type of bridge plug is being widely used in the industry from the simple Reason used so that the tool can be brought back to the surface without the need for a drilling operation is.

Very often a bridge plug is required to maintain its position within the well casing, even if the pressure differences acting on the plug change their direction during a certain operation turning back. For example, when cementing broth is forced through the casing perforations and into the earth formations If, in the vicinity of the isolated zone, the liquid pressure above the bridge plug can increase the pressure of the liquid exceed below the same. The pressure difference then acts as a force pushing the stopper down tries. As a result, a typical bridge plug

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Anchors on the tool against downward movement to back up. The zone can then be subjected to a "surge" test, i.e. the fluids in the pipe string are sucked off and removed in order to bring the hydrostatic pressure in the isolated zone to a value lower than the natural formation fluid pressure, so that formation fluid enters the Borehole flows. During this operation, the pressure of the liquid below the borehole plug can The pressure of the liquid above it will exceed, and the pressure difference acts as a force breaking the bridge plug is looking to move in the upward direction. A typical bridge plug accordingly has anchorages that hold it against secure an upward movement.

Such pressure reversal processes can also be applied to the Acting packer located within the well casing above the zone. During cement injection acts the liquid pressure below the packer so that the same tries to move upwards, while at "Flood" test process of the fluid pressure on the borehole annulus above the packer exerts downward forces on the latter. Accordingly w ± d a Packers have upper and lower anchoring devices to prevent their movement in either direction.

The need for opposing sentences vsn Anchors to prevent movement both up and down complicate such tools in structure and operation. The complexity increases the likelihood of malfunction and the cost of the maintenance.

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The present invention has the object to provide a downhole tool that in the form a retractable bridge plug and only a single anchorage and a single expander but still cannot be moved up or down within a borehole, even if the pressure difference acting on the stopper is reversed from top to bottom or vice versa. The present invention provides accordingly a tool that is less complex to construct and operate and thus less prone to malfunction and maintenance issues is.

The downhole tool according to the invention comprises a body with means for cooperating with the borehole wall, which devices can be moved out of the body in order to be anchored in a drill hole pull to become an obstacle to movement in either direction. An expander is relative to the facilities movable to move them outwards. A packer element is provided around the body, around the annulus seal between the body and the surrounding well casing wall. A hydraulically operated device is connected to the expander and responds to pressure differences between the fluids on the opposite one Sides of the packer element to exert forces on the expander in one direction to the facilities to interact with the wall to move outwards.

The invention will now be described in more detail with reference to the accompanying drawings, which represent individual embodiments explained.

Fig. 1 shows schematically a borehole with

Borehole tools for isolating a work zone in the borehole,

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Pig. 2Α is a longitudinal section through the top portion of a downhole tool according to the present invention, the parts in their relative position ^ to one another are arranged for longitudinal movement in the borehole guide,

Figure 2B is a view similar to Figure 2A

for the lower portion of the tool according to the invention; the figure shows accordingly the lower continuation of FIG. 2A,

Fig. 3 is a cross section taken along line 3-3 in Fig. 2A;

Fig. 4 is a cross section taken along line 4-4 in Fig. 2B;

FIG. 5A is a section similar to FIG. 2B, however with the parts in relative position to one another which they occupy when the tool is set in the well train,

Fig. 5B is the lower continuation of Figs. 5A, and

FIG. 6 is a partial illustration of a modified embodiment according to FIG Invention.

In Fig. 1 a typical borehole B is lined with a guide or casing C, which borehole intersects the earth formation F to be investigated, treated or stimulated. A zone Z of borehole B

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is from a packer P-I at the upper end of the zone and one Bridge plug P-2 insulated at the lower end of the zone. A pipe string T is connected to the packer P-I and creates so access to zone Z from the surface of the earth. Perforations S extend through casing C and into the formation F so that the fluids can communicate between Zone Z and Formation F. The packer P-I can any conventional device as normally in use described and illustrated e.g. in US Pat. No. 3,020,959 * or the packer can according to be embodied in accordance with the concept of the present invention, as follows with reference to a bridge plug should be explained.

Referring now to Figures 2A and 2B, details of the tool P-2 are shown which have a retractable bridge plug forms, which tool according to the present invention comprises a generally tubular body Io which extends extends through the length of the downhole tool P-2. The body Io has a central bore 11 which extends through it extends and leads to the outside through various / lateral openings 12 at the lower end. The top of the Body is closed by a screwed connection head 1J5 with J-shaped slots 14 on the circumference, to connect to a pull-out bridge plug cap 0 to enable (Fig. 1). An O-ring or other seal can make the screwed-in connection liquid-tight do.

A plurality of bypass openings 17 extend laterally through the wall of the body Io below the Connection head 13. Sealing elements l8 and 19 sit in annular grooves above and below the openings

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A valve 2o is accidentally on the body Io in the Arranged near the openings 17 and movable between a lower position, as shown in FIG. 2A, in which the bypass openings 17 are open, and an upper position where the upper end of the valve 2o at the lower end 21 of the connecting head IJ abuts. In the upper position, the valve 2o covers the openings 17 and acts in conjunction with the sealing elements 18 and 19 as a blockage for the flow of liquid through the same. Several spring fingers 22 extend from the lower end of the valve 2o and have enlarged Head sections 22 of such a size that they correspond to an upwardly directed shoulder 24 of the body can cooperate when the valve is in its upper position. A very specific downward one Force is required to cause the spring fingers 22 to flex outward and the valve 20 to move downward. This predetermined resistance against a downward movement holds the valve 2o in its upper position closing the openings.

An intermediate section of the body Io expands, to form a downward shoulder or stop 27. The shoulder '27 has a bore 28, sized to accommodate an annular compression sleeve 29. The lower end of the compression sleeve 29 has an outwardly directed annular flange 3o and thus simulates one upward stop. An elastomeric packer Jl is arranged around the compression sleeve 29, and its ends cooperate with the stops 27 and Jo. Typical O-ring seals J2 and 33 are between the upper one Stop 27 and the compression sleeve 29 on the one hand and between the compression sleeve 29 and the body Io on the other hand

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provided on the one hand to prevent leakage of liquid in between.

An annular piston 36 is displaceable in the body Io below the compression sleeve 29 and the packer 31 are arranged. An expander cone 37 is with the annular piston 36 by a Ring sleeve 38 connected, which is screwed to the ring piston is. A seal 39 seals the screw connection 4o, and a further sealing element 4l sits between the inner periphery of the annular piston 36 and an outer surface of the body Io.

The expander sleeve 31 forms an inner annular recess 43 which extends from the upper side 44 of the expander cone 37 to the lower side 45 of the associated annular piston 36. The recess 43 slidably accommodates a Fd; ^ nflanseh ^ 6, which can be integrally connected to the body Io. A suitable sealing element 47 seals between the outer periphery of the flange 46 and the inner periphery of the sleeve 38, so that a liquid-tight chamber 48 results between the top of the flange 46 and the bottom 45 of the annular piston ^ 6. It can be seen that the volume of the chamber 48 is variable in that the annular piston 36 and the body Io are movable relative to one another.

A tubular cage 5o sits movably on the lower end portion of the body lo, with its lower The end normally cooperates with the upward shoulder 51 of the body. A variety of look into extending in the radial direction and in the circumferential direction.ini Spaced recesses 52 in the cage 50 accommodate conventional drag shoe blocks 53, which are secured by springs 54 pushed outwards so as to with the well casing

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to get into engagement; the outward movement of the blocks is limited by stops 56.

The inhibiting blocks 53 act as a delay for rotational and longitudinal movements of the cage part 5o within the borehole casing C. For the control of the relative longitudinal movement between the cage 5o and the body Io, upper and lower segment-like ratchet parts 57 and 58 "are located within the inner annular recess space 59 and 6o of the cage 5o. The ratchet members 57 and 58 are commonly called "dizzy" and have internal serrations that can selectively cooperate with external complementary shaped teeth 62 and 63 of the body. The upper body teeth 62 face downward so that, when engaged with the upper ratchet parts 57, the cage 50 cannot move upward relative to the body Io, but the body teeth 62 can be disengaged from the ratchet parts 57 by clockwise rotation. The lower body teeth 63 are upward directed, so that they in cooperation with the lower ratchet teeth 58 relative mean that the body Io can be pushed upwards relative to the cage part. As in the case of the upper body teeth 62, however, the lower body teeth 63 can also be disengaged from the lower ratchet parts 58 by a clockwise rotation. As a result of the shape of the teeth 62 and 63 , it can be seen that the upper body teeth 62 can be ratcheted up by the upper ratchet parts 57 and the lower body teeth 6j5 down by the lower ratchet parts 58. Projections 64 of the cage 50 engage between segments of the ratchet parts 57 and 58, as shown in Figs. 2B and 4, so that the ratchet parts cannot rotate relative to the cage when the body Io is rotated. Spring straps

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τ Ιο '-

can be arranged within grooves 6γ around the ratchet parts 57 and 58 and serve to allow the ratchets to expand radially when the body teeth are ratcheting, while on the other hand they cause an inward pull.

A plurality of slide segments 70 are carried from the top of the cage 50. The sliding segments 70 may have outer projections or teeth 71 on the periphery that are adapted to engage the well casing wall and prevent movement of the downhole tool in any direction. The slide segments 7o may also have inner beveled surfaces 72 which diverge upwardly and outwardly of the body Io and are complementary to outer inclined surfaces 73 of the expander cone 37 in such a way that when the expander cone 37 is brought into engagement with the slide segments Yo a downward movement of the expander cone 37 relative to the sliding segments Yo will cause an outward displacement of the sliding segments 7o so as to come into engagement with the well casing wall. The lower end of each sliding segment Jo can be provided with a tongue Y ^ which engages with an inclined groove 75 of the cage part po so that the sliding segments 7o can be moved completely outward. Spring members Y6 of rectangular cross-section can be attached to the outer surface of the cage member 50, the free ends of which press against the slide segments Yo towards their retracted position.

According to the present invention, the portion of the body Io closest to the packer element 31 has at least one

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- li -

a liquid passage 8 o, as shown in FIGS. 2 and 8, which extends along openings 81 and 82, which are in communication with the borehole annulus above the packer element 31, to outlet devices 83 which communicate with the underside 45 of the annular piston 36. Accordingly, it can be seen that the underside 45 of the annular piston 36 is exposed to the fluid pressure in the borehole annular space above the packer element 3I, while the upper side 84 of the annular piston 36 is exposed to the fluid pressure in the borehole annular space below the packer element 31. It turns out that whenever the packer element is set and the liquid pressure below the packer element 31 exceeds that above it - the pressure differential acts on the piston area differential A as a force which seeks to move the expander cone 37 downwards and accordingly the slide segments 70 in will postpone more vigorous engagement with the well casing. Accordingly, instead of loosening the well packer as it normally does, an upward pressure differential will act to anchor the well packer P-2 even more firmly in the well casing. If, on the other hand, a downward pressure differential acts on the tool, the higher pressure is transferred into the chamber ^ 8 so as to act upwards on the underside of the annular piston J> 6 . The pressure, however, acts simultaneously downwards on the cross-sectional area of the expanded packer 3I and on the compression sleeve ? S _t so that the remaining forces on the expander cone 37 are still directed downwards so as to press the sliding segments 7o outwards.

A modified embodiment of a downhole tool according to the invention is shown in FIG.

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A floating annular piston 86 is slidably seated in the recess 43 above the expander cone 37. Suitable seals, e.g. O-rings 87 and 88 seal between the inner periphery of the piston 86 and the outer surface of the body lo, as well as between the outer Periphery of the piston 86 and the inner surface of the sleeve 38. An annular shoulder 89 of the body Io delimits the upward movement of the piston 86 within the recess 43, and the downward movement is limited by the upper surface 44 of expander cone 37. If the fluid pressure above packer 31 is lower as the pressure below it, the floating piston 86 cooperates with the shoulder 89 of the body Io. A higher fluid pressure below the packer 31 exerts downward forces on the piston 36, the is connected to the expander cone 37, as well as in the arrangement according to FIGS. 5A and 5B, whereby the out-. arrts-directed forces are increased, which the sliding segments Hold 7o in engagement with the well casing wall. In addition, the floating piston 86, if the pressure above the packer 31 gets higher, move it down to the upper surface 44 of the expander cone to touch, whereby forces are transmitted, which as a result this pressure act directly on the expander cone 37. Accordingly, the remaining forces are on the expander cone 37 directed downwards, as is the case with the embodiment shown in FIGS. 5A and 5B, so as to keep the sliding segments 7o in the anchoring position. In the embodiment according to Flg. 6th it can be seen, however, that the cone holding forces are even higher in that the floating piston 86 itself is directed downwards Able to transmit forces to the expander cone 37.

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The following is the mode of operation of the invention Borehole tool are described.

The individual parts are assembled as shown in Figures 2A and 2B and into the borehole line pipe C lowered to a point where a pressure bridge is to be formed, e.g. the point of the tool P-2 in Fig. 1. During the lowering, the pipe string T with the connection head 13 is through a cap 0 connected, and the in-line valve 2o is in its lower position, so that the bypass passages 17 are open. Accordingly, liquids in the borehole can be passed through the tool via the lower openings 12, the body passage 11 and the bypass openings 17 flow therethrough. In this way da.s borehole tool P-2 can be lowered quickly to the setting depth.

During the lowering, the upper ratchet part 57 is in engagement with the upper body thread 62 in order to prevent an upward movement of the cage 5o relative to the body 1 ©. The sliding segments 7o are pressed inward by the springs J6 and, since they are connected to the cage part, cannot be moved upward so as to be displaced outward by the expander cone 37.

At the setting depth, the downhole tool P-2 is stopped, and the body Io is made a right turn exposed several revolutions by manipulating the tubing string T so as to remove the upper ratchet part 57 from the upper body thread 62 to loosen. The cage is part 5o do not twist as a result of the frictional engagement of the drag shoe blocks 53 with the borehole lining wall. Loosening the upper ratchet parts 57 allows downward movement of the body Io relative to the cage 5o, so

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to move the expander cone 37 behind the sliding segments 7o. When the expander cone 37 moves down is, the sliding segments 7o are pressed outwards in Engagement with the well casing wall.

. When the sliding teeth 71 are in secure engagement, the expander cone 37 will no longer move downward and the piston 36 prevents further downward movement of the compression sleeve 29. Accordingly, the packer 31 can be compressed between the upper and lower stops 27 * Jo , by moving the body Io further downward so that it sealingly engages the well casing wall in the expanded position, as shown in Figures 5A and 5B.

When the body Io moves 5o downwards relative to the cage moved, the lower body threads 63 are through the lower parts of the ratchet ratchet, and the body is caught in its lowest position, thus releasing the pressure energy to block in the packer 31. The throw 0 can now be brought into the released position relative to the connection head I3, and an upward movement of the cap will automatically move the in-line valve 2o into its upper position, which closes the passages, whereby the Spring finger 22 come into engagement with shoulder 24 of body Io. The cross-sectional areas of the sealing elements 18 and 19 can be made essentially the same, so that the valve 2o is essentially in pressure equalization and not in response to pressure differences in the liquid moved above and below the downhole tool P-2.

The tubing string T is then raised to position the upper packer P-I above the formation F in place

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to bring, and then the upper packer is set. When cement squeezing or other pressure operation is performed in zone Z above tool P-2, the remaining forces on expander cone 37 are directed downwardly, as described above, so that slider segments Io firmly engage the well casing wall. In addition, if the pressure of the fluid above the downhole tool P-2 is lowered to levels below that below the tool, the lower pressures will be transmitted to the chamber 48 below the piston 36 via the passage 8o. The higher fluid pressure below the packer 31 acts on the upper end surface of the piston 36 and the pressure differentials act on the annular cross-section A as downward forces on the expander cone 37 to hold the slide segments 7o securely in engagement with the well casing wall.

When it is desired either to return the downhole tool P-2 to the surface or to relocate it, the upper packer PI is triggered and the tubing string T is lowered to hook the connector head 13 into engagement with the cap O. to become. The valve 20 is automatically moved to its lower position where the bypass passages 17 are open so as to equalize the fluid pressure above the packer 31 and above the cone that holds the piston 36. The body is then rotated clockwise a few times to disengage the lower ratchet members 58 from the lower body teeth 63 so that the body Io is free to move upward relative to the cage 5o. When the body is pulled upward, the pressure above the packer element 31 is released and it is completely withdrawn. The body flange ^ S will come into engagement with the piston 36, urr. so to pull the expander cone 37 out of its position behind the slide segments 7o, so that these

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also be withdrawn. When the body Io has reached the upper limit of its movement relative to the expander cone yj , the upper body teeth 62 ratchet through the upper ratchet parts 57 * in order to lock the cage 5o again against upward movement relative to the body, while a downward movement of the same through the shoulder 51 on it Body Io is prevented anyway. The downhole tool P-2 is then free to move within the downhole casing C.

A. New and improved downhole tooling has been described which has only a single anchor and a single expander, yet does not move up or down within the well casing in response to fluid pressures from above or below. The downhole tool is simple to operate and effective in isolating one
Cross-section in a well casing. It should be noted that while the invention has been described in connection with a bridge plug, the principle of the invention is equally applicable to other tools such as packers and cementers.

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Claims (4)

Claims 1. Downhole tool with a body holding a packer for sealing between the body and the borehole wall, with sliding segments anchored in the borehole wall and with an expander movable in one direction relative to the body for engaging the sliding segments with the borehole wall, which expander has a first surface directed towards one side of the packer, characterized by a fluid passage (8o) along the body (lo) for the transmission of fluid pressure from the other side of the packer (31) to a second Area (45) of the expander (37) facing away from the packer, so that the expander is relative in one direction moves towards the body in response to a pressure differential across the packer in any direction, thereby moving the sliding segments (7o) engages with the borehole wall (C). 2. borehole tool according to claim 1, characterized by an annular piston (36) connected to the expander (37) with the first and second surfaces (45, 84). 3. borehole tool according to claim 1 or 2, characterized by a flange (46) on the body (lo) sealed against the expander (37) for the prevention of the The effect of the fluid pressure on one packer surface on the other packer surface. 4. borehole tool according to claim 1, 2 or 3, characterized characterized in that the packer (31) is movable relative to the body (lo) in the direction of the expander (3 & to about this to move in the direction of expansion of the sliding segments (70). - 18 009817/0181 5 «Borehole tool according to one of claims 1 to 4, characterized by a compression sleeve (29) between the body (lo) and the expander (37) with a cross-sectional area that corresponds to the cross-sectional area of the expanded packer (J> 1) the second surface of the expander "(37), so that the expander is displaced in one direction by a pressure difference in this direction. 009817/0181