Patent Publication Number: US-2013228338-A1

Title: Device for Operating Downhole Equipment

Description:
The present invention relates to a new construction for a device for conveying a pressure pulse to activate a fluid pressure operable equipment in a pipe, such as a well, as defined in the preamble of the appended claim  1 . In particular, the invention is concerned with a construction which is capable of supporting operation of downhole equipment which is hydraulically operated. 
     BACKGROUND OF THE INVENTION 
     It has been well known for a long time that, in connection with pressure-pulse activation of mechanical equipment installed down in an oil- or gas-well, there are challenges related to convey theses pressure pulses forward to the equipment. 
     This is especially pertinent when a pipe which is introduced down into the well is pressurized up to transmit these pressure signals down to the equipment. A problem that is that is often encountered is that, over time, there is formed an accumulation of particles in liquid, which eventually forms a solid mass at a bottom of the pipe, when such particles sink to the bottom. This is especially a problem when plugs are employed in the production pipe which operates in a manner to pump up pressure over the plug from the rig. 
     A manner of limiting the problem is to couple the equipment via a hydraulic control line (a conductor) which is disposed outside the existing pipe wherein the plug is mounted. Such a control lines are routed upwards and through the wellhead-installation and further up to the rig, such that it can be subject to pressure directly from the rig, and as a consequence one is still able to operate the equipment despite an accumulation of mud over the plug in the pipe. 
     The disadvantage of such a system is that, to a major extent, it renders operation more expensive and establishing a several kilometer long control line (conductor) introduces a risk that it is possible that the pipe which generally, for example, is a thin tube with a dimension ¼″ (6.3 mm) is worn against walls of the well, and it is thereby possible to lose all control of the equipment. 
     A known solution is to use an kind of accumulator for introducing clean liquid into the well. Such a solution is described in Norwegian patent application no. 2008 0452. There is described an accumulator which includes a limited volume for supplying the equipment with clean liquid for operating it. 
     That which is described in said Norwegian patent application is a piston accumulator which pursuant to the description accumulates pressure during introduction into the well. 
     This system continues to result in a considerable number of problems associated with functionality. 
     First and foremost, it is claimed that debris (supply of contamination) are not able to penetrate into the system. But such a claim is incorrect, on account of it being known that a blockage of the canal upstream of the piston, as described, would not be able to convey the pressure pulses which are necessary for the system to function. It is correct that these particles would not be able to contaminate downstream of the piston which is to actuate the cyclic mechanism in the system, which is operable to open depending on a beforehand specified number of pressure pulses. The problem is namely that, by way of liquid communication through the canal up-stream for the piston, particles may enter into the chamber and thereby block the piston from moving, such that pressure differences can arise between upstream and downstream of the piston. 
     A cyclical-system which is based upon pressure differences would then cease to function. 
     In respect of the state-of-the-art, reference is also made to U.S. Pat. No. 2,964,116 and U.S. Pat. No. 2,898,088. 
     OBJECT OF THE INVENTION 
     It is a principal object of the invention to provide a new construction which is capable of solving the aforementioned disadvantages and problems. 
     The solution pursuant to the present invention includes installing a flexible diffusion-free membrane, for example fabricated from a rubber material, in its own housing/sleeve-section of the pipe). By using such a solution, it is possible to achieve a quite different effect than disclosed in the earlier known solutions. 
     PRESENT INVENTION 
     The device pursuant to the present invention is characterized in that the pipe includes a flexible membrane which isolates a fluid F 1  in the fluid-conveying pipe from a fluid F 2  in another canal which is in fluidic communication with the equipment, wherein the membrane, on account of its elasticity, conveys pressure changes (pressure pulses) in the fluid P 1  in the pipe to the fluid P 2  in the other canal. The beneficial implementations appear in the dependent claims  2  to  9 . 
     One of the advantages of the present invention, as defined, is that a piston which moves axial in a longitudinal direction will be limited in area which can be affected, whereas a bellows which moves radially is capable of providing an enormous area which can be affected. This area is limited only by the length of the bellow. 
    
    
     
       DESCRIPTION OF THE FIGURE 
       The present invention will now be described in more detail with reference to the accompanying diagrams. 
         FIG. 1  is an illustration of a pipe which is installed within a borehole in, for example, a hydrocarbon-bearing formation, wherein the inventive device is employed. 
         FIGS. 2 and 3  are illustrations of the details of the inventive construction  10  in two positions, in that it is disposed a distance upstream in respect of down-hole equipment  20  which is be operated hydraulically pursuant to the present invention. 
         FIG. 3B  is an illustration of an elongate cross-section of a hole which is arranged in a radial direction through the pipe wall. 
         FIGS. 4 and 5  are illustrations of an enlarged portion of  FIG. 2  and  FIG. 3 , and illustrates the hydraulic canal  30  through the pipe wall and which couples the pressure pulse device  10  with the equipment  20 . 
     
    
    
     The Figures provide illustrations of a pipe  12  which is deployed in a borehole  14  in a formation  16 . Described as a non-limiting example, a pipe section  18  is installed at a lowest portion of the pipe  12  with a seat accommodating a plug  22 . The plug  22  is used, for example, initially for testing and checking that the interior of the pipe is sufficient non-leaky under pressure, and will function as intended during production of hydrocarbons from the formation  16 . 
     As a consequence of the upwardly-facing surface of the plug  23  being susceptible to collecting large deposits  25  of contamination comprising solid particles such as slime, the device  10  is positioned a distance up over the plug  20 , and the plug  20  and device  10  are mutually coupled via a canal  30  which extends axially along and through the wall of the pipe between these two regions. 
     The device includes a perforated pipe section  27  which is installed into the pipe  12 . A hollow volume or chamber  26  is defined between the outer wall  21  of the section and the inner wall of the pipe  12 . 
     Surrounding the pipe section  25  is threaded a sleeve-shaped elastic bellows or membrane  24 , and uppermost at  31  and lowermost at  33  is attached in the solid material of the pipe section  25 . The bellows  24  can subsequently bulge out from a position where in lies bonded onto the pipe section&#39;s outer wall  21  and to an extent it bulges out and lies against the inner wall  13 . Outside the bellows  24  is a ring-shaped chamber  26  coupled with a drilled canal  30  which extends through the pipe wall downwardly to the release mechanism (not especially shown here) which is used to explode the plug away. 
     The bellow&#39;s position or bulging will be dependent upon a difference in a pressure P 1  within the pipe  12  and a pressure P 2  in the chamber or the canal  30  outside the membrane  24 .  FIG. 2  illustrates the situation where the pressure P 1  is higher than the pressure P 2  (P 1 &gt;P 2 ) such that the membrane bulges out. 
       FIG. 3  is an illustration of a situation wherein the pressure P 2  is higher or equal to the pressure P 1  and the membrane lies in a wavy manner against the outer wall  21 . 
     A release mechanism which removes the plug is adapted such that it counts a number of pulses, wherein the pulses are generated by increasing and decreasing the fluid pressure P 1 , and wherein the plug is exploded away at a predetermined number of pulses. 
     In the chamber radially outside the bellows, there is filled a clean liquid which is present in connection with an outside lying pipe or the internally bored canal  30  which again is present in connection with, for example, a pressure-pulse sensitive valve. 
     The pressure-sensitive valve can be set, or be set up, either to read the signals electronically with help of a pressure transmitter, or it can be a purely mechanical system which reads pressure pulses for opening the valve at a predetermined number of pressure pulses. 
     When the valve opens, the clean liquid flows past the valve and operates the equipment which is hydraulically operated. The technology can be used to operate down-borehole equipment which is hydraulically operated, and requires clean liquid for operating correctly. Examples of such equipment can be detonation systems for removable (disappearing) plugs, sliding sleeves, hydraulically operated ball valves and hydraulically-operated flapper valves. These are only some few example of equipment with which this new technological solution can be utilized. The hydraulically operated system can for example be a layer-divided plug  22  fabricated from glass. In whatever manner it is removed or smashed is not specifically shown in the Figures. The pressure-pulse controlled apparatus can include A device  39  which is operable the count the number of pulses, and when it has counted a correct number, the mechanism is activated and releases an explosive mechanism. This can, for example, mean that an axially-disposed piston  38  in the pipe wall is pushed downwardly with large force and slides a horizontally-orientated smashing piston in a radial direction and into the plug  22  which thereby can be smashed. The plug can be fabricated from ceramics materials which can be smashed or from glass which is adapted for this purpose. 
     By utilizing a bellows instead of a piston, it is also possible to bore a large number of holes radially through the wall around the periphery of the protective collar which supports the bellow and maintains the clean liquid in place. An elongate cross-section of these bored out holes  50  in a radial direction through the pipe wall  26 , is shown in cross-section in  FIG. 3B . On both sides thereof (from each end thereof), there is bored out a hole through the wall. The central portion of the hole through the wall beneficially has a form of a bored out region  56  with circular cross-section, whereas each end of the circular boring continue with a gradually increasing cross-section diameter towards the wall surfaces, namely showing a conical form. The bored out region is of course widest out towards the wall surfaces, namely the form of holes  52  to  54  shown in the diagrams are such that the outermost form respectively cone-shaped form or conically formed holes, or substantially of trumpet-form. These borings can have other cross-sections than circular. An advantage with this form of hole is that each hole is not so easily blocked permanently by slime and particles. 
     The risk that the holes with such a form can be blocked by debris and solid particles and slime can be reduced by the holes being bored out such that they are concentric in both directions. This form of hole through the wall having an expanding cross section of the boring, towards the outer wall, resulting in there being achieved an effect, wherein there will always be fluid/liquid streaming both ways as a result of particles bound in the conical hole which is opened up with largest diameter at an opposite side to that which is influenced by pressure with a result that the particles become loosened when pressure is applied from the side that has smallest hole. A particle  60  in the pipe fluid, which may bind and block the entrance to the bored hole  56 , when the fluid F 1  streams in a direction of the arrow P 2 , will simply loosen and be pushed back again when the fluid pressure P 2  exceeds the fluid pressure P 1  and the fluid F 2  streams back. The particle  60  will then be easier to be loosened by the back streaming. 
     Moreover, with reference to  FIGS. 2 and 3 , there are provided a breaking plate (or several), brushing disks which are arranged to break or burst when, for example, 10 Bar pressure difference between the pressure in the clean fluid behind the flexible material and the liquid in the well pipe arising, further ensuring against there arising a pressure difference between the two liquids. The flexible membrane will also always bring about that identical pressures arise on both sides and return to its original form after a pressure excursion. 
     Through the wall of the pipe  27 , namely above the perforated wall portion, there are bored out one (or more) holes  60  which forms a fluid connection between the ring-shaped chamber  26  outside the bellows and an inner of the pipe denotes by F 1 /P 1  ( FIGS. 2 and 3 ). In the hole, there is installed a metal plate for providing a bursting disk  62 , wherein this plate is attached via an anchoring denoted by  58 , such as screw or the similar on the diagrams. 
     The burst disk  62  is adapted for creating fluidic communication in an event that an excessive pressure is developed on the back side (P 2 ) of the bellows, namely when the pressure is not the same as the pressure P 1  within the pipe (tubing). 
     The boring for the break disk can, as a point of reference, be placed anywhere, as long as it stands positioned such that it separates fluid between the tubing and back side of the bellows and creates a communication path between them when it bursts. 
     The burst disk  62  will also provide an eventual operation of the equipment which is to be controlled by later re-filling with liquid when the clean liquid behind the membrane is consumed, wherein the membrane is pre set towards the walls in its respective housing, so that a pressure difference arises between the well pipe (P 1 ) and the back side (P 2 ) of the membrane, whereafter the burst disk will break and liquid from the well will thereafter pour into the system. 
     There are thus many advantages in comparison to known state-of-the-art which has a limited volume surfaces which can be influenced with associated risk that holes of the system become blocked in operation.