Patent Publication Number: US-7913753-B2

Title: System for injecting a substance into an annular space

Description:
RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 11/372,490, filed on Mar. 9, 2006 now U.S. Pat. No. 7,523,785. 
    
    
     BACKGROUND 
     The present invention relates to a system for injecting a substance into the annular space surrounding a well tubular. 
     After a well has been drilled, a well tubular is introduced into the well. Such a well tubular can be a casing or a liner. The outside diameter of the casing is smaller than the inside diameter of the wellbore, providing thereby an annular space, or annulus, between the casing and the wellbore. The well tubular is perforated at one or more zones to allow hydrocarbons to flow into the tubular. Sometimes contaminants such as water or sand are produced along with hydrocarbons from a part of the formations around a well tubular. Therefore it is sometimes required to seal off the well tubular from a part of the annular space containing undesirable contaminants. 
     To seal off a desired part of for example a casing one technique used is to isolate an internal part of the casing using temporary packers. Cement or other hardenable substance is then pumped down to the isolated zone to seal the perforated openings in the desired part of the casing. If production later on is desired from a zone situated further down in the casing, removal or penetration of the hardened zone is then required. 
     U.S. Pat. No. 6,955,216 discloses a device for injecting a fluid into an earth formation surrounding a well. The device comprises a body suitable for being arranged in a well bore and provided with a fluid chamber for storage of suitable sealant and a pair of inflatable packers arranged to isolate a portion of the well bore between the packers upon inflating of the packers. The suitable sealant is then injected under pressure into the formation through the perforations isolated between the packers. 
     BRIEF SUMMARY 
     In one aspect of the invention, a system is provided for establishing one or more barriers at any position outside a well tubular and providing a substantially free passage within the well tubular. This is achieved by a cutting part having a chamber with a first end and a second end and having a wall surrounding the chamber and including at least one entrance for a substance at the first end and including an exit for delivery of liquid through the well tubular and into the annular space at the second end. The supply of substance through the cutting part leaves the inside of the well tubular more or less untouched by the substance and therefore subsequent drilling out of a hardened zone is no longer required. 
     In another aspect of the invention, a system is provided, the system having a cutting part that is essentially automatic in operation. 
     In still another aspect of the invention, a system is provided having a cutting part that is essentially automatic in operation and always applies an essentially constant cutting force to the well tubular. 
     According to one embodiment of the invention, the system having a cutting part is adapted to cut an essentially circular hole through a well tubular. 
     According to another embodiment of the invention, the cutting part comprises a first and a second sleeve, the sleeves being interconnected such that a torque applied to the first sleeve provides axial displacement of the first sleeve. 
     In another aspect, the invention provides a method for injecting a substance into the annular space surrounding a well bore with an assembly to be inserted into a well tubular and having a hole cutting part capable of cutting a hole through a well tubular, a substance chamber for storage of the substance and a substance injecting part capable of injecting substance through substance conducting means within the cutting part and into the annular space, the method comprising the steps of: inserting the assembly into the well tubular; forming a passage through the well tubular and into the annular space by cutting a hole through the well tubular and thereby establishing a substance channel into the annular space; injection of substance through the passage into the annular space surrounding the well tubular to create at least one barrier on the outside of the well tubular and retracting the assembly providing a substantially free passage within the well tubular. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  schematically shows a partial longitudinal section of the assembly inserted in a well tubular. 
         FIG. 2  is a schematic cross sectional view of a cutting part according to an embodiment of the invention, showing the operating principle of the device when cutting. 
         FIG. 3  is a schematic cross sectional view of a cutting part according to another embodiment of the invention, showing the operating principle of the device when cutting into a well tubular. 
         FIG. 4  shows a sectional view of a well tubular with an assembly inserted and the cutting part in an extracted position. 
         FIG. 5  shows a spring loaded support for the assembly. 
         FIG. 6  is a schematic view of a cutting part being equipped with means to facilitate the mixing of substances. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS AND THE PRESENTLY PREFERRED EMBODIMENTS 
       FIG. 1  is a sectional view of an embodiment of a system for injecting a substance into the annular space surrounding a well tubular. The system is positioned within a carrier  70  which is supported by wheels  50 . The carrier is located in a well tubular  13 . The outside diameter of the well tubular  13  is smaller than the inside diameter of the wellbore, providing thereby an annular space  38 , or annulus, between the well tubular and the formation  37 . Normally hydrocarbons are recovered from the surrounding formation through perforations (not shown) in the well tubular and travel to the surface through the well tubular. 
     However, sometimes undesired elements, as for example sand or water, are produced along with hydrocarbons from a part of the formations around a well tubular. Therefore it is sometimes required to seal off the well tubular from a part of the annular space containing undesirable contaminants. The system according to the invention is capable of creating one or more barriers on the outside of a tubular or pipe. 
     The system according to an embodiment of the invention shown in  FIG. 1  comprises: a carrier  70 ; a cutting part  10  capable of making a hole through the wall of a well tubular  13 ; and two substance chambers  34 ,  35  for storage of substance and a substance injecting part  29 ,  31 ,  32 . The substance injecting part is capable of injecting the substance through the cutting part once the cutting part is extended through the wall of the well tubular  13  and into the annular space  38  surrounding the well tubular  13 . 
     The substance chamber comprises two cylinders  34 ,  35 . Each cylinder  34 ,  35  is in substance communication with the cutting part  10  via a separate tube  41 ,  42 . Each tube is provided with a valve  45  for opening and closing of the substance communication between the cutting part and the substance chamber  34 ,  35 . 
     The substance injecting part comprises two pistons  31 ,  32  capable of sliding on an internal surface of the cylinders  34 ,  35 . Each piston  31 ,  32  is connected to a force transmitting piston  29  by piston rods  48 . The force transmitting piston  29  is slidably configured within a cylinder  49 . Two chambers  28 ,  46  are provided within the cylinder, one on each side of the piston. The chamber  46  is preferably in substance communication with the well by an opening  47  thereby providing well bore pressure in the chamber  46 . The other chamber  28  is sealed off from the well bore and has an internal pressure which is lower than the well bore pressure. The internal pressure can advantageously be established at the surface and the chamber therefore has a pressure which is essentially equal to the surface pressure. 
     The difference in internal pressure between the two chambers  28  and  46  on each side of the piston  29  provides a force on the piston  29  which entails a pressure in the cylinders which is higher than the well bore pressure as long as the system is in equilibrium. 
     Once the valves  45  are opened the force exerted by wellbore pressure on the area of piston  29  will exceed the force exerted by wellbore pressure on the pistons  31  and  32 , thereby providing movement of the interconnected pistons  29 ,  31 , and  32  and thereby also injecting the substance from the substance chambers  34 ,  35  via the cutting part  10  and into the annular space  38 . 
     When the piston  29  is fully depressed, the pressure in the chamber  28  will rise due to the reduction in volume. In order to prevent the pressure from rising to a point where it acts against the emptying of the chambers  34  and  35 , the chamber  28  can preferably be in substance communication with the back side of the pistons  31  a,  32   a . Alternatively the chamber  28  may be longer than cylinders  34 ,  35 . 
     To provide an adequate counterforce and retain the device while the cutting through the wall of the well tubular  13  takes place, the assembly may preferably be provided with at least two retractable/extensible wheel assemblies  50 . The wheel assembly  50  also entails an easy insertion (rolling) of the device into the well tubular  13 . However, the shown embodiment of the wheel assembly  50  is only one method of securing the device, there are other possible solutions as extending pads and other structures. 
     Turning now to  FIG. 2 , an embodiment of the cutting part according to the invention is shown. The hollow cutting part  10  is provided with a chamber  14  with a first end  17  and a second end  15  and having a wall  3  surrounding the chamber and including at least one entrance  11 ,  12  for substance at the first end and including an exit for delivery of substance through the wall of the well tubular and into the annular space at the second end  15 . 
     The right side of the drawing shows, for illustrative purposes only, the cutting part  10  in an extracted position, and the left side of the drawing shows, also for illustrative purposes, the cutting part  10  in a retracted position. The cutting part  10  has a main tool body  18  and comprises two rotatable, concentric sleeves  1 ,  3  and a motor  26  (not shown in  FIG. 2 ). The sleeve  1  is preferably provided with internal threads for connection with the inner sleeve  3  having outer threads. Each of the two sleeves  1 ,  3  are able to rotate about a common center axis a. The outer sleeve  1  may preferably be provided with a top  16  of suitable material, such as diamond or carbide, for cutting/grinding into the wall of a well tubular. In the shown embodiment, the outer sleeve  1  is further provided with a gear mechanism  5 , which is connected to the motor  26 . The gear mechanism  5  may advantageously be supported by ball bearings  4 . 
     In the depicted embodiment, the inner sleeve  3  is connected to the main tool body  18  by a frictional connection  18 ,  9 ,  7  which comprises one frictional developing pad  9 . The frictional pad  9  is rigidly attached to the inner sleeve  3 . The pad  9  is forced against the main tool body  18  by a-spring mechanism  7 . The frictional connection  18 ,  9 ,  7 , which is described in greater details below, ensures rotation of the sleeve  3  when a torque exceeding a given value is applied to the sleeve  3 . 
     The cutting part may preferably comprise a dirt ring  2  between the inner and outer sleeve and in one embodiment the sleeve  1  further comprises a spline  6 . 
     When a motor rotates the gear mechanism  5  in the cutting part  10  according to  FIG. 2 , the outer sleeve  1  will start to translate due to the relative movement in the threads between sleeve  1  and sleeve  3 . If upwards, this translation will continue until sleeve  1  meets a restriction as e.g. the wall of a well tubular wherein a hole is to be cut. 
     At that point the torque in the system will increase until it reaches a value where the axial load on the outer sleeve causes the frictional pad  9  (between the main tool body  18  and the inner sleeve  3 ) to slip, causing the inner sleeve  3  to rotate together with the outer sleeve  1  resulting in a grinding/cutting action. This grinding will continue until the axial load on sleeve  1  decreases to a value lower than the given value where the frictional connection slips, causing the inner sleeve  3  to stop rotating and the outer sleeve  1  to travel a little distance further. 
       FIG. 3  shows another embodiment of a cutting part  10  according to the invention. The right side of the drawing shows, as in  FIG. 2  and for illustrative purposes only, the cutting part  10  in an extracted position  5  and the left side of the drawing shows, also for illustrative purposes, the cutting part  10  in a retracted position. The cutting part according to this embodiment of the invention also comprises a main tool body  18  and two rotatable interconnected concentric sleeves  1 ,  3  and a motor  26  (not shown in  FIG. 3 ). The outer sleeve in this embodiment is also provided with a top of suitable grinding material  16  for cutting into a well tubular. However, the frictional connection  9 ,  3  which allows rotation of the inner sleeve is not, as in the embodiment shown in  FIG. 2 , situated such that an axial force applied on the inner sleeve and towards the main body increases the frictional force. 
     In the shown embodiment in  FIG. 3 , the spring mechanism  7  is pushing the frictional pad  9 , which is rigidly attached to the main tool body, towards the top/upper side of a flange  8  on the sleeve  3 , thereby providing a frictional connection that has a very constant frictional level and which is also independent of the axial load being applied to the inner sleeve  3  by the outer sleeve  1  during cutting/grinding. 
     This entails that the slip between the main tool body and the inner sleeve occurs at a very well defined (downwardly) axial force and therefore this embodiment shows a cutting part that always applies an essentially constant and well defined cutting- or grinding force against the well tubular. 
     Turning now to  FIG. 4 , an embodiment of the invention is shown where the system is incorporated in a carrier  70  which is supported by wheels  50 . The system is inserted into a well tubular  13  and the wheel assembly  50  is in its extracted position so that the carrier is pushed against the well tubular  13 . The cutting part  10  extends through the wall of the well tubular  13  and the carrier  70  is advantageously provided with a seal  58  which prevents leakage of the injected substance between the well tubular  13  and the carrier  70 . 
       FIG. 5  shows a spring loaded support for the assembly  50 . The wheel assembly  50  is kept in engagement (extended) with a well tubular (not shown) by a spring mechanism  51 . The wheel mechanism  50  comprises in the shown embodiment two legs  56  and  57 . Each of the legs  56 ,  57  is connected to a shared support  53  by a helical spring  51  and each of the two legs  56  and  57  is also rotatably connected to a wheel. Furthermore, the legs  56 ,  57  are rotatably connected to the carrier  70  by supports  52   55 . The two supports  52  and  55  are different in that support  52  (on the left side of the drawing) is rigidly connected to the leg  56  and support  55  is slidably mounted in a slit  54  in the leg  57  thus making the wheel assembly self extending. 
       FIG. 6  shows another embodiment of a cutting part according to the invention. The cutting part  10  is provided with internal walls,  60 ,  61 ,  62 ,  63 , and  64  which constrain a substance to change direction and speed during its passage through the cutting part. This construction ensures that the substance(s) is sufficiently mixed during its passage through the cutting part  10 . The plate  60  facing the exit  15  may advantageously be provided with relatively small holes to ensure a high delivering speed of the substance(s). 
     Although the cutting part has been discussed in relation to a system having two interconnected sleeves where the outer sleeve extract into grinding contact with the well tubular, the cutting part in another embodiment may instead show an extractable inner sleeve for grinding contact with the well tubular. 
     When a system according to the invention is used, initially the assembly is inserted and rolled into a well tubular and to a position where a seal has to be made. The position of the device may advantageously be monitored by, for example, a transmitter  101  for receiving and transmitting data from or to a control unit  102 , but other suitable means may be used. The assembly may comprise means being adapted for rotation of the carrier so that the carrier can be positioned in any position in the radial plane of the pipe. 
     Once the assembly has reached the desired position, the motor in the hole cutting part is activated to cut a hole through the well tubular. When the hole is established and while the cutting sleeves extend through the well tubular, one or more substances are injected into the hollow cutting part and further into the annular space thus facilitating mixing of e.g. a two component system prior to its introduction into the annular space. 
     Once a sufficient amount of substance is introduced into the annular space, the motor may be counter-rotated to retract the sleeve into the cutting part. Having forced a sealing composition into the annular space, the system is removed from the tubular. If many holes are to be drilled, it might be advantageous to finish the substance injection by finally flushing the cutting part with a relatively small amount of non-hardenable substance to prevent obstruction of the cutting part by hardened material. 
     The system is especially suitable for repairing of wells producing hydrocarbons, but since the overall energy consumption of the device is very low and the device is self-contained (the drilling forces are generated within the cutting part) it is therefore independent of external units. As a result, a barrier outside a tubular can be made in virtually any type of pipe or tubular residing in the ground. It can even be applied to any pipe within an annular space. 
     It should, however, be noted that the cutting part is able to work and function independently of the other technical features mentioned in the application and it may be independently implemented in many other connections. 
     It should be noted as well that a substance chamber and a substance injecting part as described above are also able to work and function independently of other technical features. 
     It is therefore intended that the foregoing detailed description be regarded as illustrative rather than limiting, and that it be understood that it is the following claims, including all equivalents, that are intended to define the spirit and scope of this invention.