Injector head chain synchronization device

Abstract

The invention relates to an injector head (2) comprising; a pair of oppositely located, cooperatively movable, segmented continuous belt drive chains (21; 22), said each belt drive chain (21, 22) running over a respective pair of drive sprockets (25a, 25b) and tension sprockets (26a, 26b), wherein a tubing receiving section (7′) is defined between the belt drive chains (21, 22). The tubing receiving section (7′) having a tubing section centerline (46) extending through the center of the tubing receiving section (7′). The injector head (2) having an injector centerline (45) extending through the centerline of the injector head (2), said injector centerline (45) and said tubing section centerline (46) being substantially aligned in the longitudinal direction in an initial position, a pair of elongate counter-force members (32a, 32b) is positioned at each side of the tubing receiving section (7′). The injector head (2) has at least one actuator (35) adapted to move at least one of said elongate counter-force elongate member (32a, 32b) in order to bring the tubing section centerline (46) out of alignment with said injector centerline (45).

Claims

1. An injector head comprising: a pair of oppositely located, cooperatively movable, segmented continuous belt drive chains, each belt drive chain of the pair of belt drive chains running over a respective pair of drive sprockets and tension sprockets; wherein a tubing receiving section is defined between the pair of belt drive chains, said tubing receiving section having a tubing section centerline extending through a center of the tubing receiving section, said injector head having an injector centerline extending through a centerline of the injector head, said injector centerline and said tubing section centerline being substantially aligned in a longitudinal direction in an initial position; a pair of elongate counter-force members positioned on opposite sides of the tubing receiving section; wherein said injector head comprises a first actuator adapted to move a first elongate counter-force member of the pair of elongate counter-force members in order to bring the tubing section centerline out of alignment with said injector centerline, said first actuator being connected to the first elongate counter-force member in order to actively move the first elongate counter-force member a distance away from said injector centerline; and wherein a second elongate counter-force member of the pair of elongate counter-force members is moved an equal distance away from said injector centerline in order to compensate for any unsynchronized movement of the pair of belt drive chains.

2. The injector head according to claim 1, further comprising a second actuator oppositely disposed from the first actuator and connected to the second elongate counter-force member, said first and second actuators adapted to actively move the first and second elongate counter-force members an equal distance in a same direction that is transverse to the injector centerline.

3. The injector head according to claim 2, wherein the first and second actuators are configured to set a clamping force between the pair of elongate counter-force members.

4. An injector head according to claim 1, wherein said injector head further comprises at least one sensor for monitoring a position of oppositely arranged chain blocks that are in contact with a continuous tubing while the continuous tubing passes through the injector head.

5. An injector head according to claim 4, wherein the sensor is a shaft torque sensor arranged to register a torque difference between the pair of drive sprockets.

6. An injector head according to claim 4, wherein the sensor is adapted to monitor the position, in a plane transverse to a longitudinal direction of the tubing passing through the injector head, of the two oppositely arranged chain blocks that are initially in contact with the tubing.

7. An injector head according to claim 4, wherein the at least one sensor includes a first sensor coupled to a first drive sprocket of the pair of drive sprockets and a second sensor coupled to a second drive sprocket of the pair of drive sprockets.

8. An injector head according to claim 1, wherein the first actuator is configured to set a clamping force of the first elongate counter-force member and to adjust a position of the first elongate counter-force member with respect to the injector centerline.

9. An injector head comprising: a pair of oppositely located, co-operatively movable, segmented, continuous belt drive chains, each belt drive chain of the pair of belt drive chains running over a respective pair of drive sprockets and tension sprockets, each belt drive chain comprising an inner flight and an outer flight, each respective inner flight and outer flight extending between the pair of drive sprockets and the pair of tension sprockets, at least a first portion of the inner flights defining a tubing receiving section for a coiled tubing; and at least one first roller arranged in contact with a second portion of a first of the inner flights and at least one second roller arranged in contact with a second portion of a second of the inner flights; wherein said at least one first roller is moveable to displace at least said second portion of said first of the inner flights toward the tubing receiving section in order to compensate for any unsynchronized movement of the pair of belt drive chains; and wherein said at least one second roller is moveable to displace at least said second portion of said second of the inner flights away from the tubing receiving section in order to compensate for any unsynchronized movement of the pair of belt drive chains.

10. An injector head according to claim 9, wherein said at least one first roller is coupled to at least one actuator.

11. An injector head according to claim 10, comprising a first set of rollers and a second set of rollers, wherein the first and second set of rollers each comprise at least two rollers, wherein the first set of rollers contacts the inner flight of a first belt chain drive of the pair of belt chain drives and the second set of rollers contacts the inner flight of a second belt chain of the pair of belt chain drives, and wherein the first set of rollers and the second set of rollers are arranged on opposite sides of an injector centerline.

12. An injector head according to claim 9, wherein the injector head comprises at least one sensor for monitoring a position of two oppositely arranged chain blocks, wherein a first chain block of the two oppositely arranged chain blocks is attached to the inner flight of a first of the pair of belt drive chains and a second chain block of the two oppositely arranged chain blocks is attached to the inner flight of a second of the pair of belt drive chains.

13. An injector head according to claim 12 wherein the at least one sensor is a shaft torque sensor arranged to register a torque difference between the pair of drive sprockets.

14. An injector head according to claim 12, wherein the at least one sensor is adapted to continuously monitor the position of the two oppositely arranged chain blocks, each of the two oppositely arranged chain blocks initially being in contact with the coiled tubing while the coiled tubing is being mated to the injector head.

15. An injector head according to claim 14, wherein the at least one sensor includes a first sensor coupled to a first drive sprocket of the pair of drive sprockets and a second sensor coupled to a second drive sprocket of the pair of drive sprockets.

16. An injector head according to claim 12, wherein at least one actuator is in communication with the at least one sensor via a control system.

17. An injector head according to claim 9, wherein a pressure device is adapted to allow movement of each belt drive chain in a longitudinal direction parallel with the tubing receiving section.

18. An injector head comprising: a pair of oppositely located co-operatively moveable, segmented continuous belt drive chains, each belt drive chain of the pair of belt drive chains running over a respective pair of drive sprockets and tension sprockets, each belt drive chain comprising a plurality of chain blocks adapted to be in contact with a continuous tubing when the continuous tubing is being mated into the injector head; and at least one sensor for measuring a parameter associated with two oppositely arranged chain blocks, the at least one sensor cooperating with a control system configured to adjust a position of one or both of the two oppositely arranged chain blocks when the two oppositely arranged chain blocks are in contact with the continuous tubing in different planes that are transversely arranged relative to a longitudinal axis of the continuous tubing in order to maintain the two oppositely arranged chain blocks in a same plane when in contact with the continuous tubing.

19. An injector head according to claim 18, comprising an actuator in operationally connected with the control system, said actuator being arranged to displace a portion of one of the pair of belt drive chains towards an injector head centerline.

20. An injector head according to claim 19, wherein said actuator is coupled to at least one roller.

21. An injector head according to claim 19, wherein said actuator is coupled to a pair of elongate counter-force members positioned on either side of the injector head centerline and wherein said actuator is adapted to move the pair of elongate counter-force members an equal distance in a same direction transverse to the injector head centerline.

22. An injector head comprising: a pair of oppositely located co-operatively moveable, segmented, continuous belt drive chains, each belt drive chain of the pair of belt drive chains running over a respective pair of drive sprockets and tension sprockets, each belt drive chain comprising a plurality of chain blocks adapted to be in contact with a continuous tubing when the continuous tubing is passing into the injector head; and a control system configured to adjust a position of one or both of two oppositely arranged chain blocks of the plurality of chain blocks when the two oppositely arranged chain blocks are in contact with the continuous tubing in different planes perpendicular to a longitudinal direction of the continuous tubing in order to maintain the two oppositely arranged chain blocks in a same plane when the two oppositely arranged chain blocks are in contact with the continuous tubing.

23. A method for synchronizing a pair of oppositely located, co-operatively movable, segmented continuous belt drive chains of an injector head, each belt drive chain running over a respective pair of drive sprockets and tension sprockets, each belt drive chain comprising an inner flight and an outer flight, each respective inner flight and outer flight extending between the pair of drive sprockets and the pair of tension sprockets, at least a portion of said respective inner flights defining a tubing receiving section for a continuous tubing, said belt drive chain comprising a plurality of chain blocks continuously arranged on the belt drive chain adapted to be in contact with the continuous tubing when the continuous tubing is being mated into or retrieved out of the injector head, the method comprising: a) rotating each of the pair of belt drive chains via the pair of drive sprockets so that a portion of the inner flight of the respective belt drive chain engages the continuous tubing; b) measuring a respective position of two oppositely arranged chain blocks that are in contact with the continuous tubing while said continuous tubing passes through the injector head; c) checking the respective positions of the two oppositely arranged chain blocks to determine if the two oppositely arranged chain blocks are arranged perpendicular to a longitudinal axis of the continuous tubing; and d) adjusting a portion of one or both of said inner flights by moving an actuator towards the continuous tubing receiving section when respective chain blocks are not arranged in a same plane that is perpendicular to the longitudinal axis of the continuous tubing.

24. The method according to claim 23, wherein steps a) through d) are repeated.

25. The method according to claim 23, wherein an initial contact position of the two oppositely arranged chain blocks is measured by at least one sensor.

Description

BRIEF DESCRIPTION OF THE INVENTION

(1) Having described the main features of the invention above, a more detailed and non-limiting description of non-limiting embodiments of the conveyor apparatus according to the invention and aspects thereof is given below, with reference to the attached drawings.

(2) FIG. 1 is a principle view of the injector head according to an embodiment of the invention.

(3) FIG. 2 is a perspective view of the injector tube according to the invention.

(4) FIG. 3 is a perspective view of the injector tube according to the invention shown without the frame.

(5) FIG. 4 is a sectional view of the injector tube according to the invention shown without the frame.

(6) FIG. 5 is a detailed view of synchronized chain blocks.

(7) FIG. 6a-f shows principle drawing of the running of the injection head according to one embodiment of the invention which uses regulators that moves the skate.

(8) FIG. 6a-6c shows an injector head with belt drive chains where the roller means are attached to the chain blocks.

(9) FIG. 6d shows an injector head with belt drive chains where the roller means are attached to the skate.

(10) FIG. 7a-7d shows a principle drawing of the running of the injector head according to another embodiment of the invention where there are arranged separate regulators on each side of the skates which have the purpose of maintaining the same position between the skate and move the skate in the horizontal direction.

(11) FIG. 8a-8b shows a principle drawing of another embodiment of the invention with at least on roller moving a portion of the belt drive chain.

(12) FIG. 9 shows a block diagram of the adjusting process of the chain in the injector head.

(13) FIGS. 10a and 10b shows a principle drawing of an embodiment of the invention where the injector head drive unit is moved.

DETAILED DESCRIPTION OF THE INVENTION

(14) The following describes preferred embodiments of the conveyor apparatus of the present invention and which is exemplary for the sake of understanding the invention and non-limiting.

(15) In the present context, the term “injector head” is to be construed as being synonymous with the term conveyor apparatus as defined in the claims.

(16) Further, the term “counter-force member” is synonymous with the term “skate” frequently used in the art.

(17) All throughout the specification including the claims, the words “continuous tubing”, “skate”, “belt drive chain”, “actuator”, “coiled tubing”, “borehole”, “wellhead”, “lubricator strings”, “bearing”, “BOP”, “injector head”, “sensor”, “control system”, “roller” are to be interpreted in the broadest sense of the respective terms and includes all similar items in the field, known by other terms, as may be clear to persons skilled in the art.

(18) Restriction/limitation, if any, referred to in the specification, is solely by way of example and understanding the present invention. More specifically, hereinafter, the term “coiled tubing” has been referred to for the sake of convenient understanding of the invention. It should be understood that “coiled tubing” also includes other similar continuous tubing as may be known to persons skilled in the art of the present invention. Further, it will be appreciated by the expert in the art that the invention is also applicable to other continuous elongate devices (CED's), such as rods, wires or wirelines.

(19) Although the injector head is, in a currently preferred mode of operation, primarily to be used for operation with coiled tubing, the use of the injector head in conjunction with other CED's lies within the scope of the invention.

(20) It should also be understood that the orientation of some of the apparatus components may exhibit configurations other than those shown in the drawings, without deviating from the principle of the invention, and such different configurations which to not affect the overall operation of the apparatus are to be construed as merely technical equivalents within the scope of the present invention. The term upper and lower are used only to simplify the description of the invention.

(21) The various essential aspects of the injector head will now be described in more detail with reference to FIGS. 1-9.

(22) The figures illustrate the same representative injector but with different examples of the synchronization.

(23) The injector head 2 enables the injection of a continuous tubing 7 down through the injector head 2 and then through a lubricator strings (not shown) located between the apparatus 2 and the wellhead (not shown), suitably via a BOP (blow out preventer) to enable insertion of tools (not shown) in the wellhead and further into a well below (not shown) or up through the injector head 2 by pulling action enabling retrieval of the tool from the wellhead and the well below.

(24) FIG. 1 shows a perspective view of the injector head 2. All the details of the invention is not present but it is a simplified drawing of a typical injector head 2 according to the invention.

(25) The injector head 2 comprising a pair of upright, cooperatively movable, segmented, continuous belt drive chains 21, 22. The first continuous chain 21 and the second continuous chain 22 are oppositely located and installed in a frame 23. The chains 21, 22 form parts of two separate chain system arranged on both sides of the continuous tubing 7.

(26) Each of the chain 21, 22 comprises a plurality of interconnected tubing chain blocks 24a, 24b and are respective running over a chain drive sprockets 25a, 25b and a tension sprocket 26a, 26b. In the figure it is shown that the tension sprocket 26a, 26b is arranged beneath the drive sprocket 25a, 25b. (FIG. 3). Each of the sprockets 25a, 25b is connected to a chain drive and a powerful torque creating motor 27a, 27b. The motor 27a, 27b is suitably a hydraulic motor, but could just as well be an electric or pneumatic motor. A gear 20a, 20b is also arranged in connection with each of the motors 27a, 27b.

(27) The motors 27a, 27b and gears 20a, 20b are each connected to in one end to a drive shaft 19a, 19b extending through each of the drive sprockets 25a, 25b.

(28) At the opposite end of the drive shaft there is arranged a sensor 40a, 40b. There are arranged at least one sensor, but in the figure there are shown two sensors 40a, 40b. The sensors could measure the position of two oppositely positioned chain blocks 24a, 24b attached to the first chain 21 and second chain 22. The sensor cooperates with a control system and adjusting means to correct the positioning of the opposite chain blocks. The sensor could for instance be a chain speed encoder which converts the angular position or motion of the shaft to an analog or digital code.

(29) The invention is applicable with injector heads running without synchronization gear. The constant torque on the motors gives different speed on the first chain 21 and second chain 22. The sensors or chain speed encoder 40a, 40b will then register the speed and a regulator will adjust the position of the skate 32a, 32b which lead to synchronized chain blocks 24a, 24b.

(30) The invention is also applicable with toothed drive sprockets which are attached together to drive the belt drive chains synchronously, ie injector head running with synchronized gear. With the chain running with constant torque on motors the synchronization gear will synchronize the chain blocks 24a, 24b, sensors ie shaft torque sensors 40a, 40b will register torque differences and a regulator will adjust the center position of the skate.

(31) A first counterforce elongate member 32a is extending between said drive sprocket 25a and tension sprocket 26a and a similar second counterforce elongate member 32b is extending between said drive sprockets 25b and said tension sprocket 26b. The first and second elongate member are arranged on each side of the continuous tubing 7 and in contact with each of the respective chains 21, 22. The longitudinal space between the chains 21, 22 where the continuous tubing are led through is defined as a tubing receiving section 7′. The first and second counterforce elongate member 32a, 32b will hereinafter be called “skates”.

(32) The provision of the skates 32a, 32b is to make sure that a gripper block 33a, 33b attached to the chain block 24a, 24b sufficiently engages the continuous tubing 7 when it is forcibly driven through the injector head 2.

(33) In order to adjust the transverse position of both skates and their mutual distance there is provided a plurality of clamping force devices 28 in the transverse position of the skate 32a, 32b and the continuous tubing 7. These clamping force devices 28 having at least one actuator 29, preferably one actuator 29 connected to each of the clamping force devices 28. This could for instance be a hydraulic cylinder or ram. The clamping force device 28 have also customized elongate rods 30. These racks or rods 30 are extending on either transverse side of the chains 21, 22 and powered by the at least one actuator 29.

(34) In FIGS. 2, 3 and 4 the injector head according to the invention is shown in greater detail. In FIGS. 3 and 4 the injector head is shown without the frame 2. Each of the chain blocks 24a, 24b comprises interconnected tubing gripper shoe carriers 37a, 37b with roller means (not shown) configured to roll in the longitudinally direction of the skate 32a, 32b on each side of the tubing 7. The tubing gripper shoe carriers 37a, 37b arranged on the opposite side of the gripper block 33a, 33b. The chain block 24a, 24b comprising the shoe carrier 37a, 37b and the gripper block 33a, 33b.

(35) The figures further shows a pressure device 34a, 34b attached to each of the chain systems. The pressure device 34a, 34b is in one end connected to a shaft 36 through the respective tension sprocket 26a, 26b and in the other end connected to the frame 2. The purpose of the pressure device is to make sure that the chain 21, 22 is held tightly around each of the respective sprockets 25a, 26a and the sprockets 25b, 26b by pushing the sprocket 26a, 26b downwards and to avoid slack in the chain 21, 22. The pressure device 34a, 34b comprises for instance a tension cylinder that regulates the distance between the tension sprocket 26a, 26b and the frame 23 in the vertical direction.

(36) Another purpose of the pressure device 34a, 34b is to allow a little movement of the chain 21, 22 when one of the chain 21, 22 is moved towards an injector head centerline 45. This will be described further below.

(37) Position sensors 40a, 40b are attached to an end of a shaft extending through each of the upper sprocket 25a, 25b. The position sensors could also be attached to other parts of the injector head suitable for measuring the position, angle difference, speed or torque etc. of the opposite chain 21, 22 or chain blocks 24a,24b.

(38) The purpose of the sensors 40a, 40b is to measure the position, torque difference, speed difference, angle difference etc of the chain blocks 24a, 24b on each side of the tubing receiving section 7′. The chain blocks 24a, 24b and consequently the gripper blocks 33a, 33b are synchronized when the chain blocks 24a, 24b on each side of the tubing receiving section 7′ are positioned in the same horizontal plane. There are different ways to measure the position of two oppositely arranged chain blocks 24a, 24b. This could for instance be performed by measuring two opposite chain blocks 41a, 41b that initially engage with the continuous tubing 7, that is what angle or speed the initial chain blocks 41a, 41b engage with the continuous tubing 7 and difference between the two opposite initially chain blocks 41a, 41b.

(39) Synchronized chain blocks 24a, 24b are shown in FIG. 5. To be synchronized the top of the chain blocks 24a, 24b are arranged in a same plane 18a extending through the top boundary of a pair of chain blocks 24a, 24b arranged on the two opposite chains 21, 22. The bottom of the chain blocks 24a, 24b are also arranged in the same plane 18b extending through the bottom boundary of the chain blocks 24a, 24b. The plane 18a and 18b are substantially parallel. The gripper block 33a, 33b of each chain blocks 24a, 24b will in this position engage equally with both sides of the continuous tubing 7.

(40) When the tubing 7 is pulled or pushed through the injector head 2, one of the gripper block 33a, 33b attached to the first or second chain 21, 22 will tend to engage with the continuous tubing 7 before the corresponding gripper block 33a, 33b attached to the opposite first or second chain 21, 22. This will after a while lead to unsynchronized chain blocks 24a, 24b. This again could result in wear and fatigue on the tubing.

(41) The chains 21, 22 are unsynchronized when the chain blocks 24a, 24b are not arranged in the same plane 18a, 18b when interconnecting with the continuous tubing 7.

(42) In order to maintain the chain blocks 24a, 24b to be synchronized throughout the whole feeding/pulling of the continuous tube 7, there are arranged at least one inner adjustment actuator 35. The at least one inner adjustment actuator 35 are in the FIGS. 2, 3 and 4 attached to one of the skates 32a, 32b. There could be several inner adjustment actuator 35 attached to one of the skates 32a or the skate 32b or both.

(43) In the figures there are shown two inner adjustment actuator 35 attached to the second skate 32b but there could be more than two or just one adjustment actuator 35. The inner adjustment actuator 35 could optionally be attached to the first skate 32a. The inner adjustment actuator 35 could for instance be hydraulic, pneumatic or electric driven and has the purpose of moving the skate 32a, 32b attached to the inner adjustment actuator 35 towards the tubing 7 or away from the tubing 7. The tubing 7 will then be moved accordingly in the transverse direction. The skates 32a, 32b are fixed by the clamping force device 28 in a distance corresponding to the continuous tubing from each other. The second skate 32b will move accordingly of the first skate 32a in the same direction.

(44) FIG. 6a-c shows the principle of the running of the injection head 2 according to one embodiment of the invention.

(45) In FIG. 6a the chain blocks 24a, 24b and the corresponding gripper blocks 33a, 33b are in a synchronized position. In this position a tubing section centerline 46 extending through the center of the tubing receiving section 7′ are aligned and congruent to an injector centerline 45 extending through the centerline of the injector head 2. This could be a start or initial position of the pulling/pushing of the tubing 7 in the injector head 2.

(46) The tubing section centerline 46 is defined by the centerline of the space between the first chain 21 and second chain 22 where the continuous tubing 7 is normally positioned when pushed or pulled into or out of the well.

(47) In FIG. 6b the gripper block 33a of the first chain 21 tend to engage the continuous tubing 7 slightly prior to the gripper block 33b of the second chain 22. To prevent the gripper blocks 33a, 33b and the chain blocks 24a, 24b to have unsynchronized positions, the inner adjustment means 35 pulls the second skate 32b and therefore also the chain blocks 24a, 24b interconnecting the continuous tubing 7, the tubing 7 and the first skate 32a, towards the adjustment means 35. The tubing section centerline 46 is moved away from the injector centerline 45. (In the FIG. 7b the skates 32a, 32b and the continuous tubing 7 are moved to the left from the centerline 45 of the injector head 2.) The drive sprocket 25a and the tension sprocket 26a are not moved in the horizontal direction. Since only the first chain blocks 24a abutting the continuous tube 7 is moved to out of position this will lead to a movement of the tension sprocket 26a in the vertical direction as a compensation because the circumference of the chains 21, 22 have to be the same in all positions of the chain 21, 22.

(48) When the skates 32a, 32b together with the continuous tubing 7 and the chain blocks 24a, 24b are shifted to the position shown in FIG. 7b, the gripping shoes 33a of the chain blocks 24a on the first chain 21 will have a slightly longer distance to rotate from the position on top of the drive sprocket 25a to the engagement with the continuous tubing 7.

(49) The gripper block 33b attached to the chain block 24b on the second chain 22 will correspondently have a shorter distance from the top of the sprocket 25b to a position where it engages with the continuous tubing 7. The inner adjustment actuator(s) 35 will position the skates 32a, 33b in a position so that the gripper blocks 33a, 33b on two oppositely corresponding chain blocks 24a, 24b are engaging the continuous tube 7 on opposite sides of the tube 7 synchronously.

(50) FIG. 6c shows the opposite case than in FIG. 6b. The gripper block 33b of the second chain 22 tend to engage with the continuous tubing slightly prior the gripper block 33a of the first chain 21. To compensate for this and to achieve synchronized chains 21, 22 the adjustment actuators are moving the second skate 32b connected to the adjustment actuator 35 away from the adjustment actuator 35. The first skate 32a, the continuous tubing 7 and the gripper block 33a, 33b of the chain blocks 24a, 24b abutting the continuous tubing 7 are moved correspondently in the same direction. The tubing section centerline 46 is moved away from the injector centerline 45 (In FIG. 7c the first and second skates 32a, 32b and the continuous tubing 7 are moved to the right out of alignment of the injector centerline 45.

(51) The skates 32a, 32b and chains 21, 22 in FIGS. 6b and 6c are moved in a direction along a plane parallel to the tubing receiving section centerline and perpendicular to a rotational axis of the sprockets (25a, 26a).

(52) To compensate for the difference between the gripper blocks 33a, 33b, there are arranged a pair of sensors 40a, 40b which could measure an initial gripping shoes 41a, 41b that initially engages with the continuous tubing 7. The sensors 40a, 40b could also measure other different parameters in order to analyze if the chain blocks 24a, 24b for instance the initially gripper blocks 41a, 41b are synchronized or not.

(53) The different parameters could be for instance measure of the speed or difference in the angle of the initially gripper blocks 41a, 41b. The sensor 40a, 40b could also measure the torque difference on the drive shaft 19a, 19b for instance if the injector head are running with synchronized gear, as described earlier.

(54) The sensors 40a, 40b are connected to a control system (not shown) cooperating with the actuator. Based on the measurement of the sensor the actuator will compensate for any unsynchronized movement of the chains by moving the skates in the horizontal direction.

(55) There are two different types of skates. These are illustrated in the FIG. 6a-c and FIG. 6d.

(56) In FIG. 6a-6c the roller means 17a, 17b are connected to the skate 32a, 32b and that the tubing gripper shoe carriers 37a, 37b attached to the chain 21, 22 having an even surface where the roller means 17a, 17b are configured to be in contact with and roll on.

(57) FIG. 6d shows the other principle which are described earlier, where the roller means 17a, 17b are connected to the belt drive chain 21, 22.

(58) In FIGS. 6e and 6f, the possible position of the sensors 40a, 40b are shown.

(59) FIG. 7a-7d shows a principle drawing of another embodiment of the running of the injector head according to the invention.

(60) In this figures the inner adjustment actuator and the clamping force device which are described as independently actuator in the previous embodiment, are arranged in the same adjusting device 50a, 50b. There are arranged at least one adjusting device 50a, 50b on each side of the continuous receiving section 7. A first adjusting device 50a is connected to the first skate 32a and a second adjusting device 50b is connected to the second skate 32b. The figure only shows one adjusting device on each side of the skates 32a, 32b, but there could be more than one adjusting device 50a, 50b attached to each of the skates 32a, 32b.

(61) The function of the embodiment of FIG. 7a-7d is in principle the same as in FIG. 6a-6c but instead of one active skate which is moved by the adjustment actuator 35 in FIG. 6a-c there are similar adjustment devices 50a, 50b that both can actively position the skates 32a, 32b. If the chain blocks 24a, 24b are not running synchronously, the adjusting devices 50a, 50b will compensate for this by actively moving the first or second skate 32a, 32b so that the chain blocks 24a, 24 are synchronized. They are interacting so that the clamping force between the skates 32a, 32b are maintained.

(62) FIG. 8a-8b shows another possible embodiment of the invention.

(63) The chains 21, 22 comprises of an inner flight 51a, 51b which are extending from the drive sprockets 25a, 25b two the tension sprocket 26a, 26b. At least a part of the inner flight 51a, 51b is engaging or gripping the continuous tubing 7 that are pushed of pulled through the injector head 2.

(64) The outer part of the chain 21, 22 is referred to as an outer flight 52a, 52b. The outer flight 52a, 52b is extending from the tension sprocket 26a, 26b to the drive sprocket 25a, 25b on the outside of each of the inner flights 51a, 51b.

(65) In these figures there are arranged first rollers 53a, 53b in connection with the upper portion 54a, 54b of the inner flights 51a, 51b and additionally there are arranged second rollers 53c, 53d in the lower portion 55a, 55b of the inner flight 51a, 51b. The upper and lower portion of the inner flights are the part of the chains restricted respectively between the drive sprockets 25a, 25b and the upper part of the skate 32a, 32b and the lower part of the skate 32a, 32b and the tension sprocket 26a, 26b.

(66) The rollers 53a, 53b, 53c, 53 are connected to actuators that will move the rollers towards the injector centerline 45 and therefore also move the upper and/or lower portion of the inner flights 51a, 51b towards the injector centerline 45. They could for instance be connected to the actuators through brackets 55a, 55b, 55c, 55d

(67) The skates 32a, 32b are in this embodiment held in a fixed position. Likewise, the outer flights 51a, 51b will have a fixed distance to the injector centerline 45 and will not move in relation to this.

(68) The rollers 53a, 53b, 53c, 53d could be moved independently of each other.

(69) In FIG. 8a there is shown a position where the roller are positioned at an equal distance from the injector centerline 45.

(70) An angle α1 which is defined as the angle between the first chain 21 and the injection centerline. An angle α2 is defined as the angle between the second chain 22 and the injection centerline, The angle α1 and angle α2 are in this position equal.

(71) In FIG. 8b the roller 53a, 53d which are in communication with the first chain 21 are moved towards the injector centerline 45 so that the angle α1 is smaller than the angle α2 to compensate for unsynchronized movement of the chains. Similarly could the rollers 53b, 53c which are in communication with the second chain 22 move towards the injector centerline 45 so that the angle α2 is smaller than the angle α1.

(72) The same applies for the previous mentioned embodiments where the skate 32a, 32b or the whole injector drive unit is moved. The angle α1 or α2 will decrease according to the movement of the skates 32a, 32b or injector drive unit. This embodiment where the whole injector drive unit is moved is shown in FIGS. 10a and 10b.

(73) FIG. 9 is a block diagram of the adjusting process of the chain in the injector head. The adjusting process is a continuous process to secure that the chains 21, 22 are running synchronously throughout the injection process. The sensors will monitor when the chains 21, 22 are unsynchronized and send signal to the actuator 35, 50a, 50b, 54a, 54b, 54c, 54d to adjust the position of the skates 32a, 32b or rollers 53a, 53b, 53c, 53d if two oppositely orientated chain blocks are not synchronous.

(74) The movement of the actuators depends on which of the chains 21, 22 that needs to be adjusted and brought into synchronization with the other.

(75) The present invention has been described with reference to preferred embodiments and aspects thereof and related to the accompanying drawings for the sake of understanding only and it should be obvious to persons skilled in the art that the present invention includes all legitimate modifications within the ambit of what has been described hereinbefore and claimed in the attached claims.