EP4133156A1

EP4133156A1 - Apparatus and method of handling tubes for light workover rigs

Info

Publication number: EP4133156A1
Application number: EP20719782.3A
Authority: EP
Inventors: Robert Gabriel BLASIUS
Original assignee: Pax Elevans Srl
Current assignee: Pax Elevans Srl
Priority date: 2020-04-06
Filing date: 2020-04-06
Publication date: 2023-02-15
Anticipated expiration: 2040-04-06
Also published as: EP4133156C0; EP4133156B1; WO2021206576A1

Abstract

Apparatus for handling tubes for light workover rigs, comprising: - a support body (1), - three pairs of legs (2), - a beam (4) connected to the support body (1), - two lateral safety elements (6), connected to the beam (4), - two fixed U-shaped elements (7) fixed to the beam (4), - a conveyor belt (8) connected to a frame (9) and drivable by a first actuator (A1), - wherein the frame (9) is fixed to two tiltable U-shaped elements (10) that are capable to tilt in respect to a respective fixed U-shaped element (7), - a lifting member (11) capable to move the beam (4) between two extreme positions, - an open box (12) provided with a removable shoe (13) and capable to travel simultaneously with the conveyor belt (8).

Description

APPARATUS AND METHOD OF HANDLING TUBES FOR LIGHT WORKOVER RIGS

[001] The present invention relates to an apparatus and to a method of handling tubes, from a rack situated at the level of the lower part of the apparatus, up to the rig floor of a light workover rig, and vice versa.

[002] Apparatuses for handling tubes, for example pipes, are known in the art, such as the apparatus disclosed in the document PCT/RO2019/000026, which has the same applicant as the applicant of the present invention, said apparatus comprising:

- a lower arm connected at one of its ends to a support body by means of a joint, the lower arm being driven by a first actuator and being capable to pivot about the joint in respect to the support body, the lower arm being provided with a first drive chain arranged in an elongated loop extending along the entire length of the lower arm,

- a second actuator capable to drive the first drive chain,

- a cradle situated above the lower arm and capable to receive a cylindrical part on its upper surface,

- a second drive chain arranged in an elongated loop and mounted in a frame between the lower arm and the cradle.

Upon driving the first drive chain by the second actuator, the second drive chain together with its frame and with the second connection element is capable to move relative to both the first drive chain and the lower arm, between a first extreme position and a second extreme position, while at the same time the cradle together with the third connection element is capable to move relative to the first and second drive chains and relative to the lower arm, between a first cradle extreme position and a second cradle extreme position.

[003] The disadvantage of the apparatus disclosed in PCT/RO2019/000026 is that it is designed to work for drilling rigs, and is inappropriate to work for light workover rigs that are much smaller and narrower than drilling rigs.

[004] According to the applicant’s knowledge, until the date of filing of the present application, there has never been on the market an apparatus designed especially to pick-up and lay-down the tubes (drill pipes) for light workover rigs. [005] The scope of the present invention is to provide an apparatus that is capable to carry out all the specific tasks for light workover operation:

- to pick-up tubes from very low pipe racks (i.e. 0.1m);

- to lay-down tubes on very low pipe racks (i.e. 0.1m);

- to pick-up tubes from several rows laid on the rack, up to 1 7m height;

- to lay-down tubes on several rows on a pipe-rack, up to 1.7m height;

- to deliver the tubes at rig floor heights between 1 m and 3m;

- to deliver the tubes at optimal angle and position to any rig floor height between 1m and 3m;

- to handle the tubes avoiding any metal-metal contact;

- to have front, lateral and back safety elements to protect the tube from falling in case of any human mistake;

- to increase the general safety of operation (90% of accidents are in the tubes handling area);

- to increase productivity (3 to 5 times faster than in the case of manual handling);

- to have a narrow footprint - a reduced distance between the apparatus and the rack;

- to have no physical contact between the structure of the apparatus and the structure of the light workover rig (which is a very light structure, usually mounted on a truck, not designed to support additional weight);

- easy to transport (inside one truck) and easy to assemble (less than 30 minutes rig-up and rig-down).

[006] The apparatus for handling tubes according to the invention comprises:

- a support body,

- three pairs of legs, fixed to the body,

- the legs of each pair being situated symmetrically and on opposite sides in respect to the support body,

- each leg being provided with a movable claw mechanism for transporting a tube along the leg from a region situated at the lower part of the leg up to the upper part of the leg or vice versa,

- a beam connected to the support body by means of a hinge provided at a back end of the beam, wherein the hinge is capable to roll on a horizontal linear guide provided on the support body, - two lateral safety elements, each having a lower end thereof connected to and capable to roll on said linear guide, and each lateral safety element being connected at a middle portion thereof to a median portion of the beam by means of an articulation,

- two fixed U-shaped elements, each having a base fixed to the beam,

- a conveyor belt

- configured to receive a tube on its upper surface,

- bordered by and connected to a frame,

- having a length between 90% and 95% of the length of the frame,

- being drivable by a first actuator,

- wherein the frame is fixed to two tiltable U-shaped elements, each tiltable U-shaped element being connected to a respective fixed U-shaped element by means of a respective second actuator,

- wherein each second actuator is configured to tilt a respective tiltable U-shaped element, and implicitly the frame and the conveyor belt, in respect to the fixed U-shaped elements,

- a lifting member

- connected at one end thereof to the support body by means of a joint,

- connected at the other end thereof to a front end of the beam, that is opposed to the hinge,

- connected in a middle area thereof, situated between its two ends, to a third actuator, wherein the third actuator is also connected to the support body,

- wherein the lifting member is capable to pivot about the joint, upon the action of the third actuator, between a first extreme position in which the beam is parallel to the linear guide and a second extreme position in which the beam forms an angle with the linear guide in the range of 11 ° to 15°,

- an open box, provided with a removable shoe, connected at an extremity of the conveyor belt that is distal in respect to the lifting member, and capable to travel simultaneously with the conveyor belt, wherein the bottom of the open box is situated about 0.1m-0.2m below the level of the conveyor belt.

[007] In a preferred embodiment of the apparatus according to the invention, instead of the removable shoe, the apparatus comprises a back extension element, fixed at an end of the frame that is distal in respect to the lifting member, and capable to support an extension plate provided with a fixed shoe. [008] In a preferred embodiment of the apparatus according to the invention, the second actuators are configured to tilt the tiltable U-shaped elements, and implicitly the frame and the conveyor belt, with a 30° angle in respect to the horizontal, in a plane perpendicular to the length of the frame.

[009] In a preferred embodiment of the apparatus according to the invention, each lateral safety element has an upper end, opposed to the lower end, that surpasses the conveyor belt when the lifting member is not in its first extreme position.

[0010] In a preferred embodiment of the apparatus according to the invention, the lifting member is provided with two spaced apart through holes situated at different distances in respect to the beam and the support body is also provided with two spaced apart through holes situated at different heights and with a pin, wherein the joint is defined: either by said pin simultaneously passing through the through hole of the lifting member that is the closest in respect to the beam and the lower through hole of the support body, or by said pin simultaneously passing through the through hole of the lifting member that is the farthest in respect to the beam and the upper through hole of the support body.

[0011] In a preferred embodiment of the apparatus according to the invention, the apparatus further comprises a pair of bumpers with sensors, surpassing the conveyor belt, said bumpers being fixed to the frame in an end region thereof proximal to the lifting member.

[0012] In a preferred embodiment of the apparatus according to the invention, the apparatus further comprises two transfer arms, each removably fixed at an extremity thereof, to a respective leg, on the same side of the support body, said legs belonging to the first and respectively to the second pair of legs.

[0013] In a preferred embodiment of the apparatus according to the invention, the apparatus further comprises one pair of path compensators fixed to the frame such that, when the beam is in the horizontal position, said path compensators are situated between the second and the third pairs of legs, in close vicinity of the third pair of legs.

[0014] In a preferred embodiment of the apparatus according to the invention, the apparatus further comprises one pair of primary bending compensators fixed to the frame in a region between the two tiltable U-shaped elements.

[0015] In a preferred embodiment of the apparatus according to the invention, the apparatus further comprises two pairs of secondary bending compensators fixed to the frame between a front part of the frame and one tiltable U-shaped element and respectively between an end part of the frame and the other tiltable U-shaped element.

[0016] In a preferred embodiment of the apparatus according to the invention, the distance between the first pair of legs, situated the closest to the lifting member, and the second pair of legs is about 5m, same distance as between the tiltable U-shaped elements, while the distance between the second pair of legs and the third pair of legs is about 0.8m, same distance as between the second tiltable U-shaped element and the path compensator. This configuration ensures the capability to handle tubes between 5m and 13m using the first two or all three pairs of legs and to handle tubes between 1 m and 5m length, using the second and third pair of legs of the apparatus.

[0017] In a preferred embodiment of the apparatus according to the invention, the surfaces of the components that during operation come in contact with the tube are covered or coated with a layer of rubber or plastic. Namely, said components are: the claws of the claw mechanisms, the lateral sides of each leg, the tiltable U-shaped elements, the path compensators, the top of the conveyor belt, the open box, the removable shoe, the extension plate, the fixed shoe.

[0018] According to another aspect, the present invention refers to a method of transporting a tube from a rack to a rig floor, comprising the following steps: a) providing an apparatus according to the invention; b) providing tubes arranged in several rows on a rack, wherein the lowest row height is minimum 0.1m and the top row height is maximum 1.7m; c) inserting a first respective extremity of two transfer arms under the highest row of tubes; d) removably fixing a second respective extremity of each transfer arm, opposed to said first extremity, to a respective leg, on the same side of the support body, the slope of each transfer arm, descending from the rack to the apparatus, being about 1° to 2°; e) rolling a tube, from the rack, on the rolling paths defined by said two transfer arms until it contacts the respective legs; f) grabbing, by means of the claw mechanisms associated to the respective legs, and lifting the tube until the upper part of each leg, in a position from where the tube rolls, under its own weight, on the conveyor belt; g) lifting the conveyor belt by means of the lifting member; h) moving the tube forward, by means of the conveyor belt and the removable shoe or the fixed shoe, until a front sensor detects the arrival of the tube to a rig floor in an optimal position to be grabbed by a rig’s elevator; i) lifting a front part of the tube by a rig elevator while moving forward the conveyor belt, such that a back part of the tube, opposite to the front part of the tube, is accommodated in the open box; j) lifting the front part of the tube until the tube leaves the box and reaches a vertical position in which it is ready to be released in a well.

[0019] The above mentioned method of transporting a tube from a rack to a rig floor may further comprise the following steps between the steps f) and g): f1 ) tilting the conveyor belt on the side of the tube for receiving the tube; f2) after receiving the tube, tilting the conveyor belt together with the tube back in horizontal position.

[0020] According to another aspect, the present invention refers to a method of transporting a tube from a rig floor to a rack, comprising the following steps: a) providing an apparatus according to the invention; b) providing a tube in vertical position, sustained by a rig elevator, with the back part of the tube inserted in the open box positioned at the front extremity of the conveyor belt; c) moving the conveyor belt backwards, synchronized with the lowering movement of the rig’s elevator, thus laying the tube on the conveyor belt; when the tube is laid completely on the conveyor belt, the back movement of the conveyor belt stops; d) unlatching the tube from the rig elevator; e) lowering the conveyor belt by means of the lifting member while moving the conveyor belt backwards until the conveyor belt is in a horizontal position and the tube is positioned on the conveyor belt, symmetrically to the tiltable U-shaped elements; f) tilting the tiltable U-shaped elements together with the conveyor belt and the tube on the desired side while the claws are in upper position on the legs, for rolling the tube over the claws; g) lowering the claws until the tube reaches the transfer arms and rolls over the rack, the slope of each transfer arm in this case, descending from the apparatus to the rack, being about 1° to 2°.

[0021] The following non-limiting embodiment of an apparatus according to the invention relate to Figures 1-11, representing:

Fig. 1a, 1b: apparatus according to the invention, with the lifting member in its first extreme position and its second extreme position, with enlarged details of different zones of the apparatus;

Fig. 2a, 2b: detail of apparatus according to the invention, provided either with the open box and removable shoe, or with a back extension element, extension plate and fixed shoe;

Fig. 3: detail of the zone neighboring the lateral safety elements;

Fig. 4a, 4b: lateral section view of the apparatus, detailing the horizontal linear guide and the movement of the lateral safety elements;

Fig. 5a-5c: lateral view of apparatus, in different positions, with details of the joint connecting the lifting member to the support body;

Fig. 6a, 6b: detail of the open box and its valve;

Fig. 7a-7c: detail section view from the back of the apparatus, with the conveyor belt in un-tilted (horizontal) position and respectively in tilted position;

Fig. 8a, 8b: detail section view from the back of the apparatus, through the path compensators;

Fig. 9a, 9b: apparatus with a tube on the transfer arms;

Fig. 10a-10d: sequence of handling a tube, from the lower part of the leg, up to the conveyor belt;

Fig. 11a-11e: sequence of handling a tube from the conveyor belt, up to the rig floor, with details on the tube position in the open box. [0022] As shown in Figures 1a and 1b, the apparatus according to the invention comprises a support body 1, three pairs of legs 2 fixed to the body 1, the legs 2 of each pair being situated symmetrically and on opposite sides in respect to the support body 1. When the apparatus is placed at the working site, the legs 2 rest on the ground. Each leg 2 is provided with a movable claw mechanism 3 for transporting a tube T (not represented in Figures 1a, 1b) along the leg 2 from a region situated at the lower part of the leg 2 up to the upper part of the leg 2, or vice versa. A claw mechanism 3 comprises, for example, a claw driven along the leg 2 by means of an actuator consisting of a chain and a motor. The apparatus further comprises a beam 4 connected to the support body 1 by means of a hinge H provided at a back end of the beam 4, wherein the hinge H is capable to roll on a horizontal linear guide 5 provided on the support body 1. The apparatus further comprises two lateral safety elements 6, each having a lower end thereof connected to and capable to roll on said linear guide 5, and each lateral safety element 6 being connected at a middle portion thereof to a median portion of the beam 4 by means of an articulation. The apparatus further comprises two fixed U-shaped elements 7, each having a base fixed to the beam 4. The apparatus further comprises a conveyor belt 8 configured to receive a tube T on its upper surface, and is bordered by and connected to a frame 9; the conveyor belt 8 has a length between 90% and 95% of the length of the frame 9, and is drivable by a first actuator A1. The frame 9 is fixed to two tiltable U-shaped elements 10, each tiltable U- shaped element 10 being connected to a respective fixed U-shaped element 7 by means of a respective second actuator A2. Each second actuator A2 is configured to tilt a respective tiltable U-shaped element 10, and implicitly the frame 9 and the conveyor belt 8, in respect to the fixed U-shaped elements 7. The apparatus further comprises a lifting member 11 that is connected at one end thereof to the support body 1 by means of a joint J1 or J2, is also connected at the other end thereof to a front end of the beam 4, that is opposed to the hinge H, and is also connected in a middle area thereof, situated between its two ends, to a third actuator A3, wherein the third actuator A3 is also connected to the support body 1. The lifting member 11 is capable to pivot about the joint J1 or J2, in respect to the support body 1, upon the action of the third actuator A3, between a first extreme position in which the beam 4 is parallel to the linear guide 5 and a second extreme position in which the beam 4 forms an angle with the linear guide 5 in the range of 11° to 15°. The apparatus further comprises an open box 12, provided with a removable shoe 13, connected at an extremity of the conveyor belt 8 and capable to travel simultaneously with the conveyor belt 8, wherein the bottom of the open box 12 is situated about 0.1m - 0.2m below the level of the conveyor belt 8. The apparatus further comprises a pair of bumpers 14 situated at the front of the frame 9. The bumpers 14 have the same purpose as the lateral safety elements 6, namely preventing the tube to roll laterally and fall from the conveyor belt 8. The apparatus further comprises a pair of transfer arms 15 being removably fixed at an extremity thereof to a respective leg 2 on the same side of the support body 1, said legs 2 belonging to the first and respectively to the second pair of legs 2. The apparatus further comprises, on the frame 9, a pair of path compensators 16, a pair of primary bending compensators 17 and two pairs of secondary bending compensators 18. The primary 17 and secondary pairs of bending compensators 18 have the purpose to prevent the bending of the tube T under its own weight, in case of small diameter and very flexible tubes. The primary bending compensators 17 support the middle part of the flexible tube T, and the secondary bending compensators 18 support the end parts of the flexible tube T, ensuring a correct transfer over the conveyor belt 8.

[0023] We define the front end of the beam as the end proximal to the lifting element 11 (and also to the rig, when the apparatus is in operation) and the back end of the beam as the end distal to the lifting element 11. Similarly, we define the first pair of legs as the pair proximal to the lifting element 11, the third pair of legs as the pair most distal to the lifting element 11, and the second pair of legs as the pair between said first and third pairs of legs. Similarly, we define the first tiltable U-shaped element as the one proximal to the lifting element 11, and the second tiltable U-shaped element as the one distal to the lifting element 11.

[0024] In Figure 2a, the apparatus according to the invention is provided with the open box 12 and the removable shoe 13. In Figure 2b, the apparatus according to the invention is provided with the open box 12, with a back extension element 19 fixed at the end of the frame 9 and supporting an extension plate 20 provided with a fixed shoe 13’. In either configuration, the open box 20 together with the removable shoe 13 or with the extension plate 20 and the fixed shoe 13’, are capable to travel simultaneously with the conveyor belt 8. In the latter configuration, the apparatus can handle tubes having a length of 11 m to 13 m. [0025] The extension plate 20 with fixed shoe 13’ (in case the apparatus is provided with a back extension element 19) and the removable shoe 13 (in case the apparatus is provided just with the open box 12) have the purpose to serve as abutment for the tube T when the tube T is on the conveyor belt 8. In the absence of either shoe 13, 13’, when lifting the conveyor belt 8, the tube T would slide under its own weight along the conveyor belt 8 and fall off the apparatus.

[0026] Figure 3 discloses, in greater detail, the zone neighboring the lateral safety elements 6.

[0027] Figures 4a, 4b show in greater detail the active and passive positions of the safety element 6 and the manner in which the beam 4 (by means of its hinge H) and the lower end of the lateral safety elements 6 are connected to and have the possibility to roll on the horizontal linear guide 5.

[0028] Figures 5a-5c disclose two variants in which the lifting member 11 pivots about joint J1 and respectively about joint J2.

The lifting member 11 is provided with two spaced apart through holes J1’, J2’, a first through hole J1’ being closer in respect to the beam 4 than the second through hole J2’. The support body 1 is also provided with two spaced apart through holes J1”, J2”, situated at different heights, and with a pin.

The joint J1 is defined by said pin simultaneously passing through the first through hole J1’ of the lifting member 11 that is the closest in respect to the beam 4, and the lower through hole J1” of the support body 1. The joint J2 is defined by said pin simultaneously passing through the second through hole J2’ of the lifting member 11 that is the farthest in respect to the beam 4 and the upper through hole J2” of the support body 1.

The lifting member 11 in its first extreme position, in which the first through hole J1’ of the lifting member 11 is aligned with the lower through hole J1” of the support body 1 and the second through hole J2’ of the lifting member 11 is aligned with the upper through hole J2” of the support body 1. In this position, the pin may be inserted either through the pair of holes J1’-J1” (thereby defining the joint J1) or through the pair of holes J2’-J2” (thereby defining the joint J2). In case the apparatus needs to deliver tubes to a workover rig with the height between 1m-2m, the pin is inserted through the pair of holes and consequently the lifting member will pivot about joint J1 , as shown in Figure 5b.

In case the apparatus needs to deliver tubes to a workover rig with the height between 2m-3m, the pin is inserted through the pair of holes J2’-J2” and consequently the lifting member will pivot about joint J2 as shown in Figure 5c.

[0029] Figures 6a, 6b disclose the operation of the open box 12. During the lay-down operation, a small quantity of drilling fluid flows from the tubes inside the box 12. For environmental protection reasons, this drilling fluid is collected in recipients situated under the apparatus. The collection of the drilling fluid is carried out automatically, as shown in Figures 6a, 6b: the box 12 is provided with a valve 21 connected to a spring 22, the valve 21 having a valve lever 23. In normal position, the elastic force of the spring 22 determines the valve 21 to remain closed. Only when the box 12 reaches a position in which the valve lever 23 is pressed against an end plate 24 of the conveyor belt 8, the tension in the spring 22 is increased, surpassing the elastic force necessary for keeping the valve 21 closed, and thus opening the valve 21 for discharging the drilling fluids. When the box 12 leaves the position in which the valve lever 23 is pressed against the end plate 24, the spring 22 is de-tensioned and automatically closes the valve 21.

[0030] Figure 7a shows the conveyor belt 8 in untilted (horizontal) position, when both second actuators A2 are passive (not actuated). The second actuators A2 may be, for example, hydraulic cylinders.

[0031] Figure 7b shows the conveyor belt 8 in a tilted position, when a first A2’ of the second actuators A2 is passive and a second A2” of the second actuators A2 is actuated. In case the conveyor belt 8 needs to be tilted on the opposite side, the first A2’ of the second actuators A2 is actuated and the second A2” of the second actuators A2 is passive as shown in Figure 7c.

[0032] Figures 8a, 8b show the role of the path compensators 16. The transfer of the tube T from the first two pairs of legs 2 to the conveyor belt 8 is done on the path defined by the tiltable U-shaped elements 10, placed in front of each of the first two pair of legs 2. On the third pair of legs 2, the gap between the legs and the conveyor belt (a necessary gap to allow the tilt movement) is filled in by the path compensators 16, placed in the front of the third pair of legs 2.

[0033] The apparatus according to the invention operates, in the case of the picking-up of the tubes T, as follows: initially, the lifting member 11 is in the first extreme position, the beam 4, the conveyor belt 8 and the frame 9 are all parallel to the linear guide 5, in a horizontal position, and the claw mechanisms 3 are situated at the lower part of the respective legs 2. From this initial position of the apparatus there are three stages: rolling the tube T from a pipe rack over the claws 3, transfer the tube T from the claws 3 to the conveyor belt 8 and transfer the tube from the conveyor belt 8 to the rig floor.

[0034] Figures 9a, 9b show a perspective and respectively a back view of the apparatus and the tubes T arranged in several rows on a pipe rack PR. Bringing the tubes on the claw mechanisms 3 is achieved by means of two transfer arms 15, each of said transfer arms 15 having a first extremity inserted under the highest row of tubes and the second respective extremity of each transfer arm 15, opposed to said first extremity, removably fixed to a respective leg 2 on the same side of the support body 1, said legs 2 belonging to the first and respectively to the second pair of legs 2, the slope of each transfer arm 15, descending from the rack to the apparatus, being about 1° to 2°. The transfer arms 15 are capable to pick tubes from the rack at a height within the range 0.1m - 1.7m. The tube T may have an outer diameter of up to 7 inch, a length up to 13m and a weight up to 1 ton. When the length of the tube T is between 11m and 13m, the removable shoe 13 is removed and a back extension element 19 is fixed at the end of the frame 9. Said back extension element 19 supports an extension plate 20 with a fixed shoe 13’ that is capable to travel simultaneously with the conveyor belt 8, in order for the apparatus to be able to accommodate the whole length of the tube T.

[0035] Then, the tube T is rolled, from the rack, on the rolling path defined by said two transfer arms 15 until it contacts the respective legs 2 and the claw mechanisms 3.

[0036] Figures 10a-10d show the sequence of handling a tube T, from the claws 3, up to the conveyor belt 8. In Figure 10a the claw mechanisms 3 grab and lift the tube T, from the lower part of the legs up to the upper part of the legs, as shown in Figure 10b. In the meantime, the tiltable U-shaped elements 10 are tilted towards the tube T, as shown in Figure 10c. Then, the tiltable U-shaped elements 10 go back in their untilted position, making the tube T to roll, under its own weight, on the conveyor belt 8, as shown in Figure 10d.

[0037] Tilting the conveyor belt 8 in the direction of the tube T ensures that the tube T will reach the conveyor belt 8 very gently (i.e. at a relatively low rolling speed). In the absence of the tilting, there is a risk that the tube T will roll down very fast and even reach the claws 3 from the other side of the conveyor belt 8, then roll back again, back and forth, until it will eventually stop on the conveyor belt 8. Said claws 3 from the other side of the belt 8 have also the role of safety stops. In order to realize a smooth transfer of the tube T from the claws 3 to the belt 8, the optimal tilting angle was empirically determined to be 30°, in respect to the horizontal, in a plane perpendicular to the length of the frame 9.

[0038] Figures 11a-11e show the sequence of handling a tube from the conveyor belt, up to the rig floor, with details on the tube position in the open box. Figure 11a corresponds to the same position of the apparatus and the tube T as Figure 10d. Then, the conveyor belt is lifted to its second extreme position, the lateral safety elements become active, and the tube T is moved forward by means of the conveyor belt until a front sensor detects the arrival of the tube T to the rig floor, in an optimal position to be grabbed by the rig’s elevator as shown in Figure 11b. Then, the rig elevator (not shown in figures) lifts the front part of the tube T while the conveyor belt moves again forward, such that a back part of the tube T is accommodated in the open box 12, as shown in Figures 11c and 11 d. The movement continues until the tube T reaches a substantially vertical position, in which one end of the tube T is sustained by the rig elevator and the opposite end of the tube T abuts on the bottom of the open box 12, as shown in Figure 11 e. Then, tube T is lifted until it leaves the box and reaches a vertical position in which it is ready to be released in a well.

[0039] The apparatus according to the invention operates, in the case of laying-down tubes, as follows: while the tube T is in vertical position, sustained by the rig’s elevator, the lower part of the tube T is inserted in the open box 12 which is at the front extremity of the conveyor belt 8. Then, the conveyor belt 8 starts moving backwards synchronized with the lowering movement of the rig’s elevator, laying the tube T progressively on the conveyor belt 8. While the back end of the tube T comes out from the box 12, the lateral safety elements 6 are already reached. The back movement of the conveyor belt 8 is stopped during the time when the rig’s elevator is unlatched, here the front bumpers 14 preventing a lateral fall of the front part of the tube T in case of any shock from an incorrect unlatching of the elevator. The back movement of the conveyor belt is resumed, until the tube T is positioned symmetrically to the tiltable U-shaped elements. The conveyor belt is lowered by means of the lifting member until the horizontal position. The tiltable U-shaped elements tilt, on the desired side, the whole conveyor belt 8 with the tube T on it, while the claws 3 are in upper position on the legs 2, causing the tube T to roll gently over the claws 3. Then the claws 3 start the lowering movement until the tube T reaches the transfer arm 15 and rolls over the rack, the slope of the transfer arms 15 in this case descending from the apparatus to the rack.

[0040] We define the moving forward of the conveyor belt 8 as its movement in the direction towards the rig. We define the moving backwards of the conveyor belt 8 as its movement in the direction opposite to the moving forward.

[0041] The upper end, that is opposed to the lower end, of each lateral safety element 6, surpasses the conveyor belt 8 when the lifting member 11 is not in its first extreme position. That means that after a tube T is placed on the conveyor belt 8, immediately as the lifting member starts to lift the beam 4 and the conveyor belt 8, the lateral safety elements 6, surpass the conveyor belt 8, thus preventing the tube T to roll laterally and fall from the conveyor belt 8, thus ensuring the tube T securely remains on the conveyor belt 8.

[0042] The bumpers 14 provided at the front of the frame 9 have the same purpose as the lateral safety elements 6, namely preventing the tube T to roll laterally and fall from the conveyor belt 8. [0043] List of references:

1 support body

2 legs

3 claw mechanisms

4 beam

5 horizontal linear guide

6 lateral safety elements

7 fixed U-shaped elements

8 conveyor belt

9 frame

10 tiltable U-shaped elements

11 lifting member

12 open box

13 removable shoe

13’ fixed shoe

14 bumpers

15 transfer arms

16 path compensators

17 primary bending compensators

18 secondary bending compensators

19 back extension element

20 extension plate

21 valve

22 spring

23 lever

24 end plate

A1 first actuator, for driving the conveyor belt A2 second actuators, for tilting the tiltable U-shaped elements A3 third actuator, for the lifting member

H hinge

J1, J2 joints

J1’, J2’ through holes of the lifting member J1”, J2” through holes of the support body PR pipe rack

T tube

Claims

1. Apparatus for handling tubes for light workover rigs, comprising:

- a support body (1),

- three pairs of legs (2), fixed to the body (1),

- the legs (2) of each pair being situated symmetrically and on opposite sides in respect to the support body (1),

- each leg (2) being provided with a movable claw mechanism (3) for transporting a tube (T) along the leg (2) from a region situated at the lower part of the leg (2) up to the upper part of the leg (2) or vice versa, characterized in that the apparatus further comprises:

- a beam (4) connected to the support body (1) by means of a hinge (H) provided at a back end of the beam (4), wherein the hinge (H) is capable to roll on a horizontal linear guide (5) provided on the support body (1),

- two lateral safety elements (6), each having a lower end thereof connected to and capable to roll on said linear guide (5), and each lateral safety element (6) being connected at a middle portion thereof to a median portion of the beam (4) by means of an articulation,

- two fixed U-shaped elements (7), each having a base fixed to the beam (4),

- a conveyor belt (8)

- configured to receive a tube (T) on its upper surface,

- bordered by and connected to a frame (9),

- having a length between 90% and 95% of the length of the frame (9),

- being drivable by a first actuator (A1),

- wherein the frame (9) is fixed to two tiltable U-shaped elements (10), each tiltable U- shaped element (10) being connected to a respective fixed U-shaped element (7) by means of a respective second actuator (A2),

- wherein each second actuator (A2) is configured to tilt a respective tiltable U- shaped element (10), and implicitly the frame (9) and the conveyor belt (8), in respect to the fixed U-shaped elements (7),

- a lifting member (11)

- connected at one end thereof to the support body (1) by means of a joint (J1,

J2), - connected at the other end thereof to a front end of the beam (4), that is opposed to the hinge (H),

- connected in a middle area thereof, situated between its two ends, to a third actuator (A3), wherein the third actuator (A3) is also connected to the support body (1),

- wherein the lifting member (11) is capable to pivot about the joint (J1 or J2) upon the action of the third actuator (A3), between a first extreme position in which the beam (4) is parallel to the linear guide (5) and a second extreme position in which the beam (4) forms an angle with the linear guide (5) in the range of 11° to 15°.

- an open box (12), provided with a removable shoe (13) connected at an extremity of the conveyor belt (8) that is distal in respect to the lifting member (11), and capable to travel simultaneously with the conveyor belt (8), wherein the bottom of the open box (12) is situated about 0.1m-0.2m below the level of the conveyor belt (8).

2. Apparatus according to claim 1 , characterized in that, instead of the removable shoe (13), it comprises a back extension element (19) fixed at an end of the frame (9) that is distal in respect to the lifting member (11), and capable to support an extension plate (20) provided with a fixed shoe (13’).

3. Apparatus according to any of the claims 1-2, characterized in that the second actuators (A2) are configured to tilt the tiltable U-shaped elements (10), and implicitly the frame (9) and the conveyor belt (8), with a 30° angle in respect to the horizontal, in a plane perpendicular to the length of the frame (9).

4. Apparatus according to any of the claims 1-3, characterized in that each lateral safety element (6) has an upper end, opposed to the lower end, that surpasses the conveyor belt (8) when the lifting member (11) is not in its first extreme position.

5. Apparatus according to any of the claims 1-4, characterized in that the lifting member (11) is provided with two spaced apart through holes (J1’, J2’) situated at different distances in respect to the beam (4), and the support body (1) is also provided with two spaced apart through holes (J1 ”, J2”), situated at different heights, and with a pin, wherein the joint (J1, J2) is defined: either by said pin simultaneously passing through the through hole (J1’) of the lifting member (11) that is the closest in respect to the beam (4) and the lower, through hole (J1”) of the support body (1), or by said pin simultaneously passing through the through hole (J2’) of the lifting member (11) that is the farthest in respect to the beam (4) and the upper, through hole (J2”) of the support body (1).

6. Apparatus according to any of the claims 1-5, characterized in that it further comprises a pair of bumpers (14) with sensors, surpassing the conveyor belt (8), said bumpers (14) being fixed to the frame (9) in an end region thereof proximal to the lifting member (11).

7. Apparatus according to any of the claims 1-6, characterized in that it further comprises two transfer arms (15), each removably fixed at an extremity thereof, to a respective leg (2), on the same side of the support body (1), said legs (2) belonging to the first and respectively to the second pair of legs (2).

8. Apparatus according to any of the claims 1-7 characterized in that it further comprises one pair of path compensators (16) fixed to the frame (9), such that, when the beam (4) is in the horizontal position, said path compensators (16) are situated between the second and the third pairs of legs (2), in close vicinity of the third pair of legs (2).

9. Apparatus according to any of the claims 1-8, characterized in that it further comprises one pair of primary bending compensators (17) fixed to the frame (9) in a region between the two tiltable U-shaped elements (10).

10. Apparatus according to any of the claims 1-9, characterized in that it further comprises two pairs of secondary bending compensators (18) fixed to the frame (9) between a front part of the frame (9) and one tiltable U-shaped element (10) and respectively between an end part of the frame (9) and the other tiltable U-shaped element (10).

11. Apparatus according to any of the claims 1-10, characterized in that the distance between the first pair of legs (2), situated the closest to the lifting member (11), and the second pair of legs (2) is about 5 m, same distance as between the tiltable U-shaped elements (10), while the distance between the second pair of legs (2) and the third pair of legs (2) is about 0.8 m, same distance as between the second tiltable U-shaped element (10) and the path compensator (16).

12. Apparatus according to any of the claims 1-11, characterized in that the surfaces of the components that during operation come in contact with the tube (T) are covered or coated with a layer of rubber or plastic.

13. Method of transporting a tube (T) from a rack to a rig floor, comprising the following steps: a) providing an apparatus according to any of the claims 1-12; b) providing tubes (T) arranged in several rows on a rack, wherein the lowest row height is minimum 0.1m and the top row height is maximum 1.7 m; c) inserting a first respective extremity of two transfer arms (15) under the highest row of tubes; d) removably fixing a second respective extremity of each transfer arm (15), opposed to said first extremity, to a respective leg (2), on the same side of the support body (1), the slope of each transfer arm, descending from the rack to the apparatus, being about 1° to 2°; e) rolling a tube (T), from the rack, on the rolling paths defined by said two transfer arms (15) until it contacts the respective legs (2); f) grabbing, by means of the claw mechanisms (3) associated to the respective legs (2), and lifting the tube (T) until the upper part of each leg (2), in a position from where the tube (T) rolls, under its own weight, on the conveyor belt (8); g) lifting the conveyor belt (8) by means of the lifting member (11); h) moving the tube (T) forward, by means of the conveyor belt (8) and the removable shoe (13) or the fixed shoe (13’) until a front sensor detects the arrival of the tube (T) to a rig floor in an optimal position to be grabbed by a rig’s elevator; i) lifting a front part of the tube (T) by a rig elevator while moving forward the conveyor belt, such that a back part of the tube (T), opposite to the front part of the tube (T), is accommodated in the open box (12); j) lifting the front part of the tube (T) until the tube (T) leaves the box (12) and reaches a vertical position in which it is ready to be released in a well.

14. Method according to claim 13, further comprising the following steps between the steps f) and g): f1) tilting the conveyor belt (8) on the side of the tube (T) for receiving the tube (T); f2) after receiving the tube (T), tilting the conveyor belt (8) together with the tube (T) back in horizontal position.

15. Method of transporting a tube (T) from a rig floor to a rack, comprising the following steps: a) providing an apparatus according to any of the claims 1-12; b) providing a tube (T) in vertical position, sustained by a rig elevator, with the back part of the tube (T) inserted in the open box (12) positioned at the front extremity of the conveyor belt (8); c) moving the conveyor belt (8) backwards, synchronized with the lowering movement of the rig’s elevator, thus laying the tube (T) on the conveyor belt (8); when the tube (T) is laid completely on the conveyor belt (8), the back movement of the conveyor belt stops; d) unlatching the tube (T) from the rig elevator; e) lowering the conveyor belt (8) by means of the lifting member (11) while moving the conveyor belt (8) backwards until the conveyor belt (8) is in a horizontal position and the tube (T) is positioned on the conveyor belt (8), symmetrically to the tiltable U-shaped elements (10); f) tilting the tiltable U-shaped elements (10) together with the conveyor belt (8) and the tube (T) on the desired side while the claws (3) are in upper position on the legs (2), for rolling the tube (T) over the claws (3); g) lowering the claws (3) until the tube (T) reaches the transfer arms (15) and rolls over the pipe rack (PR), the slope of each transfer arm (15) in this case, descending from the apparatus to the rack, being about 1 ° to 2°.