EP3688270A1

EP3688270A1 - Systems and methods for removing equipment from inside oil wells

Info

Publication number: EP3688270A1
Application number: EP18782149.1A
Authority: EP
Inventors: João Evaristo DE FRANCA JUNIOR
Original assignee: Petroleo Brasileiro SA Petrobras
Current assignee: Petroleo Brasileiro SA Petrobras
Priority date: 2017-09-27
Filing date: 2018-09-27
Publication date: 2020-08-05
Anticipated expiration: 2038-09-27
Also published as: BR102017020708A2; AU2018343115A1; AU2018343115B2; BR102017020708B1; WO2019064005A1; CN111279048A; CA3077262A1; EP3688270B1

Abstract

The present invention relates to systems and methods for removing equipment such as foot valves and bottom-hole pumps from inside oil wells by means of "fishing" techniques. In this scenario, the present invention provides a system for removing equipment from inside oil wells, comprising: a rod string positionable at least partially inside an oil well; a fishing element connected to a first portion of the rod string, said fishing element comprising a connector for rotatably attaching to equipment to be removed from the oil well by rotating the rod string; and a manipulator fixed to a second end of the rod string, positionable external to the oil well, suitable for manual rotation by at least one operator, wherein a periphery of the manipulator extends continuously around the rod string.

Description

SYSTEMS AND METHODS FOR REMOVING EQUIPMENT FROM INSIDE OIL WELLS

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of priority to BR 10 2017 020708- 0, filed 27 September 2017, which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

[0002] The present invention relates to systems and methods for removing equipment from inside oil wells. More particularly, the present invention relates to systems and methods for removing equipment such as foot valves and bottom-hole pumps from inside oil wells by "fishing" techniques. BACKGROUND OF THE INVENTION

[0003] Throughout the production period of an oil exploration well, particularly onshore oil wells, interventions are necessary for maintenance and/or replacement of components inside the well.

[0004] One of the most-used techniques for withdrawing components from inside wells consists of utilizing rigs for performing this task. However, intervention using rigs is quite expensive owing to the complexity of the equipment.

[0005] To eliminate the need to use rigs for this type of intervention, a cheaper technique for removing components from inside wells, usually called "fishing", has appeared on the market.

[0006] Fishing, is normally used for withdrawing equipment such as foot valves and bottom-hole pumps, but could be applied to any suitable down- hole equipment that might need to be withdrawn. The technique consists of inserting a rod string, comprising at its bottom end a fishing element, also called a fishing tool, inside the well. The fishing tool comprises a screw thread, for example, suitable for screwing into the component to be withdrawn from the well (foot valve, bottom-hole pump, among others). [0007] Once inserted in the well, the rod string comprising the fishing tool at its end is rotated, so that the fishing tool also rotates and screws into the component to be withdrawn from the well. After the component to be withdrawn from the well is fully screwed onto the fishing tool, the rod string is pulled by a crane to withdraw it together with the "fished" component.

[0008] Documents US2075241A and US1462099, for example, disclose devices for pulling a foot valve from an oil well by the technique described above.

[0009] Rotation of the rod string so that the fishing tool screws into the component to be withdrawn from the well is normally effected by means of an extender fixed perpendicularly to the rod string. The extender is simply a straight metal bar that increases the force for manual application of torque on the rod string.

[0010] However, when the user executes the activity of rotating the extender connected to the rod string and transmits rotation to the fishing tool, the extender is under tension, supporting the stress of the twisted column. The stress supported may cause violent reversal in the column, rotating the extender, which is connected to the rod string, in the opposite direction.

[0011] Since driving (rotation) of the extender for fishing requires the user to be within its radius of action, reversal of the rod string may cause serious accidents (even fatal) since the users may be struck violently by the extender.

[0012] As will be presented in greater detail below, the present document presents a solution to the problem of the prior art described above in a practical and efficient manner.

SUMMARY OF THE INVENTION

[0013] Systems and methods for removing equipment from inside oil wells are presented.

[0014] According to a first aspect of the invention, there is provided a system for removing equipment from inside oil wells, comprising one or more of: a rod string positionable at least partially inside an oil well; a fishing element connected to a first portion of the rod string, said fishing element comprising a connector for rotatably attaching to equipment to be removed from the oil well by rotating the rod string; and a manipulator fixed to a second end of the rod string, positionable external to the oil well, suitable for manual rotation by at least one operator, wherein a periphery of the manipulator extends continuously around the rod string.

[0015] Optionally, the manipulator is circular. The circular manipulator can be fixed removably to the second portion of the rod string by means of fasteners.

[0016] Optionally, the circular manipulator is formed from two semicircles fixed together. The two semicircles can be fixed together and to the rod string. The two semicircles can be fixed together and to the rod string by a two-part clamp and fasteners.

[0017] Optionally, the manipulator comprises a non-slip finish on its outermost portion. The non-slip finish can comprise at least one of rubberizing and texturing.

[0018] According to a second aspect of the invention, there is provided a system for removing equipment from inside oil wells, comprising one or more of: a rod string positionable at least partially inside an oil well; a fishing element connected to a first portion of the rod string, said fishing element comprising a connector for rotatably attaching to equipment to be removed from the well by rotating the rod string; and a manipulator fixed to a second end of the rod string, positionable external to the oil well, suitable for manual rotation by at least one operator, wherein the manipulator does not have any radial projections from a periphery of the manipulator.

[0019] According to a third aspect of the invention, there is provided a system for removing equipment from inside oil wells, comprising one or more of: a rod string positionable at least partially inside an oil well; a fishing element connected to a first portion of the rod string, said fishing element comprising a connector for rotatably attaching to equipment to be removed from the well by rotating the rod string; and a manipulator fixed to a second end of the rod string, positionable external to the oil well, suitable for manual rotation by at least one operator, wherein the manipulator is only operable by the operator from outside a radius of action of the manipulator.

[0020] According to a fourth aspect of the invention, there is provided a method of removing equipment from inside oil wells, comprising one or more of: positioning a rod string at least partially inside an oil well, the rod string having a fishing element connected to a bottom portion of the rod string, said fishing element comprising a connector for rotatably attaching to equipment to be removed from the oil well; and providing a manipulator at a top portion of the rod string, external to the oil well, wherein a periphery of the manipulator extends continuously around the rod string; rotating the manipulator by an operator, so as to rotate the rod string and to thereby attach the fishing element to the equipment to be removed from the oil well.

[0021] Optionally, the method further comprises a step of fixing the manipulator to the rod string. The step of fixing can comprise removably fixing the manipulator to the rod string by means of fasteners.

[0022] Optionally, the manipulator is circular.

[0023] Optionally, the method comprises a step of forming the circular manipulator by fixing two semicircles together. The step of forming can comprise fixing the two semicircles together and to the rod string. The two semicircles can be fixed together and to the rod string by a two-part clamp and fasteners.

[0024] Optionally, the manipulator comprises a non-slip finish on its outermost portion. The non-slip finish can comprise at least one of rubberizing and texturing.

[0025] According to a fifth aspect of the invention, there is provided a method of removing equipment from inside oil wells, comprising one or more of: positioning a rod string at least partially inside an oil well, the rod string having a fishing element connected to a bottom portion of the rod string, said fishing element comprising a connector for rotatably attaching to equipment to be removed from the oil well; and providing a manipulator at a top portion of the rod string, external to the oil well, wherein the manipulator does not have any radial projections from a periphery the manipulator; rotating the manipulator by an operator, so as to rotate the rod string and to thereby attach the fishing element to the equipment to be removed from the oil well.

[0026] According to a sixth aspect of the invention, there is provided a method of removing equipment from inside oil wells, comprising: positioning a rod string at least partially inside an oil well, the rod string having a fishing element connected to a bottom portion of the rod string, said fishing element comprising a connector for rotatably attaching to equipment to be removed from the oil well; and providing a manipulator at a top portion of the rod string; rotating the manipulator by an operator, from outside a radius of action of the manipulator, so as to rotate the rod string and to thereby attach the fishing element to the equipment to be removed from the oil well.

[0027] According to another aspect, there is provided a system for removing equipment from inside onshore oil wells, comprising (i) a string of rods positioned at least partially inside the onshore oil well, (ii) a fishing element connected to the bottom end of the string of rods, the fishing element comprising means for screwing to equipment to be removed from the well by rotating the string of rods and (iii) a circular manipulator fixed to the top portion of the string of rods, outside the onshore oil well, suitable for manual rotation by at least one operator.

[0028] There is also disclosed a system for removing equipment from inside onshore oil wells, comprising: a string of rods (20) positioned at least partially inside the onshore oil well (10); a fishing element (40) connected to the bottom end of the string of rods (20), said fishing element comprising means for screwing to equipment to be removed from the well (50) by rotating the string of rods (20); characterized in that it additionally comprises: a circular manipulator (60) fixed to the top portion of the string of rods (20), external to the onshore oil well (10), suitable for manual rotation by at least one operator.

[0029] Optionally, the circular manipulator (60) is fixed removably to the top portion of the string of rods (20) by means of fasteners (62).

Optionally, the circular manipulator (60) is formed from two semicircles fixed together and to the string of rods (20) by a two-part clamp (64) and fasteners (62).

[0030] Optionally, the circular manipulator (60) comprises a non-slip finish on its outermost portion.

[0031] Optionally, the non-slip finish comprises at least one of rubberizing and texturing. BRIEF DESCRIPTION OF THE FIGURES

[0032] The detailed description presented hereunder refers to the appended figures and their respective reference numbers.

[0033] Fig. 1 shows a schematic side view of a system according to a preferred embodiment.

[0034] Fig. 2 shows a bottom view of a circular manipulator according to a preferred embodiment, as might be used in the system of Fig. 1.

DETAILED DESCRIPTION OF THE INVENTION

[0035] Firstly, it is emphasized that the following description will be based on a preferred embodiment of the invention. As will be obvious to a person skilled in the art, however, the invention is not limited to this particular embodiment.

[0036] Fig. 1 shows a schematic side view of a system according to a preferred embodiment applied in an oil well 10, such as an onshore oil well. As already known in the fishing techniques of the prior art, a rod string 20 is positioned at least partially inside the oil well 10 in such a way that its top portion is above the production head 30, i.e. above ground level. The rod string 20 comprises at least one rod, and usually a plurality of rods connected together.

[0037] A fishing element 40, also know as a fishing tool, is connected to a first portion of the rod spring 20 to be inserted into the well 10 - in other words the bottom end of the rod string 20 as shown in Fig. 1. The fishing element 40 comprises a connector for rotatably attaching to the equipment to be removed 50 from the well 10, such as a bottom-hole pump or a foot valve.

[0038] The fishing element 40 may be rotatably attachable to the equipment to be removed 50 by means of screwing. For example the fishing element 40 may comprise a male thread suitable for screwing into a female thread of the equipment to be removed from the well 50. Alternatively, the fishing element 40 may comprise a female thread suitable for screwing onto a male thread of the equipment to be removed from the well 50. However, the rotatable attachment is not limited to screw attachment, and may also comprise arrangements in which a projection on one side of the connection is rotatably locked into a receiving cavity on the other side of the connection, for example.

[0039] Whatever the specific means of attachment, since the fishing element 40 is fixed relative to the rod string 20, it is sufficient for it to be rotated so that the fishing element 40 is attached to the equipment to be removed from the well 50.

[0040] A manipulator 60 to permit safe manual rotation of the rod string 20 for fishing the equipment to be removed from the well 50 is provided. In one embodiment, a circular manipulator 60 is provided. The manipulator can be fixed to a second portion of the rod string 20, outside the oil well in use. The manipulator 60 may be provided at the very opposite end of the rod string 20 to the fishing element 40. However, it need not be at the very end of the rod string 20, and may be provided proximal the very end point, as shown in Fig. 1. The manipulator 60 is suitable for manual rotation by at least one operator.

[0041] Since the manipulator 60 of the present embodiment is circular, a periphery of the manipulator 60 extends continuously around the rod string 20. In other words, the manipulator 60 helps prevent any operator from coming into its radius of action whilst rotating the manipulator. That is, the continuous periphery helps prevent an operator from stepping within the radius of action (i.e. within the radius of the rotating circle of the manipulator 60 in the depicted embodiment). This means that in case of sudden reversal of the rotation of the rod string 20, there is no risk to the operators. That is, because the operators are outside of the periphery of the manipulator 60 and the radius of action, any sudden reversal will not result in the manipulator 60 striking the operators. Put another way, the manipulator does not have any handles or bars acting as radial projections from the periphery that might strike the operators. Instead, the manipulator 60 is operable from outside the radius of action of manipulator.

[0042] In the depicted embodiment, the manipulator 60 is circular. This is preferred for ease of operation and continuous turning by the operators. However, other shapes may also be used. That is, other shapes can provide a continuous periphery around the rod string 20, without radial projections extending from the periphery.

[0043] After rotation of the manipulator 60, and consequently engagement of the fishing tool element in the equipment to be removed from the well 50, a crane (not shown) can pull the rod string 20 by its top portion to remove the entire assembly from inside the well.

[0044] Optionally, the manipulator 60 is fixed removably to the top portion of the rod string 20. This may be by means of fasteners 62. This allows the manipulator 60 to be removed, for example for connecting the crane to the rod string 20. In addition, it allows adjustment of the height of the circular manipulator 60 along the top portion of the rod string 20 to optimize the operators' effort.

[0045] Optionally, a circular manipulator 60 can be formed from two semicircles fixed together. The two semicircles may be fixed together and to the rod string 20 by means of a two-part clamp 64 and fasteners 62. In such an arrangement, each of the semicircles of the circular manipulator 60 may have a different side of the two-part clamp 64 fixed to it by welding for example.. The two-part clamp may be positioned on the underside of the circular manipulator 60, as illustrated in Fig. 1, or on the topside (not shown).

[0046] Optionally, the fasteners 62 are screws or sets of screws and nuts. In this case, the two-part clamp 64 comprises holes for passage of the screws. It should be emphasized that any mechanisms for fastening the manipulator 60 to the rod string 20 may be employed according to the particular embodiment, including both reversible and permanent fastenings such as welding, insertion, fastening with pins, fastening with rivets, etc. Thus, it is emphasized that the present invention is not limited to a specific type of fastening of the manipulator 60 to the rod string 20.

[0047] Optionally, the manipulator 60 can comprise a non-slip finish on its outermost portion. As one example, the non-slip finish could comprise rubberizing around the outermost portion of the manipulator. Alternatively, the non-slip finish could comprise texturing around the outermost portion of the manipulator, such as corrugations and/or a roughened surface. A non- slip finish improves the operators' experience in applying rotation to the manipulator 60.

[0048] Optionally, weight-reducing holes can be employed in the body of the circular manipulator 60, as illustrated in Fig. 2. This reduces the weight of the component and the costs of material used in its manufacture. Such holes do not interfere with the continuous periphery of the manipulator 60.

[0049] Thus, there is provided a system for removing equipment from inside onshore oil wells comprising a manipulator that can only be operated manually by a user located outside its radius of action. The shape of the manipulator prevents the operator from being within its radius of action, and consequently avoids possible accidents in case of sudden reversal of the rotation of the rod string 20.

[0050] Numerous variations falling within the scope of protection of the present application are permitted. This reinforces the fact that the present invention is not limited to the particular configurations/embodiments described above. As such, modifications of the above-described apparatuses and methods, combinations between different variations as practicable, and variations of aspects of the invention that are obvious to those of skill in the art are intended to be within the spirit and scope of the claims.

Claims

1. System for removing equipment from inside oil wells, comprising: a rod string positionable at least partially inside an oil well;

a fishing element connected to a first portion of the rod string, said fishing element comprising a connector for rotatably attaching to equipment to be removed from the oil well by rotating the rod string; and

a manipulator fixed to a second end of the rod string, positionable external to the oil well, suitable for manual rotation by at least one operator, wherein a periphery of the manipulator extends continuously around the rod string.

2. System according to claim 1, wherein the manipulator is circular.

3. System according to claim 2, wherein the circular manipulator is fixed removably to the second portion of the rod string by means of fasteners.

4. System according to claim 2 or 3, wherein the circular manipulator is formed from two semicircles fixed together, and are optionally further fixed to the rod string.

5. System according to claim 4, wherein the two semicircles are fixed together and to the rod string by a two-part clamp and fasteners.

6. System according to any one of the preceding claims, wherein the manipulator comprises a non-slip finish on its outermost portion.

7. System according to claim 6, wherein the non-slip finish comprises at least one of rubberizing and texturing.

8. System for removing equipment from inside oil wells, comprising: a rod string positionable at least partially inside an oil well; a fishing element connected to a first portion of the rod string, said fishing element comprising a connector for rotatably attaching to equipment to be removed from the well by rotating the rod string; and

a manipulator fixed to a second end of the rod string, positionable external to the oil well, suitable for manual rotation by at least one operator, wherein the manipulator does not have any radial projections from a periphery of the manipulator.

9. System for removing equipment from inside oil wells, comprising: a rod string positionable at least partially inside an oil well;

a fishing element connected to a first portion of the rod string, said fishing element comprising a connector for rotatably attaching to equipment to be removed from the well by rotating the rod string; and

a manipulator fixed to a second end of the rod string, positionable external to the oil well, suitable for manual rotation by at least one operator, wherein the manipulator is only operable by the operator from outside a radius of action of the manipulator.

10. Method of removing equipment from inside oil wells, comprising: positioning a rod string at least partially inside an oil well, the rod string having a fishing element connected to a bottom portion of the rod string, said fishing element comprising a connector for rotatably attaching to equipment to be removed from the oil well; and

providing a manipulator at a top portion of the rod string, external to the oil well, wherein a periphery of the manipulator extends continuously around the rod string;

rotating the manipulator by an operator, so as to rotate the rod string and to thereby attach the fishing element to the equipment to be removed from the oil well.

11. Method according to claim 10, further comprising a step of fixing the manipulator to the rod string.

12. Method according to claim 11, wherein the step of fixing comprises removably fixing the manipulator to the rod string by means of fasteners.

13. Method according to any one of claims 10 to 12, wherein the manipulator is circular.

14. Method according to claim 13, further comprising a step of forming the circular manipulator by fixing two semicircles together.

15. Method according to claim 14, wherein the step of forming comprises fixing the two semicircles together and to the rod string.

16. Method according to claim 15, wherein the two semicircles are fixed together and to the rod string by a two-part clamp and fasteners.

17. Method according to any one of the preceding method claims, wherein the manipulator comprises a non-slip finish on its outermost portion.

18. Method according to claim 17, wherein the non-slip finish comprises at least one of rubberizing and texturing.

19. Method of removing equipment from inside oil wells, comprising: positioning a rod string at least partially inside an oil well, the rod string having a fishing element connected to a bottom portion of the rod string, said fishing element comprising a connector for rotatably attaching to equipment to be removed from the oil well; and

providing a manipulator at a top portion of the rod string, external to the oil well, wherein the manipulator does not have any radial projections from a periphery the manipulator;

20. Method of removing equipment from inside oil wells, comprising : positioning a rod string at least partially inside an oil well, the rod string having a fishing element connected to a bottom portion of the rod string, said fishing element comprising a connector for rotatably attaching to equipment to be removed from the oil well; and

providing a manipulator at a top portion of the rod string;

rotating the manipulator by an operator, from outside a radius of action of the manipulator, so as to rotate the rod string and to thereby attach the fishing element to the equipment to be removed from the oil well.