METHOD OF MANUFACTURING A SIDE POCKET MANDREL BODY

Abstract

A method of producing a side pocket mandrel body for use in a hydrocarbon well side pocket mandrel assembly includes providing a continuous, solid piece of material with the through-going main conduit; in the solid piece of material, forming said at least one side pocket by machining a bore, displaying an external entrance opening, into a laterally offset section of the solid piece of material generally parallel to the main conduit such that an internal wall section of the solid piece of material is brought to separate the main conduit from the machined bore; plugging the entrance opening of the machined bore with a fluid-tight plug; providing at least one opening from an outside of the mandrel body into the at least one side pocket; providing at least one opening in the wall section; and providing the solid piece of material with the first and the second connection arrangements, thereby rendering the mandrel body connectable to the up-hole and down-hole sections of the production tubing.

Claims

1. A method of producing a side pocket mandrel body for use in a hydrocarbon well side pocket mandrel assembly, which side pocket mandrel body comprises: a first end displaying a first connection arrangement for connecting the side pocket mandrel body to an up-hole section of a production tubing of the hydrocarbon well, and a second end displaying a second connection arrangement for connecting the side pocket mandrel body to a down-hole section of the production tubing; a longitudinal, through-going main conduit for communicating with a central passageway of the production tubing; and a side pocket section comprising at least one side pocket for retrievably housing an injection fluid flow control device, wherein the method comprises the steps of: providing a continuous, solid piece of material with the through-going main conduit; in the solid piece of material, forming said at least one side pocket by machining a bore, displaying an external entrance opening, into a laterally offset section of the solid piece of material generally parallel to the main conduit such that an internal wall section of the solid piece of material is brought to separate the main conduit from the machined bore; plugging the entrance opening of the machined bore with a fluid-tight plug; providing at least one opening from an outside of the side pocket mandrel body into the at least one side pocket, thereby forming an injection fluid inlet; providing at least one opening in the wall section, thereby forming an injection fluid outlet; and providing the solid piece of material with the first and the second connection arrangements, thereby rendering the side pocket mandrel body connectable to the up-hole and down-hole sections of the production tubing.

2. The method according to claim 1, wherein the step of forming said at least one side pocket further comprises the step of machining structures for interacting with latches and seals of the injection fluid flow control device in an internal surface of the machined bore.

3. The method according to claim 1, wherein the step of forming said at least one side pocket further comprises the step of inserting a hollow cylinder into the machined bore prior to the step of plugging the entrance opening, which cylinder, on the inside surface thereof, comprises structures for interacting with latches and seals of the injection fluid flow control device.

4. The method according to claim 1, wherein the step of plugging the entrance opening of the machined bore with a fluid-tight plug further comprises the steps of: providing the plug with external threads; providing the entrance opening with internal threads; and screwing the plug into the entrance opening.

5. The method according to claim 1, further comprising the steps of: forming a recess within the side pocket mandrel body by machining the inside of the main conduit removing material internally from said solid piece of material; and bringing the recess to communicate with said at least one side pocket, thereby bringing the at least one side pocket accessible via the recess.

6. The method according to claim 5, further comprising the step of machining guides for an injection fluid flow control device replacement tool in an internal surface of the recess.

7. The method according to claim 2, wherein the step of plugging the entrance opening of the machined bore with a fluid-tight plug further comprises the steps of: providing the plug with external threads; providing the entrance opening with internal threads; and screwing the plug into the entrance opening.

8. The method according to claim 3, wherein the step of plugging the entrance opening of the machined bore with a fluid-tight plug further comprises the steps of: providing the plug with external threads; providing the entrance opening with internal threads; and screwing the plug into the entrance opening.

9. The method according to claim 2, further comprising the steps of: forming a recess within the side pocket mandrel body by machining the inside of the main conduit removing material internally from said solid piece of material; and bringing the recess to communicate with said at least one side pocket, thereby bringing the at least one side pocket accessible via the recess.

10. The method according to claim 3, further comprising the steps of: forming a recess within the side pocket mandrel body by machining the inside of the main conduit removing material internally from said solid piece of material; and bringing the recess to communicate with said at least one side pocket, thereby bringing the at least one side pocket accessible via the recess.

11. The method according to claim 4, further comprising the steps of: forming a recess within the side pocket mandrel body by machining the inside of the main conduit removing material internally from said solid piece of material; and bringing the recess to communicate with said at least one side pocket, thereby bringing the at least one side pocket accessible via the recess.

Description

[0029] FIG. 1 is a cross-sectional view of a side pocket mandrel body produced using a method according to the present invention.

[0030] FIG. 2 discloses the mandrel body according to FIG. 1 in a cut-open, perspective view.

[0031] FIG. 3 discloses the mandrel body according to FIG. 1 in a cut-open, perspective partial view.

[0032] FIG. 1 discloses an embodiment of a side pocket mandrel body 1 according to the invention. The mandrel body 1, which is elongated, comprises a first end 2 displaying a first connection arrangement 3 for connecting the mandrel body 1 to an up-hole section (not disclosed) of a hydrocarbon well production tubing, and a second end 4 displaying a second connection arrangement 5 for connecting the mandrel body 1 to a down-hole section (not disclosed) of the production tubing. The first and second connection arrangements 3, 5 comprise inner and outer threads for forming threaded connections with the up-hole and down-hole production tubing sections, respectively.

[0033] The mandrel body 1 comprises a main or central, longitudinally extending through-going channel or conduit 6, which is arranged to communicate with a central passageway of the production tubing when the mandrel body 1 is connected to the up-hole and down-hole production tubing sections. The main conduit 6 typically has a diameter which corresponds to the diameter of the central passageway of the production tubing, and when the mandrel body 1 is mounted in the hydrocarbon well, the main conduit is typically aligned with the central passageway of the up-hole and down-hole production tubing sections.

[0034] The mandrel body 1 also comprises a side pocket section 7 which comprises at least one elongated, laterally offset side pocket 8 for receiving and harboring an injection fluid flow control device, e.g. a gas lift valve, e.g. a gas lift valve of the type disclosed in the above-mentioned document WO2007/091898A1. The side pocket 8, which displays generally circular-symmetric cross-sections, is laterally offset the main conduit 6 and extends generally parallel to the same such that the side pocket 8 and the main conduit 6 is separated by an internal wall section 9 in the mandrel body 1. The side pocket 8 discloses an opening 10 which is in communication with the main conduit 6 via an elongated recess 11 in the side pocket section 7, which recess 11 extends in the axial direction of the mandrel body 1 adjacent to the main conduit 6. In other words, the recess 11 is open towards the main conduit 6 such that the side pocket 8 can be accessed from the main conduit 6 via the recess 11.

[0035] In a manner which is known as such, the injection fluid flow control device can be retrieved and replaced via the recess 11 and the opening 10 by running a tool (not depicted) down the central passage-way of the production tubing and into the main conduit 6. To this end, an internal surface 12 of the main conduit 6 and an internal surface 13 of recess 10 exhibit internal guides 14, 15, e.g. elevated tracks or recesses, which are arranged to interact with the tool in order to align the tool in a correct position vis-à-vis the side pocket 8 when the injection fluid flow control device is retrieved and replaced.

[0036] The mandrel body 1 further comprises at least one first opening or passage 16 providing a fluid conduit from an outside of the mandrel body 1 into the side pocket 8, and at least one second opening or passage 17 providing a fluid conduit from the side pocket 8 to the main conduit 6, which first and second passages 16, 17 provide a passageway for an injection fluid from the outside of the mandrel body 1 into the main conduit 6 via an injection fluid flow control device (not depicted) arranged in the side pocket 8, thus allowing the injection fluid flow control device to regulate the flow of injection fluid from the outside of the mandrel body 1 into the main conduit 6 via the passages 16 and 17 which is, as such, known by the skilled person. To this end, an internal surface 18 of the side pocket 8 exhibits structures 19, e.g. annular recesses and elevated sections, for interacting with latches and seals of the injection fluid flow control device such that the flow path of the injection fluid is directed from the first passage 16 to inlet ports of the injection fluid flow control device, and from outlet ports of the injection fluid flow control device to the second passage 17, when the injection fluid flow control device is mounted in the side pocket 8.

[0037] A plug 20 is positioned in the side pocket 8 providing a fluid-tight termination of the side pocket 8 at the end of the side pocket 8 which is opposite the opening 10. Consequently, the side pocket 8 extends from the opening 10 to the plug 20.

[0038] According to the invention, the mandrel body 1 is produced from a continuous, solid piece of material, or blank, made from a steel alloy suitable for down-hole hydrocarbon well applications.

[0039] The method of producing the mandrel body 1 comprises the step of machining the blank externally using any suitable means such that the blank obtains a generally elongated, cylindrical form displaying a laterally offset section which is to house the side pocket section 7. The process of machining may comprise turning, boring, drilling, milling, broaching, sawing, electrical discharge machining (EDM) or any other prior art machining method.

[0040] The method of producing the mandrel body 1 further comprises the step of forming the main conduit 6 in the mandrel body. This may be achieved by machining, e.g. drilling, a through-going bore in the blank and machining the inside surface 12 of the through-going bore, e.g. using electrical discharge machining (EDM), such that the desired guides 14 for the injection fluid flow control device replacement tool, and other desired structures, are obtained. Alternatively, if the blank is produced by casting, a through-going opening or channel in the blank may be formed already during the casting process, which through-going opening or channel is subsequently machined internally, e.g. using EDM, to form the main conduit 6.

[0041] The method of producing the mandrel body 1 also comprises the step of forming the recess 11 by machining the inside of the main conduit, e.g. using EDM, removing blank material. This step also comprises machining the internal surface 13 of the recess 11 such that the desired guides 15 for the injection fluid flow control device replacement tool, and other desired structures, are obtained.

[0042] The method of producing the mandrel body 1 also comprises the step of forming the side pocket 8 by machining, e.g. drilling, a bore 21 into the offset section 7 generally parallel to the main conduit 6, i.e. into the laterally offset section, leaving an internal wall section 9 between the main conduit 6 and the bore 21. Once completed, the bore 21 displays an external entrance opening 23. If the recess 11 is formed prior to the bore 21, the bore 21 is advantageously bored into the recess 11. The step of forming the side pocket 8 also comprises machining the internal surface 18 of the bore 21 such that the desired structures for interacting with latches and seals of the injection fluid flow control device, and other desired structures, are obtained. The step of forming the side pocket 8 further comprises plugging the entrance opening 23 of the bore 21, i.e. at the surface of the mandrel body 1, using the above-disclosed plug 20. This may advantageously be performed by the step of screwing the plug 20 into the bore 21, in which case external threads (not disclosed) are formed on the plug 20 and internal threads 22 (cf. FIG. 3) are formed at the entrance of the bore 21 prior to the plugging operation.

[0043] It may be advantageous to produce the plug 20 from the same material as the blank, i.e. from a steel alloy which is suitable for down-hole hydrocarbon well applications.

[0044] The method of producing the mandrel body 1 further comprises the step of forming said at least one first opening or passage 16 by machining, e.g. drilling, one or a plurality of bores from the outside of the side pocket section 7 and into the bore 21, and also the step of forming said at least one second opening or passage 17 by machining, e.g. using EDM, one or a plurality of bores through the internal wall section 9.

[0045] The method of producing the mandrel body 1 also comprises the step of forming said first and second connection arrangements, allowing the mandrel body 1 to be connected to up-hole and down-hole sections of a production tubing.