METHOD AND APPARATUS TO EFFECT INJECTION OF FLUIDS INTO A SUBSEA HORIZONTAL TREE

Abstract

An apparatus for effecting injection of fluids into a subsea horizontal tree includes a fluid injection tree cap having a body with a bore extending therethrough so as to open at one end to a top of the body. An isolation valve is cooperative with the bore of the body so as to open or close fluid flow through the bore. The fluid injection tree cap is connected to the horizontal subsea tree. The horizontal subsea tree has only a single crown plug therein. The bore of the fluid injection tree cap communicates with an annulus of the horizontal subsea tree. The horizontal subsea tree has valving therein so as to selectively direct fluid from the bore of the tree cap to the annulus of the well or to the horizontal subsea tree.

Claims

1. An apparatus comprising: a fluid injection tree cap having a body with a bore extending through the body so as to open at one end of said body, said fluid injection tree cap having an isolation valve cooperative with said bore of said body so as to open or close a flow of a fluid through said bore; a horizontal subsea tree having only a single crown plug therein, said horizontal subsea tree having said fluid injection tree cap affixed to an upper end thereof such that said bore of said fluid injection tree cap communicates with an annulus of said horizontal subsea tree; and a well connected to said horizontal subsea tree, said well having an annulus, said horizontal subsea tree having valving therein so as to selectively direct fluid from said bore of said tree cap to said annulus of said well or to said horizontal subsea tree.

2. The apparatus of claim 1, said horizontal subsea tree having a tubing hanger positioned in said annulus of said horizontal subsea tree.

3. The apparatus of claim 1, said well being a wellhead, said horizontal subsea tree having a connector at a lower end thereof that is affixed to said well.

4. The apparatus of claim 1, said isolation valve positioned above said body of said fluid injection tree.

5. The apparatus of claim 1, said horizontal subsea tree having a mandrel at the upper end thereof, said fluid injection tree cap being connected by a metal-to-metal seal with said mandrel.

6. The apparatus of claim 1, said annulus of said horizontal subsea tree having a workover valve cooperative therewith so as to allow workover fluids to flow to said bore of said body of said fluid injection tree.

7. The apparatus of claim 2, further comprising: a line extending from said well and through said tubing hanger and outwardly of said horizontal subsea tree so as to cause production fluid to flow outwardly of said horizontal subsea tree.

8. The apparatus of claim 1, said valving of said horizontal subsea tree selectively directing fluid from said bore of said tree cap to production tubing extending outwardly of said horizontal subsea tree.

9. An apparatus comprising: a fluid injection tree cap having a body with a bore extending through said body so as to open at one end at a top of said body, said fluid injection tree cap having an isolation valve cooperative with said bore of said body so as to open or close a flow of fluid through said bore; and a horizontal subsea tree having only a single crown plug therein, said horizontal subsea tree having said fluid injection tree cap affixed to an upper end thereof such that the bore of said fluid injection tree cap communicates with an annulus of said horizontal subsea tree, said horizontal subsea tree having valving therein so as to selectively direct fluid from the bore of the tree cap to an annulus of a well or to the horizontal subsea tree or to production tubing.

10. The apparatus of claim 9, said horizontal subsea tree having a tubing hanger positioned in said annulus of said horizontal subsea tree.

11. The apparatus of claim 9, further comprising: a well connected to said horizontal subsea tree, said well having an annulus, said valving of said horizontal subsea tree selectively directing fluid from said bore of said tree cap to the annulus of the well.

12. The apparatus of claim 11, said well having a wellhead, said horizontal subsea tree having a connector at a lower end thereof that is affixed to said wellhead.

13. The apparatus of claim 9, said isolation valve positioned above said body of said fluid injection tree cap.

14. The apparatus of claim 9, said horizontal subsea tree having a mandrel at the upper end thereof, said fluid injection tree cap being connected by a metal-to-metal seal with said mandrel.

15. A method of effecting injection of fluids into a subsea horizontal tree, the method comprising: affixing a fluid injection tree cap onto a mandrel of the horizontal subsea tree; removing a single crown plug of said horizontal subsea tree so as to expose an annulus flow path; connecting the fluid injection tree cap to a fluid-delivering pipe; and opening a valve so that the fluid-delivering pipe flows through a bore in a body of the fluid injection tree cap and into the mandrel of the horizontal subsea tree and then flows into an annulus portion of the horizontal subsea tree.

16. The method of claim 15, further comprising: directing fluid from the annulus portion of the horizontal subsea tree into an annulus of a well.

17. The method of claim 15, further comprising: directing the fluid from the annulus portion of the horizontal subsea tree to a production side of the horizontal subsea tree.

18. The method of claim 15, further comprising: connecting an isolation valve to the fluid injection tree cap and of the fluid-delivering pipe.

19. The method of claim 18, further comprising: opening the isolation valve so as to allow fluid to flow from the fluid-delivering pipe into the bore of the fluid injection tree.

20. The method of claim 15, further comprising: affixing a tubing hanger into a bore of said horizontal subsea tree.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0028] FIG. 1 is a schematic illustration showing the application of the tree cap of the present invention onto a horizontal subsea tree.

DETAILED DESCRIPTION OF THE INVENTION

[0029] Referring to FIG. 1, there is shown the apparatus 10 of the present invention for effecting injection of fluids into a subsea horizontal tree 12. In particular, the tree cap 14 is applied onto the upper mandrel 16 of the subsea tree 12. The subsea tree 16 has a lower connector 18 that is secured to the wellhead 20. A tubing hanger 22 is positioned within the bore 24 of the hanger portion of the subsea tree 12.

[0030] The tree cap 14 includes a body 26 that has a bore 28 extending therethrough. In the preferred embodiment the present invention, this bore is a two inch bore. However, the bore can be larger or smaller. An isolation valve 30 is connected to the bore 28. The isolation valve 30 can be manually or remotely operated. For example, an ROV actuator 32 can be used with the isolation valve 30 so as to open or close the isolation valve. A hub 34 is connected to the bore 28 and located on a side of the isolation valve 30 opposite to the body 26. The hub 34 allows the bore 28 to be connected to an injection system, such as a fluid-delivering pipe. The cap 14 also includes a wellhead-type of connector 36 or similar device that locks onto the upper mandrel 16 of the horizontal subsea tree 12 and provides a metal-to-metal seal.

[0031] In the subsea horizontal subsea tree 12, there is illustrated in broken lines a crown plug 38. This illustration is to show the location of the crown plug 38 prior to removal. In actual operation, when the tree cap 14 is positioned on the mandrel 16, the crown plug 38 is removed so as to expose the annulus flow path of the subsea tree 12.

[0032] The subsea tree 12 includes an annulus flow path 40 therein. An annulus workover valve 42 extends outwardly of the subsea tree 12 and allows fluid flow into the annulus. The annulus workover valve 42 can be controlled or actuated by a remotely operated vehicle or can be actuated from a surface location. The annulus workover valve 42 allows workover fluids to be introduced into the apparatus 10. The annulus master valve 44 is connected to the annulus and extends to the bore 28 of the subsea tree 12 so as to allow annulus fluids to be delivered into the bore. An annulus auxiliary valve 46 is also provided so as to extend to the bore 24. A line 48 will extend from the annulus workover valve 42 and from the annulus so as to pass to the bore 28.

[0033] Production fluids can flow through line 50 from the wellhead 20, through the connector 18, through the hanger 22 and toward a series of production valves. The first valve 52 is the production master valve so as to control the flow of production fluids outwardly of the subsea tree 12. A production wing valve 54 is connected in line with the master production valve 52. A crossover valve 56 allows fluids from the bore 28 or from the annulus 40 to pass therethrough and into the production fluids flowing along line 50. A production isolation valve 58 is positioned along line 60 so as to stop the flow of fluids through the line 50. A hub 62 is formed at the end of the line so as to allow the production line 50 to ultimately be connected to piping so that production fluids can be ultimately delivered to a surface location.

[0034] Typical horizontal subsea trees contain two independent crown plugs in the bore 24 so as to isolate the main production flow path from the environment. However, for certain horizontal subsea trees that require more continuous injection of fluids, it would be beneficial to remove the upper crown plug 38 so as to expose the annulus flow path. In order to maintain the required dual barriers, the externally-fitted fluid injection tree cap 14 is installed with the necessary valving and connection points. This fluid injection tree cap 14 provides the required secondary metal-to-metal barrier by this locking connection with the mandrel 16. It also provides the necessary intervention valves to isolate the upper mandrel of the tree. This effects injection of fluids in the testing of the seals. The tree cap 14 also provides the required hub connection system so as to allow for the connection of a hose/pipe/equipment or to facilitate injection of fluids into the tree cap and thus into the upper mandrel of the subsea tree. The fluid injection tree cap 14 can be installed permanently or semi-permanently in order to facilitate a single or routine fluid injection program.

[0035] In the method of the present invention, fluid injected from the tree cap 14 into the upper mandrel 16 and through the annulus auxiliary valve 46 will flow into the annulus portion of the subsea tree. Fluid can then be directed either into the annulus of the well or into the production side of the tree.

[0036] The foregoing disclosure and description of the invention is illustrative and explanatory thereof. Various changes in the details of the illustrated construction or in the steps of the method can be made within the scope of the present claims without departing from the spirit of the invention. The present invention should only be limited by the following claims and their legal equivalents.