Control line sharing between a lower and an insert safety valve

Abstract

A system involving a lower tubing mounted safety valve having one or two control lines further contains a landing nipple above for a wireline insert valve. One line that serves the lower safety valve is tied to a connection on the landing nipple for the insert valve. When the lower safety valve malfunctions the landing nipple wall is penetrated to get communication to the line coming from the lower safety valve so that such line can serve as a balance line for the insert valve. The other line from the surface to the other connection on the landing nipple serves as the operating line for the insert valve. Making one line serve a dual purpose eliminates one control line from the surface.

Claims

1. A subterranean safety valve system for a borehole, comprising: a tubing string mounted safety valve operable in the borehole by at least one control line; an insert safety valve selectively mounted to a landing nipple on the tubing string; said at least one control line extending from said tubing string mounted safety valve to said landing nipple and continuing uphole along said tubing string such that said at least one control line is initially isolated from fluid communication with said insert valve and thereafter communication from said at least one control line through said landing nipple is established for operation of said insert valve in place of said tubing string mounted safety valve with said tubing string mounted safety valve held in an open position.

2. A subterranean safety valve system for a borehole, comprising: a tubing string mounted safety valve operable in the borehole by at least one control line; an insert safety valve selectively mounted to a landing nipple on the tubing string; said at least one control line extending from said tubing string safety valve to said landing nipple and continuing uphole along said tubing string such that said at least one control line selectively is in fluid communication with said insert valve for operation of said insert valve in place of said tubing string mounted safety valve; said at least one control line comprises a first and second control lines; said first control line in selective fluid communication with said landing nipple and continuing to said tubing string mounted safety valve and said second control line extending along said tubing string to said landing nipple.

3. The system of claim 2, wherein: said second control line transmits pressure that operates said insert safety valve and said first control line offsets hydrostatic pressure that is in said second control line.

4. The system of claim 2, wherein: said second control line terminates at said landing nipple.

5. The system of claim 2, wherein: said second control line extends beyond said landing nipple to said tubing string mounted safety valve.

6. The system of claim 5, wherein: said second control line selectively delivers operating pressure to said tubing string mounted safety valve and then to said insert valve as said tubing string mounted safety valve is out of service, while said first control line balances hydrostatic pressure in said second control line independently of whether said tubing string mounted safety valve or said insert valve are in service.

7. The system of claim 2, wherein: said first and second control lines extend into discrete hubs on said landing nipple.

8. The system of claim 7, wherein: said hubs initially isolated from a passage in said landing nipple by a wall.

9. The system of claim 8, wherein: said wall is selectively penetrated for access to said first and second control lines through said hubs.

10. A method for providing a backup safety valve to a safety valve, comprising: running a tubing string with said safety valve to a subterranean location; providing a landing nipple on said string ahead of said safety valve; selectively using a control line to extend in initial fluid communication only to said safety valve and selectively thereafter to said landing nipple; pressurizing said control line in operation of both said safety valve and said backup safety valve landed in said landing nipple.

11. The method of claim 10, comprising: running fewer control lines to a surface location because of said first control line extending in selective fluid communication to both said safety valve and said landing nipple.

12. A method for providing a backup safety valve to a safety valve, comprising: running a tubing string with said safety valve to a subterranean location; providing a landing nipple on said string ahead of said safety valve; selectively using a first control line to extend in selective fluid communication to said safety valve and said landing nipple; selectively using said first control line in operation of both said safety valve and an insert safety valve landed in said landing nipple; providing a second control line to extend at least to said landing nipple.

13. The method of claim 12, comprising: using said first control line as a balance line for said second control line at said landing nipple.

14. The method of claim 13, comprising: omitting a charged fluid chamber for hydrostatic pressure offset in said insert safety valve due to the presence of said first control line to offset hydrostatic pressure in said second control line.

15. The method of claim 14, comprising: extending said second control line to said safety valve.

16. The method of claim 12, comprising: initially operating said safety valve with said first control line; locking open said safety valve after said safety valve malfunctions; providing a second control line to said landing nipple; initially operating said insert safety valve in said landing nipple with said second control line while offsetting hydrostatic in said second control line with said first control line at said landing nipple.

17. The method of claim 16, comprising: obtaining pressure communication to said first and second control lines by penetrating a wall in said landing nipple at two locations.

18. The method of claim 16, comprising: extending said second control line past said landing nipple and to said safety valve; initially operating said safety valve with said second control line and using said first control line for offsetting hydrostatic pressure in said first control line at said safety valve; taking said safety valve out of service by locking said safety valve open; opening access from a passage in said landing nipple to said first and second control lines for operation of the insert valve landed in said landing nipple with hydrostatic pressure balance between said first and second control lines.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) The FIGURE shows a lower safety valve and an insert valve in a landing nipple above where the operating line for the lower safety valve serves as a balance line for the insert valve above.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(2) The FIGURE shows a lower tubing mounted safety valve 10 with a single control line 12. Mounted above the safety valve 10 is a landing nipple 14 that has a control line 16 leading from it to the surface. Control line 12 runs from the surface to safety valve 10 and passes through the hub 18 and continues to the surface.

(3) When there is a problem with the safety valve 10 the procedure is to lock the valve 10 open in a manner known in the art so that safety valve 10 becomes a part of the tubing string in its wide open and locked position. After safety valve 10 is locked open a penetrating tool that is also known in the art is positioned opposite hubs 18 and 20. Control line 16 is isolated when the safety valve 10 is in operation. After safety valve 10 is locked open the penetrating tool that is not shown is placed in two locations in the landing nipple 14 and openings are formed to communicate into hubs 18 and 20 from the central passage where the penetrating tool, schematically illustrated by arrow P, is placed and actuated. After the penetrating tool is operated twice into hubs 18 and 20 the insert valve 22 of a type known in the art is landed and latched into the landing nipple 14. When that happens control line 16 can be used to operate the insert valve 22 and control line 12 becomes the balance line. The advantage is that the insert valve 22 has no need for a pressurized gas chamber atmospheric chambers or other means because the hydrostatic pressure in one line is offset with the hydrostatic pressure in the other line. Additionally, because line 12 is shared between safety valve 10 which is now locked open and the landing nipple 14 there are but two control lines to the surface instead of what would have been three lines in the configuration shown in the FIG. On the other hand it is also possible that the safety valve 10 could be a two line system rather than the single line system that is shown. In that instance line 16 can be made to extend to the safety valve 10 by way of hub 20 and there are still two lines to the surface rather than the four that would be needed to equip two standalone safety valves for independent operation. The space saving from running less lines makes room for other lines or just a smaller umbilical cable. Thus depending on the design of the lower safety valve 10 there is the potential of saving one or two control lines in the borehole and providing an insert safety valve with a balance line so that compressed gas chambers to offset hydrostatic are not needed. This allows use of an insert valve that has a lower pressure rating and a more reliable reputation for operation that is desired by the well operator.

(4) The above description is illustrative of the preferred embodiment and many modifications may be made by those skilled in the art without departing from the invention whose scope is to be determined from the literal and equivalent scope of the claims below: