Patent Application
20080264626
Coiled tubing rigs rely on coiled tubing injectors to inject coiled tubing into a well. Generally, the bottom of the coiled tubing injector is mounted directly to a stripper assembly through which the coiled tubing moves prior to entering a well stack and the well. Attempts have been made to provide greater flexibility in the ability to connect a given coiled tubing injector to a variety of well stacks by using telescoping risers between the stripper assembly and the well stack. However, the use of telescoping risers incurs a high cost and a high level of active maintenance. Additionally, the telescoping risers are required to maintain wellbore pressure.
In general, the present invention provides a system and method for improving the ability to inject coiled tubing at a variety of wells. The system and method utilize a telescopic, anti-buckling guide through which coiled tubing is moved before entering the stripper assembly and ultimately entering the well. The telescopic, anti-buckling guide is designed to support the coiled tubing to prevent buckling under operating loads. Additionally, the telescopic, anti-buckling guide facilitates connection to a variety of well control stacks of different heights without requiring vertical movement of the coiled tubing injector and without the need for pressure containment members in the guide.
Certain embodiments of the invention will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements, and:
In the following description, numerous details are set forth to provide an understanding of the present invention. However, it will be understood by those of ordinary skill in the art that the present invention may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible.
The present invention relates to a system and methodology for facilitating the injection of coiled tubing into a well. A telescopic, anti-buckling guide enables deployment of a coiled tubing injector head onto a well control stack without requiring vertical movement of the injector head. The telescopic character of the guide also enables adjustment of the distance between the coiled tubing injector and the well control stack which allows the injector head to be used with well control stacks of different heights without requiring vertical movement of the injector head. The guide also supports the coiled tubing and prevents buckling of the coiled tubing between the coiled tubing injector and a stripper assembly positioned at the top of a well control stack.
Generally, the telescopic, anti-buckling guide provides a conduit for directing the coiled tubing from the injector head without requiring pressure seals. All pressure containing equipment can be located within the well control stack which reduces the cost and simplifies the structure of the telescopic, anti-buckling guide. For example, the cost of manufacturing the guide is reduced, and there are no maintenance requirements that would otherwise be associated with pressure seals. By avoiding the need to contain pressure, the telescopic, anti-buckling guide also avoids the need for locks that would otherwise be necessary to prevent unwanted expansion of the guide when exposed to internal well pressure.
One embodiment of a guide system 10 is illustrated in
Well control stack 18 is positioned on a surface 22 above a well 24 having a wellbore 26. Well control stack 18 comprises pressure control equipment 28 to control the internal well pressure within wellbore 26 and to prevent unwanted passage of well fluids through well control stack 18. Pressure control equipment 28 may comprise one or more members that can form the desired pressure seals able to hold back the internal well pressure. For example, blowout preventers or other pressure seals can be used. In the embodiment illustrated, all pressure control and all pressure control equipment is located below telescopic, anti-buckling guide 14 in, for example, well control stack 18. Accordingly, telescopic, anti-buckling guide 14 can be manufactured without pressure seals.
Coiled tubing injector 16 is designed to deliver coiled tubing 30 (shown in dashed lines) into well 24. Pressure control equipment 28 can be used to form a seal with the coiled tubing 30 to prevent passage of internal well pressure. Furthermore, telescopic, anti-buckling guide 14 is sized to support coiled tubing 30 and to prevent buckling of the coiled tubing between the coiled tubing injector 16 and the well control stack 18, e.g. between coiled tubing injector 16 and stripper assembly 20. Guide 14 supports coiled tubing 30 against buckling when exposed to operating loads.
The telescopic capability enables guide 14 to be compressed or extended as necessary to enable the connection of stripper assembly 20 to a variety of well control stacks 18 of different heights without requiring vertical movement of coiled tubing injector 16. When a coiled tubing injection operation is completed or the coiled tubing injector 16 is to be moved to another well stack, the stripper assembly 20 can simply be uncoupled from well control stack 18. Once uncoupled, the stripper assembly 20 is lifted upwardly to compress telescopic, anti-buckling guide 14 so as to clear well control stack 18 without requiring vertical movement of coiled tubing injector 16. The coiled tubing injector 16, guide 14 and a stripper assembly 20 can then be moved to the next desired location.
One embodiment of telescopic, anti-buckling guide 14 is illustrated in
By way of example, lower guide 34 may comprise a body portion 36 that is tubular in shape and has a hollow interior 38 sized to slidably receive upper guide 32. As also illustrated in
By way of further example, upper guide 32 may comprise a body portion 52, as further illustrated in
As illustrated in the expanded view of
Depending on a variety of factors, including well stack size and style, environment, coiled tubing injector type, and well operation performed, the size and configuration of telescopic anti-buckling guide 14 may vary. The telescopic characteristics can be achieved with a variety of upper and lower guides that are coupled together for selective expansion and contraction. The internal diameters of cylindrical style guides can be adjusted to accommodate different coiled tubing sizes, and a variety of inserts or other mechanisms can be used to provide the desired guidance of coiled tubing into well control stack 18 and well 24. Furthermore, the telescopic, anti-buckling guide 14 can be designed with ends configured for engagement with a variety of coiled tubing injectors and stripper assemblies.
Accordingly, although only a few embodiments of the present invention have been described in detail above, those of ordinary skill in the art will readily appreciate that many modifications are possible without materially departing from the teachings of this invention. Accordingly, such modifications are intended to be included within the scope of this invention as defined in the claims.
