Patent Application
20150226030
1. Field of the Invention
The invention relates generally to devices and methods for operation of downhole valves. In particular aspects, the invention relates to the control of valves used in wellbore intervention technology.
2. Description of the Related Art
Following a primary production period for a wellbore, wellbore intervention is often needed to pump fluids, chemicals, etc. or transport tools into and out of the wellbore. Deviated or horizontal wellbores or wellbore portions can preclude the use of wireline intervention. Where tubulars, and particularly coiled tubing, are used to facilitate such interventions, the string will typically require one or more internal safety valves such as flapper-type or check-type valves. These safety valves prevent the flow of wellbore hydrocarbons into the coiled tubing but also may limit some preferable intervention operations.
The present invention provides systems and methods for allowing intervention into a wellbore with a valve assembly that can be selectively opened and closed. In described embodiments, the present invention relates to an intervention work string having a multi-cycle open/close valve assembly. The valve assembly is preferably used in a coiled tubing intervention bottom hole assembly wherein the coiled tubing has electrical or fiber optic communication within it. The valve assembly could be run in in either a normally-opened or normally-closed position and functioned by means of communication from the surface via electric or fiber optic conduit.
In a described embodiment, the valve assembly includes a plurality of flapper valves that are spring biased toward a closed position. The valve assembly also includes a valve actuation mechanism that can move each of the flapper valves between closed and open positions. An exemplary valve actuation assembly includes a roller screw member that is rotatable within the valve housing. Rotation of the roller screw member will move a prong member axially within the valve housing to urge the flapper valves open. Rotation of the roller screw member in the opposite direction will move the prong member axially within the valve housing in the opposite direction, thereby allowing the flapper valves to close.
When the valve assembly is in an open position, various intervention related tasks can then be performed. For example, tools could be passed down through the intervention work string and emplaced in the wellbore. In addition, fluids or chemicals could be flowed into the wellbore or out of the wellbore internally via the coiled tubing conduit.
For a thorough understanding of the present invention, reference is made to the following detailed description of the preferred embodiments, taken in conjunction with the accompanying drawings, wherein like reference numerals designate like or similar elements throughout the several figures of the drawings and wherein:
An intervention work string 22 is disposed within the wellbore 10. The intervention work string 22 can be used to perform workover tasks, such as pumping chemicals into the wellbore 10 or running tools into the wellbore 10. The exemplary intervention work string 22 includes a coiled tubing running string 24 that is injected from surface 13 in a manner known in the art. Although a land-based well is depicted, those of skill in the art will understand that the systems and methods of the present invention can also be applied to subsea wells.
A multi-cycle open/close safety valve assembly 26 is secured to the distal end of the coiled tubing string 24. Referring now to
A valve actuation mechanism 44 is located within the flow bore 30 proximate the flapper valves 34, 36.
The exemplary valve actuation mechanism 44 also includes a gear wheel 52 that is affixed to the rotary shaft 48. A tubular roller screw member 54 is disposed within the flow bore 30. The roller screw member 54 is rotatable within the outer housing 28 and is retained against axial movement within the flow bore 30 by locking ring 56. The roller screw member 54 presents a toothed upper end 58 whose teeth intermesh with teeth 60 on gear wheel 52. In addition, the roller screw member 54 has a radially interior surface with threading 62 formed thereupon.
A prong member 64 is located within the roller screw member 54. Preferably, the prong member 64 includes a radially enlarged upper end 66 and a reduced diameter prong portion 68. An axial passageway 70 is defined through the prong member 64. The outer radial surface 72 of the enlarged upper end 66 has threading formed thereupon which is complementary to the threading 62 on the roller screw member 54. As a result of the intermeshing of the threading on the outer radial surface 72 of the prong member 64 and the threading 62, the prong member 64 will be moved axially within the housing 28 when the roller screw member 54 is rotated within the housing 28. The prong member 64 will be moved axially either upwardly or downwardly depending upon the direction of rotation of the roller screw member 54.
In operation, the intervention work string 22 is disposed within the wellbore 10 until the valve assembly 26 is located at a point wherein it is desired to perform an intervention task. A particular intervention task might be flowing chemicals through the coiled tubing string 24 and the valve assembly 26. Alternatively, flow or circulation (reverse) may be performed. In order to do these things, the valve assembly 26 must be opened.
Opening of the valve assembly 26 is depicted in
Once the valve assembly 26 has been opened, one or more intervention-related tasks can be performed through the open valve assembly 26. For example, fluids or chemicals could be flowed downwardly or upwardly through the intervention work string 26.
An operator can also close the flapper valve assemblies 34, 36 by energizing the motor 46 to rotate the shaft 48 and gear wheel 52 in the opposite direction. This will rotate the roller screw member 54 in the opposite direction and cause the prong member 64 to move axially upwardly within the housing 28.
Those of skill in the art will recognize that numerous modifications and changes may be made to the exemplary designs and embodiments described herein and that the invention is limited only by the claims that follow and any equivalents thereof.
