Lift frame with pivoting lift sub

Abstract

A lift frame for conducting wireline or coiled tubing operations on an oil rig comprises a main frame and a substantially cylindrical lift sub for lifting the lift frame assembly by means of a block. A pivot is provided between the main frame and the lift sub. The lift frame is provided with skids for supporting the assembly in an undeployed position with the main frame being substantially parallel to a resting surface such as a rig floor. In the undeployed position, the lift sub extends vertically upward from the resting surface. When the lift sub is engaged by elevators coupled by links to the lifting block, the lift frame assembly can be raised into a deployed position wherein the main frame pivots relative to the vertical lift sub to be substantially perpendicular to the resting surface. Difficulties in engaging a horizontally-oriented lift sub are therefore eliminated.

Description

FIELD OF THE INVENTION

The present invention relates generally to operations in and around oil and gas wells, and more particularly to a lift frame for use in wireline or coiled tubing operations.

BACKGROUND OF THE INVENTION

Often during the drilling and completion of oil and/or gas (hydrocarbon) wells, it is necessary to install and/or remove a variety of downhole tools into or out of the well. Examples of these tools include, without limitation, isolation packers, bridge plugs, wellhead plugs, cement retainers and sump packers, and other similar devices.

Typically, such tools are set and retrieved using various methods, including wireline, slickline, or coiled tubing. Those of ordinary skill will appreciate that each of these methods has its own advantages and disadvantages. A conventional wireline has been a traditional method of choice because it is less costly and faster than other methods, such as coiled tubing. Also, its portability enables it to be cost-efficient when performing these services in remote locations and on offshore platforms.

When performing wireline or coiled tubing operations, it is customary to employ a lift frame to assist in the introduction of the wireline or coiled tubing into the well. A lift frame is suspended from the lift block of an oil rig and includes a hoist or winch mechanism used in the deployment of wireline or coiled tubing. In particular, links off of the rig's lift block are engaged with a lift sub of the lift frame using elevators designed for this purpose, as would be familiar to those of ordinary skill in the art. One example of a prior art wireline lift frame is described in U.S. Pat. No. 4,428,421 to Rankin, entitled “Wireline Winch Mounting System.” The Rankin '421 patent is hereby incorporated by reference herein in its entirety.

SUMMARY OF THE INVENTION

In view of the foregoing and other considerations, the present invention is directed to a lift frame assembly with features that facilitate its deployment with minimal effort and hazard.

In one embodiment of the invention, a wireline lift frame comprises a frame assembly having a top and a side. A lift sub is pivotally coupled to the top of the frame assembly. When the lift frame is undeployed, it is adapted to rest with its side parallel to and resting on a horizontal surface. The pivoting connection between the lift sub and the frame assembly allows the lift sub to be positioned vertically relative to horizontal surface. This orientation facilitates the process of engaging the lift sub with elevators in order to deploy the lift frame. As the lift frame is deployed, the frame assembly pivots under the force of gravity into a position where its side becomes substantially parallel to the lift sub and substantially perpendicular to the horizontal surface.

In accordance with another aspect of the invention, the wireline lift frame carries a winch assembly. In one embodiment, the winch assembly includes a pneumatically-driven winch.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is best understood with reference to the following detailed description of embodiments of the invention when read in conjunction with the attached drawings, in which like numerals refer to like elements, and in which:

FIG. 1 is a diagram of an oil rig environment including a wireline lift frame assembly in accordance with one embodiment of the invention; and

FIG. 2 is a perspective view of a wireline lift frame from FIG. 1.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

In the disclosure that follows, in the interest of clarity, not all features of actual implementations are described. It will of course be appreciated that in the development of any such actual implementation, as in any such project, numerous engineering and technical decisions must be made to achieve the developers' specific goals and subgoals (e.g., compliance with system and technical constraints), which will vary from one implementation to another. Moreover, attention will necessarily be paid to proper engineering practices for the environment in question. It will be appreciated that such development efforts might be complex and time-consuming, outside the knowledge base of typical laymen, but would nevertheless be a routine undertaking for those of ordinary skill in the relevant fields.

Referring to FIG. 1, there is shown a rig assembly 10 employing a wireline lift frame 12 in accordance with one exemplary embodiment of the invention. FIG. 1 shows a portion of a derrick 14 positioned on the floor 16 of a rig and situated over the wellhead 18 of a wellbore 20 extending into a subsurface formation 22. Although the embodiment of FIG. 1 is a wireline lift frame, those of ordinary skill having the benefit of the present disclosure will appreciate that the present invention can be advantageously utilized in connection with coiled tubing equipment and the like.

In accordance with common practice, different components such as blow-out preventers, lubricators, injection tools, and assemblies are at various times required to be installed on wellhead 18. For the sake of illustration in FIG. 1, a surface test tree 24 is shown on wellhead 18.

The wireline lift frame 12 is engaged by elevators 26 engaging the lift frame's lift sub 28. The elevators 26 in turn are coupled by relatively short links 30 to a block 32 from which the entire assembly is suspended.

The base of lift frame 12 is coupled to a pair of relatively longer bails or elevator links 34, 36, which may be, for example, fifty feet in length, and which are coupled at their bottom ends to the surface test tree 24. Together, the lift frame 12 and links 34, 36 define a working area window 38.

Referring to FIG. 2, there is shown a perspective view of a wireline lift frame 12 in accordance with one embodiment of the invention. As shown in FIG. 2, lift frame 12 comprises a frame assembly 50 having a pair of skids 52 on one side. In the perspective view of FIG. 2, frame assembly 50 is shown oriented with one side (namely, the side with skids 52) facing down and parallel to a substantially horizontal surface 54, which may be, for example, rig floor 16 from FIG. 1. The top 56 of frame assembly 14 is facing to the side with respect to surface 54.

With continued reference to FIG. 2, a lift sub 28 is coupled to the top 56 of frame assembly 50 with a pivoting connection 60. FIG. 2 shows lift sub 28 in three different positions: an undeployed position 28U, an intermediate position 281, and a deployed position 28D. Pivoting connection 60 gives lift sub 28 at least as much freedom as necessary to move between undeployed position 28U and deployed position 28D, as represented by arrow 62 in FIG. 2; this degree of freedom is approximately ninety degrees. Those of ordinary skill in the art will appreciate that together, lift sub 28, pivot 60, and frame assembly 50 must be constructed of metals such as steel and the like that are sufficiently robust to withstand the forces applied to a wireline lift frame during normal operation, up to and including supporting the weight of a production string extending into a wellbore.

In accordance with one aspect of the invention, when wireline lift frame 12 is resting in a undeployed position, i.e., resting on its side, pivot 60 enables lift sub 28 to be positioned vertically (position 28U in FIG. 2), which is substantially perpendicular to horizontal surface 54. Skids 52 provide support for lift frame 12 in its undeployed position, and maintains clearance sufficient to allow frame assembly 50 to carry a winch assembly 64, as is customary on wireline lift frames. In one embodiment of the invention, winch assembly 64 includes a pneumatically-driven winch. This has the advantage of drawing off of compressed air sources customarily found at rig sites. Alternatively, winch 64 may be hydraulic, requiring its own hydraulic power unit.

With continued reference to FIG. 2, frame assembly 50 is provided with couplings 70 for attachment of bails or elevator links 34 and 36, as previously described with reference to FIG. 1.

The vertical orientation of lift sub 58 in its undeployed position (58U) greatly facilitates the engagement of lift sub 58 by elevators, since rig blocks are best suited to engaging vertically-oriented structures such as tubular and lift subs. If lift sub 28 was not pivotally coupled to frame assembly 50, that is, when lift sub 28 is in its deployed position 28D, it would be much more difficult and hazardous to engage elevators on lift sub 28

As would be familiar to those of ordinary skill in the art, the lift frame assembly including links 34, 36 is partially assembled before deployment. In particular, lift frame 12 is first oriented its in undeployed position (as shown in FIG. 2) with its side facing down, parallel to a substantially horizontal surface 54. Links 34, 36, also substantially flat on the rig floor, are coupled to couplings 70 of frame assembly 50.

With reference to both FIG. 1 and FIG. 2, with frame assembly 50 resting in its undeployed position on skids 52, lift sub 28 is pivoted to its vertical position 28U, while block 32 and lines 30 are lowered toward the rig floor. Elevators 26 are used to couple links 30 to lift sub 28, and block 32 is raised.

As block 32 raises lift frame 12 into its deployed position, frame assembly 50 is gradually raised off of the rig floor 54. As this happens, the force of gravity causes frame assembly 50 to pivot at pivoting connection 60, since lift sub 28 is held substantially vertically by elevators 26. Eventually, frame assembly 50 pivots approximately ninety degrees, so that its side (with skids 52) is substantially perpendicular to horizontal surface (rig floor) 54. Lift frame 12 is lifted high enough for elevator links 34, 36 to likewise be suspended perpendicularly to rig floor 54.

At least one embodiment of the invention has been described herein solely for the purposes of illustrating the invention in its various aspects. It is contemplated and to be explicitly understood that various substitutions, alterations, and/or modifications, including but not limited to any such implementation variants and options as may have been specifically noted or suggested herein, including inclusion of technological enhancements to any particular method step or system component discovered or developed subsequent to the date of this disclosure, may be made to the disclosed embodiments of the invention without necessarily departing from the technical and legal scope of the invention as defined in the following claims. In particular, it is contemplated that the present invention may be practiced in the context of a coiled tubing lift frame having a pivoting lift sub as described herein.

Claims

1. A lift frame, comprising:

a frame assembly having a top and a side, said lift frame being adapted to rest with said side on a substantially horizontal surface when undeployed;

a lift sub, pivotally coupled to said top of said frame assembly, said lift sub being substantially vertical and perpendicular to said side when said lift frame is undeployed;

wherein when said lift frame is deployed by elevators engaging said substantially vertical lift sub, said frame assembly pivots under the force of gravity into a deployed position wherein said lift sub is substantially parallel to said side and said side is substantially perpendicular to said horizontal surface.

2. A lift frame in accordance with claim 1, wherein said frame assembly carries a winch assembly.

3. A lift frame in accordance with claim 1, wherein said frame assembly includes at least one skid on said side for supporting said undeployed lift frame.

4. A lift frame in accordance with claim 2, wherein said winch assembly includes a hydraulically driven winch.

5. A lift frame in accordance with claim 1, wherein said frame assembly is adapted to engage elevator links on a bottom of said frame assembly.

6. A lift frame in accordance with claim 1, wherein said lift frame is a coiled tubing lift frame.

7. A method of lifting a lift frame into deployed position above a wellbore, comprising:

providing a frame assembly having a top and a side and having a lift sub pivotally coupled to said top;

preparing for deployment by resting said side of said frame assembly on and parallel to a substantially horizontal surface and pivoting said lift sub into a substantially vertical orientation substantially perpendicular to said horizontal surface;

deploying said lift frame by engaging said lift sub with elevators and lifting said lift frame;

permitting said frame assembly to pivot under the force of gravity as said lift frame is lifted until said side is substantially parallel to said substantially vertical lift sub and substantially perpendicular to said horizontal surface.

8. A method in accordance with claim 7, further comprising:

providing a winch assembly carried by said frame assembly.

9. A method in accordance with claim 8, wherein said winch assembly includes a hydraulically driven winch.

10. A method in accordance with claim 7, wherein said lift frame comprises a coiled tubing lift frame.