Patent Application
20180128072
The invention relates generally to fishing tools and methods for removing objects from a wellbore.
Fishing tools are used to remove stuck objects from a wellbore. Typical fishing tools include a mechanical latch or set of collets which are intended to engage a lip or similar structure on a stuck object, or fish, to be removed.
The invention provides a fishing tool design which is useful for removing fish having irregular shapes and/or a lack of gripping structures to which a conventional fishing tool might be secured. An exemplary fishing tool is described which includes an overshot housing which defines an interior chamber. An inflatable gripping bladder is located within the overshot housing. In an uninflated condition, the overshot housing can be disposed over and in a radially surrounding relation to the fish without interference from the gripping bladder. When the gripping bladder is in an inflated condition, it grips a portion of the stuck fish. Inflation fluid is transmitted from surface through a running string and fills the bladder to engage the fish.
In described embodiments, inflation fluid is flowed from the running string to an axial fluid pathway within the overshot housing. Fluid flow passages transmit the inflation fluid from the axial fluid pathway to an annular intermediate space which is defined radially between the bladder element and the overshot housing.
In certain embodiments, a piston member is moveably disposed within the axial fluid pathway. The piston member includes an axial bore along its length. Lateral flow ports are disposed through the piston member. The piston member is moveable between an upper position, wherein the lateral flow ports are blocked against flow, and a lower position, wherein the lateral flow ports are open to permit inflation fluid to flow from the axial bore to the fluid flow passages and into the annular intermediate space to inflate the bladder element. Inflation of the bladder element is preferably accomplished by landing a ball or plug within a ball seat formed within the axial bore of the piston member. Fluid pressure behind the ball or plug will rupture frangible members which retain the piston member in its upper position and shift the piston member to its lower position. Preferably, a flapper valve is located within the axial bore of the piston member and prevents inflation fluid from exiting the annular intermediate space.
In preferred embodiments, the inflatable bladder presents a roughened radially interior engagement surface which will contact and secure the fish when the bladder is inflated. Inflation fluid is transmitted from surface through a running string and fills the bladder to engage the fish.
In operation, a fishing tool constructed in accordance with the present invention is incorporated into a fishing arrangement with a running string. The fishing arrangement is run into a wellbore. The overshot housing of the fishing tool is disposed around a portion of a fish to be removed from the wellbore. The bladder element of the fishing tool is then inflated to capture the fish in a gripping relation. Thereafter, the fishing arrangement and fish are pulled out of the wellbore.
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:
In
A fluid pump 28 and associated fluid source 30 are located at surface 14. The fluid pump 28 is associated with the running string 22 to flow inflation fluid from the fluid source 30 down through the flowbore 26 when desired. The fluid source 30 may include drilling fluids, oil, water or other liquids. In other embodiments, the fluid source 30 may comprise compressed air or other gases.
Referring now to
The overshot portion 34 includes a generally cylindrical overshot housing 38 with a tapered transition 40 to the neck portion 32. An interior chamber 42 is defined within the overshot housing 38. The interior chamber 42 has an upper bulkhead 44 and an open lower end 46. An inflatable bladder element 48 is disposed within the overshot housing 38 and has an annular configuration.
An axial fluid pathway 50 is defined within the neck portion 32 and will align with the fluid flowbore 26 of the running string 22 when the fishing tool 24 is affixed to the running string 22. Fluid flow passages 52 extend from the axial fluid pathway 50 to an annular intermediate space 54 between the bladder 48 and the overshot housing 38. A flow restriction 56 is formed in the axial fluid pathway 50. The flow restriction 56 has a reduced diameter with respect to the diameter of the axial fluid pathway 50.
A piston member 58 resides within the axial fluid pathway 50. The piston member 58 is axially moveable within the fluid pathway 50, but initially, as
An axial bore 62 is defined along the length of the piston member 58 and permits fluid flow axially through the piston member 58. Preferably, a ball seat 64 is formed within the lower end of the bore 62. A flapper valve 66 is also preferably located within the axial bore 62. The flapper valve 66 is moveable between an open position (
The bladder element 48 includes an annular elastomeric sheet 68 with upper and lower metallic end rings 70, 72, respectively, which are affixed to the sheet 68. Preferably, the lower end ring 72 is slidably disposed within an annular channel 74 that is formed within the overshot housing 38. The annular sheet 68 is deformable.
In operation, the fishing arrangement 20 is run into the wellbore 10 as illustrated by
In order to engage the fish 16, a plug is dropped into the flowbore 26 of the running string 22. The plug will typically take the form of a ball 76, but may have other shapes. Ball 76 lands upon the ball seat 64, as illustrated in
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.
