Mechanical release tool for downhole wireline

1 . A wireline cutting tool, comprising:

an elongated tubular body having an upper end, a lower end, and a bore extending from the upper end to the lower end;

a knife housing residing within the bore of the tubular body proximate the upper end, the knife housing having a first end, a second end opposite the first end, and a bore extending from the second end and up through the first end, wherein the bore of the knife housing tapers inwardly moving in a direction from the second end of the knife housing to the first end of the knife housing;

a plunger residing within the bore of the tubular body below the knife housing, the plunger also having a first end and a second end opposite the first end, wherein the plunger is held in place by a first shear member at a first longitudinal location and is configured to slide up the bore of the tubular body in response to shearing the first shear member at a first shear load applied by a wellbore wireline; and

at least one knife residing along the bore of the knife housing, with the at least one knife being held in place by a second shear member at a second longitudinal location above the first longitudinal location and wherein the at least one knife is configured to slide up the bore of the knife housing from the second end of the knife housing towards the first end of the knife housing in response to shearing the second member at a second shear load applied by the wellbore wireline;

and wherein:

the sliding up of the plunger causes the first end of the plunger to engage a lower end of the at least one knife; and

the sliding up of the at least one knife causes the wellbore wireline to be pinched and severed.

2 . The wireline cutting tool of claim 1 , wherein:

the elongated tubular body comprises:

an upper sub having a first end, a second end opposite the first end, and a bore extending from the second end and up through the first end; and

a lower sub having a first end, a second end opposite the first end, and a bore extending from the second end and up through the first end, wherein the first end of the lower sub is connected to the second end of the upper sub;

and wherein:

the knife housing resides within the bore of the upper sub, and

the plunger resides at least partially within the bore of the lower sub.

3 . The wireline cutting tool of claim 2 , wherein:

the first end of the upper sub comprises male threads, while the second end of the upper sub comprises female threads; and

the first end of the lower sub comprises male threads.

4 . The wireline cutting tool of claim 2 , wherein:

the bore of the knife housing and the bore of the plunger are configured to slidably receive the wellbore wireline;

the first shear load is applied to the wellbore wireline by being spooled from a surface, wherein tension is applied to the wellbore wireline that pulls the plunger upward; and

the second shear load is applied by the plunger acting against the at least one knife, also in response to the wellbore wireline being spooled from the surface, such that the plunger pushes the at least one knife upward.

5 . The wireline cutting tool of claim 4 , wherein:

the second shear load is greater than the first shear load.

6 . The wireline cutting tool of claim 5 , wherein:

an upstream portion of the bore of the lower sub holds grease; and

the grease slows the travel of the plunger as it slides up towards the knife housing after the first shear load has been applied to the wellbore wireline.

7 . The wireline cutting tool of claim 5 , further comprising:

an electrical connection sub defining a tubular body, with the tubular body of the electrical connection sub having a shoulder along an outer diameter that abuts the second end of the plunger, and a bore; and

wherein the first shear member comprises at least one shear pin holding the plunger in place along the electrical connection sub.

8 . The wireline cutting tool of claim 7 , wherein:

the wellbore wireline is an electrical wireline;

the electrical connection sub comprises an electrically conductive pin residing within the bore;

the electrically conductive pin is in electrical communication with the electrical wireline;

a lower end of the lower sub is connected to a downhole tool; and

the electrically conductive pin is configured to transmit signals from the electrical wireline through the electrical connection sub and into the downhole tool.

9 . The wireline cutting tool of claim 8 , wherein the downhole tool is a casing collar locator sub, a well logging tool, or a perforating gun assembly.

10 . The wireline cutting tool of claim 8 , wherein:

the electrical wireline comprises armors, with the armors being mechanically connected to the plunger; and

the at least one shear pin holding the plunger in place with the electrical connection sub comprises at least two shear pins, with the at least two shear pins holding the plunger in place and being designed to shear at the first shear load.

11 . The wireline cutting tool of claim 8 , wherein the second shear member comprises at least one shear pin holding the at least one knife in place along the bore of the knife housing, wherein the at least one shear pin holding the knife in place is designed to shear at the second shear load.

12 . The wireline cutting tool of claim 11 , wherein:

the at least one knife comprises a pair of knives disposed on opposing sides of the bore of the knife housing; and

the bore of the knife housing tapers inwardly moving from the second end of the knife housing to the first end of the knife housing; and

the at least one shear pin holding the at least one knife in place comprises at least one shear pin holding each of the two knives in place.

13 . The wireline cutting tool of claim 11 , further comprising:

a first grease port residing along an upper portion of the upper sub, configured to receive grease into the bore of the upper sub above the knife housing; and

a second grease port residing along an upper portion of the lower sub, configured to receive grease into the bore of the lower sub adjacent the plunger.

14 . The wireline cutting tool of claim 11 , wherein:

the first end of the upper sub comprises a tubular neck having male threads along an outer diameter of the tubular neck, and female threads along an inner diameter of the tubular neck;

the inner diameter of the tubular neck is aligned with the bore of the upper sub; and

the wireline cutting tool further comprises a bushing residing within the inner diameter of the tubular neck, frictionally receiving the wellbore wireline, and a nut threaded into the inner diameter of the tubular neck holding the bushing in place within the tubular neck.

15 . A method of cutting a wireline within a wellbore, comprising:

providing a wireline cutting tool, the wireline cutting tool comprising:

an elongated tubular body;

a knife housing residing within the tubular body proximate an upper end;

at least one knife residing within the knife housing;

a plunger residing within the tubular body proximate a lower end; and

an electrical connection sub;

releasably connecting the plunger to the electrical connection sub;

connecting the electrical connection sub to a downhole tool below the elongated tubular body;

connecting the downhole tool to the elongated tubular body;

running an electric wireline through a bore of each of the knife housing and the plunger;

mechanically and electrically connecting a lower end of the electric wireline to the electrical connection sub;

pulling the wireline cutting tool, the electrical connection sub, and the downhole tool out of a wellbore together by spooling the electric wireline from a surface;

upon detecting that the downhole tool has become stuck in the wellbore, further spooling the wireline at a first shear load, causing the plunger to separate from the electrical connection sub and travel up a bore of the elongated tubular body, such that the plunger shoulders out against a lower end of the at least one knife; and

still further spooling the wireline at a second shear load, causing the at least one knife to travel up the bore of the knife housing and sever the electric wireline within the wellbore, leaving the downhole tool in place within the wellbore;

and wherein the second shear load is greater than the first shear load.

16 . The method of claim 15 , further comprising:

still further spooling the wireline in order to remove the wireline from the wellbore.

17 . The method of claim 15 , wherein:

the elongated tubular body comprises:

an upper sub having a first end, a second end opposite the first end, and a bore extending from the second end and through the first end; and

a lower sub having a first end, a second end opposite the first end, and a bore extending from the second end and through the first end, wherein the first end of the lower sub is connected to the second end of the upper sub;

and wherein:

the knife housing resides within the bore of the upper sub, and has a first end, a second end opposite the first end, and wherein the bore extends from the second end and through the first end, and with the bore of the knife housing tapering inwardly in a direction from the second end of the upper sub up to the first end; and

the plunger resides at least partially within the bore of the lower sub, and also has a first end, and a second end opposite the first end.

18 . The method of claim 17 , wherein the wireline cutting tool further comprises:

at least one shear pin holding the plunger in place along the electrical connection sub up to the first shear load; and

at least one shear pin holding the at least one knife in place along the bore of the knife housing up to the second shear load.

19 . The method of claim 18 , wherein the downhole tool is a casing collar locator sub, a well logging tool, or a perforating gun assembly.

20 . The method of claim 18 , wherein:

the at least one shear pin holding the plunger in place comprises at least two shear pins, with the at least two shear pins holding the plunger in place being fabricated to shear at the first shear load;

the at least one knife comprises a pair of knives disposed on opposing sides of the bore of the knife housing; and

the at least one shear pin holding the at least one knife in place comprises at least one shear pin holding each of the two knives in place, respectively, with the shear pins holding the two knives in place being fabricated to shear at the second shear load.

21 . The method of claim 20 , wherein the wireline cutting tool further comprises:

a first grease port residing along a body of the upper sub in fluid communication with the bore of the upper sub above the knife housing;

a second grease port residing along a body of the lower sub; and

a grease pocket residing along an upstream portion of the lower sub that receives grease from the second grease port;

and the method further comprises:

injecting grease through the first grease port to facilitate movement of the electric wireline through the upper sub; and

injecting grease through the second grease port to provide resistance to the plunger as the plunger slides up the bore of the lower sub towards the two knives after the first shear load has been reached.

22 . The method of claim 21 , wherein:

the first end of the upper sub comprises a tubular neck having male threads along an outer diameter of the tubular neck, and female threads along an inner diameter of the tubular neck;

the inner diameter of the tubular neck is aligned with the bore of the upper sub; and

the wireline cutting tool further comprises a bushing residing within the inner diameter of the tubular neck, frictionally receiving the wireline, and a nut threaded into the inner diameter of the tubular neck holding the bushing in place within the tubular neck.

23 . The method of claim 21 , wherein:

the electrical wireline comprises one or more armors wrapped around a central conductive wire; and

the one or more armors are tied into the plunger.

24 . The method of claim 17 , further comprising:

running a fishing tool into the wellbore;

landing the fishing tool onto an upper end of the upper sub; and

pulling the wireline cutting tool and connected downhole tool out of the wellbore.