Fluid actuated energy charged well service line cutter

A well service line cutter for connection in a well conduit for cutting a line extending therethrough. A housing having a bore through which a service line may extend and the housing is adapted to be connected in a well conduit. An energy chamber for holding pressurized gas is releasably contained by a hydraulic valve mechanism which in turn is held closed by a hydraulic control line extending to the well surface. Release of the hydraulic pressure opens the valve allowing the compressed gas to actuate a piston which moves cutters into the bore for cutting any line in the bore. A biasing mechanism is connected to the piston for returning the piston and cutter to the retracted position and opening the bore after cutting the line. The energy chamber may be charged for a single operation or may be recharged by a line extending to the well surface.

BACKGROUND OF THE INVENTION 
Various types of service tools on service lines are used in oil and/or gas 
wells to perform downhole operations. The service line extends through 
safety valves and may be performing operations thousands of feet below the 
well surface in the well conduit, such as a production or test string. 
However, with the service line extending through the well conduit, the 
safety valve cannot be shut in the event of an emergency, such as a well 
blowout. That is, it is necessary to remove the service wire or cut the 
service wire in order to allow the safety valve to operate or for other 
reasons. 
The present apparatus is directed to providing a well service line cutter 
which may be installed in the well conduit and has a bore as large as the 
internal diameter of the well tubing conduit so as not to interfere with 
the well operation, but which can quickly cut the service wire in the 
event of an emergency, and which can thereafter return to its full open 
position after cutting the service wire so that the wireline tool string 
can be retrieved after the well emergency is overcome. 
SUMMARY 
The present invention is directed to a fluid actuated energy charged well 
service line cutter for connection in a well conduit for cutting a line 
extending therethrough. A cutter includes a housing which has a bore 
through which the line may extend and the housing includes connections for 
attaching the housing in a well conduit. The housing includes an energy 
chamber for holding energy with a valve means connected to the chamber for 
releasing energy from the chamber. A control passageway is connected to 
the valve means and extends to the well surface for actuating the valve 
means. Piston means are provided in the housing in communication with the 
energy chamber through the valve means whereby the piston is actuated when 
the valve means releases energy from the chamber. Cutter means in the 
housing is normally retracted out of the bore, but the cutter means is 
connected to and moved by the piston into the bore for cutting any line in 
the bore. Return means are provided connected to the piston and cutter for 
returning the piston and cutter to the retracted position. 
Still a further object is wherein the energy chamber is a pressurized gas 
chamber. Preferably the gas chamber is an eccentrically shaped chamber for 
economically manufacturing while providing a thick wall for containing a 
pressurized control line. 
Yet still a further object of the present invention is wherein the 
returning means for retracting the piston and cutter means is a biasing 
means such as a spring acting against the piston. 
Still a further object of the present invention is wherein the valve means 
includes a valve closing the energy chamber with a control piston acting 
against the valve for holding the valve initially closed against the force 
of the pressurized gas. The control means includes hydraulic fluid 
initially acting against the control piston for holding the valve closed, 
but allowing the valve to open on a decrease in the hydraulic fluid 
pressure. Thus the cutter is actuated by a decrease in the hydraulic 
pressure which can be usually be accomplished even under emergency 
conditions. 
Still a further object of the present invention is wherein the gas chamber 
includes a supply line to the well surface for charging and recharging the 
gas chamber. 
Still a further object of the present invention is wherein the piston means 
is positioned below the chamber and the cutter means is positioned below 
the piston and the piston means includes a seal which restricts but allows 
the passage of fluid whereby cleaning fluid may be inserted into the 
chamber for cleaning and bypassing the piston and cleaning the parts of 
the cutter by flushing out well fluids. 
Yet a further object of the present invention is wherein the cutter means 
includes first and second coacting cutters. Cam means are provided between 
the first and second cutters and the actuating piston means for moving the 
cutters inwardly and outwardly in response to movement of the actuating 
piston. 
A further object is wherein the cam means include first ears on the first 
cutter and second ears on the second cutter with first and second tracks 
connected to the actuating piston for receiving the first and second ears, 
respectively, and the first and second tracks cross each other. The first 
ears and the first tracks are of a different depth than the depth of the 
second ears and the second tracks for reducing the possibility of the ears 
catching in the wrong track. 
Yet a further object is the provision of a shock absorber in the cutting 
mechanism for overcoming the shock of the pressurized energy actuating the 
cutter. 
Other and further objects, features and advantages will be apparent from 
the following description of a presently preferred embodiment of the 
invention, given for the purpose of disclosure and taken in conjunction 
with the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to the drawings, particularly to FIGS. 1A, 1B and 1C, the 
reference numeral 10 generally indicates the service line cutter of the 
present invention having a housing 12 and a bore 14 therein through which 
a service line (FIG. 1C), usually having a wireline, may extend. The 
housing 12 includes connections such as upper threads 16 and lower threads 
18 for connection in a well conduit 20 such as a production or test string 
extending in an oil and/or gas well. The bore 14 is preferably as large as 
the internal diameter of the well conduit 20 so as not to interfere with 
service operations of fluid flow. 
The housing 12 includes an energy chamber 22 for holding energy which is 
preferably a compressed gas such as nitrogen or it could be other energy 
producing mediums such as explosive, chemical or electrically produced 
energy charges. Compressed gas can be charged into the chamber 22 for a 
one-time operation by means of a port 24 (FIG. 1B) which is closed by plug 
26 or as an alternative and as preferable, through a port 28 (FIG. 1A) 
which is connected to a line 30 leading to the well surface for charging 
and recharging the chamber 22 and also for introducing cleaning fluids 
therein as will be more fully discussed hereinafter. 
Preferably, as best seen in FIG. 7, the energy chamber 22 is eccentrically 
shaped in order to economically manufacture the chamber 22 while providing 
a thick wall for containing the pressurized hydraulic port 44 and line 42 
which will be described hereinafter. 
Referring now to FIGS. 1B, 5 and 6, valve means generally indicated by the 
reference numeral 32 are shown for releasably holding pressure in the 
energy chamber 22. The valve mechanism includes a valve element 34 which 
initially is seated closing the outlet 36 of the chamber 22 and is seated 
by the action of a control piston 38. The control piston 38 is in 
communication with a passageway such as annular passageway 40 which leads 
to tubular passageway 42 which in turn is connected to a port 44 (FIG. 1A) 
which is adapted to be connected to a hydraulic fluid supply such as a 
control line 46 or a casing annulus which extends to the well surface. 
Thus, application of hydraulic fluid pressure through the control 
passageways 42 and 40 acts on the piston 38 to seat the valve element 34 
closing the energy chamber 22. The hydraulic force exerted on the piston 
38 is sufficient to maintain the valve element 34 seated and to withstand 
the pressure in the pressurized gas chamber or energy chamber 22. When 
pressure is reduced in the hydraulic control passageways 42 and 40, the 
gas pressure in the gas chamber 22 will overcome the force of the piston 
38 and move out of the chamber 22 into an annular passageway 46 and into a 
tubular passageway 48. 
Referring now to FIGS. 1B, 3 and 4, actuating piston means 50 is 
telescopically movable in a cylinder 52 and the cylinder is in 
communication with the energy chamber 22 through the valve mechanism 32. 
That is when the valve 32 is opened, pressurized energy from the chamber 
22 flows into the annular passageway 46 and into the tubular passageway 48 
onto the top of the annular piston 50. Preferably, the piston 50 has a 
plurality of turbulent type seals 54 which, while restricting fluid flow 
between the piston 50 and the cyliner 52 sufficiently to cause movement of 
the piston 50, allows fluid to bypass around the piston 50 for cleaning 
purposes and for allowing the retraction of the piston 50 as will be more 
described hereinafter. 
The piston 50 is connected and actuates a cutter assembly generally 
indicated by the reference numeral 56. (FIGS. 1B, 1C, 2 and 3). The cutter 
means includes a housing 58 having first 60, and second 62, semi-circular 
cutters normally retracted in the housing 58 and out of the bore 14 (FIG. 
1C) and actuating links 64 and 66, respectively, for actuating the cutters 
60 and 62, respectively. The actuating links 64 and 66 are connected to a 
circular shoulder 68 on the piston 50 by coacting grooves 70 and the links 
64 and 66 telescopically move in windows 72 and 74, respectively, in the 
housing 58. Therefore, longitudinal movement of the piston 50 carries the 
actuating links 62 and 64 downwardly and upwardly. 
The cutters 60 and 62 are actuated by cam means. Thus, cutter 60 includes 
first ears 76 on each side and cutter 62 includes ears 78 on each side. 
Each of the links 64 and 66 includes a first track 80 and a second track 
82 for coacting with the ears 76 and 78, respectively. Preferably, the 
depth 84 of the ears 76 is greater than the depth 86 of the ears 78. 
Similarly, the coacting track 82 for the ears 78 has less depth for 
receiving the ears 78 than the depth of the track 80 which receives the 
ears 76. Thus, while the tracks 80 and 82 cross each other, the ears 76 
are less likely to catch in the track 82 and the ears 78 are less likely 
to catch in the track 80 because they will follow their own respective 
tracks because of their coacting and different depths. 
Downward movement of the piston 50 carries the links 64 and 66 downwardly. 
The downward movement of the tracks 80 and 82 coacts with the ears 76 and 
78, respectively, to cause the cutters 60 and 62 to be cammed inwardly and 
to overlap, as best seen in FIGS. 2A and 9, for cutting a service line 90. 
After the service line 90 is cut, it is desirable that the cutters 60 and 
62 return to their retracted position for clearing the open bore 14 
whereby the cut wireline tool string can be retrieved after the emergency 
has been controlled. Therefore, biasing means such as a spring 86 is 
provided between the piston 50 and the cutter housing 58 for biasing the 
piston to its initial position, carrying the links 64 and 66 upwardly 
whereby the tracks 80 and 82 move upwardly to coact with the ears 76 and 
78, respectively, to retract the cutters 60 and 62. The spring 86 is able 
to bias the piston 50 upwardly after the line 90 has been cut as the gas 
will bypass the piston 50, pass through the cutter assembly 56 and into 
the bore 14. 
In operation, the cutter 10 is installed in a well conduit 20. Hydraulic 
fluid pressure is then applied to the control passageways 40 and 42, such 
as through the control line 46 leading to the well surface, to act against 
the pilot piston 38 to close the valve element 34. The gas pressure 
chamber 22 may then be pressurized to provide an energy charge in the 
chamber 22. Of course, the force of the hydraulic fluid in te control 
passageways is maintained at a sufficient pressure to contain the gas 
pressure in the chamber 22 until it is needed. In the event of an 
emergency, the hydraulic fluid pressure in the control line 46, passageway 
42 and annular passageway 40 is reduced thereby reducing the force holding 
the hydraulic pilot piston 38 against the valve element 34. On a 
sufficient reduction of hydraulic pressure, the gas in the chamber 22 will 
move the valve element 34 downwardly and the gas will flow out of the 
annular passageway 46, through the tubular passageway 48 and act on the 
piston 50 moving the piston 50 downwardly. Downward movement of the piston 
50 carries the actuating links 64 and 66 downwardly which in turn moves 
the cutting elements 60 and 62 inwardly to cut any line therein. It is 
advantageous to merely relieve the hydraulic pressure in the control line 
46 as this can usually always be done in an emergency. In an emergency it 
is not always possible to apply increased hydraulic pressure down a well 
such as to actuate a double acting hydraulic piston for cutter operation 
as the well controls may fail. Therefore, the present cutter merely uses 
an already pressure charged chamber 22 to actuate the cutter for emergency 
purposes. 
While the line 30 may be omitted by pressurizing the chamber 22 through the 
plug 26 while holding a hydraulic force against the control piston 38, 
such an operation would only provide a one time operation. Preferably, the 
gas control line 30 by being connected between the well surface and the 
energy chamber 22 allows multiple operations of the cutter 10 without 
retrieving the entire well conduit string 20 for replacing or recharging 
the cutter 10. 
It is also to be noted that the piston 50 is positioned below the energy 
chamber 22 and that the cutter mechanism 56 is positioned below the piston 
50. Since the cutters must extend into the bore 14 for cutting any service 
lines such as 90, the cutter mechanism 56, the piston 50 and other parts 
of the valve 10 are subject to corrosive and dirty well fluids. By using 
the line 30 extending to the surface, cleaning fluids may be inserted into 
the energy chamber 22, the hydraulic control fluid pressured reduced, and 
the cleaning fluids will pass downwardly through the valve element 34, 
bypass the piston 50 by virtue of its turbulent seals 54, and through the 
cutter mechanism 56 thereby flushing and cleaning the working parts of the 
cutter 10. 
If desired, a shock absorber may be provided between the piston 50 and the 
cutting mechanism 56 to avoid the shock of the energy released from 
chamber 22. Thus rods 100 are movable in fluid chambers 102 which have 
outlet orifices 104. Downward engagement of the pistons 50 engages the 
rods 100 which are cushioned by the fluid in the chambers 102. 
The present invention, therefore, is well adapted to carry out the objects 
and attain the ends and advantages mentioned as well as others inherent 
therein. While a presently preferred embodiment of the invention is given 
for the purpose of disclosure, numerous changes in the details of 
construction and arrangement of parts will readily suggest themselves to 
those skilled in the art and which are encompassed within the spirit of 
the invention and the scope of the appended claims.