U.S. patent application number 10/294473 was filed with the patent office on 2004-05-13 for propellant-powered fluid jet cutting apparatus and methods of use.
Invention is credited to Arrell, John A. JR., LeCompte, Brian W., Slade, William J..
Application Number | 20040089450 10/294473 |
Document ID | / |
Family ID | 32229800 |
Filed Date | 2004-05-13 |
United States Patent
Application |
20040089450 |
Kind Code |
A1 |
Slade, William J. ; et
al. |
May 13, 2004 |
Propellant-powered fluid jet cutting apparatus and methods of
use
Abstract
Apparatus providing at least one high pressure fluid cutting jet
and methods employing same. A gas generator powered by a
combustible propellant supplies pressurized gas to propel a fluid
through at least one nozzle to form a cutting jet suitable for
cutting materials such as structural elements. Furthermore, nozzles
may be configured to rotate in order to circumferentially sever a
tubular structural element. Two or more fluid cutting jets may be
configured to intersect, and may be configured to intersect
proximate to at least a portion of the periphery of the tubular
structural element to be severed.
Inventors: |
Slade, William J.; (Newark,
DE) ; LeCompte, Brian W.; (Havre De Grace, MD)
; Arrell, John A. JR.; (Lincoln University, PA) |
Correspondence
Address: |
TRASK BRITT
P.O. BOX 2550
SALT LAKE CITY
UT
84110
US
|
Family ID: |
32229800 |
Appl. No.: |
10/294473 |
Filed: |
November 13, 2002 |
Current U.S.
Class: |
166/298 ;
166/223; 166/55.7 |
Current CPC
Class: |
E21B 41/0078 20130101;
B26F 3/004 20130101; E21B 29/002 20130101; B24C 3/325 20130101;
B24C 1/045 20130101; B24C 11/005 20130101 |
Class at
Publication: |
166/298 ;
166/055.7; 166/223 |
International
Class: |
E21B 029/10 |
Claims
What is claimed is:
1. An apparatus for severing a structural element, comprising: a
gas generator in communication with a pressure vessel and
comprising a combustible propellant formulated, upon initiation, to
supply pressurized gas to the pressure vessel; a fluid within the
pressure vessel; and a nozzle assembly in communication with the
pressure vessel, the nozzle assembly including at least one nozzle
configured for producing a fluid cutting jet.
2. The apparatus of claim 1, wherein the fluid includes an additive
selected from the group consisting of glass, garnet, silica sand,
cast iron, alumina, and silicon carbide.
3. The apparatus of claim 1, further comprising a pressure relief
element for releasing gas from the pressure vessel when pressure
therein substantially exceeds a preselected pressure magnitude.
4. The apparatus of claim 3, wherein the pressure relief element is
configured and sized to release gas from the pressure vessel when
the pressure therein exceeds 50,000 psi.
5. The apparatus of claim 3, wherein the pressure relief element is
configured and sized to release a gas flow of about an excess of
the gas generator gas volume production rate over a total fluid
volume flow rate of the at least one nozzle at a selected
pressure.
6. The apparatus of claim 5, wherein the selected pressure is the
preselected pressure magnitude.
7. The apparatus of claim 1, wherein the at least one nozzle
comprises a plurality of nozzles.
8. The apparatus of claim 7, wherein at least two nozzles of the
plurality of nozzles are configured, sized, and located to create
fluid cutting jets that intersect at a selected location exterior
to the apparatus.
9. The apparatus of claim 8, wherein the selected location
comprises a location proximate at least a portion of the outer
periphery of the structural element to be severed.
10. The apparatus of claim 1, wherein the at least one nozzle is
configured, sized, and located to produce a substantially
circumferential fluid cutting jet.
11. The apparatus of claim 10, wherein the at least one nozzle
configured, sized, and located to produce a substantially
circumferential fluid cutting jet comprises a plurality of nozzles,
each configured, sized, and located to produce a substantially
circumferential fluid cutting jet.
12. The apparatus of claim 11, wherein at least two nozzles of the
plurality of nozzles, each configured, sized, and located to
produce a substantially circumferential fluid cutting jet are
configured, sized, and located to create substantially
circumferential fluid cutting jets that intersect at a selected
location exterior to the apparatus.
13. The apparatus of claim 12, wherein the selected location
comprises a region proximate at least a portion of an outer
periphery of the structural element to be severed.
14. The apparatus of claim 1, wherein the nozzle assembly is
configured to be rotatable about its longitudinal axis.
15. The apparatus of claim 14, wherein the at least one nozzle
comprises a plurality of nozzles.
16. The apparatus of claim 15, wherein at least two nozzles of the
plurality of nozzles are configured, sized, and located to create
fluid cutting jets that intersect at a selected location exterior
to the apparatus.
17. The apparatus of claim 16, wherein the at least two nozzles
create fluid cutting jets that intersect proximate at least a
portion of the outer periphery of the structural element to be
severed.
18. The apparatus of claim 14, wherein the at least one nozzle is
configured to produce a fluid cutting jet that creates a reaction
force that causes a rotational moment about the longitudinal axis
of the nozzle assembly.
19. The apparatus of claim 1, wherein the at least one nozzle
comprises a movable nozzle.
20. The apparatus of claim 19, wherein the at least one movable
nozzle comprises a plurality of movable nozzles.
21. The apparatus of claim 20, wherein at least two movable nozzles
of the plurality of movable nozzles are configured, sized, and
located to create fluid cutting jets that intersect at a selected
location exterior to the apparatus.
22. The apparatus of claim 21, wherein the selected location
comprises a location proximate at least a portion of an outer
periphery of the structural element to be severed.
23. The apparatus of claim 1, further comprising an anchoring
mechanism for preventing motion in at least one degree of freedom
of the at least one nozzle with respect to a bore of the structural
element to be severed.
24. The apparatus of claim 23, wherein the anchoring mechanism for
preventing motion in at least one degree of freedom of the at least
one nozzle is configured, sized, and positioned to substantially
align a longitudinal axis of the nozzle assembly with a
longitudinal axis of the bore of the material to be severed.
25. The apparatus of claim 24, wherein the nozzle assembly is
configured to be rotatable about its longitudinal axis.
26. The apparatus of claim 24, wherein the at least one nozzle is
configured, sized, and located to produce a substantially
circumferential fluid cutting jet.
27. The apparatus of claim 1, further comprising an energy storage
device in communication with the pressure vessel.
28. The apparatus of claim 1, further comprising a separation
element defining a gas-containing volume and a fluid-containing
volume associated with the pressure vessel.
29. The apparatus of claim 28, wherein the separation element
comprises a membrane.
30. The apparatus of claim 28, wherein the separation element
comprises a piston.
31. The apparatus of claim 30, wherein the piston comprises an
annular piston.
32. The apparatus of claim 1, further including an initiator for
the combustible propellant, located in proximity thereto.
33. The apparatus of claim 32, further including a radio frequency
receiver operably coupled to the initiator and a radiofrequency
transmitter located remotely from the radio frequency transmitter
for providing an initiation signal thereto.
34. The apparatus of claim 33, wherein the radio frequency
transmitter is carried by the apparatus.
35. The apparatus of claim 34, wherein the radio frequency
transmitter is configured to receive a coded firing signal to
enable the initiation signal.
36. A method for severing a structural element, comprising:
providing a pressure vessel; disposing a fluid within the pressure
vessel; initiating a propellant to combustion; and using gas
generated by combustion of the propellant to force the fluid out of
the pressure vessel and through at least one nozzle to form at
least one fluid cutting jet.
37. The method of claim 36, further including disposing a fluid
including an additive selected from the group consisting of glass,
garnet, silica sand, cast iron, alumina, and silicon carbide within
the pressure vessel.
38. The method of claim 36, further comprising releasing gas from
the pressure vessel when the pressure therein exceeds a preselected
magnitude of pressure.
39. The method of claim 38, wherein releasing gas from the pressure
vessel when the pressure therein exceeds a preselected magnitude of
pressure comprises releasing gas from the pressure vessel when the
pressure therein exceeds 50,000 psi.
40. The method of claim 38, wherein releasing gas from the pressure
vessel when the pressure therein exceeds a preselected magnitude of
pressure comprises releasing gas flow of about an excess of a gas
volume production rate over a total fluid volume flow rate of the
at least one nozzle at a selected pressure.
41. The method of claim 40, wherein releasing gas flow of about the
excess of the gas generator gas volume production rate over the
total fluid volume flow rate of the at least one nozzle at a
selected pressure comprises releasing gas flow of about the excess
of the gas volume production rate over the total fluid volume flow
rate of the at least one nozzle at the preselected magnitude of
pressure.
42. The method of claim 36, wherein the at least one nozzle
comprises a plurality of nozzles and the at least one fluid cutting
jet comprises a plurality of fluid cutting jets.
43. The method of claim 42, further comprising orienting at least
two of the plurality of fluid cutting jets to intersect at a
selected location.
44. The method of claim 43, further comprising orienting the at
least two fluid cutting jets to intersect proximate at least a
portion of a side of the structural element opposite origin points
of the at least two fluid cutting jets.
45. The method of claim 36, wherein forming the at least one fluid
cutting jet comprises forming a substantially circumferential fluid
cutting jet.
46. The method of claim 36, wherein forming at least one fluid
cutting jet comprises forming a plurality of substantially
circumferential fluid cutting jets.
47. The method of claim 46, wherein forming a plurality of
substantially circumferential fluid cutting jets comprises
orienting at least two substantially circumferential fluid cutting
jets to intersect at a selected location.
48. The method of claim 47, wherein orienting the at least two
substantially circumferential fluid cutting jets to intersect at a
selected location comprises orienting the at least two
substantially circumferential fluid cutting jets to intersect
proximate at least a portion of an outer periphery of the
structural element from within which the circumferential fluid
cutting jets emanate.
49. The method of claim 36, further including rotating the at least
one nozzle about a longitudinal axis of a bore of the structural
element.
50. The method of claim 49, wherein forming at least one fluid
cutting jet comprises forming a plurality of fluid cutting
jets.
51. The method of claim 50, further comprising orienting at least
two fluid cutting jets of the plurality of fluid cutting jets to
intersect at a selected location.
52. The method of claim 51, further comprising orienting the at
least two fluid cutting jets to intersect proximate at least a
portion of a side of the structural element opposite origin points
of the at least two fluid cutting jets.
53. The method of claim 49, wherein forming at least one fluid
cutting jet comprises orienting the at least one fluid cutting jet
to create a reaction force causing a rotational moment about the
longitudinal axis of the bore of the structural element.
54. The method of claim 36, further including moving the at least
one fluid cutting jet.
55. The method of claim 54, wherein moving the at least one fluid
cutting jet comprises moving a plurality of fluid cutting jets.
56. The method of claim 55, wherein forming a plurality of
substantially circumferential fluid cutting jets comprises
orienting at least two substantially circumferential fluid cutting
jets to intersect at a selected location.
57. The method of claim 56, wherein orienting the at least two
substantially circumferential fluid cutting jets to intersect at a
selected location comprises orienting the at least two
substantially circumferential fluid cutting jets to intersect
proximate at least a portion of an outer periphery of the
structural element from within which the circumferential fluid
cutting jets emanate.
58. The method of claim 36, further comprising anchoring the at
least one nozzle in at least one degree of freedom with respect to
a bore of the structural element.
59. The method of claim 58, wherein anchoring the at least one
nozzle in at least one degree of freedom comprises anchoring the at
least one nozzle to substantially align a longitudinal axis of a
nozzle assembly including the at least one nozzle with a
longitudinal axis of the bore of the structural element.
60. The method of claim 58, further comprising rotating the nozzle
assembly about a longitudinal axis of the bore of the structural
element.
61. The method of claim 58, wherein forming at least one fluid
cutting jet comprises forming at least one substantially
circumferential fluid cutting jet.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates generally to apparatus and
methods for severing tubing, casing, drill pipe, and other
structural elements and materials. More specifically, the present
invention relates to an apparatus and method for cutting structural
elements with a fluid cutting jet powered by a solid
propellant-powered gas generator.
[0003] 2. State of the Art
[0004] As known in the art, one of the first steps in oil and gas
production is drilling a wellbore, or borehole, into the
hydrocarbon-bearing formation. Boreholes are commonly drilled into
subterranean formations by applying rotary motion to a cutting
instrument, or rotary drill bit, by way of one or more of a rotary
table, top drive, drilling rig, or downhole motor, which penetrates
and removes the subterranean formation material. The rotary drill
bit is generally either a fixed cutter (drag) or rolling cone
(tri-cone) type drill bit, as known in the art, depending on the
formation, the drilling equipment, and drilling conditions. The
drill bit is threadedly connected to a pipe structure comprised of
threadedly connected pipe sections that extend upwardly to the
surface of the formation. The pipe structure, together with other
components which may be attached to the bottom end or in between
the pipe sections for drilling the borehole are collectively called
a drillstring.
[0005] Some subterranean formations may be sensitive to the
drilling process, or they may lack mechanical integrity when a
borehole is drilled therein due to the pressures experienced within
the borehole, or other conditions within the formation. Such a
formation may occasionally swell, i.e., dilatation of a rock
formation due to changing pressure, or slough into the open
borehole during drilling. If the sloughing or swelling is severe
enough, the drillstring may become lodged in the borehole in such a
way as to prevent further drilling, or removal of the drillstring
from the borehole by applying a force at the end of the drillstring
that exits the surface of the formation.
[0006] If it is determined that removal of the drillstring is not
possible by applying a force at the end of the drillstring that
exits the formation because it has become stuck, it is often
desirable to attempt to remove as much of the drillstring as
possible from the borehole. Removal of the greatest possible amount
of drillstring from the borehole both reduces the amount of
drillstring abandoned in the borehole, and reduces the amount of
borehole that would have to be drilled again if the drilling
contractor should choose to attempt to redrill the borehole to the
same target subterranean formation.
[0007] After a borehole is successfully drilled to the target
subterranean formation and the drill string is removed, a
protective pipe called a liner or casing may be typically set into
the borehole to a predetermined depth. The casing is generally
steel and is used to form a hydraulic seal between different
subterranean formations penetrated by the borehole as well as to
ensure the integrity of the borehole, i.e., so that it does not
collapse. Another reason for installing casing is to isolate
different geologic zones, e.g., an oil-bearing zone from an
undesirable water-bearing zone. Sometimes while the casing is being
lowered into the borehole it can become stuck from some of the same
causes which may cause the drillstring to become stuck. In order to
complete the borehole it is typically necessary to remove as much
casing as possible and redrill the borehole to the depth of the
target formation.
[0008] Once the casing is inserted into the borehole, it is then
cemented in place, by pumping cement into the gap between casing
and borehole (annulus). By placing a casing in the borehole and
cementing the casing to the borehole, then selectively forming
holes in the casing, one can effectively isolate certain portions
of the subsurface, for instance to avoid the co-production of water
along with oil. However, it may be desired to remove casing from
boreholes that have produced substantially all of the economically
recoverable oil and gas from the subterranean formations penetrated
by those boreholes, in an attempt to salvage some of the casing
before plugging and abandoning the borehole.
[0009] In still other boreholes, an additional pipe may be inserted
coaxially inside the casing. The additional pipe is called a tubing
string. The tubing string generally serves the purpose of
increasing the velocity of fluids flowing up the borehole so that
more dense components of the fluid, such as water, will become
entrained in the fluid flow and be carried to the earth's surface,
thereby reducing hydrostatic pressure opposing the entry of fluids
into the borehole. When a borehole having a tubing string is to be
recompleted into a different formation or is to be abandoned, it is
usually desirable to remove the tubing string from the borehole.
Occasionally the tubing string may become stuck in the borehole,
thereby preventing the removal of the tubing string from the
borehole.
[0010] In all of the situations described herein in which a tubular
structural element, which may be termed "pipe" for convenience,
becomes stuck in or is desired to be removed from the borehole, it
may prove necessary to sever the pipe above the point at which it
is stuck in order to enable recovery of the portion of the pipe
which is not stuck.
[0011] Conventional mechanical cutting tools for removing stuck
pipe from a borehole have been developed and are relatively well
known in the art. Various types of downhole cutting and milling
tools have been utilized in the oil and gas industry for removing
components from within wellbores including cutting existing
casings, for boring through permanently set packers and for
removing loose joints of pipes. Typically, a plurality of cutting
blades having a suitable hard cutting material, such as carbide,
are placed on a body at spaced intervals extending outwardly
therefrom. The tool may be placed at a desired location within the
wellbore and rotated to cut the intended material, by using the
weight on the tool and the rotational speed to determine the
cutting speed. One disadvantage to mechanical cutters is that the
cutting material wears and must be replaced periodically. In such
cases, the cutting tool must be retrieved from the borehole, which
results in lost time for the well and/or rig and, thus, increases
costs.
[0012] The conventional practice in chemically severing downhole
tubular structural elements is to arrange the cutting ports in the
cylindrical wall of the cutting head, as disclosed for example in
U.S. Pat. No. 4,125,161 to Chammas. The Chammas cutting tool
incorporates an anchor sub having a plurality of wedges pivoted on
an actuating piston near the upper end of the tool in which gas
from a propellant charge displaces an actuating piston to cam the
wedges outwardly against the tubing string or other object to be
cut. The gas from the propellant charge is employed to force the
cutting chemical into contact with a reactant material and then
outwardly through the cutting ports. Disadvantageously, as with all
chemical cutters, highly reactive and potentially dangerous
chemicals (such as bromine trifluoride, a highly reactive acid) are
expelled into the borehole in order to cut the tubular structural
element and often must be subsequently removed from the borehole.
Furthermore, conventional chemical cutting tools are limited to
cutting tubular structural elements having a wall thickness of
about 0.45 inch or less, and must be maintained at a maximum
clearance of about 0.35 inch from the inner wall of the tubular
structural element.
[0013] Jet cutters are explosive cutting tools known in the art for
severing pipe in a borehole. A jet cutter comprises a charge of
high explosive compound in the form of a "shaped" charge configured
to, upon detonation, create a "jet" of high pressure, high
temperature gas which is directed circumferentially from inside the
pipe to cut the pipe. A jet cutter may be actuated by an
electrically powered initiator such as a blasting cap. Further, a
jet cutter may also utilize thermite or other relatively sensitive
explosives. One example of is described as a "JRC Drill Collar
Severing Tool," offered by Jet Research Center, Inc., Alvarado,
Tex. The severing tool comprises a plurality of high explosive
charges adapted to detonate is a coordinated sequence to generate
an extremely powerful cutting jet.
[0014] In addition, because the jet cutter typically utilizes
initiation of a short duration, powerful explosive charge, reactive
forces may be generated on the cutting tool by the detonation, and
may cause the tool to move within the borehole, cables suspending
the tool to become tangled, or the cutter and associated equipment
to become damaged. Further, it may be difficult to tailor the
output of a jet cutter to properly contact the desired area of the
tubular component in which it is suspended.
[0015] In addition, there have been attempts to utilize fluid
cutting jets for removing stuck drill pipes or casings from a
borehole. U.S. Pat. No. 5,381,631 to Raghaven et al. describes a
tool for cutting metal casings by way of an ultrahigh-pressure
abrasive fluid cutting jet. An ultrahigh pressure pump generates an
ultrahigh-pressure fluid stream that may range from 20,000-100,000
psi. that is conveyed by a first feed line to a jet manifold.
Further, a second feed line to the jet manifold conveys abrasives
that are mixed with the ultrahigh-pressure fluid stream, thereby
generating an abrasive fluid stream. The abrasive fluid stream
exits the mixing chamber and ultimately exits a nozzle block,
forming an abrasive fluid cutting jet for cutting casing
elements.
[0016] U.S. Pat. No. 6,155,343 to Nazzal et al. describes a cutting
tool that includes a cutting end that is adapted to discharge a
high pressure fluid therefrom. A power unit including a series of
pressure stages that successively increase the pressure of the
fluid until a desired level of pressure has been reaches are used
to power the cutting tool. A "pulsar" to pulse the pressure of the
fluid before it is discharged through the nozzle as well as an
imaging device are also described.
[0017] Both the cutting tool of Nazzal et al. and the cutting tool
of Raghaven et al. include relatively complicated fluid
pressurizing machinery for creating a suitable fluid pressure for
the cutting tool to function effectively. In addition, the
machinery to create suitable pressure sources for the Raghaven and
Nazzal inventions may not be easily configured for supplying
different pressures for different operating conditions or for
cutting different materials. Further, while it would be desirable
to effectuate fluid jet cutting in remote locations where power is
not readily available and transportability becomes a significant
issue, the state of the art fails to provide such a capability.
[0018] In view of the foregoing, a cutting tool utilizing high
pressure fluid which improves on conventional cutting tools and
eliminates some of their respective disadvantages would be
desirable.
BRIEF SUMMARY OF THE INVENTION
[0019] The present invention comprises an apparatus for cutting
into, and through, a structural element, including without
limitation cutting through the wall of a tubular structural
element, using at least one high pressure fluid cutting jet and
methods employing same. Fluid cutting jet, as used herein, refers
to a fluid jet which possesses cutting ability due, in part, to its
velocity and/or its momentum.
[0020] More specifically, the apparatus of the present invention
comprises a gas generator powered by a propellant, such as a
combustible propellant, that supplies pressurized gas to propel a
fluid contained in a pressure vessel through at least one nozzle to
form a cutting jet. The gas generator of the present invention may
be comprised of relatively simple components that generate the
pressure required to create a fluid cutting jet. In addition, the
gas generator of the present invention may be configured so that it
may be reused by reloading the tool with a solid propellant
cartridge and refilling the pressure vessel with fluid. The solid
propellant may comprise a composite fuel and oxidizer, and may be
formed or cast into a tube as known in the art. The propellant may,
by way of example only, comprise a Class 1.3 propellant. Exemplary
types of suitable propellants for the gas generator include,
without limitation, composite solid propellants, double base solid
propellants, liquid propellants and pyrotechnic materials. Also,
the gas generator may include an actuation device for igniting the
solid propellant, as known in the art. A remote, wireless actuation
system may be optionally employed.
[0021] Generally, the propellant-powered fluid jet cutting
apparatus of the present invention, being self-contained may, in
one embodiment, be suitably configured to be lowered into a tubular
structural element, either by a drill string or, more preferably,
by a wireline or coiled tubing string, as known in the art, to a
location within a borehole just above the point where it is
believed or has been determined that the tubular structural element
is stuck within the borehole. Alternatively, in the case of removal
for salvaging, such as casing in an abandoned borehole, the
propellant-powered fluid jet cutting apparatus of the present
invention may be lowered to a desired depth. Further and
optionally, an anchoring mechanism may be used to fix the position
of the propellant-powered fluid jet cutting apparatus during use
and may be used in conjunction with a centering device for
centering the propellant-powered fluid jet cutting apparatus within
the tubular structural element to be cut by the propellant-powered
fluid jet cutting apparatus.
[0022] In one embodiment of the propellant-powered fluid jet
cutting apparatus of the present invention, an electrical signal
may be generated and transmitted from a remote location to cause
the propellant to ignite within the gas generator. As the
propellant bums, the gases that are produced pressurize a pressure
vessel containing fluid in communication with the propellant gas
generator. The pressure vessel containing fluid may contain a gas
as well as a fluid and each may be physically separated from one
another by way of a separation element, e.g., a piston or a
membrane, so that the gases produced by the gas generator do not
contact or mix with the fluid within the pressure vessel or visa
versa. In addition, an energy storage device such as a piston or
bladder accumulator may be used to store the pressure produced via
the gas generator and may be installed on either side of the
separation element. Use of such an energy storage device may
facilitate prolonged release of pressure and thus propulsive energy
for driving the cutting fluid. Attached to the pressure vessel is a
nozzle assembly comprising at least one nozzle configured, under
suitable supply pressure, to produce a fluid cutting jet for
cutting through tubular metal structures. A burst disc may prevent
the pressurized fluid from exiting the pressure vessel and passing
to the nozzle assembly until a threshold pressure above which
causes the burst disc to rupture is reached. In addition, a
pressure relief element may be installed between the gas generator
and the separation element to prevent the gas generator from
over-pressurizing the pressure vessel.
[0023] The nozzle assembly may comprise a plurality of nozzles and,
if intended for cutting a tubular structural element, may be
configured, sized, and located to rotate as high pressure fluid
exits therefrom. Rotation may be desirable to circumferentially
equalize the cutting of a tubular structural element. "Equalizing
the cutting" as used herein means that any unequal cutting that may
occur because of differences in the nozzles or in the pressure
distribution within the nozzle assembly may be equalized
periodically by exposing the interior surface of the tubular
structural element to be cut to all of the nozzles, thereby
equalizing the overall cutting process of the tubular structural
element. Rotation of the nozzle assembly may be caused by way of a
mechanical system, i.e., a gear system, or may be powered by the
pressure or flow of the fluid in the pressure vessel or gas
escaping from the relief element to drive a rotor, an
electric/hydraulic motor, or by way of reactive forces of the high
pressure cutting jets. In addition, due to the relatively high
reactive forces created by the cutting jets, the nozzles of the
nozzle may be located, sized and oriented so as to eliminate
unwanted moments on the nozzle assembly. The nozzle assembly may
further comprise dynamic seals to accommodate rotation thereof.
[0024] Alternatively, the entire propellant-powered fluid jet
cutting apparatus may be rotated by a motor, drill string, or as
otherwise known in the art, without independent rotation of the
nozzle assembly. However, in the case of a rotating nozzle
assembly, it may be advantageous to rotate the entire
propellant-powered fluid jet cutting apparatus in the opposite
direction as the rotation of the nozzle assembly, so that the
rotation of the nozzle assembly with respect to the tubular
structural element to be cut may be adjusted. For instance, the
nozzle assembly may rotate relatively quickly and by simultaneously
rotating the propellant-powered fluid jet cutting apparatus in the
opposite direction, the nozzle assembly rotation with respect to
the surface to be cut may be slowed. Conversely, rotation of the
propellant-powered fluid jet cutting apparatus in the direction of
rotation of the nozzle assembly may increase the speed of the
cutting jets in relation to the tubular structural element to be
cut.
[0025] Alternatively, the nozzle assembly, the nozzles, or both,
may be configured to cut a desired area without rotation. Nozzles
may be focused at a particular area, or may be positioned to
overlap along the circumference of the tubular structural element
to be cut. Furthermore, a substantially circumferential fluid
cutting jet may be created so that rotation of the nozzle assembly
may be unnecessary. Similarly, the nozzle assembly may be
configured for cutting a nontubular structural element such as a
steel plate, using a series of suitably located nozzles or a drive
assembly to move the nozzle assembly in a desired path, or
both.
[0026] The nozzle assembly may also comprise one or more nozzles
attached to the nozzle assembly and movable with respect thereto so
that different diameters of tubular structural elements may be cut.
A movable nozzle may be rigidly attached and adjustable in position
and orientation as known in the art, i.e., bolts, fixtures, pins,
etc. A movable nozzle may be hingedly or pivotably attached to the
nozzle assembly so that during rotation of the nozzle assembly, the
nozzle is biased radially outward until the nozzle, a roller, or
another contact element touches the inner diameter of the tubular
structural element to be cut. Thus, it may be advantageous to
employ a movable nozzle to achieve a desired standoff or distance
between the nozzle exit and the tubular structural element to be
cut.
[0027] Moreover, the propellant-powered fluid jet cutting apparatus
of the present invention may include a cutting enhancement material
as part of the fluid cutting jet produced by a nozzle in the nozzle
assembly to further enhance the cutting capability of the fluid
cutting jet. The cutting enhancement material may comprise an
abrasive such as glass, garnet, silica sand, cast iron, alumina,
silicon carbide or other suitable medium. Further, it is
contemplated by the present invention to add chemicals to the
pressure vessel fluid to enhance the cutting capability of a fluid
cutting jet as it exits a nozzle of the nozzle assembly in
communication with the pressure vessel. Therefore, the cutting
enhancement material may comprise either a solid or fluid and may
be soluble or insoluble with the pressure vessel fluid with which
it is mixed. It may be advantageous to hold the cutting enhancement
material in solution so that the cutting enhancement material will
not segregate from the fluid. In addition, it may be advantageous
to add the cutting enhancement material to the high pressure fluid
within the pressure vessel near a nozzle exit forming a cutting
jet, to reduce wear or erosion of the internal fluid passageways of
the fluid jet cutter.
[0028] As a further consideration, it may be desired to cut only a
certain radial amount or thickness of tubing or pipe, thereby
preserving the materials surrounding the tubing or pipe intended to
be cut by the propellant-powered fluid jet cutting apparatus.
Similarly, for cutting nontubular structural elements, a limited
cutting range may be desirable to minimize damage to components or
materials "behind" the wall of the structural element. Therefore,
the propellant-powered fluid jet cutting apparatus of the present
invention may be configured to have a selected, effective cutting
range by configuring the cutting jets with limited velocity and/or
duration. In addition, it may be advantageous to orient and direct
fluid cutting jets so that they intersect proximate an outer
diameter of the tubular structural element to be cut, or proximate
an outermost periphery that is desired to be cut. Because cutting
jets have limited effective cutting range, depending on their
coherency, such an arrangement may inhibit the cutting jets from
cutting beyond their intersection position, because interference of
the intersecting jets may reduce or eliminate their effectiveness
as cutting implements.
[0029] As a further application, it is within the scope of the
present invention that forming apertures or "windows" in a
structural element may be accomplished with the propellant-powered
fluid jet cutting apparatus. The present invention further
contemplates that the propellant-powered fluid jet cutting
apparatus may be used to create so-called "perforations" through a
casing disposed within a borehole and, optionally, into the
surrounding formation in order to initiate or increase hydrocarbon
production from the borehole.
[0030] Features from any of the above mentioned embodiments may be
used in combination with one another in accordance with the present
invention. In addition, other features and advantages of the
present invention will become apparent to those of ordinary skill
in the art through consideration of the ensuing description, the
accompanying drawings, and the appended claims.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0031] In the drawings, which illustrate what is currently
considered to be the best mode for carrying out the invention:
[0032] FIG. 1 is a schematic side cross-sectional view of an
embodiment of a propellant-powered fluid jet cutting apparatus of
the present invention;
[0033] FIG. 2A is a schematic top view of a nozzle assembly of the
present invention;
[0034] FIG. 2B is a schematic side view of the nozzle assembly
shown in FIG. 2A;
[0035] FIG. 3A is a schematic top view of a nozzle assembly of the
present invention;
[0036] FIG. 3B is a schematic side view of the nozzle assembly
shown in FIG. 3A;
[0037] FIG. 4A is a partial cross-sectional schematic side view of
a nozzle assembly body of the present invention;
[0038] FIG. 4B is a partial cross-sectional schematic side view of
a nozzle assembly body of the present invention;
[0039] FIG. 4C is a partial cross-sectional schematic side view of
a nozzle assembly body of the present invention;
[0040] FIG. 5A is a partial cross-sectional schematic side view of
a movable nozzle of the present invention;
[0041] FIG. 6 is a schematic side cross-sectional view of another
embodiment of a propellant-powered fluid jet cutting apparatus of
the present invention;
[0042] FIG. 7 is an enlarged schematic side cross-sectional view of
an anchoring mechanism shown in FIG. 6;
[0043] FIG. 8 is a schematic side cross-sectional view of an
embodiment of a nozzle assembly of the present invention;
[0044] FIG. 9 is a schematic side cross-sectional view of another
embodiment of a nozzle assembly of the present invention; and
[0045] FIG. 10 is a schematic side cross-sectional view of a
further embodiment of a propellant-powered fluid jet cutting
apparatus of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0046] FIG. 1 shows a schematic side cross sectional view of the
propellant-powered fluid jet cutting apparatus 10 of the present
invention. Propellant-powered fluid jet cutting apparatus 10
includes gas generator 14 in communication with pressure vessel 16,
which is hydraulically connected to nozzle assembly 34. More
specifically, gas generator 14 supplies gas to at least a small
gas-containing volume 18 of pressure vessel 16, thus increasing the
pressure in the gas-containing volume 18. Use of a gas-containing
volume is desirable to accommodate gas suddenly developed by gas
generator 14 upon initiation, accommodating the necessary time
involved in transferring energy to fluid-containing volume 20
within pressure vessel 16 and alleviating the risk of bursting
pressure vessel 16 from overpressuring in excess of its designed
pressure rating plus safety margin. As gas generator 14 creates
gases and increases the pressure within the gas-containing volume
18, separation element 26 transmits the force on the gas-facing
surface 27 thereof through the separation element 26 to the
liquid-facing surface 29 of separation element 26 to increase the
pressure within fluid-containing volume 20. Upon reaching a
sufficient pressure within the fluid-containing volume 20, burst
disc 31 ruptures to allow fluid to flow from the fluid-containing
volume 20 of pressure vessel 16 into the nozzle assembly 34 and out
of nozzles 36. Pressure relief element 22 allows gas to escape from
pressure vessel 16 in order to limit the amount of pressure within
pressure vessel 16 and may be sized and configured according to
anticipated gas generation rate and volume of gas generator 14 and
total fluid flow rate of nozzle assembly 34. Of course, the
pressure at which pressure relief element 22 allows gas to escape
from pressure vessel 16 must be higher than the pressure at which
the burst disc 31 ruptures, otherwise the burst disc 31 may not
rupture and the gas generated via the gas generator 14 may simply
vent through the pressure relief element 22. Alternatives to burst
disc 31 may include a diaphragm or a check valve. Fill port 24
extends from pressure vessel 16 and is in communication with
fluid-containing volume 20 so that fluid-containing volume 20 may
be refilled with a suitable fluid after operation of fluid jet
cutter 10 causes the fluid within containing volume 20 to be
expelled from the pressure vessel 16.
[0047] Nozzle assembly 34 may include one or more nozzles 36 that
may be configured and sized to cut an intended area of a tubular
structural element 40 in which propellant-powered fluid jet cutting
apparatus 10 is deployed. Although the present invention has been
described as cutting the entire circumference of a tubular
structural element 40 for removal, the present invention may be
used to cut only a particular area of the tubular structural
element 40. For instance, cutting windows within casing elements in
a borehole may be accomplished. It may be possible to configure and
size nozzles 36 so that particular areas of the tubular structural
element are severed relatively more quickly than other areas of the
tubular structural element. Such a configuration may be suited for
tubular structural elements having varying compositions or wall
thicknesses, so that relatively increased severing capability may
correspond to the configuration of the tubular structural element
to be cut.
[0048] Nozzle assembly 34 may be rotatably attached to stem 32
extending from pressure vessel 16 via bearings 28 and 30. Bearings
28 and 30 are shown schematically above and below nozzle assembly
34, but may, for example, be pressed into the body of nozzle
assembly 34 at each bearing 28/30 outer diameter and also installed
onto the stem 34 at each bearing 28/30 inner diameter, as known in
the art. Stem 32 includes one or more fluid ports (not shown) for
communicating fluid from the fluid-containing volume 20 of pressure
vessel 16 into the nozzle assembly 34 and ultimately through
nozzles 36. Nozzle assembly 34 may include a rotating seal (not
shown) that allows rotation of nozzle assembly 34 while providing a
dynamic fluid seal between the stem and the nozzle assembly 34. An
electric motor (not shown) may be operably coupled to stem 32 as
well as nozzle assembly 34, in order to rotate nozzle assembly 34
about longitudinal axis 15 of propellant-powered fluid jet cutting
apparatus 10 with respect to stem 32 during operation of
propellant-powered fluid jet cutting apparatus 10.
[0049] During operation of propellant-powered fluid jet cutting
apparatus 10, a number of factors may affect the cutting ability of
propellant-powered fluid jet cutting apparatus 10. For instance,
the amount of standoff 37 between a nozzle 36 and the tubular
structural element 40 to be cut, the thickness 41 of tubular
structural element 40, the pressure that the pressure relief
element 22 may be configured and sized to maintain, the
configuration and size of the nozzle assembly 34 and nozzles 36,
the rotational speed of the nozzle assembly 34, as well as the
fluid contained within the fluid-containing volume 20 of pressure
vessel 16 may affect the cutting capability of propellant-powered
fluid jet cutting apparatus 10.
[0050] Further, in operating propellant-powered fluid jet cutting
apparatus 10, it may be desirable to center propellant-powered
fluid jet cutting apparatus 10 within the tubular structural
element 40 so that standoff 37 may be substantially constant around
the circumference of propellant-powered fluid jet cutting apparatus
10, or in other words, propellant-powered fluid jet cutting
apparatus 10 may be centered within tubular structural element 40.
Inflatable packers, or other centering or anchoring devices such as
circumferentially placed bow springs, may be disposed within
tubular structural element 40 above, below, and/or integral to
propellant-powered fluid jet cutting apparatus 10 in order to
center propellant-powered fluid jet cutting apparatus 10 within
tubular structural element 40. Failure to center propellant-powered
fluid jet cutting apparatus 10 within tubular structural element 40
may result in the cutting of tubular structural element 40 being
circumferentially uneven. Circumferentially uneven cutting may not
be desirable because the jets extending from nozzles 36 may exit
the outer radial surface of tubular structural element 40 intended
to be cut and may begin to cut another tubular structural element
which may not be intended for severing, or may damage the formation
behind the tubular structural element being cut.
[0051] As shown in FIG. 1, tubular structural element 40 may be
stuck within borehole 50 at annular area 51, where the formation 50
may engage with tubular structural element 40 in an interference
fit therewith, thus affixing the tubular structural element 40
within the borehole. As discussed above, propellant-powered fluid
jet cutting apparatus 10 may be radially disposed within tubular
structural element 40 and may be preferably substantially centered
within tubular structural element 40 during severing of the tubular
structural element 40. In addition, propellant-powered fluid jet
cutting apparatus 10 may be disposed longitudinally above annular
area 51 so that cutting of tubular structural element 40 effected
by the nozzle assembly 34 will occur above annular area 51 as well.
Therefore, after tubular structural element 40 may be severed by
the jets exiting nozzle assembly 34 and nozzles 36 thereof, the
section of tubular structural element 40 vertically above area 51
may be removable from the formation 50.
[0052] Turning to FIGS. 2A and 2B, each is a schematic
representation, and therefore may not be construed to limit the
present invention. For instance, bearing 28 and bearing 30 are
represented schematically to illustrate that the nozzle assembly
body 35 may be rotationally decoupled from and may rotate with
respect to stem 32. More specifically, in a two-race ball bearing,
comprising two bearing races separated by balls therebetween, one
race may be affixed to the nozzle assembly body 35 and the other
race may be affixed to the stem 32. Often, bearing races may be
press fit within or shrink fit onto a recess or shaft,
respectively, depending on the bearing race to be affixed, but may
be affixed to another component via threaded connectors, welding,
or as otherwise known in the art. Further, nozzles 36 of nozzle
assembly 34 are shown to extend radially outwardly from nozzle
assembly body 35, but may be disposed so that nozzles 36 do not
extend past the outermost radial extent of the nozzle assembly body
35, as shown in FIGS. 4A and 4B. Such a configuration may protect
the nozzles 36 during use.
[0053] As shown in FIG. 2A, nozzle assembly 34 may include a
plurality of nozzles 36. Nozzle assembly 34, as shown in FIGS. 2A
and 2B, includes six nozzles 36 disposed about the circumference of
a nozzle assembly body 35. Nozzles 36 may be arranged to be equally
spaced about the circumference of the nozzle assembly body 35. Such
a symmetric arrangement may reduce or substantially eliminate net
forces and moments generated by the fluid cutting jets, due to the
acceleration of the fluid as it exits the nozzles 36. More
specifically, each jet from each nozzle 36 creates a reaction
force, analogous to the reaction force created from fluid exiting a
garden hose or fire hose that may be transferred to each nozzle 36
and therethrough to the nozzle assembly 34. In the configuration
shown in FIGS. 2A and 2B, each nozzle 36 may be substantially
diametrically opposed by another nozzle 36 positioned at
substantially 180.degree. from the first nozzle, so that each
reaction forces generated by the two opposing fluid cutting jets
substantially cancel one another. This may aid in prolonging
bearing longevity by reducing forces thereon and facilitate
rotation thereof. In addition, each nozzle 36 may be configured so
that its reaction force passes through the rotational axis of the
nozzle assembly 34. Since the reaction force of a fluid cutting jet
may be exerted in the opposite direction of the fluid cutting jet,
the fluid cutting jets depicted in FIGS. 2A and 2B by arrows
extending from nozzles 36, it may be seen that the nozzles 36 may
be positioned and oriented so that the reaction forces of each
fluid cutting jet pass through the center of rotation 5 of the
nozzle assembly 34. As such, the nozzles 36 may be oriented and
positioned so that substantially no moment may be produced via the
fluid cutting jets about the nozzle assembly 34 or nozzle assembly
body 35.
[0054] Accordingly, the nozzle assembly 34 in a configuration shown
in FIGS. 2A and 2B may not, during operation, produce a sufficient
net moment to cause the nozzle assembly 34 to rotate with respect
to stem 32 as well as longitudinal axis 15. Therefore, a moment may
be supplied to the nozzle assembly 34, and more specifically, to
the nozzle assembly body 35 so that the nozzles 36 are caused to
rotate about the longitudinal axis 15 of the propellant-powered
fluid jet cutting apparatus 10. For instance, a motor may be used
to rotate the nozzle assembly 34. More specifically, a motor
powered by electricity supplied from the surface of the formation
or via batteries or other storage devices may be used to rotate the
nozzle assembly 34. Similarly, hydraulic motors, turbines, or other
rotation devices may be employed, and may be powered via the gas
generator 14 used to power the propellant-powered fluid jet cutting
apparatus 10, or may be powered as otherwise known in the art.
[0055] Alternatively, the reactive force generated by the fluid as
it exits a nozzle 36 may be oriented and positioned to rotate the
nozzle assembly body 35 about the stem 32 and longitudinal axis 15.
FIGS. 3A and 3B illustrate, schematically, a nozzle assembly 34
with nozzles 36 that are oriented so that a moment may be generated
on the nozzle assembly body 35. As in FIGS. 2A and 2B, bearing 28
and bearing 30 are represented schematically to illustrate that the
nozzle assembly body 35 may be rotationally decoupled from and may
rotate with respect to stem 32. However, each nozzle 36 may be
oriented so that the reaction force may create a moment about the
center of rotation 5 of the nozzle assembly 34. As shown in FIG.
3A, the line 7 along which the reaction force acts may be
positioned at a perpendicular distance d from the center of
rotation 5 of nozzle assembly 34. Therefore, the counter-clockwise
moment generated by way of one nozzle 36 equals the product of the
reaction force of one nozzle 36 and distance "d." The cumulative
moment acting on the nozzle assembly 34 may equal the summation of
the products of the reaction forces and the perpendicular distances
from the center of rotation 5 of the nozzle assembly 34.
[0056] Accordingly, the orientation and position of the nozzles 36
of the nozzle assembly 34 may be configured to produce a desired
moment during operation of a propellant-powered fluid jet cutting
apparatus. Also, since the size of the exit orifice of a nozzle 36
may, to an extent, determine the acceleration of a fluid and
thereby the reaction force produced via the nozzle 36, the size of
the exit orifice of a nozzle 36 may be adjusted to produce a
desired moment during operation of a propellant-powered fluid jet
cutting apparatus. However, orienting a nozzle so that a moment may
be created via the jet exiting therefrom may affect the ability of
the fluid cutting jet to cut a tubular structural element.
Therefore, the present invention contemplates that particular
nozzles may be oriented, sized, and positioned in order to create a
moment that may cause the nozzle assembly 34 to rotate, while other
nozzles are sized, configured, and positioned to cut a tubular
structural element. Of course, if a moment-producing nozzle may be
configured to adequately cut a tubular structural element, then
such a combination may be unnecessary.
[0057] FIG. 4A shows a partial cross-sectional schematic view of a
nozzle assembly body 35 including a nozzle 36 and a fluid aperture
39 for communicating fluid therethrough to create a fluid cutting
jet exiting the nozzle 36 in a direction perpendicular to the
longitudinal axis 56 of nozzle assembly body 35. Nozzle 36 may be
formed from tungsten carbide, silicon carbide, ceramic, or may be
formed of steel with a ceramic coating. One particularly suitable
steel, by way of example only is so-called "Maraging" steel, as
described in approved for public release Military Specification
MIL-S-46850D of Mar. 21, 1991, entitled STEEL: BAR, PLATE, SHEET,
STRIP, FORGING, AND EXTRUSIONS, 18 PERCENT NICKEL ALLOY, MARAGING,
200 KSI, 250 KSI, 300 KSI, AND 350 KSI, HIGH QUALITY. The nozzle
orifice should be formed or lined with a material to resist wear
thereof and may include a jewel having an aperture therethrough, as
known in the art, typically of ruby, sapphire, diamond or other
superabrasive configured to resist wear or erosion as the fluid
exits therefrom. Alternatively, a jewel surface coating or surface
treatment may be employed to form at least a portion of the nozzle
36. Nozzle 36 may be threaded into the nozzle assembly body 35, or
otherwise affixed therein and may preferably be replaceable. In
addition, it may be preferable to introduce abrasives proximate to
the fluid cutting jet exiting the nozzle to prevent unwanted or
excessive wear on the fluid passageways and the nozzle of the
propellant-powered fluid jet cutting apparatus. However, in the
alternative, abrasives or other additives that enhance the cutting
ability of a fluid cutting jet may be introduced into the fluid at
any stage within the propellant-powered fluid jet cutting apparatus
of the present invention, or prior to placing the fluid within the
propellant-powered fluid jet cutting apparatus. For instance, the
fluid and a cutting enhancement material may be in solution or held
in suspension in the form of a slurry within the propellant-powered
fluid jet cutting apparatus of the present invention so that no
additional materials are mixed with the fluid as it travels
therethrough and exits the nozzle assembly 34.
[0058] As a further consideration, the present invention
contemplates tilting a nozzle 36 vertically, as shown in FIG. 4B,
so that the jet may not be perpendicular with angle with the
longitudinal axis 15 of the nozzle assembly 34. As shown in FIG.
4A, the direction of the jet forms angle .theta. with respect to
reference line 66, line 66 being perpendicular to longitudinal axis
56. The jet created thereby may be directed to cut an annulus of a
tubular structural element that may differ in longitudinal position
from another nozzle 36 within the same nozzle assembly 34. Such a
configuration may be useful for ensuring that the tubular
structural element may be severed, or may be useful in cleaning
applications, where it may be desired to increase the area affected
by fluid cutting jets exiting the nozzles 36. Of course, nozzles 36
may be configured to be substantially diametrically opposed with
regard to their vertical reaction forces, so that the vertical
reaction force generated by each fluid cutting jet exiting a nozzle
is substantially cancelled by the force generated via a
substantially diametrically opposed fluid cutting jet exiting
another nozzle 36.
[0059] As another contemplation of the present invention, fluid
cutting jets exiting nozzles 36 may be positioned and oriented to
intersect. Fluid cutting jets that intersect may be advantageous
for altering the cutting ability of the jets, particularly for
limiting the cutting ability thereof. For instance, it may be
advantageous to configure nozzles so that a wide range of materials
and material thicknesses may be severed. A fluid cutting jet may
possess cutting ability related to its coherency until intersection
with another fluid cutting jet, thus reducing coherency and greatly
reducing or eliminating cutting ability of each fluid cutting jet.
As further shown in FIG. 4C, the intersection location of fluid
cutting jets of nozzle 76 and nozzle 77 may be configured to be
substantially proximate to the outer radial surface of a tubular
structural element 40. Nozzle 77 forms a fluid cutting jet in a
direction that forms angle y with reference line 87, reference line
87 being perpendicular to longitudinal axis 56. Similarly, nozzle
76 forms a fluid cutting jet in a direction that forms angle
.theta. with reference line 86, reference line 86 being
perpendicular to longitudinal axis 56. During operation, the fluid
cutting jets formed via nozzles 77 and 76 exit each nozzle,
respectively, and travel radially outwardly until contacting the
inner radial surface 43 of tubular structural element 40. FIG. 4C
is schematic and therefore the nozzles may be much closer to
tubular structural element 40 in actual practice. The fluid cutting
jets of nozzle 76 and 77 each cut through tubular structural
element 40, and may possess, if unhindered, cutting ability that
extends radially beyond the outer radial surface 45 of tubular
structural element 40. However, it may be desired to limit the
cutting ability of the fluid cutting jets exiting nozzle 76 and 77
by orienting and positioning nozzles 76 and 77 so that the fluid
cutting jets exiting therefrom intersect. As shown in FIG. 4C, the
fluid cutting jets formed via nozzles 76 and 77 intersect at point
90, substantially corresponding to the radial position of outer
radial surface 45 of tubular structural element 40. Such a
configuration may prevent fluid cutting jets from cutting materials
that are not intended to be cut, such as a casing in which another
tubular structural element may be stuck. It may be desired to cause
fluid cutting jets to intersect at a position slightly radially
outward from the outermost radial surface of the tubular structural
element to be cut as a factor of safety to ensure that the entire
thickness of the material may be cut.
[0060] Of course, many configurations of intersecting fluid cutting
jets are possible, and are contemplated by the present invention.
Turning to FIG. 2A, at least two nozzles 36 may be oriented and
positioned along the circumference of nozzle assembly body 35 to
cause the fluid cutting jets exiting therefrom to intersect at a
desired radial position. In addition, multiple nozzles may be
oriented and positioned so as to create fluid cutting jets that
intersect.
[0061] As an additional nozzle embodiment, FIG. 5A shows a movable
nozzle configuration in a partial cross-sectional schematic view.
Movable nozzle 92, shaped generally as a multi-diameter piston,
includes a movable nozzle passageway 93 for communicating fluid to
the nozzle 96, which may be formed from a highly wear resistant
material as discussed hereinabove, or include a jewel insert with
an aperture therethrough as known in the art. Fluid moving through
nozzle passageway 39 travels toward movable nozzle 92. Pressure
developed within nozzle passageway 39 acts on surface 95 of movable
nozzle 92 forcing the movable nozzle 92 radially outward. Surface
98 of retention element 94 matingly engages surface 97 of movable
nozzle 92, thus positioning movable nozzle 92 at its outermost
radial position. Of course, sealing elements may be disposed
between movable nozzle 92 and nozzle passageway 39, retention
element 94 as desired and known in the art to prevent high pressure
fluid from escaping therebetween. Movable nozzle passageway 93
communicates fluid therethrough to the nozzle 96 from which the
fluid exits, thus forming a fluid cutting jet. Retention element 94
may be threaded into nozzle assembly body 35, or otherwise affixed
thereto. Further, retention element 94 may be configured to be
replaceable, and may be configured to be adjustable so that the
outermost radial position of the movable nozzle 92 may be adjusted.
Furthermore, a biasing element (not shown) such as a coil, leaf,
belleville or other spring may be disposed between surface 97 of
movable nozzle 92 and surface 98 of retention element 94 so as to
force the movable nozzle 92 radially inwardly when fluid pressure
within nozzle passageway 39 may be less than the force provided by
the biasing element. A biasing element (not shown) may be useful in
positioning a movable nozzle 92 radially inward so as to prevent
damage to the movable nozzle 92 during deployment within a tubular
structural element or removal therefrom.
[0062] Although the embodiment of the movable nozzle 92 shown in
FIG. 5A is configured as a multi-diameter piston so that pressure
developed within the nozzle passageway 39 cause the movable nozzle
92 to be forced radially outwardly, there are many contemplated
alternatives. For instance, nozzles may be configured on the ends
of flexible high pressure hoses, or attached to nozzle arms that
are hingedly attached to the nozzle assembly body so that in either
case the nozzles may be displaced radially outwardly and toward the
surface of the material to be cut. In such a configuration, if the
nozzle assembly rotates, the centrifugal force from the rotation of
the nozzle assembly may cause the nozzles to be forced radially
outwardly, or the reaction force of a fluid cutting jet may be used
to force the nozzles radially outwardly. Further, combinations of
pressure, reaction force via fluid flow, or centrifugal force may
be used as desired to position a movable nozzle in relation to a
material to be cut.
[0063] A movable nozzle may be particularly useful for positioning
a fluid cutting jet in relation to material to be cut, so that the
fluid cutting jet may be effective for cutting the desired
thickness of material. As mentioned hereinabove, a fluid cutting
jet's cutting ability may be related to its coherency, which may
deteriorate as the distance from the nozzle exit increases.
Therefore, it may be advantageous to position the exit of the
nozzle immediately proximate to the material to be cut. Conversely,
if the fluid cutting jet has cutting ability, in terms of distance
from the nozzle exit that may be cut, that exceeds the desired
outermost extent of the material to be cut, the nozzle size may be
limited so that its effective cutting distance only slightly
exceeds or equals the outer extent of the material to be cut.
[0064] In the case that it is desired to position a movable nozzle
as closely as possible to the material to be cut, and where the
nozzle assembly may rotate, it may be advantageous to include a
rolling element (not shown) such as a wheel near the radial tip of
the movable nozzle, so that the rolling element contacts the
surface of the material to be cut, and thereby positions the nozzle
in substantially constant dimensional relation to the surface of
the material to be cut and provides ease in rotation of the nozzle
along the material to be cut.
[0065] FIG. 6 shows another embodiment of a propellant-powered
fluid jet cutting apparatus 110 of the present invention generally
depicted as a number of tubular structural elements threadedly
attached to one another. An end cap 115, including an eyelet 107
for connecting a wireline thereto, may be threadedly connected to a
gas generator 114 formed via a tubular structural element 111 that
contains a propellant 117. As noted previously, the propellant may
comprise a solid propellant including a composite fuel and
oxidizer, and may be formed or cast into a tube as known in the
art. The propellant may, by way of example only, comprise a Class
1.3 propellant. Exemplary types of suitable propellants for the gas
generator include, without limitation, composite solid propellants,
double base solid propellants, liquid propellants and pyrotechnic
materials. The total burn time of an initiated propellant may
comprise, by way of example only, about 30 seconds to a minute and
will, of course be dependent upon the type, volume and shape of the
propellant. In addition, the selected propellant should have a
self-energizing temperature at or above 400.degree. F. (or above
whatever the expected ambient temperature to be encountered, for
example downhole, will be) and a flame temperature between about
2000.degree. and about 4000.degree. F. One specific but exemplary
suitable propellant is an AN-based composite solid propellant.
[0066] Gas generator 114 may be threadedly connected to an optional
anchoring mechanism 170 at threaded joint 121, anchoring mechanism
170 containing movable elements for engaging the surface of the
material to be cut, e.g., the inner diameter of a tubular
structural element. An igniter or initiator 101 may be disposed at
the lower, distal end of tubular structural element 111 of the gas
generator 114 or in the upper distal end of the anchoring mechanism
170 for igniting the propellant 117 within the gas generator 114.
An igniter location proximate the lower end of propellant 117 is,
of course, desirable so that ignition thereof will generate gas
immediately in communication with gas-containing volume 118 (see
below). Igniter 101 may be configured as a flat wire sized and
positioned to produce an electrical arc between the end of the wire
and a portion of the anchoring mechanism 170 or the gas generator
114. Alternatively, the igniter 101 may be disposed within
propellant 117, and may comprise a small explosive charge, a
resistance heater or a percussion primer. A high voltage or low
voltage bridge wire initiator may be employed, and one particularly
suitable initiator is a semiconductor bridge igniter disclosed in
U.S. Pat. No. 4,708,060 to Bickes, Jr. et al. Anchoring mechanism
170 preferably includes a longitudinally extending port 180 for
communicating gas generated by the gas generator 114 to the
pressure vessel 116 threadedly connected to the anchoring mechanism
170 at threaded joint 123. Pressure vessel 116 may be formed from
tubular structural element 113 and may also contain a separation
element 126 (depicted by way of example only as a piston) for
separating a gas-containing volume 118 from a fluid-containing
volume 120 within the pressure vessel 116. Pressure vessel 116 is
shown in a condition where the gas generator 114 has not been
deployed, so that fluid-containing volume 120 may be relatively
large compared to the gas-containing volume 118. Of course,
fluid-containing volume 120 may be adjusted prior to assembly of
the propellant-powered fluid jet cutting apparatus 110 by
positioning the separation element 126 appropriately and filling
the fluid-containing volume 120 with fluid. The lower end of
tubular structural element 113 forming pressure vessel 116 may be
threadedly attached to nozzle assembly 134 at threaded joint
125.
[0067] It is also contemplated, to simplify construction of a
propellant-powered fluid jet cutting apparatus such as apparatus
110, that a remote, wireless igniter or initiator assembly
including one of the foregoing types of igniters or initiators 101
be employed. As previously noted, since it is desirable for
propellant 117, if a solid propellant to end-burn the propellant
grain from the bottom of propellant 117 upwardly, use of a remote,
wireless and disposable radio frequency receiver 102 to actuate
igniter or initiator 101 enables fabrication of the gas generator
114 without the need for running wires internally or externally.
Thus, a simple battery-powered receiver with, if necessary an
enhanced power source such as a chargeable capacitor for actuating
igniter or initiator 101, may be disposed adjacent and operably
coupled with igniter or initiator 101 and a cooperating radio
frequency transmitter 103, which may be powered and actuated with a
coded initiation signal for safety through a wire line, or which
may be self-powered and be actuated through a suitable pressure
transducer-type receiver by a coded mud-pulse signal through
drilling fluid in the bore hole, to transmit a firing signal to
igniter or initiator 101. The transmitter 103 is desirably
reusable, although this is not a requirement.
[0068] Moving to FIG. 7, the anchoring mechanism 170 shown in FIG.
6 is depicted in greater detail. Anchoring mechanism 170 includes
an upper threaded connection 182 and a lower threaded connection
184, as known in the art, that may be used to connect to a gas
generator and pressure vessel as shown in FIG. 6. Port 180 extends
longitudinally through the body 183 of anchoring mechanism 170 and,
when threadedly connected to gas generator 114 and pressure vessel
116, may allow gas produced via the gas generator 114 to
communicate with the pressure vessel 116 therethrough. Further, a
pressure relief element 181 may optionally be included within
anchoring mechanism 170 and in communication with port 180 to
relieve excess pressure generated by way of the gas generator 114.
It is contemplated that gas pressure employed for operation of the
present invention may be generally in a range of about 30,000 psi
and up, with the desired pressure being attributable to the
characteristics and thickness of the material to be cut. For
example, 50,000 psi may be selected as a maximum selected operating
pressure . In addition, anchoring mechanism 170 includes pistons
172 and 174, each including sealing elements 173 and 175,
respectively, for sealing the piston to the body 183 of the
anchoring mechanism 170, the radially inward end of each of the
pistons 172 and 174 being in communication with port 180. Thus,
during operation, as high pressure gas from gas generator 114 fills
port 180, pistons 172 and 174 are forced radially outward against
respective retention elements 176 and 178. Of course, additional
pistons such as 172 and 174 may be disposed to extend radially from
anchoring mechanism 170 at different circumferential locations to
better retain and center apparatus 110 within a borehole. Retention
elements 176 and 178 may be affixed respectively to the body 183 of
anchoring mechanism 170 by way of threaded connectors 186 and 188
as shown in FIG. 7, or as otherwise known in the art. Retention
elements 176 and 178 may be configured to bend as pistons 172 and
174 may be forced radially outward so that the lower end of each
retention element 176 and 178 may be forced radially outward and
may engage the inner surface of a tubular structural element
intended to be severed by the propellant-powered fluid jet cutting
apparatus 110 of the present invention. Thus, the anchoring
mechanism 170 may be used to temporarily affix a propellant-powered
fluid jet cutting apparatus 110 within a tubular structural element
intended to be severed thereby. In addition, retention elements 176
and 178 may bias associated pistons 172 and 174 radially inward as
pressure within port 180 decreases below the pressure sufficient to
cause the retention elements 176 and 178 to engage the surface of a
tubular structural element intended to be severed. In addition, the
retention elements 176 and 178 may serve to protect the sealing
elements 173 and 175 from encountering debris when the anchoring
mechanism 170 may not be in use by covering the outer radial
surface of the pistons 172 and 174 as shown in FIG. 7.
[0069] Of course, many alternatives exist for providing an
anchoring mechanism and are contemplated by the present invention.
For instance, the anchoring mechanism may include one or more
multi-diameter pistons that may be displaced radially outwardly so
that the piston contacts the inner diameter of the tubular
structural element intended to be severed when pressure within port
180 forces the piston radially outward. The pistons may be
configured so that a portion of the piston may matingly engage the
inner surface of the body of the anchoring mechanism to prevent
further outward radial movement, similar to the multi-diameter
piston as shown in FIG. 5A. Further, a biasing element, e.g., a
spring, may be configured, sized, and positioned to return the
piston radially inward when the pressure within port 180 may not be
sufficient to maintain the piston's radial position. Furthermore,
tapered, mechanically set elements such as packer-type slips,
inflatable elements, or other mechanisms known in the art may be
used to anchor and/or position a propellant-powered fluid jet
cutting apparatus of the present invention. It is contemplated that
an anchoring mechanism that contacts the wall of the tubular
element throughout an entire inner periphery thereof may be
employed for anchoring and centering apparatus 110.
[0070] Turning to FIG. 8, the nozzle assembly 134 shown in FIG. 6
is depicted in detail. The nozzle assembly 134 includes a nozzle
housing 152 threadedly affixed to a nozzle retainer 156, the nozzle
retainer 156 being also threadedly affixed to nozzle end cap 154.
Burst disc 131 may be affixed to the upper longitudinal end of
nozzle housing 152, thus preventing flow therethrough until a
sufficient pressure may be supplied to rupture burst disc 131. Of
course, valves, pressure actuated valves, electric valves, or other
flow control devices may be used in place of or in combination with
burst disc 131. Nozzle retainer 156 may be threadedly affixed to
nozzle end cap 154 by way of inner threaded surface 155 as well as
nozzle housing 152 by way of outer threaded surface 157, the nozzle
retainer 156 having one or more passageways 159 for allowing fluid
to pass therethrough. During operation, fluid may pass through
ruptured burst disc 131, through the upper longitudinal area of
nozzle housing 152, through one or more passageways 159, and then
through area 163 formed between the nozzle housing 152 and the
nozzle end cap 154, and then exiting circumferentially between a
nozzle ring 158 affixed to nozzle housing 152 and a nozzle ring 160
affixed to nozzle end cap 154. Nozzle ring 158 and nozzle ring 160
may be separated by, for example, about 0.005 to about 0.015 inches
and may also include a jeweled (diamond, sapphire, etc.) or
otherwise wear/erosion resistant surface for producing a
sufficiently coherent fluid cutting jet for severing a tubular
structural element. In addition, it may be necessary to provide
spacers (not shown) or other spacing elements (not shown) for
adjusting and/or maintaining the relative positions of nozzle ring
158 and nozzle ring 160 during use. Spacing elements (not shown)
may be positioned between nozzle ring 158 and nozzle ring 160, or
alternatively, between nozzle housing 152 and nozzle end cap 154 in
order to adjust or maintain the position of nozzle ring 158 with
respect to nozzle ring 160 to adjust the clearance therebetween.
Thus, nozzle assembly 134 may produce a substantially
circumferential fluid cutting jet for cutting a tubular structural
element. A circumferential fluid cutting jet may be advantageous in
that a rotating nozzle assembly may not be required if the inner
diameter of a tubular structural element may be severed by way of a
substantially circumferential fluid cutting jet.
[0071] FIG. 9 shows a nozzle assembly 134 for providing two
substantially circumferential jets for severing tubular structural
elements. Nozzle assembly 134 includes nozzle housing 152
threadedly affixed to nozzle retainer 156, nozzle retainer 156 also
being threadedly affixed to nozzle stem 161 and nozzle stem 161
being also threadedly affixed to nozzle end cap 154. Nozzle
assembly 134 may include a burst disc 131 affixed to the upper
longitudinal end of nozzle housing 152, thus preventing flow
therethrough until a sufficient pressure may be supplied to rupture
burst disc 131. During operation, fluid may pass through ruptured
burst disc 131, through the upper longitudinal area of nozzle
housing 152, through one or more passageways 159, and then through
annular area 163 formed between the nozzle housing 152 and the
nozzle stem 161, and may exit nozzle assembly 134 circumferentially
between a nozzle ring 158 affixed to nozzle housing 152 and a
nozzle ring 160 affixed to nozzle stem 161. During operation, fluid
may also pass through passageway 164, through the area 153 formed
between nozzle stem 161 and nozzle end cap 154, and may exit
between nozzle ring 168 affixed to nozzle stem 161 and nozzle ring
169 affixed to nozzle end cap 154. Nozzle rings 158 and 160 as well
as nozzle rings 168 and 169 may be separated by about 0.005 inches
and may also include a jeweled or otherwise wear/erosion resistant
surface for producing a sufficiently coherent fluid cutting jet for
severing a tubular structural element. Thus, the nozzle assembly
134 of the present invention may be configured to produce more than
one substantially circumferential fluid cutting jet.
[0072] It is also contemplated by the present invention that
substantially circumferential fluid cutting jets may be configured
to intersect. Referring back to FIG. 4C, nozzle assembly 134 shown
in FIG. 9 may be configured so that the substantially
circumferential fluid cutting jet exiting between nozzle ring 158
and nozzle ring 160 may intersect with the fluid cutting jet
exiting between nozzle ring 168 and nozzle ring 169, similar to the
intersection at point 90 as shown in FIG. 4C, except that the
intersection of substantially circumferential fluid cutting jets
may generate a substantially circumferential intersection. Further,
during operation, the substantially circumferential fluid cutting
jet exiting between nozzle ring 158 and nozzle ring 160 and the
fluid cutting jet exiting between nozzle ring 168 and nozzle ring
169 may travel radially outwardly until contacting the inner radial
surface of a tubular structural element. Similar to FIG. 4C, the
substantially circumferential fluid cutting jet exiting between
nozzle ring 158 and nozzle ring 160 and the substantially
circumferential fluid cutting jet exiting between nozzle ring 168
and nozzle ring 169 may be configured to intersect
circumferentially at substantially the radial position of outer
radial surface of the tubular structural element to be severed.
Such a configuration may prevent substantially circumferential
fluid cutting jets from cutting materials that are not intended to
be cut, such as a casing in which another tubular structural
element may be stuck. It may be desired to cause substantially
circumferential fluid cutting jets to intersect at a position
slightly radially outward from the outermost radial surface of the
tubular structural element to be cut as a factor of safety to
ensure that the entire thickness of the material is cut.
[0073] Turning to FIG. 10, another embodiment of the
propellant-powered fluid jet cutting apparatus 310 of the present
invention is shown. End cap 312 may be threadedly connected to
tubular structural element 311, tubular structural element 311
forming both gas generator 314 as well as pressure vessel 316.
Separation element 326 separates gas-containing volume 318 from
fluid-containing volume 320. In addition, pressure relief element
322 allows for gas within gas-containing volume 318 to escape in
order to limit the magnitude of pressure within pressure vessel 316
and may be sized and configured according to anticipated gas
generation of gas generator 314 and total fluid flow rate of nozzle
assembly 334. Separation element 326 is shown as an annular piston,
which allows for storage element 313 to be installed central to the
tubular structural element 311 so that separation element 326 may
move along the outer circumference of storage element 313. Of
course, separation element 326 may include on its inner and outer
circumferences sealing elements (not shown) for sealing the
pressure generated via gas generator 314 within the gas-containing
volume 318 from the fluid-containing volume 320. Storage element
313 may include at least one passageway 308 in fluid communication
with fluid-containing volume 320, and may be used to store an
abrasive for mixing with the fluid contained within
fluid-containing volume 320. Alternatively, storage element 313 may
be configured as an energy storage device, e.g., an accumulator,
and may also contain fluid that may be used to create a fluid
cutting jet. Adaptor 315 may be configured to be threadedly affixed
to tubular structural element 311 as well as nozzle assembly 334,
and, in addition, may provide a threaded connection to storage
element 313, as shown in FIG. 10. Nozzle assembly 334 includes a
nozzle housing 352 threadedly affixed to a nozzle retainer 356
wherein the nozzle retainer 356 may also be threadedly affixed to
nozzle end cap 354. A burst disc 331 may be affixed to the upper
longitudinal end of nozzle housing 352, thus preventing flow
therethrough until a sufficient pressure may be supplied to rupture
burst disc 331. Nozzle retainer 356 may be threadedly affixed to
nozzle end cap 354 as well as nozzle housing 352, the nozzle
retainer 356 having one or more passageway 359 for allowing fluid
to pass therethrough. During operation, fluid may pass through
ruptured burst disc 331, through the nozzle housing 352, through
one or more passageway 359, and then through area 363 formed
between the nozzle housing 352 and the nozzle end cap 354, and then
exiting between a nozzle ring 358 affixed to nozzle housing 352 and
a nozzle ring 360 affixed to nozzle end cap 354. Nozzle ring 358
and nozzle ring 360 may be separated, by spacers (not shown) or
otherwise, by about 0.005 inches and may also include a jeweled or
otherwise wear/erosion resistant surface for producing a
sufficiently coherent fluid cutting jet for severing a tubular
structural element.
[0074] As may be appreciated from the foregoing description, the
present invention may be used to cut wall thicknesses in excess of
one inch in thickness using a high pressure fluid cutting jet. The
nozzles of the fluid jet cutting apparatus of the present invention
may be used to accelerate, for example, a small beam of water to a
velocity of Mach 2 plus, producing a finely controlled, clean cut
with little or no burr at the periphery thereof and no
heat-affected zone of the material of the tubular structural
element. The self-contained nature of the fluid jet cutting
apparatus of the present invention facilitates deployment in deep
bore holes at remote locations, as does its reusable nature.
Specifically, by refilling the pressure vessel with fluid and
inserting a new propellant cartridge in the gas generator, the
apparatus may be quickly and easily readied for reuse. Further, as
the nozzle assembly may be easily replaced with one of a different
lateral extent for cutting a tubular structural element of a
different bore diameter, one apparatus with several nozzle
assemblies may be used to sever a wide variety of sizes of tubular
structural elements.
[0075] The present invention also has wide applicability to a
number of non-downhole situations. Further, the compact and robust
nature of the apparatus of the present invention as well as its
self-contained and self-powered design, renders it suitable for use
in remote and difficult to access locations such as mine shafts,
subsea applications, demolition applications including without
limitation military applications, and others. Of course, the
apparatus and the configuration, location and arrangement of the
nozzle or nozzles may be custom-tailored to cut, for example, a
substantially planar sheet of material, a wall of material, a
rectangular or other cross-sectional shaped hollow structural
element, as well as windows, slots and other apertures as desired
and to cut through solid (non-hollow) structural element. The
apparatus of the present invention may also be configured for
cutting through chamber, vessel or other compartment walls from the
interior or exterior thereof. As noted previously, the apparatus of
the present invention, and specifically the nozzle or nozzles, may
be associated with a drive mechanism to propel and guide the size
and shape of a desired cut. A variety of shapes and sizes of nozzle
orifices, as well as orientations thereof, including cooperative
orientations, are also contemplated as within the scope of the
present invention. As used herein, the term "structural element" is
one of convenience, and not of limitation. Accordingly, any
material to be cut, whether forming a portion of a "structure" per
se or otherwise, is encompassed by the term.
[0076] As may also be seen from the foregoing description, many
variations and configurations of gas generators, pressure vessels,
separation elements, nozzle assemblies, nozzles, and other
propellant-powered fluid jet cutting apparatus components may be
possible. Therefore, although the foregoing description contains
many specifics, these should not be construed as limiting the scope
of the present invention, but merely as providing illustrations of
some exemplary embodiments. Similarly, other embodiments of the
invention may be devised which do not depart from the spirit or
scope of the present invention. Features from different embodiments
may be employed in combination with one another. The scope of the
invention is, therefore, indicated and limited only by the appended
claims and their legal equivalents, rather than by the foregoing
description. All additions, deletions, and modifications to the
invention, as disclosed herein, which fall within the meaning and
scope of the claims are to be embraced thereby.
* * * * *