US3066736A - Hydraulic perforating gun - Google Patents

Description

Dec. 4, 1962 A. VENGHIAT-rls HYDRAULIC PERFORATING GUN JNVENToR. ALEX\S VENGHAT'US 3 Sheets-Sheet l FIG. 2

Rabbit-WM Filed June l5. 1960 "121i tl..

Dec. 4, 1962 A. VENGHIATTIS HYDRAULIC PERFORMING GUN 5 Sheets-Sheet 2 Filed June l5. 1960 INVENTOR. ALEXIS VENGHlATTlS Rm w. M

Dec. 4, 1962 A. VENGHIATTls 3,066,736

HYDRAULIC PERFORATING GUN Filed June l5l 1960 3 Sheets-Sheet 3 INVENToR. ALEXS VENGH\ATT|S BYRMWM United States Patent @dice 3,066,736 Patented Dec. 4, 1962 ware Filed June 15, 1960, Ser. No. 36,325 5 Claims. (Cl. 16655.1)

This invention relates to apparatus and method for forming perforations in lthe sidewall of earth well boreholes and more particularly to apparatus and method useful in connection with the injection of liquids into perforations extending through casing and a surrounding cement annulus into a traversed earth formation containing oil or gas.

In the completion of oil wells, it has long been the practice to perforate potentially productive earth formations traversed by the well with bullets or shaped charges. It has been recognized that the rate of oil or gas production obtained from a formation depends to some extent upon the depth of such perforations. It has been proposed to improve perforating depth and, therefore, increase production by the injection of reactive liquids, such as hydrochloric acid, into the perforations either concurrently with or subsequent to their formation. No satisfactory method of accomplishing this has been found however because, among other reasons, of the diiculty in aligning liquid injection means with the perforation as it is formed.

Perforation through cemented casing by jets of high pressure drilling fluid has been proposed, the jets being ejected through tubing under pressure supplied by pumps located at the well head. In addition to the obvious dificulty of developing suicient pressure during considerable lengths of time to perforate steel casing, this method also has the disadvantages of requiring a substantial power absorbing length of pipe to conduct the fluid which leads to a poor ratio of power developed to power utilized. A self-contained wireline tool would have the advantages of economy and ease of operation but heretofore none has been available.

It is an object of the present invention to provide a wireline tool capable of both opening steel casing and subsequently accurately injecting liquid jets into such openings.

It is another object of the invention to provide a wireline tool, as aforesaid, which is capable of being firmly positioned within the well casing for accuracy of liquid injection, but which is readily retrievable after use.

These objects are attained by a wireline tool having an expansion chamber which contains a quantity of a gas generating combustible material or of a propellant and means, actuable from the top of the Well, for igniting of this material. The increase of pressure within the chamber resulting from the combustion process actuates a piston working against a body of the liquid to be injected into the earth formation. A plurality of shaped charge units are arranged around the tool and electrically controlled to re into the sidewall of the well forming an initial perforation through the casing and extending at least into cement annulus. Arranged behind the shaped charge units and pointing along their line of discharge, are a corresponding number of orifice members through which liquid is ejected by downward movement of the aforementioned piston. In order to maintain alignment between the orifice means and the perforations created by the shaped charge, a number of radially expansible anchoring dogs, actuated and held in extended position by pressure on the liquid body, are also provided on the f tool.

The liquid is expelled through the orifice means under very high pressure and velocity so that it cuts into the earth formation and greatly deepens the initial perforations formed by the shaped charge means. As the piston, actuated by the expanding gases, nears the end of its stroke, a spike projecting therefrom ruptures a diaphragm that separates the liquid from a low-pressure chamber in the bottom of the tool thus reducing the internal pressure. As a result, the pressure of the surrounding well fluid forces the expanded dogs back into retracted position, thus permitting withdrawal of the tool.

In the accompanying drawings:

FIG. l is an elevation View, partly in section and partly diagrammatic, showing the upper portion of a tool in accordance with the present invention suspended within an earth well borehole;

FIG. 2 is a similar View of the bottom half of the same tool;

FIG. 3 is a View in section on line `ln-3 of FIG. 2;

FIG. 4 is a view similar to FIG. 3, showing the condition of the tool and the surrounding well sidewall immediately after the discharge of the shaped charge units;

FIG. 5 is a diagrammatic and fragmentary View illustrating the discharge of a single liquid jet into a perforation formed by a shaped charge means; and

FIG. `6 is a View partly in Vertical section similar to FIG. 2, but showing the tool near the end of its operating cycle.

FIG. l shows the upper portion of the tool 10 positioned Within the earth well borehole 11 containing well fluid l2. The borehole is defined by the steel casing 13 set in place by the annular body of cement 14 between the casing and the traversed earth formation 16.

The tool 10 comprises a conventional cable head 17, which is supported by a wireline, shown diagrammatically at l5, the latter including the grounded conductor 18 and the conductor 19 which is connected through switch 21 to battery 22 or to some other convenient source of electrical energy. The cable head 17 is connected to a hol low, tubular body 23 which may have mounted on its outside conventional bow springs 24 for centering the tool Within the well.

The walls of the body 23 define a generally cylindrical expansion chamber 26, the bottom of which is formed by the slidable piston 27. O-rings 2S are provided in grooves inside of the piston to form a fluid-tight seal.

Within the expansion chamber 26, a body of combustible material or propellant 31 is connected to the cable head through conductor 29. The material used in propellant 3-1 is preferably a fast burning propellant of the so-called double-base powder type. It may include a conventional booster charge, not shown,vwhich is actuated by a current conducted through the conductor 29 in order to initiate combustion.

Conductor 32, also connected to the cable head, runs through the expansion chamber 26 and passes through passageway 30 formed in piston 27, which has the fluidtight and electrically isolating conductor-holding members 33 and 34 formed in its top and bottom. Conductor 32 is connected to a delay fuse 35 from which extends detonating fuses 36 preferably of the kind known in the industry as primacord Below the piston 27 is a container 37 lled with a body of liquid 38. The liquid employed is preferably one that will react chemically with the earth formation being perforated in order to increase the permeability of the formation around the perforation and increase the rate of fluid therefrom. Hydrochloric or other mineral acids are typically used. Alternatively, liquid 3S may be ay slurry containing suspended abrasive material to increase the cutting effect of the ejected jet. However, water -cr other inert liquids are eiective with the perforating effect being provided solely by the high speed,

high p're'ssure liquid jets. The piston 27 is provided with a sharp spike 39 depending into the container 37.

A charge carrier 41 is attached to the lower end of the body 23 and together with the body 23, the piston 27 and the diaphragm 42 d'ene the' container 37. The carrier 41 holds three shaped charge units 44, angularly spaced 120 from one another, as shown in FIGS. 3 and 4. Each of these units is of conventional construction and, as shown in FIG. 3, includes an outer case 61, a conical metal liner 62, a main explosive body 63 and a booster charge 64. Air spaces 46 are provided behind each of the charge cases with O'rings 47 forming a liquid seal against the borehole l'luid.

As best shown in FG. 3, an orifice member 48 is positioned behind each of the shaped charge units 44 pointing along the line of discharge of each unit. Each orifice member is provided with a sealing plug 49 to form a seal against liquid 38.

The carrier 41 is also provided with three anchoring dogs 51 slidably positioned in the radial passages 53 and each provided with an O-ring 52 to form a liquid seal. Like the shaped charge units 44, the dogs 51 are also angularly spaced at 120 from one another and are adapted to slide along the bisector of the angle formed by the lines of discharge of adjacent shaped charge units.

Carrier 41 is formed as a unit readily separable from the rest of tool 10. This is because the oriice members 4S may be damaged by successive firings of shaped charge units. Either the damaged orifice members or the entire carrier 41 may be easily replaced as desired.

A hollow nose piece 56 is attached to the lower portion of the carrier 41 (FIG. 2), and denes a chamber S4 which is initially at atmospheric pressure, being sealed from the liquid container 37 by the diaphragm 42. Taken together nose piece 56, carrier 41, body 23 and cable head 17 constitute an assembly referred to in the appended claims as a body member.

Operation of the tool 1t), positioned within the well borehole opposite a formation to be perforated, is initiated by closing the switch 21 and providing an electrical current to actuate the explosive or propellant body 31. The pressure built up in expansion chamber 26 by such combustion is transmitted through piston 27 to the liquid body 38, thus driving the anchoring dogs 51 radially outwardly to the position shown in FIG. 4. Each of the dogs 51 is made of hard steel and provided with a sharp point which bites into the casing 13 so that they are eifective to hold the tool 16 against longitudinal or angular movement.

At the same time, closing of the switch 21 supplies current to the delay fuse 35, which after a predetermined interval (of the order of 50 milliseconds) to allow setting of the dogs 51, ignites the three primacord fuses 36, which in turn actuates the shaped charge units 44. Explosion of these units perforates the casing 13 and the cement annulus 14 into the formation 16, the perforation being indicated in FIG. 4 by the reference character 55.

The pressure exerted through the liquid body 38 by the piston 27 is now sulicient to dislodge the seals 49 so that jets of liquid under high pressure and at great velocity are discharged through oriiice members 48 which are pointed directly into the perforations 55. The pressure exerted on the liquid body is typically in the order of 50,000 p.s.i. with the velocity of the liquid being emitted from the orifices 48 typically being about 450() feet per second. This high velocity is sufficient to increase the depth of penetration of the perforation 5S, as shown in FIG. 5 by the somewhat narrowed portion 55a. The high-pressure jet 60 of liquid 38, indicated diagrammatically bythe arrows, follows a path whereby it doubles back upon itself, thus enlarging the diameter of the opening to about twice the diameter of the jet itself. lf liquid 38 is chemically reactive with the formation 16 the size of tho perforation is further increased by such reaction. The liquid 38 may also be in the form of a slurry of abrasive particles whose cutting action against the formation will deepen and widen the perforation.

As the piston 27 moves longitudinally through the container 37, forcing liquid 38 through orice member 48, it reaches the position shown in FIG. 6, wherein the sharp spike 39 ruptures the diaphragm 42. The remaining liquid in container 37 is thus emptied into the lowpressure chamber 54 and the pressure within container 37 is drastically lowered. This sets up a dilerential pressure between the container 37 and the borehole fluid 12 across the dogs 51 (which are shown in FIG. 6 as still in expanded position) thus forcing them radially inward and releasing the tool 1()` from contact with the casing 13 so that the tool 10 may :be withdrawn from the well.

In an alternative embodiment of the invention, useful in dry holes not containing well fluid, the dogs 51 m-ay be made of a hard, but frangible material so that a strong upward pull on the wireline 15 will fracture them and release the tool 10.

It will thus be seen that the present invention provides a wireline tool which is capable of injecting liquids such as acids or slurries selectively into perforations formed through well casing. By employing a self-contained propellant and an expansion chamber, it is possible to provide the driving force for these liquid jets from a selfcontained unit within the tool requiring only a conventional electrical connection to the top of the well for actuation thereof. The combination of the low-pressure chamber with a diaphragm that is ruptured after most of the liquid has been expelled provides a quick and easy means of releasing the tool from the well after perforations have been made.

l claim:

1. Apparatus for use in fluid-containing earth well boreholes or the like comprising: an elongated body member; means, including a longitudinally movable piston, defining an expansion chamber within said body member; pressure generating means within said expansion chamber; means adjacent said expansion chamber defining a liquid container within said body member; a body of liquid within said container against which said piston is moved by generation of pressure within said expansion chamber; a plurality of shaped charge units carried on the outside of said body member adjacent said liquid container and directed laterally of said body member; orice means formed in said body member adjacent each of said shaped charge units and positioned for ejecting liquid under pressure from said container into perforations in the wall of said bore hole formed by discharge of said shaped charge units; pressure releasable closure means closing each of said orice means; anchoring means laterally movable into holding position for holding said body member against movement with respect to said borehole, said anchoring means carried on said body member adjacent said container and moveable against the pressure of borehole fluid in response to application of pressure to said liquid; means for discharging said shaped charge units; means for actuating said pressure generating means to move said piston against said liquid thereby applying pressure therethrough to move said anchoring means into holding position, dislodge said closure means from said orifice means and eject liquid jets therefrom; and means responsive to movement of said piston effective to release said liquid from said container and thereby reduce liquid pressure to a value below that of the adjacent borehole Ifluid whereby such borehole fluid pressure is effective to move said anchoring means from holding position subsequent to ejection of said liquid jets and release said apparatus for withdrawal from said borehole.

2. Apparatus according to claim l wherein said means responsive to movement of said piston include: a closed low pressure chamber formed at the bottom of said apparatus; and a spike depending fro-m said piston adapted tol open said chamber.

3. Apparatus for use in earth well boreholes or the like comprising: a body member; means, including a longitudinally moveable piston, defining an expansion chamber within said body member; pressure generating means within said expansion chamber; means adjacent said expansion chamber defining a liquid container within said body member; a body of liquid within said container against which said piston is moved by generation of pressure within said expansion chamber; a plurality of shaped charge units carried on the outside of said body member adjacent said liquid container and directed laterally of said body member; orifice means formed in said body member adjacent each of said shaped charge units and positioned for ejecting liquid under pressure from said container into perforations in the wall of said borehole formed by discharge of said shaped charge units; pressure releasable closure means closing each of said orifice means; anchoring means carried on said body member adjacent said container and moveable in response to application of pressure to said liquid; means for discharging said shaped charge units; means for actuating said pressure generating means to move said piston against said liquid thereby applying pressure therethrough to move said anchoring means into holding position, dislodge said closure means from said orifice means and eject liquid jets therefrom; and means responsive to the movement of said piston for reducing said liquid pressure on said anchoring means subsequent to the ejection of said jets 'from said orifice means.

4. Apparatus for use in earth Well boreholes or the like; a body member; means defining a liquid container within said Ibody member; a body of liquid within said container; displacement means for displacing said liquid from said container; means Within said body member for actuating said displacement means; a plurality of shaped charge units carried on the outside of said body member and directed laterally of said body member; orice means formed in said body member adjacent each of said shaped charge units and positioned for ejecting liquid under pressure from said container into perforations formed by the ldischarge of said shaped charge units; normally closed closure means closing each of said orifice means and openable in response to actuation of said displacement means; anchoring means moveable into anchoring position for holding said body member against movement with respect to said borehole, said anchoring means carried on said body member adjacent said container and moveable in response to actuation of said displacement means; means for discharging said shaped charge unit; means -for actuating said displacement means thereby moving said anchoring means into holding position, dislodging said closure means from said orifice means and ejecting liquid jets therefrom; means connected to and moveable with said displacement means; and mean co-operating with said connected means and responsive to the movement thereof to eifect release of said anchoring means from anchoring position subsequent to the ejection of said jets from said orice means.

5. Apparatus for use in earth well boreholes or the like comprising: a body member; pressure generating means Within said body member; means within said body member dening a liquid container; a `body of liquid withing said container; means for applying pressure generated within said body member to said liquid; perforating means carried on said body member adjacent said liquid container and directed laterally of said body member; orifice means formed in said body member adjacent each of said perforating means and positioned for ejecting liquid under pressure from said container into perforations in the Wall of said borehole formed by the charge of said perforating means; pressure releasable closure means closing each of said oriiice means; anchoring means moveable into the anchoring position in response to application of pressure to said liquid for holding said body against movement with respect to said borehole; means for actuating said perforating means; means for actuating said pressure generating means to apply pressure to said liquid and thereby move said anchoring means into anchoring position, dislodge said closure means from said orice means and eject liquid jets therefrom; `a low pressure chamber adjacent said liquid container; and means moveable in cooperation with said means for applying pressure for permitting said liquid in said container to iiow into said chamber to reduce pressure on said liquid and effect release of said anchoring means from anchoring position subsequent to the ejection of said jets yfrom said orifice means.

References Cited in the file of this patent UNITED STATES PATENTS 2,171,416 Lee Aug. 29, 1939 2,315,496 Boynton Apr. 6, 1943 2,381,929 Schlumberger Aug. 14, 1945 2,876,843 Huber Mar. 10, 1959 2,918,125 Sweetman Dec. 22, 1959 2,975,834 Nest et al Mar. 21, 1961 2,986,214 Wiseman et al May 30, 1961 2,988,143 Scotty June 13, 1961

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