BAKER HUGHES, A GE COMPANY,
`LLC AND BAKER HUGHES
`OILFIELD OPERATIONS LLC
`Exhibit 1037
`BAKER HUGHES, A GE COMPANY,
`LLC AND BAKER HUGHES
`OILFIELD OPERATIONS LLC v.
`PACKERS PLUS ENERGY
`SERVICES, INC.
`IPR2016-01380
`
`Page 1 of 9
`
`

`

`0
`United States Patent
`[19]
`[11] Patent Number:
`5,499,678
`
`Surjaatmadja et al.
`[45] Date of Patent:
`Mar. 19, 1996
`
`Illllllll|l||||||||||||l|||||||||||l|llllllllll|||||lllllllllllllllllllllll
`USOOS499678A
`
`[54] COPLANAR ANGULAR JETTlNG HEAD
`FOR WELL PERFORATING
`
`3/1992 Clark ....................................... 166/187
`5,097,902
`
`5,174,340 12/1992 Peterson et al.
`.
`138/110
`......................... 166/298
`5,335,724
`8/1994 Verditto ct a1.
`
`[75]
`
`Inventors: Jim B. Surjaatmadja; Timothy W.
`Helton; Hazim H. Abass, all of
`Duncan, Okla.
`
`NTS
`FOREIGN PATENT DOC
`1314023
`5/1987 Russian Federation ............... 166/298
`
`U} [E
`
`[73] Assignee: Halliburton Company, Duncan, Okla.
`
`[21] Appl. No.: 284,961
`
`OTHER PUBLICATIONS
`Halliburton Services Sales & Service Catalog No. 43, p.
`2575 (1985).
`
`[22] Filed:
`Aug. 2, 1994
`Primary Examiner—William P. Neuder
`[51]
`Int. C16 .................................................... E21B 43/114 @2333 Age“ 0’ “W‘smphe” 1" emu“; Neal R'
`[52] US. Cl. ............................. 166/298; 166/308; 166/55
`[58] Field of Search ..................................... 166/298, 308,
`[57]
`ABSTRACT
`166/55’ 222
`A coplanar jetting head for well perforating. The apparatus
`comprises a housing defining a plurality ofjetting openings
`therein. The Jetting operungs are substantially coplanar and
`are angularly disposed with respect to a longitudinal axis of
`the housing. Each of the jetting openings has a jetting nozzle
`disposed therein. In the preferred embodiment, the angle of
`1
`f h .
`.
`.
`.
`h
`1
`the P if“? 0 t Clams °Pemngs 15 .5110
`that “161??“ may
`be pqsmoned sqbstantlally Demendlcqlar to an ans of least
`princtpal stress in a well forrnatton adjacent to the well bore
`when the housing is disposed in the well bore. A method of
`fracturing a well is also disclosed and comprises the steps of
`positioning a jetting head in a well bore and directing a
`plurality of fluid jets from the jetting head at an angle with
`.
`.
`.
`“3st to the longmdmal am 0f the well bore'
`
`[56]
`
`References Cited
`
`US. PATENT DOCUMENTS
`.
`
`7/1968 Goodwm ..................
`.. 166/298 X
`166/298X
`9/1977 Tagirov et a1.
`
`405/184
`6/1987 Nussbaumer .
`
`9/1988 Yte .......................
`239/3
`11/1988 Dickinson, 11] e: a].
`_ 175/57
`
`4/1989 Mueller ................
`.. 418/48
`6/1990 Turin et a1.
`. 175/25
`
`8/1990 Szarka 6131-
`155/285
`1%;33(1) 31:!“ ----------
`igggfg
`c wegman .
`2/1991 Brandell et a1.
`..
`166/332
`
`2/1991 Wilkes, Jr. ct a1.
`..... 175/61
`........................... 166/223
`7/1991 Szarka et a1.
`
`-
`
`3,393,736
`4,050,529
`4,673,312
`4,768,709
`4,787,465
`4,818,197
`4,930,586
`4,949,788
`$33,221},
`,
`,
`4,991,654
`4,991,667
`5,029,644
`
`15 Claims, 4 Drawing Sheets
`
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`
`Page 1 of 9
`Page 1 of 9
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`

`

`US. Patent
`
`Mar. 19,1996
`
`Sheet 1 of 4
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`5,499,678
`
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`WE- E
`PRIOR ART
`
`Page 2 of 9
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`
`US. Patent
`
`Mar. 19, 1996
`
`Sheet 2 of 4
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`5,499,678
`
`5@*
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`52
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`Page 3 of 9
`Page 3 of 9
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`

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`US. Patent
`
`Mar. 19, 1996
`
`Sheet 3 of 4
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`5,499,678
`
`
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`Page 4 of 9
`Page 4 of 9
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`

`

`US. Patent
`
`Mar. 19, 1996
`
`Sheet 4 of 4
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`5,499,678
`
`/07
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`
`
` 52
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`Page 5 of 9
`Page 5 of 9
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`

`

`5,499,678
`
`1
`COPLANAR ANGULAR JETTING HEAD
`FOR WELL PERFORATING
`
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`
`This invention relates to apparatus and methods for per-
`forating wells, and more particularly, to a jetting head with
`a plurality of coplanar jets which are used to penetrate the
`well casing.
`2. Description of the Prior Art
`There are a number of methods used in perforating wells
`which are well known. The present invention overcomes
`problems associated with these prior methods and provides
`an apparatus and method which is particularly well suited
`for, but not limited to,
`the special situations which are
`presented in the completion of deviated wells. A brief
`discussion of several different techniques currently used for
`the completion of deviated wells follows.
`A first, very common manner of completing a deviated
`well is to case and cement the vertical portion of the well and
`to leave the deviated portion of the well which runs through
`the production formation as an open hole, i.e., without any
`casing in place therein. Hydrocarbon fluids in the formation
`are produced into the open hole and then through the casing
`in the vertical portion of the well. The problem with this is
`there is no case to prevent collapse of the well bore.
`A second technique which is commonly used for the
`completion of deviated wells is to place a length of slotted
`casing in the deviated portion of the well to prevent the open
`hole from collapsing. A gravel pack may be placed around
`the slotted casing. The slotted casing may run for extended
`lengths through the formation, for example, as long as one
`mile.
`
`A third technique which is sometimes used to complete
`deviated wells is to cement casing in both the vertical and
`deviated portions of the well and then to provide commu-
`nication between the deviated portion of the casing and the
`producing formation by means of perforations or casing
`valves. The formation may also be fractured by creating
`fractures initiated at the location of the perforations or the
`casing valves.
`In this technique, the formation of perforations is often
`done using shaped charge methods. That
`is, explosive
`charges are carried by a perforating gun, and these explosive
`charges create holes which penetrate the side wall of the
`casing and penetrate the cement surrounding the casing.
`Typically, the holes will be in a pattern extending over a
`substantial length of the casing.
`A problem with the use of explosive charges to perforate
`is that this method generally creates high damage in the
`formation by increasing skin and also creating high localized
`stresses in the formation. By doing this, fractures created by
`stimulation processes tend to become very tortuous and
`restrict the production of oil and gas. This problem of
`tortuosity, literally meaning “marked by repeated twists and
`bends” reduces the potential production rate of the well
`because even though the rock moves to open the fracture,
`severe restrictions still remain.
`
`Tortuosities thus are generally caused by the situation
`wherein the initial fracture does not coincide with the
`maximum stress plane. Under such a circumstance,
`the
`fracture will twist or bend to finally direct itself to the
`maximum stress plane. This can be caused by incorrect
`fracture initiation procedures or high localized stresses
`
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`which prevent the fracture from initiating properly. An
`additional problem closely associated with tortuosity is the
`creation of multiple fractures which will increase leakoif and
`hence cause screenouts.
`
`When the communication between the casing and pro~
`duction formation is provided by casing valves, those valves
`may be like those seen in U.S. Pat. No. 4,949,788 to Szarka,
`et al., U.S. Pat. No. 4,979,561 to Szarka, U.S. Pat. No.
`4,991,653 to Schwegman, U.S. Pat. No. 5,029,644 to Szarka
`et 21., and US. Pat. No. 4,991,654 to Brandell et al., all
`assigned to the assignee of the present invention. Such
`casing valves also provide a large number of radial bore type
`openings communicating the casing bore with the surround—
`ing formation.
`When utilizing either perforated casing or casing valves
`like those described, fracturing fluid enters the formation
`through a large multitude of small radial bores at a variety
`of longitudinal positions along the casing, and there is no
`accurate control over where the fracture will initiate and in
`what direction the fracture will initiate. As mentioned, this
`lack of proper fracture initiation results in tortuosity.
`Fracture initiation is largely influenced by the shape and
`orientation of the initial cavity, maximum and minimum
`stress direction, near well bore conditions such as localized
`stresses, or other irregularities that may be encountered such
`as natural fractures, fossils, etc.
`To solve the problems of these prior methods, hydrajetting
`has been developed. Generally, hydrajetting does not result
`in skin damage, and no residual stresses occur since jetting
`is performed at pressures below the yield strength of the
`rock. Moreover, the jetting tool is positioned in the correct
`direction for proper fracture initiation. Thus, tortuosities are
`reduced or eliminated. This is because in hydrajetting, holes
`are formed by removal of material, rather than compaction.
`Removal is performed below the compressive strength of the
`rock, and thus there is no highly stressed area formed.
`Further, hydrajetting is a slower process. Therefore, tempo-
`rary deflection or reflection by abnormal positioning will not
`jeopardize the quality of the cutting process. The main intent
`of hydrajetting perforating is to be able to position a cavity
`such that the shape is basically flat and located in the
`direction of maximum principal stress. By doing this, frac-
`tures will start at the edges of such cavities, and tortuosities
`will therefore not occur.
`
`Examples of hydrajetting perforating tools are disclosed
`in U.S. Pat. Nos. 5,249,628 and 5,325,923 and U.S. Pat.
`application Ser. No. 08/206,560, all of which are assigned to
`the assignee of the present invention. Each of these discloses
`apparatus and techniques designed to create a cavity which
`promotes fractures to initiate perpendicular to the well bore,
`thus being particularly suitable for deviated wells or very
`shallow vertical wells. These devices are designed for wells
`drilled in the direction of least principal stress and to create
`a cavity perpendicular to the well bore.
`Jetting parallel
`to the casing also may be done and
`involves the movement of the jetting tool up and down the
`casing. In order to make a cut which is sufliciently deep, the
`jetting tool must move at a very slow speed. To introduce a
`good slot in deviated wells, an in-line, multiple jet system
`must be used.
`
`While such hydrajetting tools substantially reduce the
`problem of tortuosities in the fractures, tortuosity can still be
`a problem. This is due to the fact that many operators place
`their holes randomly, and thus initiate fractures which are
`uncontrolled. The apparatus and method of the present
`invention are designed to solve these previous problems by
`
`Page 6 of 9
`Page 6 of 9
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`

`

`5,499,678
`
`3
`placing the perforations in one plane which is preferably
`perpendicular to the least principal stress. This is accom-
`plished by placing jets coplanarly and positioning them such
`that the jets make a cutting angle that is at the steepest
`possible angle at the contact point in the casing. This
`improves cutting efficiency through the casing wall.
`
`SUMMARY OF THE INVENTION
`
`The present invention includes an apparatus and method
`for jetting a plurality of coplanar fluid jets. The apparatus
`and method are used for well perforating and provide such
`perforation with a minimum of tortuosity problems in the
`fractured well formation.
`
`The jetting apparatus of the present invention comprises
`a housing defining a plurality of jetting openings therein.
`The jetting openings are preferably substantially coplanar
`and are angularly disposed with respect to a longitudinal
`axis of the housing. Each of the openings has a removable
`jetting nozzle disposed therein. Each jetting nozzle has an
`orifice, and jetting nozzles with one orifice size are inter-
`changeable with jetting nozzles having differcnt orifice
`Sizes.
`
`The angle of the plane in which the jetting openings are
`disposed is preferably such that the plane may be positioned
`substantially perpendicular to an axis of the least principal
`stress in a well formation adjacent to the well bore when the
`housing is disposed in the well bore.
`In one embodiment, the openings are substantially radi-
`ally oriented. That is, they are oriented in directions which
`substantially originate from, and therefore intersect,
`the
`longitudinal axis of the housing.
`In another embodiment, at least some of the openings are
`oriented and originate from a direction spaced from the
`longitudinal axis. At least some of the openings in this
`second embodiment may be substantially parallel.
`However, the invention is not intended to be limited to
`one with only parallel openings. Thus,
`in still another
`embodiment,
`the nozzles are evenly angularly disposed
`around the housing of the jetting apparatus, and the nozzles
`generally face to one side. However, the nozzles diverge
`slightly at angles which can be calculated as functions of the
`cut angle through the fracture formation, the outside diam-
`eter of the jetting tool, and the inside diameter of the casing
`string. This third embodiment
`is similar to the second
`embodiment, except that the nozzles are not parallel. A
`preferred orientation of the jetting openings is such that they
`are at the steepest possible angle at the contact point of the
`jetted fluid in the well bore.
`The present invention also includes a method of fracturing
`a well formation comprising the steps of positioning ajetting
`head in a well bore and directing a plurality of coplanar fluid
`jets from the jetting head at an angle with respect to a
`longitudinal axis of the well bore. Basically, the method is
`carried out using the apparatus described.
`Numerous objects and advantages of the invention will
`become apparent as the following detailed description of the
`preferred embodiment is read in conjunction with the draw-
`ings which illustrate such embodiment.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 illustrates a well formation exhibiting the problem
`- of tortuosity.
`FIG. 2 shows a prior art hydrajetting tool using jets
`perpendicular to-the axis of the tool.
`
`4
`FIG. 3 illustrates the coplanar angular jetting head for
`well perforating of the present invention shown in position
`in a substantially horizontal portion of a deviated well.
`FIG. 4 is a cross section taken along lines 4—4 in FIG. 3.
`FIG. 5 shows a cross section of an alternate embodiment
`also taken along lines 4—-4 in FIG. 3.
`FIG. 6 illustrates a third embodiment of the invention
`shown in position in a substantially horizontal portion of a
`deviated well.
`
`FIG. 7 is a cross section taken along lines 7—7 in FIG. 6.
`FIG. 8 is a schematic version of FIG. 7 illustrating a
`specific example of the apparatus with divergent nozzles.
`
`DESCRIPTION OF THE PREFERRED
`EMBODIMENT
`
`Referring now to the drawings, and more particularly to
`FIG. 1, the phenomenon of tortuosity in a well formation
`will be discussed. A subterranean well formation 10 is
`shown with a fracture 12. Fracture 12 provides a flow path
`as shown by arrow 14 and is created by rock movement
`indicated by arrows 16.
`Tortuosity occurs when the flow path is twisted or has
`bends which can result in the flow path being at least
`partially closed off by restrictions, such as 18 and 20. It will
`be seen in such instances that even as the rock opens the
`fracture, restrictions 18 and 20 still remain. This reduces the
`potential production rate of the well.
`Tortuosities are normally caused by the situation where
`the initial fracture does not coincide with a maximum stress
`plane. Under such a circumstance, the fracture will twist or
`bend to finally direct itself to the maximum stress plane. As
`previously mentioned, this is generally caused by incorrect
`fracture initiation procedures for high localized stresses
`which prevent proper fracture initiation.
`In the hydrajetting tools of the prior art, no real attempt
`has been made to align the jetting with the plane of maxi—
`mum stress. For example, referring to FIG. 2, a prior art
`jetting tool 22 is illustrated in a well bore 24. Well bore 24
`has a casing string 26 disposed therein and cemented in
`place by cement 28.
`Tool 22 comprises a plurality of jetting nozzles, such-as
`jetting nozzles 30, 32 and 34, which are disposed perpen-
`dicular to the longitudinal axis of tool 22.
`Jetting with such a prior art tool 22 provides a plurality of
`jetted holes, such as holes 36 and 38, which are also
`perpendicular to the axis of well bore 24. The jetting nozzles
`jet these holes through casing string 26, cement 28 and into
`formation 40. Such radial holes will cause fractures to
`initiate and initially propagate outwardly in radial planes,
`such as indicated at 42 and 43, and will then turn in a
`direction generally perpendicular to the least principal stress
`axis 44 as indicated at 46 and 48, respectively. This type of
`jetting results in holes which are not in the same plane, so
`multiple fractures will occur. These multiple fractures and
`the turning to the direction generally perpendicular to the
`least principal stress axis 44 can result in tortuosity, although
`it is generally not as severe a problem with jetted holes as
`with perforations using explosive charges.
`Referring now to FIG. 3, the coplanar angular jetting head
`of the present invention is shown and generally designated
`by the numeral 50. As with the prior art jetting tool 22
`previously described, jetting head 50 is positioned in a well
`bore 52. Well bore 52 has a casing string 54 disposed therein
`which is cemented in place by cement 56. Well bore 52 as
`
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`5,499,678
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`5
`illustrated is a substantially horizontal portion of a deviated
`well which intersects a subterranean formation 58, although
`the invention is not limited to this application. It will be
`understood that “deviated” wells include those without
`horizontal sections. “Horizontal” wells are just a specific
`type of “deviated” well.
`Referring also to FIG. 4, jetting head 50 includes a
`housing 60 with a plurality of jetting openings 61 therein. In
`each jetting opening 61 is a jetting nozzle, such as 62, 64, 66
`and 68, letting nozzles 62, 64, 66 and 68 are attached to
`housing 60 by any means known in the art, such as the
`illustrated threaded engagement. Each jetting nozzle 62, 64,
`66 and 68 has an orifice 70 defined therein through which the
`jetting fluid is jetted.
`It will be seen that all of nozzles 62, 64, 66 and 68 are
`coplanar. That is, they are all disposed on a single plane
`which is in angular relationship to the longitudinal axis of
`jetting head 50. Ideally, the plane of jetting nozzles 62, 64,
`66 and 68 is substantially perpendicular to the least principal
`stress axis 72 of formation 58. In this way, jetting tool 50 is
`used to jet a plurality of jetted holes 74 which are also
`substantially coplanar. These holes 74 in turn cause substan-
`tially coplanar fractures 76 to occur. It will be seen by those
`skilled in the art that fractures 76 are on the plane of
`maximum principal stress. This results in a consistent and
`even fracture formation which does not have the turns of the
`prior art methods and therefore eliminates, or at least greatly
`minimizes, the problem of tortuosity.
`In the first embodiment of FIG. 4, all ofjetting nozzles 62,
`64, 66 and 68 are radially disposed from the central axis of
`housing 60. That is, the direction of each of jetting nozzle
`originates from the center of jetting head 50.
`Referring now to FIG. 5, a second embodiment jetting
`head 50' is shown which comprises a housing 60' with two
`sets of jetting openings 78 and 80 defined therein facing in
`opposite directions. In this embodiment, there are two sets of
`substantially coplanar jetting nozzles 82 disposed in jetting
`openings 78 and jetting nozzles 84 disposed in jetting
`openings 80. letting nozzles 82 and 84 have orifices 86
`therein and may be attached to housing 60’ by any means
`known in the art, such as the threaded engagement illus-
`trated.
`
`The orientation of jetting nozzles 82 and 84 in second
`embodiment jetting head 50' differ from that of first embodi-
`ment jetting head 50 in that the direction of the jetting
`nozzles in the second embodiment do not all originate from
`the center of the jetting head. As illustrated in FIG. 5, each
`of jetting nozzles 82 is substantially parallel and coplanar,
`and they are positioned such that jetting nozzles 82 make a
`cutting angle that is the steepest possible at the contact point
`in the casing. This greatly increases cutting efficiency
`through the casing wall. This in turn results in better fracture
`formation extending from a corresponding parallel plurality
`of jetted holes. letting nozzles 84 are similarly disposed, but
`generally face in the opposite direction from nozzles 82.
`The number and orientation of jetting nozzles 82 and 84
`may be varied as desired depending upon the well formation,
`so long as they are coplanar. The plane on which the jetting
`nozzles are coplanarly disposed may also be varied to
`correspond to the angle of the axis of least principal stress
`so that the plane is substantially perpendicular to that axis.
`Referring now to FIGS. 6 and 7, a third embodiment
`jetting head 50" is shown which comprises a housing 60"
`with a plurality ofjetting openings 88, 90, 92 and 94 defined
`on one side thereof, and a substantial identical set of jetting
`openings 88, 90, 92 and 94 disposed on an opposite side
`
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`6
`thereof. A plurality of coplanar jetting nozzles 96, 98, 100
`and 102 are disposed in each set of jetting openings 88, 90,
`92 and 94, respectively. As best seen in FIG. 6, jetting
`nozzles 96, 98, 100 and 102 lay in a cut plane 104. Cut plane
`104 is disposed at an angle 106 with respect to a substan—
`tially vertical plane 107 perpendicular to the axis of the well
`bore.
`
`letting nozzles 96, 98, 100 and 102 have orifices 108
`defined therein, and the jetting nozzles may be attached to
`housing 60" by any means known in the art, such as the
`threaded engagement illustrated.
`Third embodiment jetting head 50" is similar to jetting
`head 50' except that jetting nozzles 96, 98, 100 and 102 are
`not parallel to one another as are the jetting nozzles in the
`second embodiment. The orientation of jetting nozzles 96,
`98, 100 and 102 is mathematically calculated as a function
`of cut plane angle 106, the outside diameter of jetting tool
`50" and the inside diameter of easing string 54.
`Referring also to FIG. 8, the orientation ofjetting nozzles
`96, 98, 100 and 102 will be discussed. Basically, FIG. 8 is
`a schematic version of FIG. 7 in which the jetting nozzles are
`indicated by points on an ellipse representing a section
`through housing 60".
`letting nozzles 96, 98, 100 and 102 are equally angularly
`spaced. Therefore, for a total of eight jetting nozzles, the
`jetting nozzles are 45° apart. Preferably, jetting nozzles 98
`and 100 are located at a 221/2° angle from minor axis 110 of
`the ellipse, and jetting nozzles 96 and 102 are thus 671/2"
`from the minor axis. This gives two sets of jetting orifices
`generally facing in opposite directions from major axis 111.
`In the following example, angle 106 is approximately 60°,
`the outside diameter ofjetting tool 50" is approximately four
`inches and the inside diameter of casing string 54 is approxi—
`mately five inches. In FIG. 8, the jetted spray from nozzles
`96, 98, 100 and 102 are designated by arrows 112, 114, 116
`and 118,
`respectively. By mathematical calculation to
`achieve the steepest possible angle of contact with casing
`string 54, the preferred angle of jetting nozzles 98 and 100
`is approximately 21.137° from a line extending through the
`jetting nozzle and the center line of the ellipse toward minor
`axis 110. It will thus be seen in FIG. 8 that jetting nozzles
`98 and 100 will direct slightly divergent jetting streams 114
`and 116 therefrom, respectively.
`Also by mathematical calculation to achieve the steepest
`possible angle of contact with casing string 54, the preferred
`angle of jetting nozzles 96 and 102 is approximately 47.96‘3
`from a line through the center of the nozzle and the center
`of the ellipse toward minor axis 110. The maximum angle of
`contact for jetting nozzles 98 and 100 for this example is
`approximately 53° from vertical.
`Those skilled in the art will thus see that nozzles 96 and
`102 diverge from one another, nozzles 96 and 98 diverge
`from one another, and nozzles 100 and 102 diverge from one
`another. That is, the jetted streams 112, 114, 116 and 118 are
`not parallel to one another as in the second embodiment, but
`rather all diverge slightly.
`In this example, the cutting angle is the steepest possible
`for each jetting nozzle at the contact point of the jetted fluid
`with casing string 54. This greatly increases cutting efii-
`ciency through the casing wall and results in better fracture
`formation extending from the jetted holes.
`the
`With this mathematically calculated embodiment,
`number and orientation of jetting nozzles may be varied,
`thus resulting in a variation in the angular location of the
`jetting nozzles around the elliptical cross section through the
`housing with a corresponding variation in the angles of
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`divergence of the jetted streams. As with the other embodi—
`ments, the main requirement is that all of the jetting nozzles
`are coplanar.
`It will be seen, therefore, that the coplanar angular jetting
`head for well perforating of the present invention is well
`adapted to carry out the ends and advantages mentioned, as
`well as those inherent therein. While presently preferred
`embodiments of the apparatus and method of use have been
`described for the purposes of this disclosure, numerous
`changes in the arrangement and construction of parts in the
`apparatus and steps in method may be made by those skilled
`in the art. All such changes are encompassed within the
`scope and spirit of the appended claims.
`What is claimed is:
`1. A jetting apparatus for use in perforating a well bore,
`said apparatus comprising a housing defining a plurality of
`jetting openings therein, said jetting openings being sub-
`stantially in a single plane which is disposed at an angle
`other than perpendicular with respect to a longitudinal axis
`of said housing, such that fluid is jetted in said plane from
`said jetting openings.
`2. The apparatus of claim 1 wherein each of said jetting
`openings has a jetting nozzle disposed therein.
`3. The apparatus of claim 1 wherein the angle of said
`plane is such that said plane may be positioned substantially
`perpendicular to an axis of least principal stress in a well
`formation adjacent to the well bore when said housing is
`disposed in said well bore.
`4. The apparatus of claim 1 wherein said openings are
`angularly disposed on said plane.
`5. The apparatus of claim 1 wherein said openings are
`oriented in directions which substantially originate from said
`longitudinal axis.
`6. The apparatus of claim 1 wherein the direction of at
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`least some of said openings originates from a direction
`spaced from said longitudinal axis.
`7. The apparatus of claim 6 wherein at least some of said
`openings are substantially parallel.
`8. The apparatus of claim 1 wherein said jetting openings
`are disposed at the steepest possible angle with respect to the
`well bore when said housing is disposed in said well bore.
`9. A method of fracturing a well formation comprising the
`steps of:
`selecting a jetting head With a plurality of fluid jets
`positioned in a single plane at an angle other than
`perpendicular with respect to a longitudinal axis of said
`jetting head;
`positioning said jetting head in a well bore; and
`directing fluid from said plurality of fluid jets on said
`jetting head in said plane at an angle other than per-
`pendicular with respect to a longitudinal axis of said
`well bore.
`
`*
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`10. The method of claim 9 wherein said angle is substan~
`tially perpendicular to a plane of least principal stress in the
`well formation.
`11. The method of claim 9 wherein said fluid jets are
`directed from locations angularly disposed on said plane.
`12. The method of claim 11 wherein at least one of said
`fluid jets is oriented in a direction which substantially
`intersects said longitudinal axis.
`13. The method of claim 9 wherein at least some of said
`fluid jets are substantially parallel.
`14. The method of claim 9 wherein said angle is the
`steepest possible at the contact point in said well bore.
`15. The method of claim 9 wherein said fluid jets are
`directed from jetting nozzles disposed in said jetting head.
`*
`>l<
`*
`*
`*
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