BAKER HUGHES, A GE COMPANY,
`LLC AND BAKER HUGHES
`OILFIELD OPERATIONS(cid:15) LLC
`Exhibit 1144
`BAKER HUGHES, A GE COMPANY,
`LLC AND BAKER HUGHES
`OILFIELD OPERATIONS(cid:15) LLC v.
`PACKERS PLUS ENERGY
`SERVICES, INC.
`IPR2017-00247
`Page 1 of 5
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`

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`Patented Sept. 14, 1954
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`2,689,009
`
`UNITED STATES PATENT OFFICE
`
`.
`.-
`
`2,639,009
`acmrzmc WELLS
`
`Harold W. Brainerd, Jr. Clarence It. Fast. and
`George 0. Howard, Tulsa, Okla... assignors to
`StanOIind Oil and Gas Company, Tulsa, 01:13.,
`a corporation of Delaware
`No Drawing. Application April 14. 1951,
`Serial No. 221,136
`
`20 Claims.
`
`(Cl. 166—25)
`
`VI
`
`10
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`15
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`1
`This invention pertains to a well-treating solu-
`tion and to an improved method of treating wells
`to increase their productivity.
`In the art of completing wells or working over
`old wells to increase the output, acid is injected
`into the producing zones to increase the perme-
`ability of the formation around the well. Since
`acid reacts very rapidly with calcareous forma-
`tions, it appears that the action of the acid is
`very close to the well. Accordingly, the effect of
`acidizing a well is generally to increase output,
`but the increase appears to be much less than
`would be possible if the acid could be made to
`react into long channels deep into the formations
`It has been proposed that strong mineral acids
`which are used to acidize formations penetrated
`by a well be incorporated as the discontinuous
`phase in an acid-oil emulsion. By thus shielding
`the acid, it is prevented from contacting the well
`tubing and the calcareous formations as the acid
`is injected into a well. Corrosion of the tubing
`is avoided. and the reaction of the acid on the
`formation is retarded. Certain oils are known to
`emulsify with acids: and. in some cases. the emul-
`sion may be produced by incorporating in the oil
`or the acid certain emulsiiying agents. This pro-
`posal has not been used, since. in practice, it has
`been found that the emulsifying agents proposed
`are either too stable or too unstable That is.
`if the emulsion is too stable. the emulsion may
`not be easily broken down in the well or in the
`formation; and, if injected into a formation, as
`by the application of a high pressure. the emul-
`sion cannot be displaced from the pores of the
`formation by the relatively small available natu-
`ral driving force. The formation would thus be
`plugged if such stable emulsions were forced into
`the capillaries surrounding a well.
`If the emul-
`sion is unstable, it is of no value for the intended
`purpose.
`In either case, however. the action of
`the acid is close to the well, and long flow chan-
`nels into the formation are not produced.
`It is an object of this invention to provide an
`improved well-treating solution.
`It is another
`object of this invention to provide a well-treating
`solution comprising an emulsion of an acid and
`an oily vehicle which can be injected into a for-
`mation at high pressure to iracture the formation
`and which subsequently can be removed from the
`at D
`formation without plugging the pores thereof. A '
`
`2
`still further object of this invention is to provide
`an improved process for increasing the permea-
`bility of calcareous formations which produce oil
`or gas or other valuable fluids.
`This invention, in brief, comprises a well-treat-
`ing solution in which acid is emulsified in an oil
`dispersion of Batu gum and an improved procesa
`in which the viscous emulsion is injected into a
`formation at a. pressure great enough to fracture
`the formation.
`Batu gum is a natural resin related to the
`Damar natural resins and is a secretion or exuda-
`tion of the Shores tree of the East Indies.
`It is
`soluble in and or coal tar hydrocarbons and in
`hydrogenated aliphatic petroleum solvents but is
`generally only very slightly soluble in crude petro»
`leurn or refined paradinic petroleum hydrocar—
`bons. It is, however, compatible with and can be
`dispersed in paraflinic hydrocarbons, both crude
`and refined. It is available commercially as bold
`scraped, unscraped. nubs and chips, and as dust.
`The acid phase of the emulsion may be any
`acid, such as hydrochloric, nitric, or hydrofluoric.
`which reacts with the formation and produces a
`water-soluble salt. The most important well acid
`is hydrochloric acid in the concentration range
`from about 5 to about 30° 1353. The higher con-
`centrations are preferred in view of the increased
`reaction rate and the decrease in breakdown time
`for the emulsion. The vehicle in which the acid
`of our treating solution is emulsified may consist
`of non-aqueous liquids, such as liquid petroleum
`hydrocarbons, e. g.. crude oil, kerosene. diesel fuel,
`or other light liquid hydrocarbons of this class.
`but we prefer kerosene, since it is practically uni-
`versally available. the composition is relatively
`uniform, and it is not considered hazardous to
`handle While any of the commercial grades of
`- Batu gum will emulsiiy oil and acid in accord-
`40
`ance with this invention. bold scraped and nubs
`and chips are preferied. This gum is preferably.
`ground to pass through a wo-mesh U. S. standard
`sieve or flner. Larger particles may be incorpo-
`rated. We have found, for example. that. with
`Batu hubs and chips, the viscosity of the emul-
`sion varies as a function of the particle size.
`As an example of
`this effect of particle size,
`emulsions having the same proportions of con—
`stituents—namely. 100 parts hydrochloric acid.
`12 parts kerosene. land 2 parts Batu nubs and
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`2,689,009
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`Table
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`Particle see (Mesh)
`—40.....................................
` -100__.
`3‘2
`-200 _____
`3‘?
`-325_____
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`3
`chips by weight—were prepared with different
`sizes of gum particles. The viscosity after 30
`minutes as measured on the Halliburton thicken—
`ing time tester which is described in A. P. I.
`RP 10 13, Recommended Practice for Testing Oil
`Well Cements, third edition, increased as the par-
`ticle size of the gum decreased, as indicated in
`the following table:
`
`4
`can be arranged, so that a viscosity in the pre—
`ferred range is obtained. Higher concentrations
`of the emulsifying agent may be used at increased
`breakdown time where mixing facilities do not
`provide adequate emulsion viscosity. Where the
`emulsifier does not provide a shear rate high
`enough to form a sufficiently viscous emulsion, it
`has been found that increased viscosity can be
`obtained by increasing the mixing time at a mod-
`erately high shear rate. In one case, for example.
`where 2 per cent by weight Batu nubs and chips
`through loo-mesh U. S. standard sieve and 9.6
`per cent by weight kerosene were incorporated in
`13° Be. hydroehloric acid, the viscosity using a
`propeller—type mixer running at 1750 R. P. M.
`was found to increase from about 33 poises after
`5 minutes to about 38 poises after mixing the
`emulsion 15 minutes.
`Since, as pointed out hereinafter, a high initial
`This emulsion is pumped or flowed into the
`viscosity for the emulsion is desirable, it can be
`well, preferably into a confined zone at the bot-
`seen that particles of 100 meshersmallerare
`tom: of
`the well,
`through tubing or the like.
`substantially superior to larger particles.
`another fluid—such as water, oil, or acid—is then
`The emulsion is prepared by first mixing be—
`tween about 5 and about 30 parts of this finely
`injected into the tubing following the emulsion.
`If purnping or injection-of the emulsion or the
`divided gum per 100 parts by weight of liquid
`fluid following the emulsion is continued after
`hydrocarbon. They are nuxedfipreferably. at
`the confined zone in the well becomes filled with
`high shear. rates—until the gum isevenly dis—
`the viscous emulsion, the hydraulic pressure on
`persed in the hydrocarbon. The ratio may be
`the fluid rises until the strength of the formation
`varied substantiaill-F, particularly on the high end,
`is overcome and the formation is fractured. The
`since pumpability is the limiting factor, and very
`hydraulic pressure in the confined zone necessary
`viscous emulsions can be pumped. The amount
`to produce a fracture has been found to vary in
`of hydrocarbon used depends upon the amount
`wells 2,000 feet or more in depth between about
`of acid used, the hydrocarbon-acid ratio being in
`0.7' and about 1 pound per square inch per foot
`the range of about 6 to about 24 parts hydrocar-
`of well depth. This pressure—i. e., the pressure
`bon by weight per 100 parts acid.
`It has been
`required to fracture a formation or the pressure
`found that these proportions may be varied sub-
`beyond which an increase in rate of injection will
`stantially and still obtain a desirable emulsion;
`not materially increase the pressure—is herein—
`but, when the ratio of hydrocarbon to acid is
`after referred to as the formation-breakdowu
`reduced materially below the preferred range.
`there is often excess acid which separates from
`pressure. It is generally recognized by an obser-
`the emulsion'on standing. Also, when the ratio
`vation of the pressure in the tubing or the pres-
`of hydrocarbon to acid is above the preferred
`sure on the pumps, or it may be measured with
`a bottom-hole pressure gage. After the confined
`range, excess hydrocarbon separates from the
`zone in the well becomes filled with emulsion, the
`emulsion on standing. In general, it can be said.
`pressure rises ‘sharply—assummg a substantial
`however, other things. including agitation. being
`volume, e. g.. twu or more barrels per minute, is
`equal, that the viscosity of the emulsion increases
`as the concentration of the kerosene decreases,
`being injected—until the pressure rise ceases to
`untila point is reached at which excess acid
`be proportional to the volume or fluid injected
`into the well.
`In fact, in many cases, after the
`separates from the emulsion on standing. The
`confined zone has been filled with the emulsion
`preferred composition range is, therefore, on a
`and the formationnbrealcdown pressure has been
`weight basis, between about 1 and 5 parts—typi-
`reached, the pressure may decrease sharply, indi—
`cally 2 parts—gum and between about 6 and
`cating that the emulsion is flowing into a free-
`about 24 parts—typically 10 parts—liquid hydro-
`carbon per 100 parts acid.
`ture in the formation.
`In some cases, namely,
`about 25 per cent of the jobs done to date, there
`The oily vehicle containing the dispersed finely
`is.no material breakdown in pressure when the
`divided gum may be emulsified with the acid by
`formation fractures, since the tensile strength of
`any number of means.
`It has been found. how-
`the rock is so low that, when the pressure in the
`ever, that, by mixing the two in any of a number
`confined zone is sufficient to lift the effective over-
`of well-known homogenizers, the viscosity of the
`burden at that point, the formation parts, and
`emulsion is higher than where they are mixed
`the emulsion enters the formation and extends
`at lower shear rates. For example, the acid and
`the fracture to great distances from the well.
`the oily vehicle containing the Batu maybe mixed
`Obviously, after the emulsion commences to enter
`by running them together through an ordinary
`pump, and viscosities as high as 50 pulses mal1r
`and extend the fracture, the friction in the frac-
`ture being small. an increase in the pump rate
`be obtained; where the same concentration of
`will not materially increase the pressure at the
`constituents is used and the rate of shear is
`elevation of the fracture. A formation fracture
`increased by using a ”jet-type homogenizer, the
`and the formation-breakdown pressure are there-
`viscosity of the emulsion may be increased by
`two or more times. Accordingly, it can be seen
`fore readily recognized. Another means of indl-.
`that a viscosity in the range or between about
`eating a formation fracture is to note the slope
`of the-pressure vs. volume curve at the surface.
`25 and about 50 poises, which is the preferred
`If, after the confined-zone of the well is filled.
`range, may be obtained by varying the ratio of
`the constituents and by the method of mixing.
`the emulsion is pumped slowly into the well. it
`In general, less than about 2 per cent Batu based
`will leak away into the permeable formation at a
`on the weight of the acid is to be preferred where
`rate depending upon the differential pressure
`the rate or mixing and/or length of mixing time 75 between the well and the formation; and the
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`2,689,009
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`(inferential pressure will vary directly as the rate
`of injection. However. after the formation frac-
`tures or when the -§ormation—'breakdown pressure
`has been reached, the ratio of -volume-of.flu1d—to
`pressure increases. Accordinglr, the slope-of the
`pressure vs. pump rate curve changes when the
`formation fractures :or when the formation-
`breakdown pressure has been reached.
`after the formation fractures, the emulsion
`enters the fracture-which-may beextended- a-sub—
`stantial distance into-the formation lay-continued
`pumping of the emulsion Or the fluid following
`the emulsion. Any amoun-t-of-emuision may be
`injected mto the fracture, depending upon the
`extent of fracture-desired.
`In -a'-ty.pical treat-
`ment, between about $500 and 2,000 gallons of
`emulsion are injected into 'the fracture.
`'When
`all of the emulsion has been injected into the
`fracture, the fluid following—which,asindlcated
`above, is preferably unemulsified-orplain strong
`mineral acid—may also be injected into the
`fracture.
`As is well known, when strong mineral acids
`are reacted with well-formations, water-soluble
`salts are produced. Whilethe emulsions-and-the
`emulsifying cm are not broken or affected by
`the acid per so, we have found that, When the
`emulsion contacts a calcareous formation-and-the
`water-Soluble salt is produced, the emulsion is
`broken. Apparently this-salt, some surface effect,
`a catalytic-effect of the calcareous formation. or.
`perhaps, the partial reaction of the acid with the
`formation breaks the emulsion, freeing the acid
`for reaction with-the formation.
`The-plain acid following the-emulsion-also con-
`tacts the formation-surrounding the .fracture,.and
`the excess of reaction product or the additional
`reaction itself appears to insure breakdown of
`any emulsion which might not otherwise break
`down. The amount of plain acid following the
`emulsified acid is not believed to be critical-
`In
`fact, none is-actuallyrequire'd; but, byemuisify-
`ing only part-oi the-acid, there is some—economic
`advantage plus the assurance that the .emulsion
`breaks more rapidly. Equal volumes of emulsi-
`fied and plain acid produce very desirable results.
`After the plain acid is injected into the forma-
`tion, the well may be closed in for a short time
`to allow the emulsion to break and the acid to
`react with the formation.
`In-general, the time
`delay is greater than the delay where plain acid is
`injected into a formation, since the reaction rate
`of the emulsion appears to be retarded by the
`emulsion. However, in about 24 hours, the vis-
`cosity of a. kerosene-hydrochloric acid emulsion
`of the preferred composition in the presence of
`excess limestone and at a bottom-hole'tempera-
`ture of 120° 'F. and pressure of 1500 'p. s. i. has
`been found to be reduced from about 50 noises
`to about 5 centipoises,'the viscosity of the reac-
`tion product. This reaction product may then
`be removed from the well by flowing the well.
`by pumping, or the like.
`As an example of the operation-of-this inven-
`tion. an emulsion having the following-composi-
`tion was made up and used to treats well in the
`Fullerton Field. Andrews County, Texas: 260
`pounds of Batu nuhs and chips ground to pass
`through lilo-mesh U. 8. standard sieve were dis-
`persed in 200 gallons of kerosene by circulating
`the kerosene in a tank. This kerosene was then
`emulsified with 1500 gallons of 20 per cent hy-
`drochloric acid (13.25“ Bé.) by circulating the
`two solutions through :a tank with a duplex.
`reciprocating pump for about '60 minutes. At
`
`6
`that time, the viscosity of the-olulsion was about
`30 noises. The emulsion was :then injected at
`the rate of about 110 G. P. M. into aconfined
`zone between '670'5 feet-ands 820 feet-in the Clear—
`fork, a dolomitio formation. This amount of
`emulsion was insufficient to fill the confined cone
`of the well and the two-inch tubing; and, there-
`fore. the emulsion was followed with plain acid.
`The pressure built up to a maximum of about
`4,300 p. s. 1. surface pressure before the forma-
`tion broke down and took the emulsion through
`a fracture. The emulsion was then injected into
`the fracture at about 3.000 p. s. i.
`'It was 'fol—
`lowed in sequence by 3,500 gallons of -15 percent
`plain hydrochloric acid (10.12“ Bé.) and 40 bar-
`rels of crude oil.
`Before this treatment-and after'being-acidized
`with the same amount-of acid solution, the well
`produced 14 barrels of-oil'per-day with .no wa—
`ter. Two months after-treatment and long aft-
`er the “load” all had been recovered, the well
`produced 46 barrels of 'oil per day with no wa-
`ter. The increase in production fellowing this
`treatment indicated that. even though the well
`had previously been acidized with plain acid, new
`flow channels were produced. This indicated
`then that .a permeable fracture was created in
`the formation Which increasedthe drainage area
`of the well and the permeability adjacent the
`well. Many other such treatments in wells in
`different formations, both limestone and dolomit-
`ic, have yielded similar improvements.
`While this invention has been described with
`reference to a preferred-.composition-and a pre-
`ferred procedure, it will be apparent that various
`modifications can be made without departing
`from the spirit of the invention. For example,
`it is sometimes desirable to suspend in the emul-
`sion 2. propping agent, such as sand. having a
`particle size in the range between about 10- and
`about 40-mesh U. S. standard sieve, so that.-aft-
`er the fracture is created and the emulsion is re-
`moved-therefrom, the fracture will be held open
`by these props. Other modifications will be ap—
`parent -to those skilled in the art. The inven-
`tion should therefore not :be construed to be lim-
`ited by the above examples but shonll be lim-
`ited only by the scope of the appended claims.
`We claim:
`1. A composition of matter comprising an
`emulsion of estrous mineral acid and an oily
`vehicle containing Batu gum.
`2. A well-treating emulsion comprising finely
`divided Batu gum. an oily vehicle, .and an acid
`capable of forming a water-soluble salt With.
`earth formations.
`3. A well-treating fluid comprising finely di-
`vided Batu gum dispersed in-an oily vehicle and
`an acid capable of forming a water-soluble salt
`with earth formations, said acid being emulsi-
`fied as the discontinuous phase within said oily
`vehicle.
`4. .A well treating fluid comprising an emulsion
`of hydrochloric-acid and a dispersion of a finely
`divided Batu gum in a compatible 6in vehicle,
`saidacid being the discontinuous phase, and said
`oily vehicle being the continuous phase in said
`emulsion.
`'5. A well-treating fluid comprising anemulsion
`of hydrochloric acid and [between about 3 and
`about 24 parts 'by'weight cf aliouid hydrocarbon
`per 100 parts of said acid, said hydrocarbon con-
`taining sufficient finely divided Batu gum to
`emu'ls‘ity substantially completely said acid and
`said'hv'drocarbon.
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`36. A well-treating fluid comprising an emul-
`sion of hydrochloric acid and between about 6
`and about 24 parts by weight of a liquid hydro—
`carbon and between about 1 and about 5 parts
`by weight of finely divided Batu gum per 100
`parts of said acid.
`7. A well-treating fluid comprising an emulsion
`of hydrochloric acid and between about 6 and
`about 24 parts by weight of a liquid hydrocar-
`bon per 100 parts of said acid, said hydrocarbon
`containing between about 5 and about 30 parts
`of finely divided Batu gum per 100 parts of said
`liquid hydrocarbon.
`8.191 method of increasing the productivity of a
`calcareous formation penetrated by a well com-
`prising disposing adjacent said formation an
`emulsion of an acid capable of forming a water-
`soluble salt with said formation and a dispersion
`of finely divided Batu gum in a compatible oily
`vehicle, applying a hydraulic pressure as great
`as the formation-breakdown pressure to said
`emulsion to fracture said formation, and inject-
`ing said emulsion into said fracture.
`9. A method of increasing the productivity of a
`calcareous formation penetrated by a well com-
`prising isolating a'section of said well opposite
`said formation from the remainder of said well,
`disposing in said section an emulsion of an acid
`capable of forming a water-soluble salt with said
`formation and a dispersion of finely divided Batu
`gum in a compatible, oily vehicle, applying a hy-
`draulic pressure as great as the formation-breas—
`down pressure to said emulsion to fracture said
`formation, and injecting said emulsion into said
`fracture.
`10. A method of increasing the productivity of
`a calcareous formation penetrated by a well com-
`prising isolating a section of said well opposite
`said formation from the remainder of said well,
`disposing in said section an emulsion of hydro-
`chloric acid and a liquid hydrocarbon containing
`sufficient finely divided Batu gum to emulsify
`substantially completely said acid and said hy-
`drocarbon, applying a hydraulic pressure as great
`as the fomnation-breakdown pressure to said
`emulsion to fracture said formation, and injecting
`said emulsion into said fracture.
`11. A method of increasing the productivity of
`a calcareous formation penetrated by a well
`comprising isolating a section of said well 0p~ -
`posite said formation from the remainder of said
`well, disposing in said section an emulsion of hy-
`drochloric acid solution, between about 6 and
`about 24 parts by weight of a liquid hydrocarbon
`and between about 1 and about 5 parts by weight
`of finely divided Batu gum per 100 parts of said
`acid solution. applying a hydraulic pressure as
`great as the formation breakdown pressure to said
`emulsion to fracture said formation, and inject—
`ing said emulsion into the fracture.
`12. A method of increasing the productivity of
`a calcareous formation penetrated by a. well com—
`prising isolating a section of said well opposite
`said formation from the remainder of said well,
`disposing in said section an emulsion of hydro-
`chloric acid solution, between about 6 and about
`24 parts by weight of a liquid hydrocarbon, and
`between about 1 and about 5 parts by weight of
`finely divided Batu gum per 100 parts of said acid
`solution, applying a hydraulic pressure as great
`as the formation—breakdown pressure to said
`emulsion to fracture said formation, in] acting said
`emulsion into said fracture causing said acid to
`react with said calcareous formation and break
`
`8
`said emulsion whereby the permeability of said
`formationis increased a substantial distance from
`said well and producing said well to remove the
`spent hydrochloric acid solution and liquid by-
`drocarbon from said well.
`13. A method of increasing the productivity of
`a calcareous formation penetrated by a well com-
`prising isolating a section of said well opposite
`said formation from the remainder of said well,
`disposing in said section an emulsion of hydro-
`chloric acid solution. between about 6 and about
`24 parts by weight of a liquid hydrocarbon, and
`between about 1 and about 5 parts by weight of
`finely divided Batu gum per 100 parts of said acid
`solution, applying to said emulsion a hydraulic
`pressure in the range between about 0.7 and about
`1 pound per foot of well depth to fracture said
`formation, displacing said emulsion into the frac-
`ture by injecting a plain acid solution into said
`well following said emulsion, and displacing said
`plain acid solution from said well by following said
`plain acid solution with another fluid whereby
`said emulsion is injected into said formation a
`substantial distance from said well, and said
`emulsion is broken so that the permeability of the
`flow channels to said well is increased a substan-
`tial distance from said well.
`14. A method of increasing the productivity of
`a calcareous formation penetrated by a well com-
`prising isolating a section of said well opposite
`said formation from the remainder of said Well.
`disposing in said section an emulsion of about
`100 parts by weight of about 13° Be. hydrochloric
`acid, about 10 parts by weight of kerosene, and
`about 2 parts by weight of finely divided Batu
`gum, applying to said emulsion in said section
`a hydraulic pressure in the range between about
`0.7 and about 1 pound per foot of well depth to
`fracture said formation, and displacing said emul-
`sion into the fracture.
`15. The method of increasing the productivity
`of a calcareous formation penetrated by a well
`which method comprises emulsifying a strong
`mineral acid in an oily vehicle containing an ef-
`fective amount of Batu gum to form a viscous
`emulsion initially having a viscosity in the range
`of about 25 to about 50 poises and being capable
`of becoming broken by contact with said cal-
`careous formation, introducing said viscous emul-
`sion into a confined zone of said well adjacent
`said formation, applying a hydrostatic pressure
`to said emulsion sufiicient to fracture said forma-
`tion and to displace at least a part of said emul-
`sion into passages formed in the formation, allow—
`ing said emulsion 'to contact said passages for a
`time sufficient for at least a portion of the acid
`to react with the calcareous formation and the
`emulsion to be broken, and producing said well
`to remove liquids therefrom.
`16. A process of treating a well to increase the
`productivity of a calcareous formation penetrated
`by the well, which process comprises dispersing
`finely divided Batu gum in an oily vehicle in an
`amount sufficient to effect emulsification of a
`strong acid in said vehicle, emulsifying in said
`Batu gum-containing vehicle a strong acid ca—
`pable of reacting with calcareous formations to
`form a water—soluble salt, said Batu gum-con-
`taining vehicle and said acid being mixed in
`amounts and for the period of time required to
`obtain initially an emulsion having a viscosity in
`therange of about 25 to 50 pulses. said emulsion
`being capable of becoming broken by contact with
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`2,639,009
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`said calcareous formation, disposing said viscous
`emulsion in a. confined zone in said well adjacent
`said calcareous formation. applying a pressure
`to said emulsion sufficient to fracture said forma-
`tion and to displace at least a part of said emul-
`sion into passages formed by said fracture where-
`by the acid component of said emulsion reacts
`with calcareous material to form a water-soluble
`salt and said emulsion is broken, and producing
`said well to remove fluids therefrom including
`liquid containing said water—soluble salt.
`1'7. The process of claim 16 wherein the par-
`ticle size of the finely divided Batu gum is smaller
`than 40 mesh, the oily vehicle is a hydrocarbon
`liquid, the amount of said oily vehicle is within
`the range of about 6 to about 24 parts by weight
`per hundred parts by weight of acid, and the
`amount of Batu gum is in the range of about 5
`to about 30 parts by weight based on the amount
`of 0in vehicle.
`18. The process of claim 1'? wherein the acid is
`hydrochloric acid having a concentration in the
`range of about 5" to about 20° Bé.
`19. The process of claim 17 wherein said oil?
`
`10
`vehicle and said acid are homogenized to obtain
`said emulsion having a viscosity in the range of
`about 25 to 50 noises.
`20. The process of claim 17 which includes the
`step of following said viscous emulsion in said
`confined zone with plain acid to displace unemul-
`sified acid in addition to said emulsion into pas-
`sages iormed by said fracture.
`
`10
`
`15
`
`20
`
`References Cited in the file of this patent
`UNITED STATES PATENTS
`Date
`Name
`De Groote __________ Aug. 15, 1933
`De Groote __________ Apr. 23, 1935
`De Groote __________ Aug. 11, 1936
`De Groote __________ Aug. 11, 1936
`Inomis et a]_________ July 26, 1938
`Benckenstein ______ July 25, 1944
`Reistlc, Jr. __________ Apr. 3, 1951
`OTHER REFERENCES
`
`Number
`1,922,154
`2,038,720
`2,050,932
`2,050,933
`2,124,530
`2,354,570
`2,54?,7?8
`
`"Hydrafrac Process," by J. B. Clark. The Oil
`and Gas Journal, October 14, 1948, pages 76—79.
`
`Page 5 of 5
`Page 5 of 5
`
`