CA1230219A - Polymer article of manufacture - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A solid polymeric body comprising a polymer matrix containing a substantially water-insoluble reagent leachable into a substantially hydrocarbon liquid environment, said matrix being reagent permeative and the said body preferably having a softening point substan-tially above that of the temperature of the liquid fluid environment in which it is to be employed is useful for the introduction of an additive reagent into a substan-tially liquid hydrocarbon such as crude and refined oils.

Description

~230~

1 Field of the Invention

2 This invention relates to a polymeric body

3 useful for introduction of an additive into a sub Stan-

4 tidally hydrocarbon liquid. More particularly this invent

5 lion relates to a bead containing an additive which is

6 leachable into an oleaginous hydrocarbon liquid (both

7 crude and refined) sod the method of utilizing the bead to

8 introduce the additive in useful amounts into the liquid

9 hydrocarbon.
o by 11 The recovery of oil and gas from underground 12 geological formations is of great importance in modern 13 society which uses vast amounts of fossil fuels for its 14 essential energy. The individual well productivity I declines over a period of time because of a number of 16 factors including changes in reservoir fluid kirk 17 teristics, depletion of reservoir energy, decreasing 18 permeability of the formation to the oil, the gradual 19 dissipation of the expanding pressure transient, contami-20 nation of the well bore, reduced permeability of the oil 21 through the region immediately surrounding the well bore 22 and reduction of the internal diameter of the well pipe.
23 The response to the declining productivity was 24 the development of numerous techniques which has become 25 collectively known as well work over and stimulation. The 26 concept of fracturing or formation breakdown has been 27 recognized to play a very important role in the applique-28 lion of these oil production enhancement techniques 29 including stimulation, acidizing, water injection and 30 cementing of the formation.
31 Hydraulic fracturing has found wide usage as a 32 well stimulation procedure for creating deep-penetrating 33 fractures (both horizontal and vertical) that provide high 34 capacity channels for flow from deep within the producing 1 formation to the well as well as for overcoming damaged 2 matrix permeability surrounding a Weller. In order to 3 produce gas or liquids from a well at a higher rate 4 following 8 hydraulic fracturing treatment, the reservoir 5 must contain enough fluids in place and the formation must 6 not have regions of severe permeability reduction paretic-7 ularly in regions adjacent to the well. Early export-8 mental work in shallow wells demonstrated that a 9 hydraulically formed fracture tends to heal - that is, to

10 lose its fluid carrying capacity after the parting

11 pressure is released - unless the fracture is propped.

12 Typical propping agents for retaining the integrity of the

13 fractures are nutshells, plastic beads, aluminum spacers,

14 glass beads, sand and urea pills.
Preappoints thus provide a means for meeting the 16 objective of the fracturing which is to increase the well 17 production by preventing collapse of the formation and 18 resultant decrease in fluid permeability.
I Another cause of declining well production is 20 caused by paraffin deposition from the crude oil onto the 21 inner walls of the production tubing and equipment.
22 Paraffin is a reservoir produced group of 23 straight-chain alikeness that contain more than 15 to more 24 than I carbon atoms The melting point of the paraffin 25 increases as the size of the molecule increases. Paraffin 26 is deposited in the form of crystalline solids which may 27 collect on the interior of the tubing and flow lines?
28 slowly choking off production. Paraffin deposits have 29 also caused the breaking of pump rods. In some cases, 30 paraffin deposits have caused plugging of formations 31 during stimulation treatments. Paraffin has also been 32 blamed for the difficulty in pumping crude oil at cool 33 temperatures 34 One method of handling paraffin deposition is to 35 mechanically remove the paraffin. There are several 36 mechanical methods for removing deposited paraffin from 37 tubing, flow lines and pipelines which include rod 1~302~9 1 scrapers, free-floating pistons, etc. The major advantage 2 of mechanically removing paraffin is that positive 3 cleaning is assured, however, it is limited due to time 4 and equipment involved, costly and has the danger and 5 difficulty inherent in retrieving tools lost in the hole 6 during the cleaning operation.
7 Other methods of cleaning include:
R (~) thermal methods, using bottom hole heaters, 9 circulation of hot oil, water or steam, and heat-10 liberating chemicals; and, chemical including the use of 11 paraffin solvents, dispersants and detergents and crystal 12 modifiers whereby the latter prevents paraffin deposition 13 by disrupting the nucleation, agglomeration and/or 14 deposition of the paraffin crystals environment At

15 present the chemical reagent is injected into the desired

16 location but it can be difficult to supply it uniformly to

17 the optimum location, for instance in the permeable, oil

18 bearing, mineral formation. Also it is necessary to

19 inject the reagent continuously or repeatedly singe it is

20 soluble in the produced fluid and so is rapidly removed

21 from the point of injection

22 As indicated it is known to introduce reagents

23 Donnelly during fracturing and other well stimulation

24 processes. Traditionally this is done by forcing a soul-

25 lion of the reagent down the hole and into the formation ?

26 whereupon it becomes absorbed onto the formation and is

27 released slowly from it. Unfortunately the rate of

28 release is variable and generally is quite fast.

29 It is known to force beads of ethylene-vinyl

30 acetate copolymers into the formation, but they are

31 generally too large to get into the fractures Formed in

32 the formation and smaller beads would dissolve too

33 rapidly. Also the beads are rather soft.

34 Another approach to overcoming the paraffin

35 deposition in the recovery of crude oil is by adding to

36 the oil a polymer having pendant polar and non-polar

37 moieties, such as a partially hydrolyzed ethylene-vinyl ~30~:~9 1 acetate copolymer, when by the deposition of wax From the 2 oil is inhibited (see US. Patent 3,693,720 wherein the 3 inhibitor is added to the crude petroleum oil before the 4 temperature of said oil decreases to a wax-deposition 5 temperature).
6 It is known from British Patent Specification 7 1,290,554 to inhibit scale formation Donnelly by supplying 8 Donnelly 8 solid linear carboxylic polymer having low 9 molecular weight and i-n which the carboxylic groups are 10 neutralized by an alkaline earth or other insolubilizing 11 cation to an extent such that the polymer has a controlled 12 low volubility in water. It is stated in that specific-13 lion that water soluble scale inhibitors may also be 14 supplied Donnelly with the substantially insoluble 15 polymer.
16 It is an object of this invention to provide an 17 article and its use to enhance the production of hydra-18 carbons from geological reservoirs, more particularly from - 19 fractured formations.
It has been an additional object to devise a 21 composition for providing controlled release of a reagent 22 Donnelly, in a pipeline, in other oil-containing environ-23 mints or fluids.
24 Summary of the Invention It has been discovered that it is possible to provide for the introduction of an additive reagent into a Lockwood hydrocarbon by providing solid polymeric bodies eschew comprising a polymeric matrix containing a sub Stan Shelley water insoluble reagent such as a wax crystal modifier, de~ulsifier, scale inhibitor corrosion inhibitor, buzzed, cashless dispersant, antioxidant and mixtures thereof. These bodies are, in use, positioned at aye location where it is desired to release the reagent into Thea substantially hydrocarbon fluid and, upon contact with fluid in this location, active reagent is released into Thea fluid.

:~3~2~9 l Thus in accordance with this invention there is 2 provided a solid polymeric body comprising a polymer 3 matrix containing a substantially water-insoluble reagent 4 leachable into a substantially hydrocarbon liquid 5 environment, said matrix being reagent permeative and the 6 said body preferably having a softening point sub Stan 7 tidally above that of the temperature of the liquid fluid 8 environment in which it is to be employed and optimally 9 having a leach rate in which fifty percent of the reagent 10 is leached from the bead in from 3 months to 3 years by if the fluid environment.
12 The object of this invention has been realized 13 in specific form by beads comprising a copolymeric matrix 14 of methylmethacrylate and methacrylic acid containing the 15 Bunnell half ester of a C24~C2g alkenyl succinic android 16 polymer and having a diameter ranging from 0.2 to 1 mm.
17 Such beads when introduced Donnelly in a hydraulic free-18 luring operation were fund to inhibit paraffin wax 19 deposition.
20 Detailed Description of the Invention 21 Each of the solid polymeric bodies may consist 22 solely of a polymeric matrix containing the reagent or may 23 contain a region, generally an outer region, of polymeric 24 material having a lower rate of reagent permeation than 25 that of the interior region and substantially free of 26 reagent. The polymer of such an outer shell may be of the 27 same material US the matrix or may be different, and will 28 be selected having regard to the release properties 29 required from the polymeric bodies. Matrix containing 30 reagent may be of uniform composition throughout its body 31 or its composition may vary, for instance having a 32 different polymer composition in its outermost portions 33 from its core portion By appropriate selection ox the 34 polymeric materials for forming the bodies and the 35 distribution of reagent within the bodies it is possible ~X3~)X~

l to control the rate and duration of release of reagent 2 into the fluid while retaining the physical (structural) 3 integrity of the polymeric matrix 4 It is this polymeric property of reagent 5 permeativity which makes possible the transfer of the 6 reagent from the body into the substantially hydrocarbon 7 liquid in contact with the surface of the body. During 8 and after the leaching of the reagent from the reagent 9 permeative matrix of the body! the polymeric matrix lo retains its structural integrity which is in marked if contrast to the approach taught in Egypt. I. Harm. Sat., 12 19 ND. 1-4, pages 143-62, 1980 in an article by A. Kassem 13 et at entitled Formulation and Evaluation of Controlled lo Dissolution Phenobarbitone Macro molecular Products lo Employing In Situ Suspension Polymerization With Methyl-16 methacrylate wherein the reagent coated beads were 17 compressed into a body which upon reagent dissolution in 18 the physiological aqueous fluids broke down the body into lo its component beads thus fully destroying the structural 20 integrity of the compressed body.
21 The polymeric bodies are preferably particles.
22 The particle size is generally at least ED microns and 23 preferably at least 5û, and usually at least owe microns 24 since small particles can be difficult to handle and to possession permanently in their desired environment. The particle size is generally less than 2 mm and preferably Lucy than 1 mm, since large particles also may be Defoe Colette to position in their desired environment. Best results are generally obtained with a particle size of 30 from 50 microns to 1 mm. The particles may have irregular shop and sizes, for instance as a result of having been mud by crushing, but preferably the particles are of substantial spherical or other uniform shape.
34 When being used in fracturing, the particles preferably have a size and hardness and/or resistance to 36 flow such that they can be used in sand packing and will Nat be significantly degraded by the sand. The particle ~302~

1 size distribution will be selected 50 that a pack of 2 controlled permeability to fluid flow it formed and such 3 that the particles have a controlled leach rate as set 4 forth earlier.
The reagent mutt be substantially water 6 insoluble, and so must partition into an organic phase of 7 substantially water-insoluble polymerizable monomer or 8 monomer mixture in preference to a water phase. The 9 reagent ma be in its active form or it may be in a lo blocked water-insoluble form from which an active form may 11 be released during use and that may be water soluble.
12 The reagent may be dissolved in the polymeric 13 matrix but preferably at least some, and generally 14 substantially all of the reagent is dispersed in the 15 matrix. The softening point of the reagent should be 16 above ambient temperatures encountered in use.-17 The reagent ma be any active reagent that issue usefully administered to and is soluble in refined or lo crude oil, or that is any blocked reagent that is water 20 insoluble but which, upon contact with water or oil, Jill 21 release a water soluble or water insoluble reagent that it 22 useful in the substantially hydrocarbon fluid. The 23 reagents are usefully selected from wax crystal modifiers, 24 emulsifiers, scale inhibitors corrosion inhibitor, 25 besides, dispersants, antiuxidants and mixtures thereof.
26 (a) 27 These reagents, usefully introduced in at least a wax 28 deposit inhibiting amount to the refined and crude oil, 29 are repro enter by oil-soluble polymers having pendant 30 polar and non-polar moieties and oil-soluble polymeric 31 materials having long linear side chains. The oil-soluble 32 copolymers having pendant polar and non-polar moieties are 33 represented by the formula 34 [-4-cH2cHR-~-m-4-cH2cHx~-p-~-cH2cHy 3 rig ~Z~0~:~9 l wherein X is a non-polar moiety, Y is a polar moiety, R is 2 hydrogen, an alkyd, aureole, aralkyl, or alkaryl moiety, m is 3 1.5-3, n is 0.1-0.8, p is 0.01-0.5, m/(m+n+p) is 4 0.65-0.97~ pup is 0.1-0.85, q is 2 to 500, and the S molecular weight ow of said polymer is 500-100,00û.
6 The above polymer may typically be a polymer 7 having a molecular weight ow of 500-100,000, preferably 8 1,000-10,000, commonly 1,500-4,000, say 2,000, and 9 characterized by a lung straight backbone chain on which lo there may be pendant moieties X and Y.
if In the above copolymer, the moiety 12 -I- SHAKER- m may be derived from an alpha-olefin 13 including ethylene, propylene, button, styrenes 14 3-phenyl-1-propene, octane, etc. Preferred alpha 15 olefins may be the C2-C3û alpha-olefins and most preferred 16 is ethylene. When the alpha olefin is propylene, the 17 formula SHAKER-) m may be it - -SHEA Shim 21 in which R is -SHEA. when the alpha olefin is ethylene, 22 the formula may be I- SHEA SHEA- m- The carbon 23 atoms may bear insert substituents (i.e. in place of the 24 hydrogen atoms) including alkyd, cycloalkyl, aureole, 25 alkaryl, aralkyl, etc., moieties.
26 In the above copolymer, the moiety 27 -I- CH2CHX-~- n may be derived from an alpha-olefin 28 which bears non-polar moiety X. The non-polar X moiety 29 may be characterized by the fact that it does not contain 30 a hydrogen atom active in the Zerewitinoff test fox active 31 hydrogen. Typically, the non-polar moiety will contain 32 atoms of carbon, nitrogen, Selfware, phosphorous boron, 33 oxygen, etc. The polar moiety Y may be a moiety con 34 twining carbon, oxygen, Selfware, nitrogen phosphorous 35 boron or their conveners. The Y moiety contains a hydra-36 gun atom which is capable of participating in hydrogen 37 bonding. A typically useful wax crystal modifier is a 3L~3~ lo partially hydrolyzed ethylene vinyl acetate copolymer having a molecular weight M of 1,500-4,000. For a more complete description of these co polymers reference should be made to US. Patent 3,693,720.
Another class or wax crystal modifiers are the oil-soluble polymeric materials having long linear side chains as described in US.
Patent 3,854,893 and include condensation polymers of dicarboxylic acid or android, polyol and monocarboxylic acid; addition polymers of unsaturated esters, or long chain alpha monoolefins, or copolymers of said olefins with said unsaturated ester; polystyrene assaulted with long chain fatty acids; and, mixtures thereof, Particularly useful are the copolymers of C18 to C46 olefin with a C4 to C44 straight chain alcohol per molar proportion of said dicarboxylic acid. Representative of these particularly useful copolymers are the esters formed by reaction between the reaction product of an olefin and malefic android with a long chain (typically C16-C28) aliphatic alcohol, and most preferably the reagent is the Bunnell ester of alkenyl succinic android having a molecular weight of from 3000 to 10,000 formed by polyp meriting a C22-C28 alpha-olefin with malefic android.
Other wax crystal modifiers known for use as pour point depressants are represented by: low molecular weight C16_24 alkyd acrylates and copolymers with 4-vinyl pardon, acrylamide, malefic acid, or dim ethyl-amino ethyl acrylate; copolymers of alkyd fumarate and vinyl acetate; co-polymers of ethylene or other olefins with vinyl alkylate (such as acetate, Stewart or laureate); and, copolymers of alpha-olefins with malefic android or other dicarboxylic group, for instance to form alkenyl succinic android and the reaction products of such materials with long chain epoxies and long chain alcohols.

_ g _ l (b) Emulsifiers -2 These reagents which can be introduced into a fractured 3 subterranean oil bearing formation in accordance with this 4 invention are usefully introduced to inhibit emulsifica-5 lion of the crude oil with formation water water flood 6 injection water and/or water introduced by such processes 7 as steam stimulation. These oil-soluble regents include 8 polyoxyalkylene ether and polyalkylene surfactants formed g from the alkoxylation of hydrocarbon soluble alkyd lo phenols, finlike resins, alcohols, glycols, amine, if organic acids, carbohydrates, mercaptans~ and partial 12 esters of polybasic acids.
13 (c) Scale Inhibitors 14 Since scale inhibitors are water soluble each is intro-15 duped into a fractured subterranean formation in accord 16 dance with this invention US the reagent in a blocked form 17 such that the reagent upon contact with water 9 as by 18 leaching from the polymeric matrix, is converted into a it water soluble active form, e.g. as a result of hydrolysis 20 or ion exchange. Suitable blocked forms are fatty acid - 21 esters and salts.
I Typical examples of blocked scale inhibitors are 23 the salts formed by the reaction of hydrophobic amine 24 with low molecular weight polycarboxylic acids or polyp I phosphoric acids, e.g. a tritC6-C10 aikyl) ammonium salt 26 of: polyacrylic said having a My of from 1,00û to 27 owe; or dihexylene Truman pentakis ethylene pros-28 phonic acid. It is believed that the latter reagent also 29 has activity as a corrosion inhibitor.
30 (d) Corrosion Inhibitors and Besides 31 Useful reagents which have the property of corrosion 32 inhibition andtor biocidal activity include both oil-33 soluble and water-soluble materials The latter must be I incorporated into the polymeric matrix in blocked form.

~LZ30~

1 Typical examples of oil soluble corrosion inhibitors and/or besides are ammonias dominoes, fatty famines, polyamides, alkoxylated amine, hydrogenated fatty famines, asides, fatty acid asides, .imidazolines, and trimmer acids.
6 Typical examples of water soluble corrosion inhibitors and/or besides are qua ternary amine and 8quaternized imidazolines each of which can be individually blocked by reaction with olenphilic fatty acids to form locater insoluble salts whereby it becomes useful in the 11 present invention.
12 The reagents may also be materials of value in 13 fuels and lubricating oils, for instance cashless dispel-14 slants or antioxidant A filter bed through which such 15 fluids or oils pass may contain or consist of the part-.
16 ales containing such reagents 17 (e) Cashless Dispersants 18 As used herein, the terminology cashless dispersant" is 19 intended to describe the now well-known class of non-20 metal-cuntaining oil-soluble polymeric additives or the 21 azalea derivatives ox relatively high molecular weight 22 carboxylic acids which are capable of dispersing contami 23 wants and the like in hydrocarbons such as lubricating 24 oils The carboxylic acids may be moo- or polycarboxylic 25 acids and are generally characterized by substantially 26 hydrocarbon constitu nuts containing an average of 50 to 27 250 aliphatic carbon atoms.
28 A preferred class of cashless dispersants are the 29 nitrogen-containing dispersant additives which include 30 mineral oil-soluble salts, asides and esters ma-de from 31 high molecular weight moo- and dicarboxylic acids (and 32 where they exist the corresponding acid androids) and 33 various aminPs of nitrogen-containing materials having 34 amino nitrogen or heterocyclic nitrogen and at least one 35 amid or hydroxy group capable ox salt, aside J imide or 36 ester formation. Usually, these dispersants are made by 37 condensing a mono-carboxylic acid or a dicarboxylic-acid I

l or android, preferably a succinic acid producing 2 material such as alkenyl succinic android, with an amine 3 or alkaline palomino Usually, the molar ratio of avid 4 or android to amine is between 1:1 to 5:1.
S Primarily because of its ready availability and 6 low cost, the hydrocarbon portion of the moo- 7 or 7 dicarboxylic acid or android is preferably derived from 8 a polymer of a C2 to Us monoolefin, said polymer moo-g olefin generally having between 5û an 250 carbon atoms. A
lo particularly preferred polymer is polyisobutylene if Polyalkyleneamines are usually used to make the 12 non-metal-containing dispersant. These polyalkyleneamines 13 include diethylenetriamine, tetraethylenepentamine, 14 dipropylenetriamine, octaethylenenonamine, and twitter-15propylenepentamine. Highly useful mixtures of alkaline palominos approximating tetraethylene pet amine are 17 commercially available 18 Representative dispersants are formed by l9reacting about one molar amount of an oil soluble polyp 20isobutenyl succinic android with from about one to about Al two molar amounts of tetraethylene pent amine or with from Abbott 0.5 to 1 moles of a polyol, erg pentaerythritolg 23 It is possible to modify the cashless dispersants general by the addition of metals such as boron in order Tao enhance the dispersancy of the additive.
26(9) Antio~idants assay used herein, antioxidant are oil-soluble oxidation inhibitors and generally represented by the additives for lubricating oils which include phenols, amine, sulk furrowed phenols, alkyd phenothiazines, and zinc dodder-corbel phosphorodithioates, e.g. zinc di-n-propyl 32dithiophosphate.
33 Polymeric Body Thea polymeric matrix is reagent permeative and preferably assay a softening point as measured by a temperature-graded ought bar of above 3ûC and most preferably is above 60~C~
often up to 120C. The combination of the reagent and the 2~9 1 polymeric matrix must be such that the reagent is released 2 into Surrounding fluid at the desired time and rate either 3 as a result of the fluid permeating through the matrix to 4 dissolve the reagent or as a result of the reagent 5 permeating through the matrix to dissolve into the fluid, 6 or both.
7 The polymer of the matrix is preferably formed 8 mainly of acrylic alkyd ester or styrenes or acrylonitrile 9 or a mixture thereof Suitable acrylic esters are alkyd 10 acrylates and methacrylates where the alkyd group contains 11 from 1 to 6 and preferably 1 to 3 carbon atoms. The ester 12 is preferably a methacrylate and the preferred ester is -- 13 methyl methacrylate. The polymer is preferably formed 14 mainly of methyl methacrylate or a blend of methyl 15 methacrylate and styrenes Small amounts of other ply-16 merizable monomers, for instance up to 40X, generally 17 below 20~ by weight and preferably below 10~ by weight, 18 may be included provided they do not deleteriously affect 19 the properties of the polymer Other suitable monomers 20 include hydroxyalkyl acrylates and methacrylates, Malta 21 esters, vinyl esters, dialkylaminoalkylacrylates and 22 methacrylates and cross-linking monomers such as glycol 23 dimethacrylate. It is particularly preferred to include 24 carboxylic monomers such as acrylic or methacrylic acid 25 which are useful in modification of the rate of reagent 26 permeation from the polymeric body when these monomers are 27 incorporated into the monomer mixture, they tend to I migrate toward the outer layers of the polymerizing body 29 due to their hydrophilic nature relative to the reagents 30 The result is a body having a lower rate of reagent 31 permeation through its outer region than that of the 32 interior region This approach provides a means of 33 controlling the leach rate of the reagent from the body.
34 The amount of reagent is generally at least 5 35 by weight of the total body in order to maximize the 36 amount of reagent introduced into the desired location. It 37 can be difficult to produce bodies containing very high ~:3~2~9 l amounts of reagent and so the amount is generally not more 2 than 50~, and usually not more than 30~, by weight of the 3 total body. The preferred reagent amount is usually 10 to 4 30~ by weight of the total body.
The invention has widely diverse applications 6 since it makes possible a controlled release of reagent 7 into liquids in a uniform manner and over extended time 8 periods. It makes possible the release of certain 9 reagents from previously non- or difficulty accessible and lo diverse points such as in an oil bearing mineral formation if one or more miles underground and in the flow path of a 12 circulating engine lubricant.
13 This invention provides a method for the lo controlled introduction of a reagent into a substantially 15 hydrocarbon liquid, generally a circulating liquid which 16 method comprises the steps of 17 (a) placing solid polymeric bodies each body comprising 18 a polymeric matrix containing at least one it substantially water insoluble reagent in a liquid, generally flowing, substantially hydrocarbon fluid 21 and 22 (b) leaching out said reagent from said bodies at a 23 controlled and predetermined rate into said liquid 24 fluid, said fluid preferably containing oil In a preferred manner the invention provides a 26 method of recovering a crude petroleum oil containing waxy 27 components 3 from a reservoir wherein the oil is at a 28 temperature above its wax deposition temperature which 29 comprises:
30 a. passing a portion of said crude petroleum oil from 31 said reservoir to a first central collection point, 32 ire the well bore;
33 b. passing said oil from said first central collection 34 point to a second collection point, i.e. the well head at a temperature below the wax deposition 36 temperature of said oil whereby the temperature of 37 said oil decreases and passes through a wax .

~L~3021~ -1 deposition temperature at which the waxy components 2 begin to precipitate and to deposit on surfaces with 3 which said oil comes in contact as it passes to said 4 second collection point;
5c. collecting said crude petroleum oil at said second 6 collection point; and, Ed. adding to said portion ox crude petroleum oil before 8 it passes to said first central collection point a 9 wax-deposition inhibiting amount of a wax crystal lo modifier reagent by flowing said portion through a 11 particulate grid of preappoint and solid polymeric 12 bodies each body comprising a polymeric matrix 13 containing a substantially water-insoluble wax 14 deposition inhibitor reagent, said reagent optimally the Bunnell half ester of a C24-C2g alkenyl succinic 16 android polymer and contained in said matrix in an 17 amount ranging from 5 to 50 weight percent of the 18 - total weight ox said body.
lo The method of making the bodies of polymeric 20 matrix containing substantially water-insoluble reagent 21 involves forming a dispersion in an aqueous medium of 22 particles of reagent and liquid polymerizable material and 23 polymerizing the polymerizable material while maintaining 24 the particles dispersed in the medium. the polymerization 25 results in the formation of a suspension of polymer beads 26 each containing reagent. The beads may be filtered or 27 otherwise separated from the aqueous medium. They may be 28 washed and dried.
29 The aqueous medium will generally include a 30 polymeric stabilizer suitable for suspension polymerize 31 lion. This is often a hydrophilic polymer that is 32 syllable in, and usually soluble in, the aqueous medium.
33 The hydrophilic dispersing stabilizer may be a naturally 34 occurring or modified naturally occurring polymer, such as 35 a hydroxyethyl cellulose, or a synthetic water soluble 36 polymer, for instance polyvinyl alcohol or polyethylene 37 oxide but preferably is a synthetic carboxylic acid 1~3~)2~9 , -16-containing polymer, most preferably polyacrylic acid 2 hiving a molecular weight in the range 1 million to 10 3 million. The amount is generally 0.2 to I weight of the 4 water.
In order to obtain uniform and fine distribution 6 of the reagent in the polymeric matrix, it is necessary 7 for the reagent to be monomer-we~ting rather than water-8 wetting and preferably the reagent is in liquid form 9 during polymerization of the matrix. It could be intro-10 duped as a solution in~toluene or other suitable organic 11 solvent but this would have the disadvantage of incur-12 prorating solvent in the matrix. Preferably therefore the 13 reagent is one that dissolves into the polymerizable 14 material, if necessary as a result of being heated. For 15 instance it may be insoluble in the polymerizable material 16 at ambient temperatures but may become soluble upon 17 heating to a temperature between 50 and 80~C3 in which 18 event the dispersion of the particles of reagent and 19 liquid polymerizable material is formed at such a 20 temperature. The elevated temperature may be such that 21 the reagent is then truly molten or may be such as to 22 promote volubility of the reagent in the polymerizable 23 materiel.
24 Preferably a homogeneous blend is wormed of the 25 reagent and the monomer or monomers, dispersed into the 26 aqueous medium by stirring sod polymerization is initiated 27 by using an oil soluble thermal initiator 28 The following are examples of the invention.

_.
3û the Bunnell half ester of a C24-C2g slkenyl 31 succinic android polymer produced generally according to 32 the procedure set forth for preparation of Polymer B
33 disclosed in United States Patent 3,854,893 was supplied 34 as a solution in Tulane, and this solvent was evaporated 35 to leave a waxy solid. This wax, i.e. the reagent, was 36 insoluble in methyl methacrylate monomers at temperatures 37 up to 50C. A monomer solution containing the wax reagent 123C~ 9 I was formed of 85 9 methyl methacrylate, 5 9 methacrylic 2 acid and 10 9 of the wax by heating all to 65C, at which 3 temperature the WAX dissolved into the monomers. The 4 resultant solution was then dispersed in 200 9 water containing 3 9 polyacrylic acid (molecular weight about 2 melodeon) as a dispersing stabilizer of the monomer drop-7 lets during polymerization in a one lithe enclosed vessel provided with a stirrer for controlled agitation of the contents within the vessel. Under constant agitation 1 9 loo azodiisobutyronitrile as the polymerization inhibitor Lucy added Suspension polymerization was continued with constant agitation for two hours after which time the product within thy vessel consisted of a suspension of Smalley polymeric beads in the aqueous medium, -These beads worry separated prom the aqueous medium, washed and dried Tao give tree flowing beads of from Do to 1 mm in diameter Wyeth 10~ by weight of the waxy ester polymer reagent dispraised in the polymeric matrix.
19 Since the Bunnell ester wax reagent is very syllable in hexane, to demonstrate the retardation of sealability by the invention the produced beads were sturdy in hexane at 35~C and the amount of wax released recorded. The following results were obtained.
24 of Total Wax Released Time Hours at ~5C
US 4û

EXAMPLE
32 When the above process was repeated using 10 g woks reagent (as above described), 5 9 acrylic acid, 5 9 34methacrylic acid and 80 9 methyl methacrylate followed by neutralization with sodium hydroxide dispersion, the beads avow a shell containing a high proportion of sodium polyp 37acrylate and have slower release properties compared to 1~30 -18~
like release properties of the beads of Example 1 when the 2polymerizate dispersion was similarly neutralized. In particular after 5 hours at 35C in hexane as in Example 41, only 25~ of the wax was released.

6 To produce a polymeric body according to this invention containing a leachable scale inhibitor, the polymerization mixture will be 859 of methyl methacrylate, 959 methacrylic acid and 109 tri(C6-C10 alkyd) ammonium LO salt of a poly(acryl`ic acid) having a ho of 1,000 to lls,ooo. The polymerization mixture is to be polymerized undoer the conditions of Example 1.
EXHUME
14 In order to prudes polymeric body according 15tb this invention containing a leachable corrosion inhibitor reagent the procedure of Example is to be fulled except that the 59 of methacrylic acid is repulsed with 59 of dimethylaminoethyl acrylate, the 109 luff the ammonium salt it replaced with 109 of the equimolar reaction product of tall oil fatty acid and.diethylene Truman and the anionic dispersing stabilizer is changed Tao 39 of the methyl chloride qua ternary salt of posy 23(dimethylaminoacrylate) of about 1 million ho.
24ExAMpLE 5 . .
In order to produce a polymeric body according two this invention containing a leachable emulsifier, the proceeder of Example 3 is followed except that the fulling monomer mixture is used: 659 methyl 29methacrylate, 209 styrenes 79 methacrylic acid and 109 of Ann oxyalkylated phenol formaldehyde resin of 2000 ho worry the weight ration of ethylene oxide to propylene oxide to resin is 0.5:0.5:1.5.

I In order to produce a polymeric body according Tao this invention containing a leachable cashless 36dispersant, the procedure of Example 1 is followed except ~Z3[:)2~

l that the wax it replaced with the equimolar reaction 2 product of polyisobutenyl succinic android having a ho 3 of about 900 and pentacrythritol.

The effectiveness of the present invention in 6 the inhibition of wax deposition from e crude oil was 7 shown by comparison of the product of Example 1 with a 8 solution of the reagent of Example 1 on a crude oil (in 9 which the aforesaid reagent has shown measurable wax lo deposition inhibiting activity) using the following if procedure. 0.~3 weight parts of active ingredient was 12 introduced into 100 weight parts of crude petroleum oil.
13 The mixture was placed within a test cell containing a 14 reweighed, removable standard water chilled deposition 15 steel plate, a stirrer thermometer, and an electrical 16 heater. The test cell was placed in an insulated bath 17 together with an identical reference cell containing the 18 reagent solution treated base crude oil The temperature Lo of the oils in both cells was maintained at 2 to 5.5C.
20 above the known cloud point temperature of the oil (as 21 determined by ASTM D-97-57). The test was continued for 6 22 hours and then each deposition plate was removed, and 23 weighed. The amount of wax deposit on each plate was for 24 measurable activity the same.

26 The solid particles of the present invention can 27 be used to inhibit paraffin deposition from waxy crude 28 oils by placing them Donnelly with the preappoint sand 29 during the course of a fracturing operation.
To effect the placement of the particles of the 31 invention a fracturing operation is carried out as 32 follows. A fracturing fluid is prepared by golfing a US
33 solution of potassium chloride with hydroxy propel guard 34 cross linked with a transition metal complex. As the 35 fluid is pumped Donnelly 8 lbs/1000 gals of 20-40 mesh 36 sand mixed with I of the beads of the invention are added 37 to serve as a preappoint in the fractures formed in the 31.~3~

1 producing formation. Pump pressure is increased above the 2 fracture gradient of the rock formation and the fluid 3 carries the preappoint mixture into the fractures. The well 4 is then shut in or 24 hours to allow the gust gel to 5 degrade to a low viscosity solution. The well is allowed 6 to flow back and the fracturing fluid is recovered leaving 7 the preappoint mixture of sand and polymer beads behind.
8 As the produced oil flows through the preappoint 9 pack past the beads the wax deposition inhibitor slowly 10 leaches out and deposition is inhibited in the well bore 11 and the flow lines as the oil cools and production it 12 maintained at a high level without wax blockage.
13 As used heroin by weight is based on the total 14 weight of the body, polymer composition water or bead 15 respectively.

Claims (13)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A solid polymeric body comprising a polymer matrix containing a substantially water-insoluble reagent leachable into a substantially hydrocarbon liquid environment, said matrix being reagent permeative.

2. A body, according to claim 1 having a softening point substantially above that of the temperature of the liquid substantially hydrocarbon environment in which it is to be employed.

3. A body according to claim 1 wherein said reagent is removed from within said matrix to outside of said body at a leach rate in which fifty percent of the reagent is leached from the body in from 3 months to 3 years by said environment.

4. A body according to claim 1 wherein said leachable reagent is at least one wax crystal modifier, demulsifier, scale inhibitor, corrosion inhibitor, biocide, ashless dispersant, antioxidant and mixtures thereof.

5. A leachable body according to claim 1 wherein said matrix is a copolymer of methylmethacrylate and methacrylic acid and said reagent is the behenyl half ester of a C24-C28 alkenyl succinic anhydride polymer.

6. A body according to claim 5 wherein said copolymer contains a proportion of a substantially hydro-philic comonomer.

7. A body according to claim 6 wherein said hydrophilic comonomer is acrylic acid.

8. A body according to claim 1 having a diameter ranging from 0.2 to 1 mm.

9. A body according to claim 1 having an outer region of polymeric material free of reagent.

10. A body according to claim 9 wherein said outer region is or a polymer material having a lower rate of reagent permeation than that of the interior region.

11. A body according to claim 8 wherein each particle has a size range of at least 50 microns and less than about 1 mm.

12. A body according to claim 1 wherein the polymeric matrix has a softening point temperature ranging upwards from 30°C.

13. A body according to claim 1 wherein the reagent is 10 to 30% by weight of the total weight of the body.