[1]0 3 176 768 United: States Patent Office 3,176,769 SAIND CONSOLIDATION Harry Brandt, Whittier, Phillip H. Parker, Jr., San Rafael, anil Barney R. Treadway, Brea, Calif., assignors to CaHfornia Research Corporation, San Francisco, Ca-Uf., 5 a corporation of Delaware No Drawing. Filed July 27, 1964, Ser. No. 385,498 20 CUms. (Cf. 166-33) This is a continuation-in-part of copending application 10 Serial No. 218,573, filed August 22, 1962, which in turn is a continuationin-part of application Serial No. 59,168, filed September 29, 1960, now abandoped. 0 CH3 CHZ--Ci-i-_CH2 L -,3 The present inventi6n relates to a method of consolidating an incorinpetent earth formation of loose or uncon- 20 solid ated sand or earth particles traversed by a well bore for the purpose of reducing or eliniinating the invasion of particulate matter into the well bore during fluid producti on throlgh the formation. More specifically, it is conc erned with a sand consolidation rnethod which in- 25 volv es injectin.@ into the formation a plastic of the enoxy resin type, the method moreover being independent of the temp erature characterizin.- the formation. In plastic sand consolidation, two major, g@-nerally mutu ally exclusive, op--rating principles, or techniques, 30 have been employed. One technique involves filling all of the pores or spac es bet-%,een sand particles with a consolidati-tig plastic or resin, such as an e oxy resin followed b flushing with p I y a resin-'fmmiscible fluid to displace excess resin while 35 leaving a fflm of resin on the surface of the sand grains, the sand grains then beebming ceniented to one another at the point of cbntact but having open spaces bet@veen them to provide for fluid flow. Another technique of sand consolidation involves inject- 40 ing into the formation a mixture of resin and an inert diluent therefor. VVhile the volume of the mixture is sufficient to fill all the pores between sand particles' the volume co-Titribut,-d tb by the resin itself is less than the pore volume of the formation to be treated. Res@.n is 45 deposited on the surfaces of the sand particles, solidifies, and cements therii together. The diluent is rejected and fills the spaces between particles, and upo@i fluid produetion is displaced with the producing flijid, permeability thus bein@ established without resort to a flushing sten. 50 In accordance with the present invention, a cor@ibination of the two methods described above is ii-tilized. In a first step there is injected into the formafion to wet the sand grains a solution or mixture comprising, by weight, (1) aboi-it 40 to 95% oi- an epoxy resin having 55 a molecular weight in about the ran.-e 400 to 700 and a viscosity above about 400 centip6ises at the temperiture of the formation to be treated, and (2) a normally liq-aid reactive diluent in an amount within about the range 5 to 60% to reduce the viscosity of the epoxy resin be- 60 low abotit 400 centipoises and above abbut 25 centipoises at the tenip,-rature of the forniation to be treated. Following the injection step, a flusbing operation is perfornied using a flushing fluid that is immiscible with the resin component but miscible with the reactive diluent 65 component of the solution. The fltishing step thiis performs a dual function, i.e., to drive out excess resin solution between pores of the sand grains, and to extract the reactive diluent@ As a result, permeability is effected 70 and the sand grains are t)rovided with a surface coating of resin. Patented Apr. 6, 1965 2 Following the flushing steo there is iniected 'mto the for-tnation a curing agent to harden or solidify the resin. The curing agent also reacts with the reactive diluent, includi--@ig that entrained in the resin on the sand, thlis providing a consolidated sand mass of' high compressive strength. The epoxy resins suitable in the practice of the present iTivention are well known, and are commercially available, a common cliss being the di-lycidyl ethers of bisphenol A, obtained by reacting epicblorohydrin with bisphenol A in the presence of caustic such as s6dium hydroxide or potassium hydroxide. In general, these materials may be represented by the formulaOH CH3 0 E[2-CH-CH2 -J. 1,3 wherein n is zero or an integer of I or higher number. Generally, the epoxy resins are obtained as a mixture of monomeric epoxides (ti=G) and of polymeric polyepoxides (n@!1). As is known in the art, by correlaltion of proportions of epichlorohydrin and bisphenol A, and caustic, the degree of polymerization can be controlled accordingly. Thus, increasing the opichlorohydrin to bisphenol A mol ratio, generally results in a inixture of polyepoxide having a lower average molecular weight, On the other hand, increasing the mol ratio of sodium hydroxide to epichlorohydrin generally results in a mixture of higher average molecular weight. Also, as is known in the art, other halohyqrins than epichlorohydrin, such as 1,2-dichloro-3-hydroxypropane, and dichlorohydrin, can be used. Sin-iilarly, in place bf bisphenol A there can be used mononuclear di- and trihydroxy phenols, stich as resorcipol, hydroqtilnone, pyrocatechol, and phloroglucinol; polynuclear polyhydroxy phenols, such as 4,4'-dihydroxy diphenyl methaiie trihydroxyl diphenyl dimethyl methane, and 4,4'-dihydroxy biphenyl. Particularly useful hydroxyl intermediates and the ones preferred in carrying otit the present invention are the polynuclear polyhydroxy phenols, also known as the novolac resins. Novolac resins containing 2 to 6, and as many as 12, phenol@'.c hydroxyl groups per average rnoleclue have been proposed in the preparat,'@on of the type of resin herein contemplated, the use of resins containing a hig@ter numler of flinctional groups bei.,ig here zoverned by th-, viscositli r@- quirements hereinabove sp--cified. The novolac resins are well-knowi subst,,nces, and -nany are available commei-cially. Their preparation is described in the literature, such as in th,, book Phenoplasts, 1947, pa,@e 29 et s-.q,l by T. S. Carswell. in general, thes-. resins are prepared bv condensing pheiiol with an aldehyde in th- pi,esence of an acid catalyst. Propor,ions of phenol and aldehyde in mol ratios of phenol to aldehyde -reater than l@l and up to 2.5 are tau.-ht. As the aldehyde, formaldehyde is preferred, although the us,. of other aldehydes, such as acetaldehyde, chloral, bu'Lyraldeh-vde and furfui-al is permissible. , Sinlilarly known is the condensation reaction of the epicbdorohydrin with the novolac resin. The reaction is effected at a temperature in the ringe 140' F. to 300' F. between the novolac resin and at least about 3 mols of epichloro.iydrin for each phenolic hydroxyl equivalent of the novolac res@n, in the presence of about I mol of alkali metal hyd-oxide per phenolic hydr6xyl equivalent of novolac resin. When the reaction is complete, th. I epoxy resin is isolated from the reaction mixture by removal of alkali metal salt, of unreacted alkali, epichlorohydrin and witer, and purifi--d. As above indicated, epoxy resins of the type herein contemplated are tvailable commerci,,illy,, For examt)le@
[2]a suitable materi-,ii a@,,ailable commercially cin be repre sented as follows: 0 0 dH"-\bl,-Cl-lr-o 0 - c 1,2- dH-,\C IT2 5 F CH@ -CH2--Ul 1.3 0 10 O-Cii,-Cll-CIT2 (Dow Epo.,@y Novolac 438) An additional example of a suitable material available commercially is the following: 0 o 15 cl, - d 2-CH-CH2-0 OCH 1-1-CH2 C H-- C H-@ 20 0 v 0 -CH@ O-CH2-dH (Shell Di pon 1031) 25 The reac,ive diluent component of the resin solution is a normally liquid monoepoxide, such as is derived from @the reacl-lon of epichlorohydrin and a monoh37droxyl compouiid such as allyl alcohol, butyl alcohol and phenol 30 to give, respectiv-,ly, allyl glycidyl ether, blityl glycidyl ether and phenyl glycidyl ether. Other examples of epoxide reactive diluents are styrene oxide; oetylene oxide; aliphatic epoxides having the epoxide group on terminal ,carbon, such as those derived frOM C7-C9 U-O'@CfiilS35 Aliphatic diepoxide, such as the diglycidyl ether of butane diol, can al,-zo be used. In general, the prdportion of reactive diluent component of the epoxy resin-react-@Ve diluent solution will va.-y dei,)ending on the molecular weight or viscosity of 40 the epoxy resin component, viscosity be;ng a function of the molecular weight. Thus, as the mol,-cular weight of the resin increases, and hence its viscosity, more diluent will be required to effect the desired degree of viscosity. On tlie otli,-r hand, as the temperature of the 4- formation increases a lesser quantity of r-- 2,ctive a diluent Will be reqtiired to effect the required viscosity requirement. As has already been indicated, the mixture of epoxy resin and reactive dui-lent can co-,isist essentially of 40 to 95% epoxy resin li.avin.- a molecular weight 50 in the ra-@ige of 400 to 700, and from 5 to 6OTo, preferably about 15 to 35%, of reactive diluent, the percertages being by weigh@L. As a specific example, an epoxidized novolac having a m6lecular Nveight of 450 and a viscosity of 11800 centipoises at 125' F., wl-.en niixed wiih 20% r,5 styrene oxide Nvill give a soluti6n havin.@ a viscosity of 325 centipoises at 76' F., and of 40 centipoises at 150' F. In carrying out the invention, it is desirable that the epoxy resiii conipo--ient have an initial viscopitv, before n,iixin.- with the reactive diltient, above about 400 c-.nti60 pc);ses at the ten-ip-,rature of the format;on. The ii-se of suc@h viscous resin component results in a consolidated mass of greater compressive stre-@igth However, it s also desirable that in carrying out the process.the viscosity of the solutiori be below about 400 centiooislls at the teni6,3 perature of the formatior.. When proc6--ding as thus sug,ces@,ed, it has be--n fotir-d @that the r--sin solutiop. cai be inj;octed into the l'Ormation at ieasonab.e pumpi-.ig rates withotit causing fracturin,v, f6r example, 1/2 bar@el of resin sol,,ition ucr hour per 70 vettical foot of format"@on to be treated at a piimping pressure of 2,000 p.s.i Morcolier, operating v:scos;ties belo,i@ abotit 4,'jO centipoises ocrmit the fliish,.,ig iluid to d;.@perse the resin Itiniformly through ',he sand fo.-ma@ion, thus niinin-iizing channeling. 75 A p@articularly useful aspect o'L the i@ivention is t@Llat it permits sitisfactory @treatment of uticonsolidated o-11-produc-ing format'@ons that can vary widely in temper-ature, includiitg low-temperatvre consolidation below a temperatiire of about 150' F. down to 76' F., and high tenipera.ture sand consoli@d@,i@Lion exceeding a temperature of @about 150' F. i-ip to 250' F. and higner. 1-n addition to the viscosity requiroments outlined above, it 's importantthatth.- curin.- of the resin occurs over a wide temperature range. Accordin@ly, a sui@Lible epoxy resin comi)onent of tfie plastic mixture is one that contains -the pr-eferred epoxy novolac, resin illi-istrat-,d ab-ove, alone, or iadmixed witli a-iiother t3rp-- such as ope d-@rived Lrom bisphenol A and epichlorohydrin. As stated, tle prefer-red epoxy novolac resin contains a-t le@ast two epoxy group-. in @primary posit;on. The use of sue'n resin resi-ilts in aood rure, thus producin.- a consolidated mass of hi.-Ii c6mpressive strength throughout a broad temperature range. An additional benefit fiowiig fr6m the use @of the preferred epoxy novolac resin is th@at the coripressive strer@gth of the consolidation can be reWr@ed to a satisfactory de,@ree Nvhen the treatment is applietd to b,rin3r wells, that is, where brine is present in :Lhe 0;1produ-,ing formatioii. In the placing of the plastiz n-nx'ture or Sol-ation of epo-AY resi-i and reartive dilue-it in the formation to be treated, the mixture is c-aused to permeate the fo.-ma-tion by pi-,mpipg it into -the formationthroi-igh the borehole traversing the formation. Generally, sufficient n-iixture is injected into tne fofm@ation to impregnate it to a radial distarce of a f@-w inches to 5 or more feet from the well bore, that is, in an amount of 2 to 60 gallons bf mixture per vert, @c,,,il 'Loot of well hole in the fotmation to be treated, a geiierally satisfacto ry lamount being about I barrel (?-2 gallons) per vertical foot. In a preferred embodim6-@it of the invention, the 'anconsolic,ated forma:Cion is pretreat6d with a wat,5r-remo,;ing liquid to remove w,,ater ftom the sand g@rains and thus render them preferentially wettable with the resinous mixture rather @th@an with water. For this purpose, it is preferred to Lise an o.-,-anic solvent which r-- moves water frbm the, forniiation by miscible displacement. The solvent oan then be displaced by the resin or @a miscible oil flush before resin injection. Suitable solvents are those which are miscible with brine @and either Tesin or oil. @These inclilde low molecular weigh@t ketones, such @as acet6ne land m@thyl ethyl I-,etone; aldehydes, stich as acetaldehyde, isobityraldel-.yd--, and formaldehyde; alcobols, such as metnanbl, ethano@l, propanol, isopropanol, isobtitanol, and teeli@ary butyl -,Icbhol@, ethers, such as methyl propyl ether, isopr(>pyl ether, and n-butyl ether. The volume of preilush fluid uscd is ge-@ierally 1/3 to five times the pore volume of -the formation to be consolidated, gfnerally I to 15 barrels per vertical foot of borehole trav@@rsing the formation @Lo ba treated. A.Iso tiseful for th-@ removal of water from the formation iare commonly available surfactants, such as sulfonated nlphthenic ncids sulfonated higher al@cohol and I s hydroc-,irbons, quaternaty lamm6rlium sa:lts, silico-@ies, and heavy metal soaps. The surfactant c,-,in be mixed directly witli the resin n-iixture oi- epoxy resin and reactive diluent, or can be mixed with oil, water, lor other iluids I and introduced inlo the formition as an i-iidept@ndeqt p@-econdiioning step pr@lor to the ;njeciion of the resin @nixt,,ire. Geiierally, an apaount of surfactant ra-,iging from 0.01 to 1% by weight based on resin mixture is sqtisfactory. '@Vhen the f-Orm-,ition has beeli trelted with th-- aforesaid r-,s,n solution to the extent indicated, a 'i9tishin- fluid is forced therethr6ugh to extract the reactive diluer@t and to render the forr@iation permepb-le, vjhile Ic@aving a fflr.,i of the ceirienting resin oii the surfaces o'l the pnrticles silfi'icient to bind the loose particies into an ag,,re.-ate n-iass. Considerable latitude is possible in t're injectiori, of fiii h fluid ranging fr6nl,,,immediate al)131,ication, after the,resin is
[3]3,176176s placed, to a delay of several days. T@he advantage of such flexibi-lity will be readily apparent to those engaged in completing oil wells. A suitable ffushing fluid is an aliphatic or nonaromatic hydrocarbon oil, relatively free of unsaturated hydroc@ar- 5 bons, which is a solvent for the reactive diluent, but is immiscible with the epoxy resin component. Examples of suitable fliishing fluids are kerosene, diesel 011, and the refined petroleum oils, free of aromaticity and -of olefinic ,hydrocarbons, known as the vihite oils. An amount of 10 flushing fltiid which is at least eqtial to thp, volume of resin mixture injected, iip to 10 volum-'s of the resin mixture, will in m6st cases be satisfactory, the preferred amounts being 1.5 to 4 volumes;of flushing fluid per volume of the @original Tesinous mixture introduced. 15 After the formationhas been fltished, there is then .njected into it a curing a@ent to t-ransforiii th-- lheri.-opiastic resin film on the par@ticle siirfaces to the tliermoset, tough solid state. The curing agent also reacts with residual reactive diluent present iii the Tesin, -thus to give a 20 stronger bond than would be obtainable if a non-reactive dituent were emT)Ioved. A number of curing agents or activ,,itors or catalysts are suggested in the art io harden the unset resin. These include amines, ;dibasic acids, and acid anhydrides@ In 25 accordance with the present i-,iv-.r@tion, the preferred class ,of harden-.rs or curing agents are the amines, including prim&ry, secondary, or tertiary an@nes and mixtures t-Lereof. Examples are prim,-try al,iphatic amines, such as diethylc,,-tle triamine, ethyleti@- dian-iine, - triethylene tetra30 mine, dimethylamino propylamine, and dietliylarnino @propylami e@ cyclir, aliphatic amines, slch as pip@-ridine, n I mentha-ne diainine; t-.rtiary amines, aliphatic or ,iromatic substituted derivatives, such as trietnyl amine, benzyl dimethylaniin@, dimethylaniino methyl phenol, tridimethyl 35 @amino methyl phenol, and 'a-methylbenzyl dimethylamine; aromatic amines, such as meta-xylylene diamine, 4.4- methylene dianiline, iand pyridine. As indicated, a mixture of the varic)us amines is preferred. A nu'xture of primary and tertiary amines is even 40 more preferred. T-his ican be a physical mixttire of two or more cowpounds, such as benzyl dimethylamiiie and diethylene triainine; or a singl.- cor@ipound contaiiiing both prunal'Y and tertiary an-in@- groups, as represented by dimethyl amiiiopropyl amine. 45 In iovi-temperature sa-nd consolidatioii treatm-nt, i.e.., at temperatures below about 150' @F., using the here-inabove specified novoltc res,.-ill tlie amipe eu in- a@ nt r . @e selected is o-@ie which is effective at thes-- lovver temi)eratures. Accordipgly, !good results are obtained jvhen t@ie 50 @curing agent -is a-a aliphatir, primary-tertiary am;ne, sucli a-s dimethylamino propylamine or diethylamino pr@bpylamine; or a phenolic tertiary amine, such as dimethyl amino niethylpheiol or tri-(dimethylaminomethyl) phenol. r) 5 The @eatalyst is intrbdu-,ed into t'iie format;on follo),ving the flushing operation by injecting a s6lution of the catalyst in a s6lvent such as the oil used for fluSI-lip,-, the total volume of this latter mixture. being agdn at least equal to the volume of ori-inal resili mixture @introduci,- d 60 inio the formfttioi. The amount of -catalyst used can vdty from O.i tc) 10 perce-@it, pr-,f@rably around 2 percent by weight based on the mixture of epoxy resin anc-I diluent. The effe6tiveness of the method herein contemplatd 6 5 is bbrne otit by t'@l@- followlqg tests @,,ind exarqples. For testing tiiere was tised a Hassler cell. It comprised a rubber titb-,, adapted to be fitted with end plugs, provided with screened inflow and 6utflow op,-nin,gs to prevent loss of sand tinder pressure, and to permit the flow 70 of fluids through the sand pa,.ked in the rubber ttibc, the plugs bein-a further adapted to be herm,-tically Ias,cn,-d to a metallic sleeve. Tha sleeve and rubber ttibe were of such dimensions as to hold a sand sample, of 5 feet 75 6 long by I inch in diameter. The sleeve is provided with means for exerting pressure on the s,,tnd pack (analogous to the pressilre on an incb.,npet@-nt formation from the ioarth above it, known as overburden pressure). Additional equipment comprises a pr-@ssure tank for storage Of fillids pr@ior to their injections, a pump to 'force the fluid through the sand pack, a bath for heating the Hassler cell and means, such as a gradtiate cylinder or flasl,, to measure the outflow of fluids. After the final injection of the last fluid, th,- openings of the plugs are closed (shut in) and tl-ie trcl)ted sand pack allowed to cure. Nevada sand, 95% passing a 100 mesh screen,and having grains of irregular size and shape, was placed in the rubber tube and compacted by vibrating for 15 minutes. Overburdeii pressure was held at 2,500 p.s.i,, at the indicated temperattires, to simulate the conditions of a forniation penctrat,-d by a borehole.. Diesel oil was floived throiigh the sand pack to s,-Lturate it with the oil. At this point, permeability in darcys was determined. Followina the oil saturating step, there was next l@njected the resiri solution, foll6wed by flushing with dies-.1 oil. After the flushing step, a catalyst-containing soltition was ini e,-Ited and r-uring of the resin was eff ected@ Exai?iple I Epoxylated novolac resin having an averago mole,cular weigiat of 640, a viscosity of 19,000,000 centipoises at 761 F., and an epoxide equivalent of 17@8 was mixed in eqtial parts by weight with an epoxy of di,-Iycidyl ether of bisphenol A having an epo@Kide equivalent of 173-179, aia avera,-e molecular weight of 340-350, and a viscosity of 3,600-6,400 centipoises at 76' F. To this mixttire of epoxy res@ins there was added styrene oxide in an amount of about 35% by weight based on it to give a soltition having a viscosity of about 240 centipais,-s at 76' F@ 300 cc. of diesel oil was pumped through the sand pack of th,-- Hass].--r cell mair@ta,-iied at aboil-t 76' F@ over a p@,riod of I h6ur and 25,mintites. To the, oilsaturated sand, there was then -injected 140 cr,. of the a@bove resin mixture over a period of about 3 hou@-s. The resintreated sand pack was then ffushed with 500 cc. of diesel 011, the flushing step requiring about 140 minutes, Following t'iie flushingstep, there was then ptimped through the sand 400 @cc@. of a dies-@l oil soludon containing 5% of dimeth3,laminopropylamine curing @ggent, th-@ operation reqlir,ing abotit 105 nu'n@,ites. The Hassler ceR was then shut in and allowed to set overnight at room temperature (76' F..) and at a pressure of 1,000 p.s.i. Th.e following day, permeability of the sand core using diesel oil was determined to be 1.10 darcys or 45% of the ori-inal. When the core was removed from the cell, it was found to be comT)Ietely and uniformly consolidated, with @no visible channeling. No evidence of plug@ing was noted. Average compressive stren.ath based on representative samples was determined to be 8,690 p@s.i. Example 2 I Iii 'LMs example, substantially the same proc dure was i-Ollowed as in Example 1. The epoxy resins were mixed with 30 percent of btityl glycid371 ether to give @a resin solutioji having a viscos;ty of 24-0 centi es at 76' F. Poll Following saturation with oil, 130 ml. If the solutioll was pumped through the sand. Flushing and curing as in Exani.ple I resiTIted in a sand core baving a p-,rmeability of 0.97 darey or approximately 36% of the original, and an average compressive strength of 8,520 p.s.i. Example 3 An epoxylated novolac resin having aia average molecular weight of 425, a viscosity of about 5,000 centit)oises at 150' F., and an epoxide ea.u-valent of 180 was mixed with octylene oxide in an amount of abbut 20% by weigh t
[4]7 based on the rnixtli-e to give a solution having a viscosity at 160 centipoises at 135' F. The sand pack of the Hassler cell was oil-saturated at 135' F. To the oil-saturated said was ir@jected 100 cc. of th,- above resin mixture over a period of about one hour. The resin treated sand was then flushed with 1,000 cc. of No. 5 white oil, which required ,ibout 3 Liours. Following the flushi-@l-, step, 200 cc. of a white oil solution containin.a 20% of dimethyl aminomethyl phenol was injected, the operation requiring about 1 hotir. The Hassler cell was the-,i shut in and a'@'lowed ',o set overni,--.@t at 135' F. and aboilt 2,500 p.s.i. pressu;e. The following day, the sa-id core had a permeability of 0.55 darey or 26% of th-- original permeability. Representativ6 consolidated core samples 11/@S inches long were te-sted for initial strength and aging cilqracterist-les. The initial strength was determined to be 8,890 @.s.i. To determine aging or durability, the boiling brine test was used. Accordir,.g to this test tlc test s,,tmples are placed in racks and lowered into tanks contaiping a boiling brine solution (2.5% NaCl soltition). Different samples remain in the boilirg brine solution from 10 to 360 days. At tiie end of the time period, the samples are removed and compressive stren.-ths determined. For the 360-day samples of Example 3, the strengths were determined to be 4,600 p.s@i. Similar core samples consolidated wita a typical ph enol-formaldehyde sand consol;dating resili obtained by the acid catalyzed reaction of phenol and formaldehyde h-,id no compressive strenglh after 15 days. Example 4 An epoxy resin derived from bisphenol A and epichlorohydri-Ti, and the epoyy resin descri@e-d in Example 31 were rnixed with oetylene oxide and methyl Nadic anhydride (methyl dicyclo-(2,2,1)-5- heptene - 2,3 - dicarboxylic anhydride). The epoxy resin derived froni bisphe.nol A had a molecular weight of 350 to 400 and an epoxide equivalent 6f 175-210. The resulting mixture contained the following weight percent of each component: Percent Ep6xylated novolac resin ---------------------- 28.6 Disphenol A epoxy resin ---------------------- 14.3 Octylene oxide ------------------------------ 14.3 Methyl ",Nadic" anhydride -------------------- 42.8 In this example, substantiaily the same procedure was used as in Example 3. The Hassler cell was shut in and allowed to set overnig'@it at 200' F. and 1,000 p.s.i. p , ressure. The following day the core was determined to have a permeability of 1.61 dareys or 63% of the original permeability and a com-oressive strength bf 7,000 p.s.i. The variotis fluids, inrluding the resin-diluent mixture, may be injected into the forrnation through a piping strinaer or producing tubing pl-,ced in the well bore provided with a casing. The formation to be treated may be isolated by positioning a packer just above it, and a packer just below it. Perforations are niade in the casing between the packers to provide fluid intercommunication between formation, cased well bore, and tubinIn accordance with a preferred embodime.-iit of the invention, the tlibing is filled with an inert fluid, such as diesel oil or fluid like that to be produced. The fluid in the tubing serves to establish initial injection, i.e., by its i.,,se piimpability of th,- subsequent fltiids into the formation can be deter@ilined, and anv undesirable fluids in the formation to be tre@ted are disrlaced. Treatment then co-@itinues by pumpin- into the tubing th@- follovving fiuids in senyence, each succe,-ding fluid pushing the precedin.- one out into the formation. @(1) A siiitable agent, sucli as acetone, capable Of rc3,176,768 moviig water from ti@e sa-@id grains and oj' rendering them preferentially wettable by epoxy resin. (2) A fluid caoable of washing the acetone from the tub,n- aiid th,,is -oreventi-@ig it from diluting the epoxy resin, -,i qliantity similar to V@iat of the acetone being satisiactory. This fluid is a hydrocarbon oil, such as diesel or crucle petroleum oil, i-,i which the acetone is soluble and epoxy resin is insolubl-.. (3) Epoxy resin-reactive diluent mixture. 10 (4.) Flushir@g fiuid for dispersion o@t' the resin-reactive t,irou-,hout the formation. (5) Activator or curing ag-.nt solution. The activator soltition is forced into the formation by a liquid su--h as diesel or s@ilt water, -,vhich later is permitted to fill the 15 ti3b;D-@, aiid t,@en to provide a hydrostatic head which is at le,,ist e,.!,,,.al to the formation pressure and thereby preve,,it@ng the in,ected fluid from being i'Orced back into th-@ borehole, In praclice, the various fluids are pumped into the 20 tubing at a fast r,,ite consistent with the equipment used and the objectives desired. Accordingly, the plasticreactive diluent mixtil-re is injected at a rate sufficiently coiitrolled to eflect uniform dispersion of it taroughout the formation. It has been found that a resin mixture 2,5 rate of injection of about 1/10 barrel to 5 barrels, preferably 1/2 barrel to 1 barrel, per hour per linear foot of borehole opposite the formation to be treated is satisfactory. The o'Llier fluids can be injected at a rate equal to that of the resin mixtut@e ranging up to 20 times this rate 30 a good operable rate being about 6 times that of the' resin. It is also desirable to keep the various fluids separate in the tubing, and minimize intermixing. It is particularly,desirable that the resin-reactive dillient mixture be 85 forced iiito the formation relatively uncontaminated. This can be effected by the use of separation means, such as sweep plugs, that keep the various fluids separated. Therefore, it will often be advantageous to insert sweep 40 plugs into the tubing just before and after the plasticreactive diluent mixture is plimped into the tubing. The following example illustrates low temperature sand consolidation of an unconsoedated earth formation. Exaynple 5 4,5 In t'@ie Louisiana G ulf Coast area a well was completed offshore in a typical miocene formation that had exhibitpd severe sand problems in other wells nearby. The temperature of the formation was 138' P. A 5 foot interval of the eased borehole, extending froni about 5,200'50 5,205 feet down the well, was perforated and isolated by means bf packers. A producing tube having a capacity of approximately 30 barrels was installed. The tubing was filled to capacity with 30 barrels of diesel oil. 15 55 barrels of acetore were pumped into the tubing, thusdisplacing 15 b,,irrels of d;esel oil from the tub@'.ng into the )-ormation. Next there was pumped into the tubing 10 barrels of diesel fuel to wash out the a--etone from the tubin.- and prevent mixin,@ with resin in the next step, ro a total of 25 barrels of diesel oil being thus forced out iiito the forination. At this stage a sweep plug was inserted in the tubin,@, after which 5 barrels of ttic epoxyreactive diluent plastic mixture were added to the tubing. The sweep p'.ug s,-rves to keep diesel introduced in the 65 rrevious step separate frorn the resin mixture. The enoxy resin coliponeht of the plastic mixture was an epoxidized novolac resiii having a molecular weight of 425 and an epoxide equ:lvalent of 178. The reactive diluent was styrene oxide, present in an amount of 20 70 nercent, by weigl-lt, the ei)oxy resin being present in an Elmoun@ oi' 80% by wei.-h@t. Pressuring of the olastic m-' ixture caused a displacemeiit out into the formition of 30 barrels of diesel oil. At this point a)iotber s 9 weep plu was installed to isolate 75 the resiii mixture from subseqlent fluids. 15 barrels of
[5]9 diesel were then injected into the tubing displacing 15 barrels of acetone from the tubing into the formation. 15 barrels of activator solution containing 5 percent dimethyl amino propylamine in diesel were then injected into the tubin The activator solution and flushing diesel oil fluid before it were forced into the formation by pressu-ring with 10 barrels of drilling fluid (salt water). When the resin s6lution was at the bottom of the tubing, i.e., after 10 barrels of the @activator solution had entered the tubing, the purnping rate was slowed to 1/2 barrel per hour per linear foot in order to obtain gooddistributi6n of the resin mixture into the formation. After resin injection, the pumping rate of- the subsequent fluids into the formatiop was increased to 3 barrels per linear foot@ At the end, the tubing contained 30 barrels or salt water, thus forming a hydrostatic head for the formation. The formation contained 30 barrels of diesel oil, 15 barrels of acetone, 10 barrels of diesel oil, 5 barrels of resin, 15 barrels of diesel oil, and 15 barrels of activator solution. The well was shut in for a period of 4 hours after which production was initiated from the treated zone. For ready understanding, the steps involved in this example, showing the location of the various fluids in the tubing and in theforination, may be summarized as follows, The nu@merals refer to barrels. Tubing Formation ----------------- 30 Diesel ----- ----------- 16 Acetone -------------- f (15 Diesel ---------------- 115 Diesel. Di.,l ---------------- ---------------- 11105 Acetone ------ -------- 25 DiesPl. 5 Diesel ----------------- I Resin ----------------- snvcep Plug ------------- Diesel. ............. 15 10 Diesel ---------------- 15 Acetone -------------- fIS5 Diesel ---------------- wee,p PItig ------------- V ----------------- 5 Resin ---------------- - 30 Diesel, 15 Acetone. Sweep Plug ------------- 110 Diesel ---------------- I VI ---------------- 15 Activator I ----- ------ 40 Diesel 15 Acetone. tl5 Diesel ---------------- 5 Resin.' 30 Drilling Fluid -------- 55 Diesel, 15 Acetone. VII ------------- 7- @Hydrostaiic Head ------- 5 Resin, 15 Activator. I I - I When 10 barrels of activator had been injected, resiii solution Nvas introduced at a rate of 2M barrels por hour, the otber fluids having been injetted at e, Tate of 15 barrels per hour We
