US3297089A - Sand consolidation - Google Patents

Description

United States Patent Ofitice 3,297,089 Patented Jan. 10, 1967 3,297,089 SAND CQNSOLIDATION Horace H. Spain, Houston, Tex., assignor, by means assignments, to Esso Production Research Company, Houston, Tex., a corporation of Delaware No Drawing. Continuation of application Ser. No. 191,-

409, May 1, 1962. This application Oct. 24, 1965, Ser. No. 505,051

11 Claims. (Cl. 166-33) This application is a continuation of application Serial No. 191,409, entitled Sand Consolidation, filed May 1, 1962, and now abandoned, which application is a con- -tinuation-in-part of application Serial No. 73,535, entitled Sand Consolidation, filed December 5, 1960, and now abandoned.

This invention is primarily directed to a method for consolidating the sands of loose or incompetent formations penetrated by a borehole, and in this regard the invention more particularly concerns a method for consolidating the sands of subsurface formations by injecting into them thermosetting plastics, which set in the formations and bind the sand particles of the formations together.

A primary object of the present invention is to provide a method of sand consolidation that is economical, rapid acting, and generally applicable to various types of formations. Also, the method of the invention overcomes disadvantages inherent in other sand consolidating procedures.

In producing fluids from subsurface formations, sand is produced along with the formation fluids from loosely consolidated formations. Various sand control measures to inhibit or prevent sand particles from moving into the well bore from the formations have been attempted, because sand production with its attendant accumulation in the well bore or movement to the surface causes serious operational problems. One manner of sand control that has been tried is the use of thermosetting plastics which set and bind the sand particles of the formation together while permitting flow of well fluids therethrough.

One good sand consolidating plastic makes use of the resin-forming properties of the reaction between a watersoluble aldehyde and a low molecular weight hydroxy aryl compound catalyzed by an alkaline or acid catalyst. When these compounds are injected into a sand formation, a resin forms which cements the particles of the formation together. Although any water-soluble aldehyde may be used, formaldehyde, acetaldehyde, propionaldehyde, or mixtures thereof are preferred. The low molecular weight hydroxy aryl compound may include phenol, cresol, beta naphthol, resorcinol, or cresylic acid, or mixtures thereof; for low temperature formations, xylenol, especially 3,5-xylenol, is preferred. Suitable alkaline catalysts which may be used include guanidine salts, such as guanidine carbonate and amino-guanidine bicarbonate; alkali metal hydroxides and carbonates, such as sodium hydroxide or sodium carbonate; aliphatic amines, such as ethyl amine and triethyl amine; aromatic amines, such as aniline; and aliphatic diamines, such -"as ethylene diamine. Suitable acidic catalysts which may be used include acidic salts, such as stannous chloride or magnesium chloride; mineral acids, such as hydrochloric acid or sulfuric acid; acid anhydrides, such as maleic anhydride; aromatic acids, such as picric acid or benzene sulfonic acid or sulfanilic acid; and polynuclear aromatic acids or acid salts, such as alpha naphthylamine sulfonic acid or sodium-1-naphthylamine-3,6,8-trisulfonate.

It has been found that injection of the reactive ingredients of the phenolic type plastic mixture in two parts is better than injection of a mixture of all of the reactive ingredients together, for in the latter procedure, for example, base catalyzed plastics must be refrigerated during mixing to prevent premature separation and hardening in the tanks or tubing; acid catalyzed plastics may not be used for low temperature formations because of the danger of slight deviation in a component of the composition causing premature separation; and neither the base catalyzed nor the acid catalyzed plastics can be used to consolidate unusually long producing intervals, because the prolonged injection time required to consolidatesuch intervals would cause separation of the plastic mixture before placement could be completed.

in the two-part injection procedure, the first part injected includes all the reactants except the low molecular weight hydroxy aryl compound. The second part injected includes the low molecular weight hydroxy aryl compound dissolved in oil. The second part of the plastic mixture is substantially imiscible with the first part of the mixture. Therefore, as the second part passes through the formation sand following injection thereof, a portion of the first part remains on the sand surfaces as the connate liquid and extracts a fraction of the low molecular weight hydroxy aryl compound from the second part. The concentration of the hydroxy aryl compound in the second injected part is so regulated that extraction of the hydroxy aryl compound will cease when the first part injected has dissolved the proper amount of the hydroxy aryl compound. The proper concentration of the hydroxy aryl compound in the second part of the mixture injected is experimentally determinable. This concentration is dependent on the volume of solution it is desired to use, and it is the amount that will cause the sand to be consolidated throughout the treated portion. An excessive concentration of hydroxy aryl compound in the oil causes the sand nearest the well bore to be inadequately consolidated. Conversely, too low a concentration will consolidate too little sand to withstand the pressure differential caused when the well is produced.

Another good sand consolidating plastic makes use of the resin-for ming properties of epoxy resin solutions together with a hardener or curing solution, as described and claimed in US. pat. appl. Serial No. 51,033, entitled Sand Consolidation, filed August 22, 1960, now Patent No. 3,100,527, by Albert R. Hilton, Jr. and Horace H. Spain. The formation sand is treated with a solution of epoxy resin and an oil-alcohol solvent followed by a large volume of viscous oi1-hardener solution, or a limited volume of viscous oil-hardener solution and a large volume of light-oil-hardener solution. The desirable properties of chemical inertness, high strength, and superior wetting of the epoxy resins are utilized to give an im proved sand consolidation. The epoxy resins preferred for purposes of this application are the diglycidyl ethers of bisphenol A [bis(4-hydroxypheno'l) dimethylmethane] obtained by the reaction between epichlorohydrin (1 chloro-2,3 epoxypropane) and bisphenol A using carefully controlled additions of caustic soda to control the pH neutralizing the hydrochloric acid formed in the reaction. The pH is maintained just below the endpoint of phenolphthalein, about 8 to 8.5. The ihardeners or accelerators having the property of catalyzing the reaction of the thermosetting resin at low temperatures include amines, dibasic acids, and acid anhydrides. Typical compounds that will serve as curing agents are diethylene triamine, diethylamino propylamine, ethylene diamine, triethylene triamine, ditrimethylaminome-thylphenol ,(DMP-- 30, made by Rohm and Haas and the preferred catalyst), benzyldimethylamine, metaphenylenediamine, and 4,4 methylene dianiline, are typical of the amine curing agents. The acids and anhydrides are illustrated by oxalic, .phthalic, pyromel-litic dianhydride and dodecenyl succinic anhydride.

The epoxy resin is dissolved in a solvent that can also dissolve a substantial amount of water but still have a favorable partition coefficient to extract the hardener from the oil solution which is later used to displace the epoxy solution. In order that a rather high saturation of the epoxy solution remains after immiscible displacement with the oil-hardener solution, it is desirable that the viscosity of the epoxy solution be at least 3 cps. at the temperature of the formation to be treated. The viscosity would be preferably in the range from 5 to 25 cps. at the formation temperature.

The preferred solvent for the epoxy is ethyl alcohol denatured with methyl alcohol and kerosene in the range from 60 to 90 percent by volume alcohol to 40 to percent kerosene. The kerosene must contain some aromatics to give a clear, homogeneous solution suitable for use. Other oils that may be used are diesel oil and white oil to which some aromatics, i.e., toluene, have been added. Suitable solvents other than ethyl alcohol are acetone or methyl-ethyl ketone.

The oil used for the solvent for the hardener must be substantially immiscible with the alcohol-kerosene mixture, contain no aromatics, and offer a satisfactory partition coefficient for the hardener to go into the epoxy solution. These requirements are satisfied by an acid-treated kerosene or diesel oil by the white oils such as Bayol D or White Oil 95. White oils are specially treated, refined oils that contain no unsaturated or aromatic compounds.

The hardener solution may contain from 0.5 to 10 percent hardener dissolved in the oil. The preferred range is from 1 to 5 percent hardener.

Typical commercial epoxy materials are:

1 Shell Chemical Co., Epon 815, is the preferred epoxy and the one with which the experimental work has been (lone. This composition contains an undisclosed diluent, which accounts for its high epoxide equivalent and low viscosity.

In the sand consolidation process a solution of 50 to 100 percent epoxy resin dissolved in a solvent composed of 60 to 90 percent denatured alcohol and 10 to 40 percent kerosene is prepared and injected into the formation.

The kerosene in this solution must contain some aromatics. A volume of hardener in a viscous white oil, the volume of which is about equal to the epoxy solution, then is prepared and injected into the formation. After this, about 2 to 10 volumes of a hardener kerosene solution is prepared and injected into the formation. The concentration of the hardener in the white oil and kerosene solutions preferably is in the range of 0.5 to 10 percent, and both the white oil and kerosene must be free of aromatics.

To improve the effectiveness of the phenolformaldehyde resins and the epoxy-type resins when used as sand consolidating media, it is proposed to incorporate in the solution or solutions which deposit the resin in the formation sands, a moderate quantity of a chemical agent.

The chemical agents used for this purpose are aminofunctional organo silane compounds, typical examples of which are 2,aminoethyl-aminopropyl-trimethoxy silane; 2,a'minoethyl-aminopropyl-tripropylene oxide silane; 2, a'minoethyl-aminopropyl-triethylene oxide silane; 2,aminomethyl-aminopropyl-trimethoxy silane; 2,aminopropylaminopropyl-trimethoxy silane; 1,trimethoxy-2,aminoethyl-2,aminopropyl disilane; 1,triethylene oxide-2,aminoethyl-2,-aminopropyl disilane; 1,tripropylene oxide-2, aminoethyl-2,aminopropyl disilane; l,trimethoxy-2,aminomethyl-2,aminopropy1 disilane; l,trimethoxy-2,aminopropyl-2,aminopropyl disilane; and l,trimethoxy-2,aminoethyl-2,aminoethyl disilane.

The preferred agent is the compound 2,aminoethylaminopropyl-trimethoxy silane, which is a product manufactured and marketed by the Dow-Corning Corporation, Midland, Michigan, under the trade name Z-6020.

Experiments were performed which show improved sand consolidations result when an amino-functional silane is used with the sand consolidating phenol formaldehyde and epoxy-type resins.

The following experiments illustrate the beneficial results obtainable using an amino-functional silane with the phenol formaldehyde type resin.

Two l-in. I.D. plastic tubes were packed with sand produced from a well. These sand-packed tubes were treated by flowing through the tubes ml. of salt water followed by 100 ml. of diesel oil to simulate oil sand in its natural condition. Through one of the tubes then was flowed a solution consisting of 100 ml. of commercial 37 percent formalin, 13.9 weight percent guanidine carbonate, and 2.8 weight percent sodium hydroxide. Through the other of the tubes then was flowed the same solution, including 1 weight percent of the silane compound Z-6020. Through each of the tubes then was flowed a solution consisting of 100 ml. of diesel oil, 1.4 gm. meta-para cresol, and 1.4 gm. of 3,5 xylenol. The two tubes were cured in a 140 F. water bath for 16 hours. At the end of the curing period, samples were cut from each of the tubes and the compressive strengths were measured. The compressive strength of the sample in the tube treated with the solution containing the compound Z6020 was 1275 p.s.i., while the compressive strength of the other sample was only 427 p.s.i.

The following experiments illustrate the benefits obtainable through the use of an amino-functional silane with the epoxy resins.

Eight sand tubes were prepared and saturated to simulate an oil sand containing connate water. The sand in each of the tubes was treated with epoxy resin mixed in situ using 400 cc. of resin solution containing 75 percent epoxy dissolved in a solvent of 75 percent denatured ethanol and 25 percent kerosene, 350 cc. Humble White Oil 95 (an acid-treated refined oil having a viscosity of about 25 centipoises) containing 2 /2 percent DMP-30, and 2000 cc. of kerosene (an acid-treated kerosene of a viscosity of about 2 centipoises). In four of the tubes, the silane compound Z-6020 (-0.5 percent by weight) was included in the epoxy solution, and in the other four tubes it was omitted. After treatment, the tubes were cured in a water bath at F. The treatment was substantial in "volume compared with the pore volume of the sand tube in order to simulate the effect of the flow through the sand immediately adjacent the perforation.

The results of these experiments are given in Table I.

strength on. rate is believed due to the stripping down to low residual saturation of the epoxy solution by the viscous drag of the hardener solution.

In test Nos. 1, 4, 5, and 8 of Table I the tubes were treated at about the same injection rate. In the case where no water contacted the treated sand and no silane was used, test No. 4, the strength was 815 p.s.i.; whereas when water contacted the sand, test No.1, the strength was reduced to 331 p.s.i. In contrast, the tests where the silane was used, test Nos. 5 and 8 particularly, the strength was about 850 psi. regardless of whether water contacted the treated sand or not.

The results of an additional series of tests conducted in a manner similar to that described for test Nos. 1-8 are shown in Table II.

A group of tests was performed. 2 A single test was performed.

The data of Table II are similar to the data of Table I. In the group of tests A where there was no silane used and no water flush, the sand strengths ranged from 102 to 1390 p.s.i. (dependent upon the injection rate), whereas in the group of tests B where again no silane was used, but a water flush used, the strengths were reduced to 13 to 331 p.s.i. Also, in test C a strength of 890 p.s.i. resulted using silane and no afterfiush, and in the group of tests D strengths in the range of 357 to 828 resulted using silane and the afterflush.

Although epoxy resins provide a superior sand consolidation and at the same time avoid the hazard of the exothermic reaction often encountered with phenolic resins, it is seen from the data of Tables I and II that if the epoxy resin-treated sand is contacted by water after consolidation of the sand, serious weakening of the consolidation treatment results. However, these data also show that by employing an amino-functional silane in the epoxy solution, this difliculty is overcome, and a good sand consolidation results. The importance of the discovery that the use of an amino-functional silane aids in avoiding the loss of strength of the consolidation treatment when water contacts the sand shortly after treatment is stressed, for many wells requiring sand consolidation produce water, and the loss of the strength of treatment in such wells could easily cause failure.

Having fully described the nature, objects, and operation of my invention, I claim:

1. In a method for consolidating the sands of an incompetent formation in which a resin-forming mixture is introduced into said formation in two parts, the first part injected miscibly displacing liquid wetting the sand grains of the formation and a portion of the first part remaining on the surface of the sand grains, and the second part injected immiscibly partially displacing the first part injected, the portion of the first part injected remaining on the sand grain surfaces extracting a fraction of the second part injected to form the resin and thereby consolidating the sands of the formation, the improvement comprising: including an amino-functional organo silane in one of the parts of said resin-forming mixture.

2. A method as recited in claim 1 including employing a phenol type resin-forming mixture.

3. A method as recited in claim 2 including employing said amino-functional silane in the range of .1 to 10' percent by weight.

4. A method as recited in claim 2 in which said first part of said resin-forming mixture comprises an aldehyde and a catalyst and said second part of said resin-forming mix ture comprises a low molecular weight hydroxy aryl compound.

5. A method as recited in claim 4 in which said silane is included in said first part of said resin-forming mixture.

6. A method as recited in claim 5 in which said first part of said resin-forming mixture includes an aldehyde, guanidine carbonate and sodium hydroxide and said second part of said resin-forming mixture includes cresol and xylenol.

7. A method as recited in claim 1 including employing an epoxy type resin-forming mixture.

8. A method as recited in claim 7 including employing said amino-functional organo silane in the range of .1 to 10 percent by weight.

9. A method as recited in claim 7 in which said first part of said resin-forming mixture comprises an epoxy resin solution and said second part of said resin-forming mixture comprises a hardener solution.

10. A method as recited in claim 9 in which said silane is included in said first part of said resin-forming mixture.

11. A method as recited in claim 10 in which said first part of said resin-forming mixture includes epoxy dissolved in ethanol and kerosene and said second part of said resin-forming mixture includes ditrimethyl-aminomethylphenol dissolved in oil.

References Cited by the Examiner UNITED STATES PATENTS 3,199,590 8/1965 Young 166-33 T. A. ZALENSKI, S. J. NOVOSAD, Assistant Examiners.

Claims (1)

1. IN A METHOD FOR CONSOLIDATING THE SANDS OF AN INCOMPETENT FORMATION IN WHICH A RESIN-FORMING MIXTURE IS INTRODUCED INTO SAID FORMATION IN TWO PARTS, THE FIRST PART INJECTED MISCIBLY DISPLACING LIQUID WETTING THE SAND GRAINS OF THE FORMATION AND A PORTION OF THE FIRST PART REMAINING ON THE SURFACE OF THE SAND GRAINS, AND THE SECOND PART INJECTED IMMISCIBLY PARTIALLY DISPLACING THE FIRST PART INJECTED, THE PORTION OF THE FIRST PART INJECTED REMAINING ON THE SAND GRAIN SURFACES EXTRACTING A FRACTION OF THE SECOND PART INJECTED TO FORM THE RESIN AND THEREBY CONSOLIDATING THE SANDS OF THE FORMATION, THE IMPROVEMENT COMPRISING: INCLUDING AN AMINO-FUNCTIONAL ORGANO SILANE IN ONE OF THE PARTS OF SAID RESIN-FORMING MIXTURE.