CA1184811A

CA1184811A - Particles covered with a cured infusible thermoset film and process for their production

Info

Publication number: CA1184811A
Application number: CA000419303A
Authority: CA
Inventors: Calvin K. Johnson; David R. Armbruster
Original assignee: Acme Resin Corp
Current assignee: Acme Resin Corp; Hexion Inc
Priority date: 1982-02-16
Filing date: 1983-01-12
Publication date: 1985-04-02
Also published as: MX162591A; US4439489A

Abstract

Abstract:

Analysis of hydrocarbon mixtures to determine desired characteristics, particularly a determination of octane number of gasolines, undergoing partial oxidation/cool flame reactions. Pre-analysis preformed on a target fuel sample of known composition and octane number is utilized to arrive at an optimum point of the reaction, a point believed to represent a condition where a maxi-mum of the fuel is oxidized during the reaction. In the preferred embodiment disclosed, the optimum point is the reactor block temperature that generates a maximum peak temperature rise of the cool flame reaction of the target fuel. This optimum reactor temperature is utilized in further analyses of other known samples to develop a matrix of peak temperature rise versus time to reach peak coordinates. Any unknown fuel sample whose peak amplitude/time coordinate is within the matrix is compared with matrix values to determine its octane number as well as an indication of its composition.

Description

INFUSIBLE THERMOSET F~LM AND

9 This invention relates to an improved process for coating particulate matter with cured,thermoset phenolic resins 11 and to the products, prepared by this process, which are 12 useful as propping agents for propping fractures in 13 subterranean formations.

BACKGROUND OF THE IN~ENTION
16 _ -17 Fracturing is widely used to increa3e the 18 productivity of oil and gas wells. This is generally 19 accomplished by forcing liquids into the well under pressure to open cracks in the formations surrounding the well.
21 Various solid materials are then introduced to prop open 22 the fractures that are formed.

24 Sand is frequently used as a propping agent in such applications. It is relatively inexpensive, and when suspended 26 in liquids it is readily carried into the fractures. However, 278 if the well is deep, the high pressures encountered crush some 1 of the sand giving finely-divided particles which tend to plug

2 the fracture. For this reason, alternate propping agents have been sought for use in deep wells.
One propping a~ent recently found to be suitable for 6 use in deep wells is sintered bauxite. Although this material 7 is able to withstand the high pressures developed in the wells, it is comparatively expensive and it can undergo attrition 9 by chemical action in some.applications. Consequently, less costly substances have been sought. In particular, 11 many workers have attempted to treat sand and other solid 12 particles to enable them to withstand the high pressures 13 found in deep wells.

One method for treating proppant sand is that 16 disclosed in U.S. Patent 3,026,938- According to this process, 17 sand particles are coated with a flexible material such as 1~ rubber latex. The resulting particles are compressed and 19 not broken when subjected to high pressure in the fracture.
However~ this material has found limited use in formations 21 subjected to high pressure because this proppant fails to 22 maintain good permeability when compressed.

24 Another type of coated sand is disclosed in U.S.
25 Patent 3~929,191. According to this disclosure, sand is coated 26 with an uncured, thermoplastic resin which first melts and 27 then cures in the fracture. Such a process causes the sand

3 -2-.

1 grains to be bound togethe~ preventing their move~ent out of 2 the fracture. However, for these products to be satisfactory~
3 curing must be carefully controlled. If the coating cures too

4 rapidly, it may cause plugging of the well bore or aggregation

5~ of the sand before it reaches the extremities of the fracture.

6 If the coating cures too slowly, the well has to be held under

7 pressure until the curing is completed.
9 A process for making a propping agent coated with a -cured epoxy resin is disclosed in U.S. Patent 3,935,339.
11 According to this process, a mixture of solid particles, 12 uncured epoxy resin, a surfactant, and a heated liquid in 13 which the resin is insoluble is agitated until the coating 14 cures. The coated solid is then separated from the liquid.
16 A similar process for obtaining a propping agent 17 coated with a cured furan resin is disclosed in U.S. Patent 1~ 3,492,147. According to this process, particulate matter, 19 coated with furfuryl alcohol or uncured furfuryl alcohol resin~ is stirred in heated oil containing an acid catalyst 21 to give individual particles coated with an infusible resin.
22 An alternate process which involves mixing the solid with an 23 uncured resin solution and an acid catalyst solution in a 24 continuous ribbon blender and continuously routing the mixture into a heated chamber is also mentioned.

1 The present invention is directed to a method for the 2 preparation of particulate matter uniformly coated with 2 3 cured phenolic resin which does not require the expensive 4 process of curing the product in an inert solvent. By this process, the particles are readily coated with a cured resin 6 without the formation of large amounts of agglomerated 7 material.
9 The products of this invention are resistant to crushing when subjected to high pressures, giving proppants of 11 high permeability. Their coating makes them resistant to 12 attack by acids and steam, materials often used in treating 13 wells. Finally, their lubricated coating is resistant to 14 abrasion reducing the formation of dust which could cause plugging of well openings. Such properties make these 16 products useful not only in hydraulic fracturing but also 17 in gravel pack completions and other applications as well.
lB

21 In accordance with this invention, there is provided 22 a process for the preparation of particulate matter coated 23 with a cured phenolic resin wherein the improvement comprises 24 mixing an uncured resin with the particulate matter at a 25 temperature of from about 300F to about 450F, adding with 26 continued mixing from about 0.03% to about 0.5% by weight, 28 based on the weight of the particulate matter, of a 29 _4_ .' 1 lubricant to the mix of resin and particulate matter and 2 maintaining the resultant mixture above about 300F for a 3 sufficient time to cure the resin, whereby there is obtained 4 a product containing individually coated particles having high abrasion resistance and improved crush resistance 6 suitable for use as a propping agent in subterranean 7 formations.

8 . Additionally, in.accordance with this invention, .
there is provided coated particulate matter consisting 11 essentially of particles individually coated with a cured 12 phenolic resin prepared by mixing an uncured resin with 13 the particulate matter at a temperature of from about 300F
14 to about 450F, adding with continued mixing from about 3% to about 0.5% by weight, based on the weight of the 16 particulate matter, of a lubricant to the mix of resin and 17 particulate matter and maintaining the resultant mixture 18 above about 300F for a sufficient time to cure the resin.

DETAILED DESCRIPTION OF THE INVENTION

22 The particulate matter used in the practice of this 23 invention can be any of the solld materials normally used as 24 propping agents. Such materials include sand, sintered 25 bauxite, zircon and glass beads. The material should be 26 resistant to melting or decompositlon at temperatùres below 28 about 450F. The par~icles are preferably of a relatively .
. . .

1 uniform size. Particle sizes commonly employed vary between 2 10 and 100 mesh (U.S. Standard Screen sizes). Sands which 3 conform with the American Petroleum Institute specifications 4 for fracturing sands are particularly useful.
The phenolic resins used in the practice of this 7 invention can be either novolak or resole resins. When a 8 resole resin is used, the thermosetting resin cures on the g particulate ~latter merely by heating. When a novolak resin is used, it is necessary to add a curing agent such as 11 hexamethylenetetramine to the resin in order to obtain a 12 coating of cured resin on the particulate matter. The 13 novolak and resole resins used for the process of this 14 invention can be prepared from any of the well-known phenols and aldehydes used to make such resins. The phenolics made 16 from unsubstituted phenol and formaldehyde are quite 17 satisfactory.

19 According to the process of this invention, the .
particulate matter is first heated to a temperature of from 21 about 300F to about 450F, preferably from about 350F to 22 about 400F. To the hot particles in a mixer or muller is 23 added an uncured phenolic resin. The phenolic resin can be 24 in solid or liquid form. When the resin is in liquid form, 25 it is usually a solution in water or other solvent well 26 known in the phenolic resin art. Sufficient resin is 2278 added to completely coat the part~cles. For this purpose, 29 . -6-, .', ' ` .

:3 ~ 3 ~ ~

1 from about 1.5% to about 8%, preferably from about 3% to about - 2 5~ of the resin, based on the weight of the particles, is 3 added. The hot particles and resin form a dough-like mix.
4 .
If the phenolic resin used in the process is a novolak 6 resin, a curing agent is added to the mix. A useful curing 7 agent for this purpose is hexamethylenetetramine which can be added as either a solid or a solution. If it is added in

9 a solid form, the solid must be finely divided to insure adequate mixing with the other components. The amount of 11 hexamethylenetetramine added is from about 8% to about 20%, 12 preferably from about 12% to about 18% by weight of the resin 13 on a dry solids basis.

An important step in the present invention is the 16 addition cf a small amount of lubricant to the hot mix of 17 resin and particulate matter while it is still mixing~ The 18 amount of lubricant employed can vary from about 0.03% to 19 about 0.5% by weight based on the weight of the particulate matter. This lubricant is preferably added to the dough-like 21 mixture before it breaks up into free-flowing particles.
22 It has been found that the addition of such a lubricant 23 reduces abrasion and prevents dust formation when the 24 material is mixed at high temperatures. Surprisingly, it also can increase the resistance of the product to crushing 27 and reduces agglomeration of the coated particles.

1 The lubricant used in the process of this invention 2 is one that is liquid at the temperatures used in the mixer.
3 It should have a sufficiently high boiling Point so that it is 4 not lost from the mixer during the heating process. Suitable lubricants include liquid silicone such as Dow-Corning ~ilicone 6 200, mineral oil, paraffin wax, petrolatum or the synthetic 7 lubricant Acrawax CT, a bis-stearamide of a diamine, available from Glyco Chemicals Inc., Greenwich, Connecticut.
The most preferred lubricant is a liquid silicone.
11 It is preferably added before the dough-like mixture breaks 12 up into free-flowing particles. When silicone is added in 13 this fashion, it not only reduces agglomeration of the 14 particles but also gives particles with greater resistance to crushing than those formed if no such liquid is added.

17 The mixture of particulate matter, resin and 18 lubricant is mixed at a temperature above about 300F until 19 the resin is sufficiently cured and the mass has broken up into free-flowing particles. The length of time the 21 material is maintained above 300F will vary somewhat 22 with the curing properties of the resin employed.

24 After the cure of the resin is essentially complete, -the mixture can be passed through a screen to remove 26 agglomerated partic1es. If desired, the product can be 27 subjected to further heating in order to insure complete 29 * trade mark ~3 -8-, .

1 cure of the resin. The product comprises indi-~idual particles 2 coated with a thin layer of a cured phenolic resin. The 3 cQating is hard and does not melt or compress appreciably 4 when subjected to temperatures and pressures found in deep wells.
7 The following exampl'es illustrate the invention. It is to be understood that the examples are illustrative'only ~ and are not intended to limit the invention in any way. In the examples, all parts are percentages by weight un'less 11 otherwise indicated and all screen mesh sizes are U.S. Standard 12 Screen sizes.

16 In a 3-quart mixing bowl was placed 1 kg of 20/40-mesh 17 Bellrose Silica Sand (obtained from the Bellrose Silica Company 18 of Ottawa, Illinois) preheated to 460F. The sand was stirred 19 with a Hobart C-100 Mixer (made by the Hobart Manufacturing Company, Troy, Ohio) until the temperature dropped to 400F.
21 Then 40 g of a novolak flake resin, prepared by heating 1000 22 parts of phenol, 506 parts of 50% formalin and 6.7 parts of 23 oxalic acid followed by dehydrating at 300F, was added and 24 mixing was continued for 45 seconds before 4.8 g of powdered hexamethylenetetramine was added- After 7G seconds of mixing 26 time, a lubricant was added and after about 100 seconds, the 27 mix became free-flowing. Mixing was continued for a total of 3 _g_ , .

3~ Ll 1 380 seconds, at which time the sand temperature was checked.
2 The sand was then dumped onto a No. 16-mesh screen to determine 3 the amount of agglomerates larger than this mesh sizeO ~Such 4 agglomerates contain 2 or more grains of sand bound together.
The material passing through the screen consisted of separate, 6 individually-coated sand particles. These were tested for 7 crush resistance by the American Petroleum Institute recommended test. In this procedure, 40 grams of sand is 9 placed in a 2-inch cylinder die test cell. Four thousand psi o~ pressure is applied to the die over a period of 11 1 minute. This pressure is then held for 2 minutes before 12 the sand is removed and screened through an appropriate 13 screen to remove any crushed sand grains. The crushed sand14 that passes through the screen is weighed to determine thepercent of sand crushed. The results of tests performeq 16 on sands coated using three different lubricants and a control 19 ~ i hich no lubricant was added are given in Table I.
221 ' ~225 .

-10-.

1 TABLE I .

3 Sand Temperature at 380 Séconds % Agglo~eration % Crushed 4 Sand Mix tF) >~16 Mesh 4000 psi Coated Control 265 13.5 ~0.38 6 (no lubricant) 7 Silicone Liquid ) 262 . 9.0 0.26 8 Acrawax CTb) 261 17.5 b.23 9 Mineral Oil 264 ~.9 0.33 Uncoated Control -- -- 4.07

11 a) Silicone 200, available from the Dow~Corning Corporation, Midland,

12 Michigan.

13 b) A bis-stearamide of a diamine, available from Glyco Che~icals Inc~,

14 Greenwich, Connecticut.
The results from Example 1 show that when a novolak 16 resin coated on a preheated sand is being cured, the addition 17 f a silicone lubricant~ before the mixture breaks up to 18 become free~flowing, provides a resin-coated sand with superior 19 crush resistance. There is also much less agglomeration than is observed when no lubricant is present. Example 1 further 21 shows that the solid synthetic lubricant (Acrawax CT), when 22 added to the resin-coated sand in the process of curing, 23 likewise gives a resin-coated sand with improved crush 24 resistance over that produced without the use of such a 25 lubricant. However, this additive does not prevent 26 agglomeration. Finally, Example 1 also shows that the use 27 f mineral oil as a lubricant added during the curing of a . . .

~L~

1 sand coated with a phenolic resin prevents agglomeration of .
2 the coated sand particles but imparts less additional crush 3 resistance over that obtained with the coated sand to which 4 no lubricant has been added.

The procedure of Example l was repeated except that 9 the resin used was No. 1101 CNW Flake Resin, a solid phenolic novolak resin available from the Acme Resin Corporation, 11 Forest Park, Illinois. In this case, 5.6 g of powdered 12 hexamethylenetetramine was added after 60 seconds of mixing.
13 At about 90 seconds of total mixing, the mix had broken into l~ free-flowing particles. At this time, a lubricant, was added and mixing was continued for a total of 300 seconds 16 before the sand was collected and tested. The results of 17 tests on sands prepared by this procedure is given in 21 Ta e II.

~225~ .' .

3 Sand Temperature at 300 Seconds % Agglomeration % Crushed 4 Sand Mix (F~ ~#16 ~lesh 4000 psi Coated Control302 20.3 0.47 6 (no lubricant) 7 Silicone Liquida) 303 20.2 0.33 8 Acrawax CTb) 298 19.4 0.30 9 Mineral Oi1 296 20.3 0.28 Paraffin Wax 298 19.8 0.26 11 Petro1atumC) 299 20.4 0.31 12 Uncoated Control ~ 4 07 14 a) Silicone 200, available from the Dow-Corning Corporation, Mid1and, M;chigan.

16 b) A bis-stearamide of a diamine, available from Glyco Chemicals Inc., 17 Greenwich, Connecticut.
18 c) An industrial grade of petrolatum, Penreco Red, available from 19 Penreco, a division of Pennzoil, Butler, Pennsylvania, was used.

21 Example 2 shows that a wide number of lubricants 22 can be added to a phenolic resin-sand mixture during the curing 23 f the resin to improve the crush resistance of the resin-coated 24 sand. However, when these lubricants are added after the 25 hot resin-coated mixture has broken up and become free-flowing, 26 they do little to prevent the agglomeration of the resin-coated 27 sand particles. The combined results of Examples 1 and 2 3o ~ -13-.

!

1 indicate that the best process to give a product ~ith low 2 agglomeration and good crush resistance involves addition of 3 a silicone liquid to the hot phenolic resin-sand mix before 4 the mix breaks up into free-flowing particles.

8 The procedure of Example 1 was followed except that 9 63.5 g of a 60% solution in methanol of BRPE No. 4035 Resln (a resole resin available from the Union Carbide Corporation) 11 and 2 g of Acrawax CT Lubricant was added to the sand at 430F
12 and mixed for 35 seconds. 92.3% of the product passed through 13 a No. 16-mesh screen and only 0.47% of the sand was crushed 14 when~the standard fracturing sand crush resistance test at 4000 psi was run. This compared with the 4.07% of uncoated 16 sand that was crushed in the same test. This example 17 demonstrates that a phenolic resole resin, as well as a 18 phenolic novolak-resin, can be used to prepare cured 19 resin-coated sands according to the process of this invention.

23 The general procedure of Example 1 was followed 24 except that 40 g of No. 1129 Flake Resin (a solid phenolic 25 novolak resin available from the Acme Resin Corporation, 26 Forest Park, Illinois) was added to 1 kg of 20/40-mesh 27 Bellrose Silica Sand at 422F. After 60 seconds of mixing, 1 ~ -14-' 1 14 ml of an aqueous solution containing 32.7% hexamethylene-2 tetramine was added. After 85 seconds of mixing, 3 g of 3 Dow-Corning 200 Silicone Fluid was added. After 200 seconds 4 of mixing, the sand temperature was 316F. After 320 seconds of ~ixing, 15 ml of water was added to cool the sand, and at 6 350 seconds, the sand temperature was 221F. At this time, 7 mixing was stopped and the free-flowing sand was screened through a No. 16-mesh screen. 92.3% of the material passed 9 through the screen. In the standard crush resistance test, only 0.25% of the coated sand was crushed at 4000 psi.
11 In contrast, 4.07% of the starting sand was crushed in the 12 same test.

-- -16 In a preheated Beardsley and Piper Speedmuller, 17 No. 5060 HP, available from the Bear~sley and Piper Division 18 of Pettibone Corporation, Chicago, Illinois, was placed 19 1000 lb of 20/40-mesh Badger Mining Silica Sand (available from the Badger Mining Corporation, Fairwater, Wisconsin) 21 preheated to 405F. To this was added 40 lb of No. 1101 CNW
22 Flake Resin. After 30 seconds, 6.4 lb of powdered hexa-23 methylenetetramine was added with continued mulling. After 24 80 seconds of mull time, 1 lb of Dow-Corning 200 Silicone Fluid was added and mulling was continued for 330 seconds.
26 The cured coated sand was passed through a No. 16-mesh 27 screen and cooled. Crush resistance of this coated sand .

1 was measured by the standard procedure except that a pressure of 16,000 psi was used. Under these conditions, 4.1% of the 3 coated sand was crushed, whereas 36.o% of the uncoated sand 4 was crushed. This example shows that the general procedure of this invention can be scaled up satisfactorily.
7 Thus, it is apparent.that there has been provided~
in accordance with the invention, particles individually .
9 coated with a cured, thermoset phenolic resin and a process for their production that fully satisfies the objects, aims,.
11 and advantages set forth above. While the invention has 12 been described in conjunction with specific.embodiments 13 thereof, it is evident that many alternatives, modifications~
14 and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is 16 intended to include all such alternatives, modifications, .
17 and variations as set forth within the spirit and scope of 18 ~ ~ the ap nded claims.

. . . .

Claims

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

1. A process for the preparation of particulate matter coated with a cured phenolic resin characterized in that it comprises mixing an uncured resin with particulate matter resistant to melting or decomposition at temperatures below about 450°F, preheated to a temperature of from about 300°F to about 450°F, adding with continued mixing from about 0.03% to about 0.5% by weight, based on the weight of the particulate matter, of a lubricant to the mix of resin and particulate matter and maintaining the resultant mixture above about 300°F for a sufficient time to cure the resin, whereby there is obtained a product containing individually coated particles having high abrasion resis-tance and improved crush resistance suitable for use as a propping agent in subterranean formations.

2. The process of claim 1 characterized in that the particulate material is sand.

3. The process of claim 1 characterized in that the phenolic resin is a resole resin.

4. The process of claim 1 characterized in that the phenolic resin is a novolak resin and a curing agent is added.

5. The process of claim 4 characterized in that the curing agent is hexamethylenetetramine.

6. The process of claim 1 characterized in that the lubricant is a silicone liquid.

7. The process of claim 6 characterized in that the silicone liquid is added to the mix of resin and particulate matter before said mix breaks up into free-flowing particles.

8. The process of claim 1 characterized in that the lubricant is mineral oil.

9. The process of claim 8 characterized in that the mineral oil is added to the mix of resin and particulate matter before said mix breaks up into free-flowing particles.

10. The process of claim 1 characterized in that the lubricant is a bis-stearamide of a diamine.

11. The process of claim 5 characterized in that the uncured resin is mixed with the particulate matter at a temperature of from about 350°F to about 400°F.

12. Coated particulate matter consisting essen-tially of particles individually coated with a cured phenolic resin characterised in that it is prepared by mixing an uncured resin with particulate matter resistant to melting or decomposition at temperatures below about 450°F, preheated to a temperature of from about 300°F to about 450°F, adding with continued mixing from about 0.03% to about 0.5% by weight, based on the weight of the particulate matter, of a lubracant to the mix of resin and particulate matter and maintaining the resultant mixture above about 300°F for a sufficient time to cure the resin.

13. The coated particulate matter of claim 12 characterized in that the particulate matter is sand.

14. The coated particulate matter of claim 12 characterized in that the phenolic resin is a resole resin.

15. The coated particulate matter of claim 12 characterized in that the phenolic resin is a novolak resin and a curing agent is added.

16. The coated particulate matter of claim 15 characterized in that the curing agent is hexamethylene-tetramine.

17. The coated particulate matter of claim 12 characterized in that the lubricant is a silicone liquid.

18. The coated particulate matter of claim 17 characterized in that the silicone liquid is added to the mix of resin and particulate matter before said mix breaks up into free-flowing particles.

19. The coated particulate matter of claim 12 characterized in that the lubricant is mineral oil.

20. The coated particulate matter of claim 19 characterized in that the mineral oil is added to the mix of resin and particulate matter before said mix breaks up into free-flowing particles.

21. The coated particulate matter of claim 12 characterized in that the lubricant is a bis-stearamide of a diamine.

22. The coated particulate matter of claim 16 characterized in that the uncured resin is mixed with the particulate matter at a temperature of from about 350°F to about 400°F.