Aqueous Silicon Compounds in Oil Well Recovery Methods

This invention relates to electrodeposition of silicon and other metals and to provision of hydride compounds useful in solution as aqueous electrodeposition baths.

Elemental silicon is useful as a coating in a number of different applications. Silicon is a highly effective, corrosion-resistant coating for metals. Silicon coating is used for absorption of incidence solar photons in the generation of electricity by photovoltaic means.

Prior art methods for electrolytic deposition of silicon are difficult and inconvenient in use in that they may require operation at high temperature or in a closed, inert atmosphere. For example, one such method is disclosed in G. Boe, K. Grjotheim, K. Matiasovsky and P. Felner, Electrolytic Deposition of Silicon and of Silicon Alloys, Canadian Metallurigical Quarterly, Volume 10, No. 4 (1971), pp. 281-285. In that method, silica (SiO.sub.2) and alumina (Al.sub.2 O.sub.3), were dissolved in cryolite, 3Na.sup.F.AlF.sbsp.3. The metal is held at approximately 1030.degree. C. and subjected to electrolysis. A copper cathode was utilized and at selected current densities, only silicon was deposited at the cathode. Operation at high temperature using molten materials is required.

Another method for electrolytic deposition of silicon is disclosed in U.S. Pat. No. 3,990,953 to Alfred E. Austin, issued on Nov. 9, 1976. In that method, elemental silicon is deposited on a cathode. A non-aqueous electroplating composition is provided consisting essentially of a non-aqueous solvent solution of anhydrous liquid aprotic dipolar organic solvent such as propylene carbonate containing a silicon solute, such as silicon tetrachloride or trichlorosilane. Deposition on the cathode body is provided through electrolytic reduction of a silicon halide or haloid silane compound. In this method, a nonaqueous electroplating composition must be provided, and the reaction is conducted in a sealed vessel in which inert gas must fill the space over the non-aqueous liquid. While operation at relatively low temperatures, e.g. 20.degree.-100.degree. C., is provided, operation in a sealed atmosphere is required.

The present invention comprehends combining silicon in an aqueous solution to provide a plating bath comprising a source of silicon, or by using the same principles to provide a plating bath providing a source of other metals. These compounds will be referred to as hydrides. While there structure is not completely understood at the present time, they do provide the desired electroplating bath. Therefore, the efficacy of the teachings herein should in no way be considered to be affected should reactive species eventually be determined to be other than as described or should a principle be less than fully understood. A repeatable process is provided and explained as fully as possible at the present time.

It is generally believed that provision of a hydride compound suitable as a plating substrate, for example, is impossible to provide. For example, see Douglas M. Considine, Editor, Chemical and Process Technology Encyclopedia (McGraw-Hill, Inc.; New York, N.Y.; 1974), under the description of silicon at page 1031. In describing the chemical properties of silicon, it is stated that "even with diluted bases, Si reacts vigorously, developing H.sub.2 and forming alkali silicates." Silicon hydride is also unexpected in the aqueous form. The entry also states that SiH.sub.4 and the chlorosilanes are instantaneously hydrolyzed with a nucleophilic agent, such as OH.sup.- (water and bases). Silicates do not have utility as a source of metal in an aqueous plating bath. For example, see Ralph K. Iler, The Chemistry of Silica, (John Wiley & Sons; New York, N.Y.; 1979). At page 123, the section entitled "The Nature of Silicate Solutions" discloses a plurality of equilibria between forms of silicate in aqueous solution. None are recognizable as sources of elemental silicon in a plating bath.

It is therefore an object of the present invention to provide a method for electrodeposition of silicon on a cathode from an aqueous medium.

It is a further object of the present invention to provide electrodeposition from an aqueous medium of other metals as well.

It is a further object of the present invention to provide the methods of the type described in which such methods may be performed conveniently in terms of provision of components and temperature and atmosphere constraints.

It is an additional object of the present invention to provide metal hydride compounds having utility in the electrodeposition method.

It is a particular object of the present invention to provide a silicon hydride.

It is an additional specific object of the present invention to provide a solution comprising a silicon hydride for use as a plating bath.

Briefly stated, in accordance with the present invention there is provided a method in which metal such as silicon is deposited on a substrate from an aqueous solution of a hydride compound. The hydride compound is prepared from a combination of stoichiometric amounts of silicon or other metal reacted with an alkaline metal hydroxide in water. The stoichiometric amounts require a particular ratio by mole percent which ratio is a function of the particular metal to be used.

In one form, a silicon hydride compound is formed by the combination of silicon, sodium hydroxide, and water in the ratio of 6:1:10 respectively by mole percent.

In a further preferred embodiment, the hydride is combined with water to provide a plating bath.

In another embodiment, a method for electrodeposition of metal on an electrically conductive cathode member comprises placing the member in the above-described plating bath and passing an electroplating current therethrough.

The invention, both as to its organization and manner of operation is pointed out with particularity in the claims forming the concluding portion of the specification. The invention may be further understood by reference to the following detailed description.

These and other features, objects and advantages of the present invention will become apparent from the following detailed description, wherein reference is made to the figures in the accompanying drawings.

FIGS. 1-2 are pictorial representations of apparatus used to produce the solutions of the present invention.

FIGS. 3-5 are pictorial representations of electroplating apparatus used in accordance with the present inventions.

FIGS. 6-8 are graphs depicting various results obtained under the concepts of the present invention.

FIGS. 9-20 are various micrographs, pictures, and charts, verifying the presence of substances plated according to the present invention.

FIGS. 21-23 are various graphs and charts showing the utility of the solutions of the present invention as oil recovery agents.

It has been found that by reacting certain non-alkaline metals in an aqueous medium with an alkaline hydroxide, stable metal hydride solutions can be produced. It should be noted that the precise reactive species in the reactions referred to below have not been completely defined. The term hydride as used herein means a compound produced by the below-described reactions. The term hydride is used for reactive species in the reactions or irrespective of the particular molecular structure of these compounds and is a descriptive device. Most significant of the metals which it is desired to form hydride of is silicon. Providing the hydride compound will provide for the ability to electroplate silicon from an aqueous solution. Use of the below-described examples has confirmed efficacy by confirming the presence of silicon in coatings formed on a cathode under KEVEX electron microscopic analysis.

According to the present invention, a metal hydride is formed by reacting a non-alkaline metal with an alkaline metal hydroxide in water. This reaction produces a hydride. The hydride is also referred to herein as a hydride compound. This compound will be stable and useful in electroplating. The compound is water soluble and may be diluted to provide an aqueous solution. Finally, in accordance with the present invention, the aqueous solution is prepared as a plating bath, and electroplating onto a cathode is performed utilizing the solution as a plating bath.

In order to form the hydride, the metal, hydroxide and water must be provided in specific proportions. It has been found that provision of components in proportions in accordance with the present invention will provide for a useful hydride, plating bath solution, and plating method as described above. Departures from the proper proportions (or from proper conditions as described below) will result in provision of a mass that is useless within the context of the present description. The proper amount of each component is referred to herein as an effective amount. By following the teachings herein, one skilled in the art will be able to determine where he has utilized an effective amount. Qualitative tests will be indicative of an effective amount as well as the provision of components in the proper stoichiometric relationships. For example, in the case of a silicon hydride, when components are provided in an effective amount, the resulting hydride will have a darkish grey color when prepared from low purity silicon and a substantially colorless appearance when prepared from high purity silicon. If the compound produced from the low purity silicon has a warm, irridescent, mercury-like appearance, then the practitioner has in all probability produced undesired silicate rather than the desired hydride. An effective amount is also known to be provided if the resulting compound is useful for electroplating.

The following has been found to be ratios of effective amounts by mole percent. In each case, the molecular weight of the component is calculated and that weight, or that weight multiplied by a constant, may be multiplied by the ratio number in the following list to provide a proper proportion.

Relative amounts should be measured carefully. To the extent imprecision must be accommodated, it should be noted that having an excess of metal is less likely to adversely affect the reaction than an excess of water or aqueous hydroxide. In a further embodiment (see Example XII) it is desired to provide excess metal.

The reaction rate should be kept controllable. This will be further defined below. In an uncontrollable reaction, the water is too rapidly dessicated. In the silicon example, silicate is likely to be formed when too much water is present or when too much water is removed. The reaction will vary depending on the metal and its form. For example, elemental silicon will react violently with base solutions. The temperature in exothermic reactions needs to be controlled. On the other hand, it may be necessary to add heat to make zinc react. In the case of exothermic reactions, the metal is added to the water and the hydroxide is added gradually over a period of time. It may be added in the form of pellets rather than powder to further control the rate at which heat is generated. In the example of silicon, it has been found that low purity silicon (95-98%) is more highly reactive. High purity silicon tends to react more slowly. In the case of exothermic reactions, it is desirable to provide cooling to keep the temperature in the range of 90.degree.-110.degree. C. to keep the reaction controllable. In the case of an endothermic reaction, heat may be added.

Time of reaction is not critical. However, the reaction should be permitted to continue until it has gone to completion.

A silicon hydride product was prepared utilizing the following components in the following proportions:

The artibrary constant 11 is simply a scale-up factor since it is desired to prepare more than the quantity provided by one mole of each component. The silicon metal was placed in a 6-liter reaction vessel and the water was added. Sodium hydroxide was added in the form of pellets slowly over a one-hour period. The reaction time from ambient to maximum temperature due to exothermic reaction and back was approximately six hours. The temperature reached was 110.degree. C. The resulting product was very dense. The specific gravity was difficult to measure, and probably in the vicinity of 1.8-2.0.

The product produced by Example I was diluted to specific gravity 1.3 with water. This solution of a hydride product comprised a plating bath.

A zinc hydride solution was prepared in the following manner:

The zinc was placed in a 2-liter flask, and the water was added. Zinc flakes were utilized. Sodium hydroxide was added over a one-hour period. Heat was added to the reaction since zinc is less reactive in an alkaline medium than silicon. The reaction temperature averaged 80.degree. C. The reaction was continued for 48 hours. At the end of 48 hours, the solution should contain about 2% zinc. This hydride compound may be used for plating.

Components were provided as in Example I. However, the silicon was provided in the form high purity zone refined chunks 1.5-2" in diameter. The silicon was placed in a 6-liter flask and water added. Ice was used to cool the reaction. Sodium hydroxide was added incrementally over a one-hour period. Reaction temperature was held to approximately 25.degree. C. Cooling was then removed and the reaction allowed to proceed unaided. The reaction started to become exothermic approximately four hours later and more highly exothermic another two hours thereafter. After a further hour, the reaction slowed down. The solution appeared to be relatively dense. The reaction terminated six hours after it began. A solution was produced which was clear and colorless having a specific gravity of approximately 1.5.

A silicon solution was provided using potassium hydroxide:

Again, the silicon was placed in a reaction vessel and water added. Potassium hydroxide was added over the period of an hour. The reaction went from room temperature to maximum temperature and back in about five hours. The temperature peak reached was 105.degree. C. The reaction rate of the silicon slowly decreases after the reaction reaches peak temperature and as the density of the product increases.

H.sub.2 O was added to the aluminum in a 2-liter flask. Sodium hydroxide pellets were added. As the pellet addition was completed, the reaction becomes violently exothermic, releasing water vapor. The reaction started slowing down by itself approximately 45 minutes later.

The tin reaction is similar to that for zinc in that heat must be applied to maintain a good reaction rate. The reaction time is 48 hours. The reaction time may be increased depending on the percent of tin in solution which is necessary.

A combination of hydride compounds from Example II and Example III were used to prepare a plating bath. 100 ml of the solution of Example II were combined with 100 ml of water and 100 ml of the solution of Example III. A electroplating bath was provided with a zinc anode and a carbon steel bolt comprising the cathode. The bolt was cleaned in a 25% HCl solution for approximately 15 minutes and then rinsed with water prior to its connection as a cathode. The silicon hydride solution was mixed with water and then the zinc hydride solution was added. This solution formed the electroplating bath. A current of 1 amp was applied to the bath for five minutes.

A plating bath was provided utilizing 100 cc of solution according to Example IV, 100 cc of water and 25 cc of solution according to Example III. These were combined to form an electrolyte. A zinc anode and a copper cathode were connected in the plating bath and plating conductor. It was found that heating the electrolyte reduces resistance dramatically and plating is more efficient. The dilution rates will also effect the rate of plating.

It should be noted that viscosity of the electrolyte effects conductivity. The conductivity increases with dilution or by applying heat.

A plating bath was prepared utilizing 100 ml of solution prepared by Example I, 100 ml of water and 100 ml of hydride according to Example III. The three liquids were combined to comprise a plating bath. A brass cathode and tin anode were provided. The brass was prepared by cleaning with brass cleaner. A plating current of one amp at three volts was applied for approximately one minute.

A plating bath was provided utilizing a nickel solution combined in equal amounts with water. Two nickel anodes were used for better coverage on the substrate and a steel cathode was provided. One amp was applied at five volts for one-half hour.

A hydride comprising two metals has also been produced. In this example, the following components were provided:

The silicon and zinc metal were placed in a reaction vessel and water was added. Sodium hydroxide was added over a one-hour period. The reaction continued for eight hours. The resulting compound was removed and filtered. The compound provided a concentrate for an electroplating bath.

In this example, the effective amounts for a silicon compound are utilized, and excess zinc is provided. The resulting hydride will be partially zinc and partially silicon hydride.

A hydride has also been produced utilizing an acid. In this example, nickel was utilized as the metal:

The H.sub.3 PO.sub.4 is provided at a specific gravity of 1.689. Therefore 522 ml of phosphoric acid are needed. Also, 882 grams of water are combined with the phosphoric acid.

The nickel is placed in a 2-liter flask and the phosphoric acid solution is added. The sodium hydroxide is combined slowly, and heat is applied. The temperature is maintained at about 85.degree. C.

As discussed above, each of the hydrides may be used as a plating bath, may be dissolved in water as a plating bath and may be combined with other hydrides in solution. Depending on thickness, time and other factors, temperature or dilution may be varied. Plating will not take place if an ineffective amount of component is provided since a hydride bath will not be present. The provision of plating will be readily apparent so that one skilled in the art will know if indeed, he has achieved the proper proportions in producing the desired hydride baths. The specification has been written with a view toward enabling those skilled in the art to make many modifications to the specific exemplifications illustrated herein to provide hydrides, plating baths, and plating methods in accordance with the present invention.

From experimental work, it seems apparent that by reacting certain metals (nonalkaline) with other (alkaline) metals it is possible to produce stable metal hydrides. This is accomplished by taking a nonalkaline metal, e.g., silicon, and reacting it with an alkaline metal hydroxide, e.g., NaOH or KOH in the presence of H.sub.2 O.

The Si metal reacts with the aqueous hydroxide. The reaction proceeds from ambient to an extremely exothermic one.

During the reaction the hydrogen taken from the OH groups that are present bonds with the Si forming SiH groups.

This reaction takes place without external aid.

It is important to note that the amounts of the components can be critical for the reaction mentioned above.

By using Si as a metal in the reaction and forming a stable aqueous metal hydride, it is possible to electroplate the Si from solution onto a substrate.

By using this method, multi-metal hydrides can also be produced.

Reactions using less reactive metals, i.e., Zn, Sn, Cu, etc., are accomplished by applying heat to the reaction.

Si metal placed in reaction vessel, 6-liter capacity.

H.sub.2 O added; then the NaOH pellets. The alkaline was added over a one (1) hour period.

Reaction time from ambient to exotherm was approximately six (6) hours. Temperature peak was 110.degree. C.

Product was very dense. S.G. difficult to measure. Probably 1.8-2.0.

Diluted to S.G. 1.3 with H.sub.2 O.

This solution to be used for electroplating.

The amounts of the components used in the above produce the desired product.

The Si and Zn metal is placed into the reaction vessel.

H.sub.2 O added.

Then the NaOH over a one (1) hour period.

The reaction time is a little longer than with only Si.

Duration eight (8) hours.

Product removed and filtered; will be diluted for electroplating.

Zn placed into a 2-liter flask.

H.sub.2 O added.

NaOH added over a one (1) hour period.

Zn is less reactive in alkaline medium than Si; therefore, heat must be applied to the reaction.

Reaction temperature average 80.degree. C.

Reaction time: forty-eight (48) hours straight.

After this time, the solution should contain about two percent (2%) Zn.

This solution to be used for plating.

High purity Si used (Zone Refined).

1.5 to 2 inches in diameter.

Si placed in a 6-liter flask, H.sub.2 O added. Time 10:30.

Ice bath used to cool reaction.

NaOH added incrementally over a period of one (1) hour. Reaction temperature approximately 25.degree. C.

Cooling removed. Reaction allowed to proceed unaided.

17:00 reaction continuing overnight.

Reaction starting to become exothermic.

Time 13:00. Temperature increasing slowly.

15:00 reaction quite violent.

16:00 reaction slowing down, solution appears relatively dense. Reaction terminated at 16:30, S. G. 1.5.

Solution clear.

Si placed in reaction vessel.

H.sub.2 O added.

KOH added over a period of one (1) hour.

Reaction goes from room temperature to exotherm in about five (5) hours.

Temperature peak 105.degree. C.

Once the reaction reaches peak temperature the reaction rate of the Si metal will slowly decrease as the density of the product increases.

Time Start: 13:00.

KOH added to H.sub.2 O containing Si metal. See FIG. 1.

Zn placed into a 2-liter flask.

H.sub.2 O added.

NaOH added over a one (1) hour period.

Zn is less reactive in alkaline medium than Si; therefore, heat must be applied to the reaction.

Reaction temperature average 80.degree. C.

Reaction time: forty-eight (48) hours straight.

After this time, the solution should contain about two percent (2%) Zn.

This solution to be used for plating.

Low purity Si used, approximately ninety-five to ninety-eight percent (95-98%).

6-liter flask used, H.sub.2 O added to Si metal in flask. Cooling applied. NaOH feed started 10:00, NaOH feed complete at 11:30.

Temperature approximately 31.degree. C., cooling removed. Temperature of reaction slowly climbing.

16:00 reaction violent. Reaction terminated at 16:45. Solution dense gray color.

Filtered and diluted to S.G. 1.5.

Solution greenish/gray.

Zn High Purity (Flakes).

Cooling not used for Zn reaction due to Zn slow reactivity in alkaline.

11:00 NaOH added slowly over a period of one (1) hour. Temperature after addition approximately 80.degree. C., Zn reacting slowly, but applied to maintain temperature (hot plate). Will let reaction continue for seventy-two (72) hours. See FIG. 2.

H.sub.2 O added to Al in 2-liter flask.

NaOH pellets added.

11:00.

As the pellet addition was completed, the reaction went into a violent exotherm releasing H.sub.2 O vapor. Let the reaction continue until it started slowing down by itself, which was approximately forty-five (45) minutes.

The H.sub.3 PO.sub.4 is added; the 882 g H.sub.2 O and mixed.

This solution is then added to the reaction vessel containing the Ni metal.

External heat is applied to aid the reaction rate.

Reaction temperature average is 80.degree. C.

Forty (40) hours duration.

Sn metal placed into reaction vessel.

NaOH added after the H.sub.2 O.

Sn reaction is similar to the Zn inasmuch as heat must be applied in order to maintain a good reaction rate.

Reaction time: forty-eight (48) hours uninterrupted.

Al placed in reaction vessel.

NaOH added over one-half (0.5) hour period.

The Al reaction is much more violent than the Si. That is to say, the reaction rate of the Al is much greater.

Total reaction time: two (2) hours.

For electroplating, the Si solution is used as a base. The Zn, Sn, etc., solutions are then mixed with the Si solution.

The Si used in reaction can be either high or low purity. When using high purity, the initial amount of metal (Si) is greater.

The final product of the Si reaction is a very dense, high viscosity compound, gray in color (low purity), or transparent (high purity).

This compound is water soluble and may be diluted to suit a particular need.

During the exothermic phase of the reaction, the temperature will reach approximately 100.degree.-120.degree. C.

Excess Si should be provided. The molar ratios of Si to NaOH at the start of the reaction can be 6:1. This is to insure a proper reaction rate.

The finished product (Si) aqueous hydride solution will usually contain about twelve percent (12%) Si.

Taking the finished product and exposing it to direct heat will cause it to foam. (Solid.)

Upon further heating, the solid (foam) will return to a liquid 800.degree.-1000.degree. C., and thereupon, release a gas. (Hydrogen.)

Electroplating:

Substrate: Bolts (GM Automobile Fasteners)

Solutions: Si+Zn

100 ml. Si solution @ 1.3 S.G.

100 ml. H.sub.2 O

100 ml. Zn solution

Zn anode

Bolt cathode (carbon steel)

Si solution mixed with H.sub.2 O then Zn solution added.

Electrolyte: Room temperature

Duration of electrolysis: five (5) minutes at one amp.

Preparation of substrate:

Bolt cleaned in a twenty-five (25%) HCl solution for approximately fifteen (15) minutes, then rinsed with H.sub.2 O. See FIG. 3.

Plating:

Using the H.P. Si solution along with the Zn solution: 100 cc. Si diluted with 100 cc. H.sub.2 O

25 cc. Zn solution

Zn anode, Cu cathode

Cold electrolyte

At these dilutions the cathode is being plated; however, the resistance is high.

Heating the electrolyte brings the resistance down dramatically. Plating is more efficient. The dilution rates will also effect R. However, the plating, itself, works well.

Will proceed to find the rates of dilution that will enable to plate efficiently at ambient temperature.

Also, a comparison of the low purity Si solution will have to be made.

ZnSi Plating: High purity Si solution. A solution of one (1) part Si solution; one (1) part H.sub.2 O; and, one (1) part Zn solution. Plates efficiently at ambient temperature and pressure.

A ratio of one (1) part Si solution; two (2) parts H.sub.2 O; two (2) parts Zn solution also works well.

It would seem that the viscosity of the electrolyte affects the conductivity. Conductivity increases with dilution or by applying heat.

Electroless Plating:

Solution: One (1) part Si/Na solution (low purity)

One (1) part H.sub.2 O

One (1) part ZnNa solution

Sample:

Cast Al fan blade

Fan blade painted

Paint removed using wire wheel blade then immersed in five percent (5%) HCl approximately five (5) minutes. Rinsed with H.sub.2 O.

Sample immersed in plating solution. Reaction between sample and solution occurs. Gas evolved from sample. (30 second duration.)

The Zn rod in the plating solution does not appear to react.

Zn deposited on sample.

Sample rinsed with H.sub.2 O. Towel dried.

Some of the deposit can be wiped off; however, most of it cannot; therefore, indicating surface preparation critical.

After second immersion of sample in plating solution, deposit cannot be wiped off.

Experiment:

Sample: Al rod 99.9999% pure.

1. Uncleaned sample immersed in above solution. Reaction does take place; however, not very efficient.

2. Rod cleaned (wire wheel); immersed. Much more efficient deposit.

3. Rod cleaned (wire wheel); immersed in twenty-five (25%) HCl; rinsed with H.sub.2 O. Rod immersed in plating solution and produced a much more efficient deposit.

Tool Joint Samples:

Surface preparation:

Samples had been Cu plated; Reed removed the Cu.

Threads degreased with solvent (Gumout).

Some residue still present.

Samples treated in HCl, both twenty-five percent (25%), for twenty (20) minutes; removed.

Samples placed in plating bath (ambient condition) 3 V., 4 amps. (20 minute duration.)

Samples plated; however, some areas spotty.

Surface to be plated was not clean enough. Surface preparation critical.

Samples buffed (wire wheel); then acidized fifty percent (50%) HCl solution for twenty (20) minutes; then rinsed. Surface appears cleaner.

Samples placed in plating bath (ambient condition) 3 V., 4 amps.--duration ten (10) minutes.

Anode--H.P. Zn 1.5 inch diameter.

Cathode--tool joint N 338.

Samples (pin) buffed with wire wheel; then acidized. 506HCl (20 minutes); rinsed.

Samples plated (ambient condition) 3 V., 4 amps.

Duration time: ten (10) minutes.

Three (3) anodes used H.P. Zn plates 3 inches wide, 0.5 inches thick, 6 inches long.

SiSn Plating:

Solutions used:

100 ml. Si solution

100 ml. H.sub.2 O

100 ml. Sn solution

Substrate: Brass plate

Preparation of substrate:

Brass cleaned with brass cleaner

Sn anode

Brass cathode

Duration of electrolysis: one (1) minute. See FIG. 4.

One (1) amp. at approximately three (3) volts.

Ni Electroplating:

Solutions used:

Ni solution

200 ml.

200 ml. H.sub.2 O

Substrate: Steel

Substrate cleaned in twenty-five percent (25%) solution for fifteen (15) minutes; rinsed.

Two (2) Ni anodes used for better coverage on substrate. Duration one-half (0.5) hour. See FIG. 5.

One (1) amp. at five (5) volts.

The following is field testing of a process for coupling coatings.

The plating is "Zinc Silicide." General references will be made to a zinc and silicon compound applied through an electrolyte process to the pin and to the couplings.

The cost is competitive with other zinc coatings and in line with nickel manganese phosphating with a zinc top coat used in coupling manufacturing.

The tests determined the efficacy of the coatings on four (4) couplings with pipe dope and without pipe dope on A.P.I. L-80 couplings 23/8" O.D. and 27/8" O.D.

Carbon 0.40 Max.

Manganese 0.19 Max.

Nickel 0.25 Max.

Quenched and tempered material

Rockwell C. Hardness 18-24 R.C.

Test No. 1--Materials were coated on couplings only and doped, with regular A.P.I. pipe dope to 800 lbs. torque and standard A.P.I. stand off. The coupling showed no galling apparent on pin or coupling.

This operation was repeated eight (8) times with the same results.

Test No. 2--27/8" coated coupling, uncoated pin--no dope--machine crimped back side of coupling onto pipe through personnel error--no results.

Test No. 3--23/8" L-80 coated coupling, coated pin--doped--bucked on and off L-80 four (4) times. No apparent galling or damage to threads.

Test No. 4--27/8" L-80 coated coupling, coated pin--undoped--bucked on and off one (1) time with no apparent galling. Coupling overtorqued on second run resulting in severe galling.

A fifth test was run using an 8' pup joint of L-80 23/8" tubing upset and threaded on both ends. The pins were coated and an L-80 coupling coated. The coupling was bucked on and hydrotested to 10,000 psi. The coupling was removed with no apparent galling. The coupling was bucked on two (2) more times and hydrotested to 10,000 psi. with no leakage. The coupling was removed with no apparent galling to the threads.

The coatings had a thinness of one-tenth (1/10th) of a micron allowing for use on tight tolerance connections.

Five (B 5) samples coated with a corrosion protection surface treatment were evaluated. The samples were 11/8" diameter.times.8" long ASTM A-193 B7 stud bolts with ASTM A-194 grade 2H nuts. The bolts were coated with zinc silicon material in a low temperature electrolytic process. This coating is a replacement for zinc plating, cadmium plating and hot dip galvanizing. Cadmium plating, zinc plating and galvanizing have been used to protect ferrous materials in mild to moderately corrosive environments with varied success. The protective mechanism of such platings and coatings is the ability to sacrifice by oxidizing rather than the ferrous parts coated. This phenomenon, however, leads to problems with appearance and ease of removal after service and in long-term use, a deterioration in the strength of the fastener. The zinc silicon coating relies not on the sacrifice of the coating but as as a barrier to inhibit fastener corrosion.

Zinc silicon has a dull gray appearance after coating. Under low power (20.times.) magnification the zinc silicon appears to be a continuous amorphous coating. Under higher power (500.times.) magnification zinc silicon resembles a phosphated surface. Coating thickness is approximately 0.0003 inches thick.

Chemical analysis by Energy Dispersive Spectral X-ray techniques revealed a composite surface of zinc, silicon, and iron (See Table 1). This differs from cadmium, zinc platings, and galvanized coatings in that they have surfaces composed almost entirely of cadmium or zinc.

The bolts were torqued to one hundred percent (100%) of minimum yield strength in a simulated flange fixture incorporating a strain gaged load cell for load monitoring. Torque values were increased incremently until the yield load was achieved. The bolts were examined after testing to evaluate coating damage.

After mechanical testing the five bolts were placed in an ASTM B-117 salt fog test chamber. Duration of the tests were as follows: two bolts removed after 300 hours; one bolt removed after 700 hours; one bolt removed after 1000 hours; final bolt removed after 1350 hours.

The zinc silicon surface exhibited a coating similar to a phosphated surface. Zinc silicon can retain oil for secondary corrosion protection or paint adherence. The zinc silicon surface is different from a plated surface. Bonding top coats to plated surfaces has been done by reacting a zinc phosphate over the plating. Use of zinc silicon eliminates the need for secondary operations prior to painting.

The presence of iron in the coating chemical analysis indicates that a chemical reaction occurs between the steel substrate and the zinc silicon. This is not the case with an imposed plating. Therefore, the interfacial bond with zinc silicon will be much stronger than with plating.

Zinc silicon provided adequate lubrication during assembly to allow the bolts to be torqued to one hundred percent (100%) minimum yeld strength without failure of the bolt or coating. Torque versus load relationships were more linear and reproducible than bolts plated with cadmium and zinc. Galling typically encountered with bolt platings did not occur with zinc silicon. Zinc plated bolts in sizes 11/8" diameter and larger cannot be torqued to one hundred percent (100%) minimum specified yield strength without torsional failure due to galling. No such problems were encountered with zinc silicon. The ability to perform without galling at these high percentages of yield strength is an advantage of zinc silicon among conventional plating systems.

1. Two (2) bolts removed after 300 hours. Nuts turned freely by hand along the entire length of the bolt. No visible corrosion products.

2. Bolt removed after 700 hours. Nuts turned freely by hand along the entire length of the bolt. No visible corrosion products.

3. Bolts removed after 1000 hours. Nuts previously had a prevailing break-out torque on the order of 20 to 35 ft. lbs. After starting, the bolt could be turned easily by hand. Slight surface corrosion was present, however, there was no pitting of the steel substrate.

4. Last bolt removed after 1350 hours. The bolt threads were filled with salt residue and/or corrosion products. The nut was easily removed from the bolt. The nut could not be threaded on the other areas of the bolt which were not protected by the nut during testing. In an effort to determine the extent of corrosion, the residue was removed with a solution of inhibited hydrochloric acid. The residue was easily removed. There was no gross deterioration of the fastener. There was, however, some minor corrosion pitting. The strength of the fastener was not reduced.

The zinc silicon coating did not sacrifice itself by oxidation as cadmium or zinc platings. The intermetallic compound formed by the zinc-silicon-iron is an effective passivation for steel substrates.

The silicon zinc material, although an electrolytic low temperature process, resembles a high temperature (180.degree.-205.degree. F.) phosphate chemical reaction. The zinc silicon coating will accept oils or paint for increased protection.

Zinc silicon will accommodate the required elongation and durability for fastener applications.

Zinc silicon exhibits a coefficient of friction much lower than zinc platings and approximately equivalent to cadmium plating.

Zinc silicon passivates surfaces rather than sacrificing in corrosive environments.

Zinc silicon combines the application techniques of platings with the passivation and properties of phosphate coatings.

The results of the above tests will be seen in Tables I and II, and in FIG. 7.

The extreme pressure properties of test pieces that had been coated electrolytically were examined.

The test pieces were coated electrolytically and run on a Timken extreme pressure tester using lubricating oil.

The definitions used in this test are as follows:

Load Carrying Capacity of a Lubricant is the maximum load or pressure which can be sustained without failure of moving bearings or sliding contact surfaces as evidenced by seizure or welding.

Seizure or Welding is the localized fusion of metal between rubbing surfaces of the test pieces. Seizure is indicated by streaks appearing on the surface of the test piece, an increase in friction or wear and vibrations.

Scoring occurs when the lubricant film is substantially maintained and a smooth scar is observed. When there is a breakdown of the film, scoring of the test block occurs. In its most recognized form, it is characterized by the furrowed appearance of a wide scar and by excessive metal pickup.

Wear is removal of metal from the test piece by the mechanical action of the apparatus.

O.K. Value is maximum weight, in pounds, added to the load lever weight pan, at which no scoring or seizure occurs.

Score Value is minimum weight, in pounds, added to the load lever weight pan, at which scoring or seizure occurs.

The test block was observed after each run to see if scoring had occurred, when it is observed, it is recorded as the score value. The O.K. value is taken as the reading immediately before the score value.

Three test pieces were run on the Timken tester and were identified as follows:

No. 1--Uncoated ring and block.

No. 2--Coated ring--uncoated block.

No. 3--Coated ring and block.

The loss of weight of the block in milligrams was plotted against the torque meter reading, giving a visual indication of the rate of wear, score value and O.K. value. See FIG. 8.

Examination of the curves show that the score value was 350 in.-lbs. and the O.K. value was 320 in.-lbs. for the uncoated ring and block. The coated ring and uncoated block gave a steady rate of wear and did not score or seize at the maximum torque of the instrument. The coated ring and coated block also gave a steady wear rate but at a higher rate. There was some evidence of scoring at the maximum torque of 410 in.-lbs.

FIGS. 9 and 10 are micrographs of a silicon deposition on a copper substrate. The lines running vertically are work marks on the substrate. The other lines are fractures and crystal boundaries. FIGS. 11 and 12 are pictures of the micrographs in FIGS. 9 and 10, showing a thin film electrodeposition of high purity silicon on a copper substrate. FIGS. 11 and 12 confirm the presence of silicon and indicate some zinc in the copper substrate.

FIGS. 14-16 and 18 are micrographs which confirm the presence of cerium. It is noted that cerium dioxide is a safe substitute for radioactive heavy metals used in testing the disposal of nuclear waste. A surface in which cerium dioxide has been chemically bound is shown in FIG. 17, and the presence of cerium in confirmed at 27.04% in the chart of FIG. 13.

Further micrographs of thin film silicon electrodeposition will be seen in FIGS. 19 and 20.

Until fairly recent times, it was relatively easy to find new oil reserves when a field was depleted or became unprofitable. In many fields only 15-25% of the oil in place was actually recovered before reservoir pressure or drive was depleted or other factors made it uneconomical to continue to produce the field. As long as new reserves were readily available, old fields were abandoned. However, with the crisis now confronting the domestic oil industry, coupled with the fact that most of the existing on-shore oil in the United States has already been discovered, it is obvious that such known reserves must be efficiently and economically produced.

It has been estimated that at least 50% of the known oil reserves of the United States cannot be recovered using conventional pumping methods. A substantial amount of this oil is of an abnormally low gravity, and/or high viscosity, often coupled with the fact that there is little or no pressure in the oil-bearing formation. In the absence of formation pressure, even oil of average viscosity and gravity is difficult to produce without adding external energy to the formation to move the oil into a producing borehole. Accordingly, a great deal of attention has recently been given to various methods of secondary recovery. Water flooding has been utilized with mixed results to attempt to increase the natural reservoir pressure hydraulically. Thermal flooding techinques, such as fire flooding, steam injection and hot water flooding have been utilized to alter the viscosity of the oil and hence, enhance its flow characteristics.

For a formation or reservoir to be productive, a couple of conditions must exist. First, a pressure differential must exist between the formation and the well bore. Energy for the pressure differential may be supplied naturally in the form of gas, either free or in solution, evolved under a reduction in pressure. The energy may involve a hydrostatic head of water behind the oil, or the water under compression. In cases where the natural energy forces within the formation are not sufficient to overcome the retarding forces within the formation or reservoir, external energy must be added. Secondly, the produced oil must be displaced by another fluid, either gas or water.

Reservoirs are ordinarily classified according to the type of reservoir energy that is available. The four types are solution gas drive reservoirs, gas expansion reservoirs, water driving reservoirs, and gravitational drainage reservoirs. A particular reservoir may, of course, involve more than one of these producing mechanisms.

In those cases where the natural energy of the reservoir is insufficient to overcome the resistive forces such as the forces of viscous resistance and the forces of capillary action, external energy must be applied. To illustrate such cases, this phenomenon is typically encountered in shallow formations containing high viscosity oil that has little or no reservoir energy or formation pressure available, and in those oil-producing formations in which the reservoir energy has been depleted or dissipated. In this discussion, we have been referring to "mechanical" forces acting within the producing formation. In a formation in which the natural energy of the reservoir has been depleted, the mechanical forces in the formation have reached near equilibrium and no pressure differential is available to drive the oil from the formation into the well bore. In all of the cases where reservoir energy was depleted by conventional primary production, or non-existent in the first instance, the chemical balance of the producing formation remains undisturbed and in virtual equilibrium.

Artificial forces introduced into the reservoir such as water or gas through various "pressuring" or "flood" techniques of secondary recovery can effect a mechanical change in the formation by way of pressure. Steam pressure is likewise effective, with some side benefits from heat. Combustion of some of the oil in the formation through "fire-flooding" and heating a well bore serve to reduce the viscosity of the oil in place and enhance flow characteristics but lack a drive to force the oil through the formation and into a producing well bore. However, these are primarily mechanical forces applied and operating only on an exposed face or surface of the formation, and if some chemical or molecular change is accomplished in the fluids in the formation, it is limited to a localized phenomenon. The instant invention will enhance the flow characteristics of the oil in the formation.

Waterflooding has a number of economic advantages as an oil recovery process. Although over half of the original oil in place can remain after waterflooding, there are many factors which favor its use. Water of sufficient volume and quality for flooding is generally available. Because of its hydrostatic head, it is readily injected at sufficient rates in most reservoirs and spread well throughout the formation.

The investments usually required for initiating a waterflood project include water supply wells, water treating facilities, pump stations, flow lines from the central plant to the injection wells, and the injection wells themselves. Depending upon the deliverability of the water supply wells and treating chemical costs, the cost can range from a few mills to as much as five cents or more per barrel of injected water.

Production costs have a similarly wide range. These can depend upon the type of lift equipment needed and whether any unusual treating is required to separate the produced oil and water. Where particularly troublesome oil-water emulsions exist, treatment and chemical costs can escalate rapidly.

In summary, however, through the use of available technology and equipment, waterflooding is for a large number of reservoirs an economically attractive oil recovery method.

Its limitation is that significant quantities of the oil initially in place are left unrecovered after waterflooding. This unrecovered oil is the target for improved fluid injection methods discussed below.

Viscous or thickened waterflooding differs from conventional waterflooding only in that the injected water is of increased viscosity due to the addition of a polymer or some other chemical. The ultimate residual oil saturation in viscous waterflooding is the same as in conventional waterflooding. The advantages of viscous waterflooding are two-fold:

(1) a reduction in the quantity of water required to reduce the oil saturation to its residual value in the swept portion of the reservoir;

(2) an increase in the areal and vertical coverage in the reservoir due to a reduced, and hence improved, waterflood mobility ratio.

Water soluble polymers offer relatively low concentration, low cost materials for increasing the flow resistance of the injected water. The results of a number of field tests of polymer water injection show that oil recovery efficiency increases of from 5 to 15 percent can be obtained. This is particularly true when the polymer solution is injected early in the life of the project.

In much the same manner in which a housewife uses a detergent or surfactant to remove oily dirt from the family wash, surfactant solutions are useful for removing oil from the "fabric" of reservoir rock. The mechanism for this process is that the surface active agent reduces the interfacial tension between the reservoir oil and water to such a level that additional oil is displaced from the rock pores. It has been shown that water-oil interfacial tensions of less than 0.1 dyne/cm are required for improved oil displacement in consolidated sandstone. Surfactant flooding is aimed primarily at improving the waterflood oil displacement efficiency.

It has been shown that dilute solutions of surfactants removed considerably more oil from sand cores than did water alone. However, the loss of the surfactant by adsorption at the solid-liquid interfaces has limited surfactants as economical waterflood additives. This is especially true of anionic and cationic surfactants, and to a lesser extent with nonionic surfactants.

The injection of a nonionic surfactant at concentrations of from 25 to 250 ppm into a sandstone reservoir at an advanced stage of waterflooding resulted in an additional 147,000 barrels of oil obtained, which corresponds to a nine percent increase in recovery. The total surfactant used was slightly over 50,000 pounds which represents a surfactant cost of ten cents per barrel of additional oil.

Another process designed primarily for the improvement of waterflood displacement efficiency is termed wettability alteration flooding. This process utilizes the fact that some reservoir systems can be changed from preferentially oil-wet to preferentially water-wet by the action of simple chemicals added to the injection water. This process is attractive because it utilizes the surface active agents already present in the reservoir crude oil, requires only inexpensive chemicals, and results in a gross "wettability reversal" rather than a precise adjustment to a specific wettability degree. As the wettability is altered from oil-wet to water-wet, it moves through a condition of neutral wettability. Under these conditions the capillary forces which result in oil being left trapped by water are eliminated.

The results of a field test of the wettability alteration process in a previously waterflooded Nebraska sandstone reservoir have been reported. The reservoir was preferentially oil-wet and this wettability was changed to water-wet conditions by the addition of sodium hydroxide to the water at concentrations of 0.4 moles per liter. A system is known using one well for the injection of caustic solution and an adjacent control well for the injection of conventional water. The total oil production attributed to wettability alteration was 8700 barrels, or approximately 0.2 barrel of oil per barrel of caustic solution.

The following are tests and results demonstrating the utility of the solution of Example IV as an oil recovery agent. The solution of Example IV mixed at 40 ml. per 1000 ml. of water is effective in displacing FEE "C" crude oil from a sandpack. It will be seen in Example XXXVI that oil recovery and water injectivity are substantially greater than for a conventional waterflood.

A. OIL FROM FEE C LEASE CALIFORNIA.

B. SAND USED A STANDARD COARSE "PLAY" SAND.

C. WATER USED FRESH (TAP) WATER.

D. PROCEDURE:

CONSTANT PRESSURE DISPLACEMENT.

WATER INJECTION UPWARD.

PRODUCED FLUIDS COLLECTED AS A FUNCTION OF TIME.

TEMPERATURE CONSTANT (80.degree. F.).

WATERFLOOD AND CHEMICAL FLOOD RUN SIMULTANEOUSLY.

The following is further test data, examples, and experiments that have been conducted in order to demonstrate the utility of the solutions of the present invention as oil recovery agents in addition to the use of such solutions as described hereinbefore. Where the solution is not specified, the material of Example IV may be taken as generally representative of the oil recovery agent employed.

A review of this data reveals that the chemical product is effective in producing oil from core plugs. Total oil recovery is the secondary oil recovery test was sixty-five percent of the original oil in place. The tertiary oil recovery test recovered eighty-two percent of the original oil in place. Liquid permeability at the conclusion of the tests was low.

Tabular and graphical data to describe such tests have been set forth, such as graphs of water-cut, and oil recovery and pressure drop as a function of total throughput. A summary table is also set forth for comparison of the results.

A "staged" oil recovery test is also set forth using reservoir core material. Such tests were conducted for the purpose of determining the oil recovery effectiveness of the chemical solution as a function of product concentration and slug size. These tests indicate that low concentration, low pore volume slugs in the range of about four percent and 0.30 pv produce oil sooner than a comparable waterflood process. At higher concentrations (80.0% and 0.60 pv) oil recovery significantly improved. Final brine permeability will be seen to be lower than would be expected normal for such systems. During the test procedures, emulsions were not produced at lower dosages of solution, but in higher dosage runs emulsions were observed in the final stages of the test.

In FIG. 22, oil recovery is seen graphically as a function of solution concentration. Thus, the concentration for the test number is given as follows: Test No. 1=4% and 0.25 pv; Test No. 2=4% and 0.25 pv; Test Nos. 3 and 4=8% and 0.5 pv. It will be seen that Test Nos. 3 and 4 far exceeded the standard waterflood level. Test No. 1 in Example XXXVII is Test No. 4 in FIG. 22. Test Nos. 1-3 in FIG. 22 are the "staged" Test No. 3 of Example XXXVII. In FIG. 22, the Test No. "0" is the waterflood standard.

A. OIL FROM KENDON LEASE CALIFORNIA.

B. CORES IN NATIVE STATE CONDITION.

C. WATER: SIMULATED MONARCH SAND BRINE.

D. PROCEDURE:

CONSTANT RATE DISPLACEMENT.

WATER INJECTION UPWARD (TEST NO. 2).

PRODUCED FLUIDS COLLECTED VS. TIME.

TEMPERATURE CONSTANT (150.degree. F.).

Reference should be made to FIG. 23 wherein this data will be seen as oil produced in the secondary oil recovery test. The water cut is illustrated in FIG. 24 and the pressure in FIG. 25.

Tertiary oil recovery testing was conducted as follows:

These results will be seen pictorially in FIGS. 26-28 of the tertiary system. In FIG. 26 the pressure is depicted, in FIG. 27 the water cut, and FIG. 28 the oil production.

A series of "staged" oil recovery tests were conducted and the results of such tests are set forth below:

Again, FIGS. 29-31 illustrate the results of the tests of Example XLI with FIG. 29 showing the oil production of the "staged" test, FIG. 30 the water cut, and FIG. 31 the pressure.

The following additional experiment illustrates the use of the solution of Example IV as an oil recovery agent wherein the "staged" core test was conducted in a long pack of core material. Results show that the solution was effective in mobilizing oil in the long core pack. Total oil recovery was over seventy percent of the oil in place. The test was characterized by high differential pressure above about 1000 psi per foot. Liquid permeability at the end of the test was low due to the high oil saturation at the outlet end of the core. Emulsions were not produced in any of the fluids.

FIGS. 32 and 33 portray these results with the pressure being shown in FIG. 32 and oil recovery in FIG. 33.

Thus, it should be apparent from the foregoing Examples 36-42 and FIGS. 21-33, that solutions of the present invention are useful as oil recovery agents in secondary oil recovery, tertiary oil recovery, and "staged" oil recovery methods where oil is recovered from formations and reservoir materials.

Solutions of the present invention such as that set forth in Example IV above have also been proven to be useful as fire retardant and fire blocking agents. For example, the Federal Aviation Administration has issued a "Notice of Proposed Rulemaking," Vol. 48, No. 197, 14 CFR, Part 25, 29, and 121, which Notice relates to a fire-test procedure entitled "Flammability Requirements for Aircraft Seat Cushions." In the interest of supporting the use of fire blocking layers in aircraft seat cushions to increase fire safety in aircraft, the Technical Center of the United States Department of Transportation and the Federal Aviation Administration evaluated some two hundred and forty materials submitted by industry and in accordance with the proposed test requirements set forth in the Notice. The following Example sets forth the result from a portion of a report issued by the Federal Aviation Administration of a list of materials that passed the proposed requirements of a fire blocking agent.

The solution of Example IV will be seen in the above test results as M-140 and M-141 in Column 4. The material M-124 in both instances is Brown Wool, Nylon 90/10. The material M-140 is fabricated FR urethane foam sprayed with 4.20 pounds of the solution of the present invention. The material M-141 is similarly fabricated FR urethane foam but sprayed with 4.91 pounds of the solution of the present invention. A test conducted with 2.85 pounds of the solution of the present invention sprayed on the urethane foam was found unacceptable in the FAA fire blocking tests.

In view of the foregoing results and test data, as set forth in Example 43, it should be apparent that the solutions of Example IV are useful as agents in methods of retarding the spread of flame in materials containing a fire blocking agent, particularly in foam core materials such as polyurethane, having an outer layer of blocking material fashioned as a seat cushion for aircraft, although it should be further apparent that the above tests render the solutions of Example IV suitable as fire retardants in wider applications.

It will be apparent from the foregoing that many other variations and modifications may be made in the structures and methods described herein without departing substantially from the essential concept of the present invention. Accordingly, it should be clearly understood that the forms of the invention described herein and depicted in the accompanying drawings are exemplary only and are not intended as limitations in the scope of the present invention.