Gilsonite Uses

Gilsonite Uses

Details of Gilsonite Usage

1. Mix with Asphalt

Glance Pitch and Graliamite are natural occurring hydrocarbon substances characterized by a high softening point (above 110° C) in the class known as asphaltite. They are mined much like other minerals and sold essentially in their native state.

They are fully compatible with asphalt and have long been known as asphalt hardeners and reinforcing agents. Gilsonite is currently sold all over the world as an asphalt modifier in the form of a dry bulk solid granular powder.

Gilsonite s benefits to asphalt pavements include increased stability, resistance to deformations problems such as rutting and shoving, resistance to water striping and increased load bearing ability. Gilsonite functions by making the pavements harder, stronger and increases asphalt’s adhesion to aggregates.

It is generally regarded that Gilsonite reduces pavements’ low temperature properties making them susceptible to thermal cracking. Gilsonite melted into hot asphalt will reduce penetration and increase viscosity of the asphalt binder. Gilsonite may also be mixed with aggregate prior to combining with the asphalt binder.

Gilsonite modified asphalt pavements have been particularly successfully in highly stressed traffic areas. Gilsonite, as the majority constituent, has been combined with virgin polymers such as styrene – butadiene – styrene (SBS) and Ethyl Vinyl Acetate (EVA). Gilsonite modified asphalt binders generally do not increase asphalt binder content requirement in pavement mixtures.

Performance grading of asphalt binders and pavement mixtures became a reality with the conclusion of the, “FHWA” 50 million dollar, Strategic Highway Research Program, “SHRP”, in March of 1993. “SHRP” developed new asphalt binder specifications and test criteria based on the engineering properties related to pavement performance. The new emphasis is on low temperature performance of aged binder materials.

Low temperature flexibility of aged asphalt binders became significant. Performance Grade “PG,” asphalt is based on the predicted temperature performance both high and low of asphalt binders. Neither Gilsonite nor post vulcanized crumb rubber have performed well under “SHRP” evaluations. “SHRP” specifications will cause increased demand for modified asphalt as state departments of transportation adopt the “PG” specifications

The use of bitumen (asphalt) compositions in preparing aggregate compositions (including, but not just limited to, bitumen and rock) useful as road paving material is complicated by at least three factors, each of which imposes a serious challenge to providing an acceptable product. First, the bitumen compositions must meet certain performance criteria or specifications in order to be considered useful for road paying.

For example, to ensure acceptable performance, state and federal agencies issue specifications for various bitumen applications including specifications for use as road pavement. Current Federal Highway Administration specifications require a bitumen (asphalt) product to meet defined parameters relating to properties such as viscosity, toughness, tenacity and ductility.

Each of these parameters defines a critical feature of the bitumen composition, and compositions failing to meet one or more of these parameters will render that composition unacceptable for use as road pavement material. Conventional bitumen compositions frequently cannot meet all of the requirements of a particular specification simultaneously and, if these specifications are not met, damage to the resulting road can occur, including, but not necessarily limited to, permanent deformation, thermally induced cracking and flexural fatigue.

This damage greatly reduces the effective life of paved roads.In this regard, it has long been recognized that the properties of conventional bitumen compositions can be modified by the addition of other substances, such as polymers and asphaltites such as gilsonite. Gilsonite and other asphaltites are used as performance-enhancing agents forasphalt mixes.

Gilsonite-modified paving mixes achieve higher performance grades (PG) and incorporate into an asphalt blend with no need for high shear muling as in the case with some other modifiers. The use of SBS (styrene-butadiene- styrene) polymers may be partially or totally replaced by, or complemented bys the presence of gilsonite. Gilsonite-modified asphalts can have higher stability, reduced deformation, reduced temperature susceptibility and increased resistance to water stripping as compared to non-modified asphalts. A difficulty in using gilsonite as an asphalt modifier is that it is a solid, which is more difficultly handled and incorporated into a viscous bitumen.

 

Mixing Gilsonite into Bitumen

This is a fairly simple procedure. A bitumen tank with a propeller stirrer with enough agitation action to create a vortex is recommended. The best choice is a “lightning” mixer or some other type of electrically powered mixer. An explosion proof motor is preferred if large dust concentrations are likely to occur.

Gilsonite should be added slowly at the vortex. Provisions should be made to recirculate the hot bitumen through recirculation piping. The most important item is that the minimum temperature should be about 170 to 175° C. Anything significantly less than this will extend mixing time. For typical (5-10%) substitution concentrations, 2-4 hours of mixing after addition is completed should be sufficient. For master batch concentrations (over 10% Gilsonite) recirculation overnight is preferred.

If the bitumen cannot be heated higher than 170°C then you may consider using Selects other Grade (60 mesh) or Selects Grade (200mesh) rather than HMA Modifier Grade (175°C softening point) for modification. However, each one of these Selects grades will require slightly

More Gilsonite to be added, relative to HMA Modifier grade, to achieve the same level of bitumen modification. The dry Gilsonite should be poured into the hot bitumen slowly. If it is added too fast then it may agglomerate, or “ball up” at the surface. If this happens then some manual stirring to disperse the agglomerations may be required.

If a horizontal, cylindrical tank is used, then Gilsonite should be added at an opening at the top (about 0.5-1.0 meters in diameter). Again, it should be poured in slowly and stirred with a propeller mixer or a manual paddle so it does not “ball up” or agglomerate. Recirculation piping will be necessary to insure some agitation effect and proper dissolving.

Recirculation is very important to achieve proper dissolution. If mixing is done in a horizontal tank then it is essential that the Gilsonite-modified bitumen be recirculate from the front of the tank to the back, or vice versa. This should be accomplished, even if some re-plumbing of the tank is necessary. Gilsonite does not dissolve instantly. Mixing a tank containing 10-15 MT bitumen and 5% Gilsonite addition will take about 2-4 hours to add in, and an additional 2-4 hours mixing time afterwards. Naturally, higher Gilsonite dosage levels will require longer mixing times.

Unfortunately, during mixing there is no test or checklist to determine whether the Gilsonite is blending well in the bitumen. However, if it is not, then large balls or chunks will be visible in the bitumen if it is in an open tank.
Afterwards, the best method to check whether Gilsonite was fully mixed into the bitumen is by comparing the original and final penetrations of the bitumen.

Batch Plant (Pug Mill) Mixing

First, Gilsonite should be added during the dry cycle of the mixing procedure, onto the hot aggregate rocks, before the bitumen is added. We recommend extending the total cycle time by about 15 seconds to insure proper dissolution.

Eagle petrochem Company has found that 5 additional seconds of dry mixing and 10 additional seconds of wet mixing maximized the Marshall Stability of the paving mix.

The Gilsonite can be stored in an additional silo at the pug mill and sprayed into the mixer. In Iran, there is frequently a dry mineral (ground limestone) silo and this material is sprayed onto the mix. Gilsonite would be handled in this same manner. A screw feeder or vane feeder that measures out the amount of Gilsonite per batch can be calibrated to measure the dosage level of Gilsonite per batch. Afterwards, the only residue left behind in the silo will be Gilsonite powder that can be easily cleaned out.

Meltable Bags

It may be much easier to pre-package Gilsonite into small, polyethylene bags with a measured amount of Gilsonite and toss them onto the hot aggregate in a batch plant. The sidewall thickness of the bag should be about 2 mils (0.005 cm). The aggregate temperature should be around 180°C. It is the aggregate temperature that is melting the bags and the Gilsonite, not the heat from the bitumen. Therefore a temperature of 150-165°C entering the pug mill is acceptable, as long as the aggregate is sufficiently heated.

In either case, spraying Gilsonite onto aggregate or tossing bags into the pug mill, we conservatively recommend increasing the mixing time an extra 15 seconds. This will insure the Gilsonite is melted properly and dissolving into the bitumen. Finally, it is possible to just scoop or shovel a precise number of kilos of Gilsonite per batch onto the hot aggregate, no re-packaging  just hand labor.

Continuous Plant (Drum) Mixing

Gilsonite may be introduced into a via a screw auger. It should be added at a point inside the drum where the bitumen is added. The screw auger should be controlled by a drive motor that is calibrated to the plant’s production rate. The auger should enter the drum at the opposite end from the flame. Care should be taken to insure that Gilsonite is not caught up in the air stream and delivered to the bag house. It should be added right under the bitumen output so that a part of the Gilsonite is taken down by the bitumen to mix with the aggregate.

Paving Procedures

Eagle petrochem’s gilsonite does not recommend any special paving procedures just because Gilsonite resin has been added to the paving mix. After modification with Gilsonite, the final bitumen will have a significantly lowered penetration, a significantly increased viscosity and a moderately increased softening point. Gilsonite modification creates a highly stable, easily workable paving mix.

We recommend normal paving procedures and normal lay-down temperatures. If the increase in viscosity resulting from Gilsonite’s modification presents any flow ability problems, we recommend the contractor operates at the higher end of his normal operating lay-down temperature range. During cold weather, 5 to 10°C, Gilsonite-modified mixes may tend to set-up slightly faster than standard mixes. In this case, the initial roller may follow the paver a little close and the finish roller may not have to stay back as far.

2. Construction

Asphalt has been the subject of exhaustive study to improve characteristics for use in paving. Various properties of asphalt are manipulated to produce a product that has the appropriate wear properties, rut resistance, fatigue and low temperature cracking resistance, adhesion strength,viscosity and pour point. Rut resistance is resistance to longitudinal surface depressions in the wheel paths.

Adhesion strength is the maximum adhesion strength of the joint sealant and the joint reservoir, including but not limited to, between the aggregate and the binder.

Shove resistance is resistance to permanent, longitudinal displacement of a localized area of the pavement surface caused by traffic pushing against the pavement. Heavy hydrocarbon that can be derived from, without limitation, natural asphalt (Gilsonite), shale asphalt, bottoms from a solvent deasphalting process, hard asphalt, blown asphalt, stiff refined asphalt, a flux. Asphalt is usually the base ingredient for the primer and the binder.

A primer can be asphalt, fibers (including but not limited to, mineral or cellulose), processing agent (including but not limited to, oligiomeric wax, carboxilated, derivative of oligiomeric wax, or low molecular weight polyolefin), polymeric or elastomeric additive, or asphalt-derived.

A primer melts to the aggregate. Asphalt binders without polymers are referred to as “neat”.

3. Printing ink

ER resins are “engineered resins”; the term “ER resin” or “Gilsonite ER resin”, as used herein, means a purified fraction of uintaite. These fractions are substantially enriched in maltenes or asphaltenes relative to natural uintaite. Merely dissolving uintaite in a solvent in which it is soluble (i.e., a solvent that dissolves greater than about 90% of the uintaite) and filtering this solution does not produce a purified fraction of uintaite as defined herein. Such a simple filtration process does not substantially change the asphaltene to maltene ratio from that of natural uintaite.

Therefore it does not produce the asphaltene-enriched and maltene-enriched purified fraction of uintaite useful in this invention.
The term “maltene”, as used herein, refers to the fraction of uintaite that is dissolved when finely ground uintaite is contacted with 20 volumes of hot heptane at 80 solution is filtered through a 0.8 micron filter. Maltene-enriched fractions of uintaite, such as ER-140 and ER-115, have a weight ratio of maltenes to asphaltenes of greater than about 6; preferably greater than about 15; most preferably these resins are substantially free of asphaltenes, i.e., less than 2 wt. % asphaltenes. Moreover these resins are also substantially free of ash.

Maltene-enriched ER resins as defined herein have softening points below about 140 relative to natural uintaite; they have at least 50% fewer asphaltenes than natural uintaite, preferably at least 75% fewer, and more preferably at least 90% fewer. These maltene-enriched ER resins also have reduced mineral-derived insolubles, i.e., ash. These insolubles are below 0.1% by weight, preferably below 0.05%. The maltene-enriched fractions of uintaite useful in this invention comprise at least 60% maltenes, preferably at least 80% maltenes and most preferably at least 90% maltenes.

Maltene-enriched ER resins have lower softening points than those of natural uintaite. Solution viscosity, viscosity stability and melt viscosity are also substantially improved over available grades of natural uintaite. The less soluble, high melting, asphaltene-enriched fractions are also called ER resins.

4. Roofing felt

It may be well to preliminary discuss one of the ingredients which I employnamely, what is known as gilsonite or uintahite, a comparatively new hydrocarbon product, the nature of which is explained in an article by Locke, appearing in the Transactions of American Institute of Mining Engineers, Vol. 16, page 162. This article states, among other things, thatgilsonite possesses superior qualities as the principal ingredient in a roofing composition, and appreciating this fact I have in evolvingthe presentinvention aimed to produce a composition which will effectively utilize this substance. Used alon e gilsonitehas not proven satisfactory for roofing or paving purposes, being too brittle, and, moreover, not adapted for use as a base which can be tempered down to the proper consistency. I propose to combine gilsonite with asphaltum and a suitable oil in such a manner that the advantages of the gilsonite as an ingredient of a roofing composition can be had, the asphaltum supplying the deficiencies ap-‘ parent when the gilsonite is used alone, and I am thus’ enabled to procure a mixture that possesses elastic and pliable properties such. as desired in roofing-sheets and one which is at the same time durable and possessed of the required commercial characteristics

5. Paint and coat

There are few prior art coating compositions which combine the highly desired characteristics of economy, low raw material cost and compatibility with most of the raw materials used in the paint, varnish and enamel in dustry, and at the same time are also highly resistant to acid and alkali materials, non-corrosive toward the surface upon which they are applied, weather-resistant and of high electrical insulating value. There is, however, one composition which possesses all of these properties. This composition is one containing gilsonite as a principal constituent. For example, a Gilsonite and drying oil composition possesses all of these desirable qualities to a considerable extent.

Gilsonite is one of the purest natural bituniens available and is used in the manufacture of black varnishes, coach varnishes, black baking enamels, japaris, insulating compositions and water-proofing compositions. Two counties in the State of Utah are the sole source of commercial quantities of gilsonite in this country. Gilso’nite as mined in these counties varies in its properties from one deposit to another and its properties often vary. Within a given deposit. In addition, many ofthe more accesssible deposits are being depleted. Consequently, theindustry is faced with the problem of providing a suitable replacement material for Gilsonite in such compositions.

Maximum water and Weather resistance is obtained by using a paint containing gilsonite and the gas-proofed tung or oiticica (or mixtures of the two) oil without the addition of any other drying oil, but it is found that while this combination is commercially usable, it is difficult to brush, and it is preferred to add a viscosity reducing drying oil. For this purpose it is found that perilla oil is particularly satisfactory.

Other drying oils such as linseed, soya bean, sunflower seed, hempseed, menhaden, or sardine oil may be used instead of the perilla oil. The perilla oil, however, has considerably better drying properties than the other oils mentioned.Gilsonite, when fluxed with raw tung or oiticica oil, gives an unstable liquid, that is, one which will take on excessive body when aging, and one which is not gas-proof.

On the other hand, when gilsonite is fluxed with tung or oiticicaoils which have been heat-treated with the additions of gums or resins in the ordinary fashion, the resulting paint becomes full of check marks and deteriorates rapidly, particularly upon exposure.

The use of the present type of oils, however, results in a paint which does not take on excessive body upon aging and at the same time does not check and deteriorate rapidly upon exposure.

Driers, such as lead, cobalt, or manganese oxide, or the like, may be incorporated to control the drying time of the finished paint. Thinning oils such as mineral spirits, solvent naphtha, or any good solvent for the gilsonite and the oils, may be incorporated to bring the paint to the desired consistency. This normally requires about 50% to 65% by weight of thinning oils.

As an example of the invention, 50 pounds of gilsonite and 10 pounds of perilla oil are heated to a temperature of 400 to 450 F. and are mechanically agitated until the gilsonite is completely fluxed by the perilla oil. Forty pounds of the gas-proofed tung or oiticica oil (or a mixture thereof) are then added and mechanically mixed until the oils and the gilsonite are completely incorporated into a homogeneous mass. Thinning oils may then be added to bring the paint to the desired consistency, which normally requires about 53% to 55% of the thinning oils. The driers may then be incorporated in the desired percentage.

The percentage of ingredients may, of course, vary within rather wide limits, depending upon the particular characteristics desired in the ultimate product. For example, the percentage of gilsonite in the paint base may vary from 10 to 80%, according to the intensity of the color and the hardness of the film desired. Normally this ratio will be between 25 and 60%. However, for water-proofing on certain interior surfaces it is desirable to have a much harder film, and for certain of such uses it may be desirable to increase the gilsonite to as much as 80%.
While the lower limit of 10% for the gilsonite is lower than will ordinarily be used, a satisfactory and durable paint may be made With as small a proportion of gilsonite as this by incorporating a small amount of carbon black, say 3%,; to 5% by Weight. 7
The percentage of tung or oiticica oil may likewise vary, but the higher the percentage thereof, the more durable will be the film produced. The preferred range is between 25 and 50% of either tung or oiticica oils, or a mixture thereof. However, the beneficial results of the combination of these gas-proofed oils with gilsonite are obtained over the entire range of Gilsonite concentration given.

In the above percentages any difference is normally made up by a viscosity reducing oil such as perilla. In the absence of such an oil, however, the tung or oiticica oil may be used to complete the paint base.
Pigments such as iron oxide, or chrome green may be incorporated to produce paints of attractive colors and great durability.
A paint prepared in accordance with this invention not only has greater water and Weather resisting properties, but is more resistant to acids and alkalis than a paint comprising gilsonite and a drying oil other than the gas-proofed tung oil.

The term film-forming constituents as used in the claims denote those portions of the film which do not evaporate following application of the paint, but which remain to form the paint film.

The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, but the appended claims should be construed as broadly as permissible in view of the prior art.

6. Cementing

A cement produced by Gilsonite is suitable for blocking or plugging an abandoned pipeline or back filling a mine shaft, tunnel or excavations contains Portland cement or a mixture of at least two components selected from Portland cement, A cementitious slurry, formulated from the cement mix, may have a density less than or equal to 1500 kg/m3, and exhibits good compressive strength.

In the formulation of the cementing composition of the invention, it is preferable to employ gilsonite in an amount ranging from approximately one-half to approximately ten times by volume the amount of the cement utilized, depending upon the particular result desired.

The lower range is employed where maximum strength is important; the higher range where the various qualities imparted by the gilsonite are most important.

Particle size and particle size distribution of the gilsonite determine the strength and porosity-permeability characteristics of the set cement for any given mix ratio.

Where maximum strength is desirable, a coarse gilsonite Where lightest weight and lowest porosity-permeability are important and strength is to be sacrificed or is of little importance, an aggregate of minus 50 mesh or finer ( 200 mesh ) may be used.

Conditions are often encountered in the field requiring various combinations of particle size and particle size distribution. The above examples represent extremes. The mix must, however, always be pumpable through the system from the mixing point to the final point of placement of the cement slurry. The coarser the aggregate, the less that may be present in any given slurry without impeding pumpability.

For example, a cement-gilsonite ration of 1:4, using the coarse aggregate specified above, is difficult to pump and is likely to plug restricted passages in the system, whereas the same mix, using the fine aggregate specified above, will never plug if the water-cement ratio is high enough.

An amount of a petroleum solvent which depends upon the amount of gilsonite present, may be added to the wet or dry mix for wetting the surface of the gilsonite particles and causing them to form an intimate bond with casing and earth formations of the bore hole, thus preventing corrosion and minimizing pulling away of the cement from the casing and/or bore hole wall by reason of the shrinkage normal to setting of the cement.

Instead of adding the solvent directly to the mix, it may be pumped through the casing and into the cementing zone in advance of the gilsonite-cement slurry.

7. Foundry

Gilsonite foundry sand help:
1. Reduce imperfections due to the rapid reaction between the silica sand mold and the oxidized surface of molten iron.
2. Improve sand peel from casting at shakeout.
3. Produce smoother, cleaner casting surface.
4. Minimize imperfections, casting losses, scrap.

During pouring, the gases given off from the carbonaceous additives form a gaseous film which prevents the molten metal from making direct contact with the clay-coated sand grains, reducing sand-metal contact and consequently burn-on. When heated, the carbonaceous materials provide volatile, hydrocarbon gases which then pyrolize to deposit a lustrous carbon graphitic layer in the metal-mold interface region. This deposition acts as a physical barrier to iron silicate formation as well as not being readily wetted by molten iron. The combination effect is to inhibit burn-on and penetration. When the carbonaceous materials are heated they create a mold atmosphere of reducing gases. This atmosphere keeps the surface of molten iron at the interface free from oxidation, thus preventing formation of the iron silicate necessary for penetration and burn-on. A. Burn-on: Sand grains firmly bonded to casting. B. Burn-off: Casting surface has rough, sandy appearance. C. Metal penetration: Metal penetrates into voids between sand grains forming fused mass of metal and sand, casting difficult to remove. D. Pin holes, caused by high nitrogen content.

08. Foundry sand additive

The additives evaluated were seacoal, pitch, petroleum asphalt, Gilsonite of a "coarse" and "fine" grind, and blown asphalt. The tests comprised evaluating physical properties of recent sand mixes at about 125th volatile at 900°F (482.2°C) and 400th compactability. Physical sand properties developed with non seacoal carbonaceous materials were equal to or superior to seacoal at significantly lower additive levels. Gilsonite and asphalt mixes appeared to improve physical properties of density, water requirements and green, dry, baked and hot strengths. an excellent greater improvement in foundry sand green, baked, and hot strength was obtained by increasing the fineness of grind of the Gilsonite. It’s postulated the finer material provides higher sand coating. the higher strength may be attributed to improved sand wetting by the thermoplastic asphalt materials.The gas evolution curve indicated Gilsonite and asphalt reacted faster than seacoal however  had way less total gas volume. Gilsonite and asphalt at one third the level of seacoal had the same total volatiles at one third the seacoal additive level. A foundry research study showed casting finish with Gilsonite was equal to seacoal and higher than most other sub stitutes. Another study with system sand confirmed the laboratory results of this research on new sand mixes with respect to sand properties and casting finish.

09. Steel creating additives

Gilsonite is an ingredient in many additives used in the production of steel. It’s used in limestone, Lime, Magnesium, and calcium carbide additive systems. The operate of those additives is to remove impurities like sulfur, silica, and phosphorus from the molten steel and move them to the molten slag layer. Gilsonite fulfills many roles as a part in Steel creating Additives. First, Gilsonite is approximately 75th volatile at 1900°F, and once additional to the molten steel it promotes the mixing of the additives therefore the chemical reactions which will move the impurities to the molten scum layer will take place. Next, the volitiles that are given off are high in lustrous carbon, which is able to more reduce the Iron oxide to steel. Though CO reduces most of the Fe3+ by indirect reduction, some should be reduced directly by elemental carbon. Finally, the portion of Gilsonite that's not volatilized could be a terribly extremely structured asphaltene structure that's nearly pure carbon. This can add carbon content to the steel

10. Oil base drilling.

Oil based drilling fluids and advances in drilling fluid compositions are described in applicant’s co-pending application PCT CA2007/000646 filed April 18, 2007 and incorporated herein by reference. This co-pending application describes the chemistry of organoclays and primary emulsifiers for use in various applications including oil-based drilling fluids and various compositions wherein the viscosity of the compositions may be controlled.
By way of background and in the particular case of oil muds or oil-based drilling fluids, organophilic clays have been used in the past 50 years as a component of the drilling fluid to assist in creating drilling fluids having properties that enhance the drilling process. In particular,oil-based drilling fluids are used for cooling and lubrication, removal of cuttings and maintaining the well under pressure to control ingress of liquid and gas.

A typical oil-based drilling mud includes an oil component (the continuous phase), a water component (the dispersed phase) and an organophilic clay (hereinafter OC) which are mixed together to form a gel (also referred to as a drilling mud or oil mud). Emulsifiers, weight agents, fluid loss additives, salts and numerous other additives may be contained or dispersed into the mud. The ability of the drilling mud to maintain viscosity and emulsion stability generally determines the quality of the drilling mud.

A. Fluid Loss Control

The invention relates to a composition comprising an HPHT fluid loss control aid, stable at elevated temperatures and which also acts as an excellent shale stabilizer, bore hold lubricant, sealant for depleted sand, and wall cake conditioner. The HPHT fluid loss control aid broadly comprises a Gilsonite (asphaltite, asfaltit,Gilsonita,uintaite, natural asphalt, natural bitumen) which also contains a surfactant such as a nonionic surfactant.

The HPHT fluid loss control aid also contains a solubilized lignite such as causticized lignite and carbon black. The fluid loss control aid reduces HPHT filtrate loss, has good stability at elevated temperatures such as at 300 °F, stabilizes troublesome shales and decreases bore hole erosion, helps seal depleted sands, reduces torque and drag, causes no adverse effects on the flow properties of the properly conditioned drilling fluid, and lowers total well costs.

To achieve these and other advantages, and in accordance with the purpose of the invention, as embodied and broadly described, the invention comprises a composition comprising an HPHT fluid loss control aid stable at elevated temperatures, and which also acts as an excellent shale stabilizer, bore hole lubricant sealant for depleted sands, and wall cake conditioner.

The HPHT fluid loss control aid broadly comprises Gilsonite, an asphaltic material or solidified hydrocarbon. The Gilsonite employed according to the present invention also contains a surfactant, especially, a nonionic surfactant.

Combination of these compounds as a HPHT fluid loss control aid, reduces HPHT filtrate loss has good stability at elevated temperatures such as at about 300 °F and sometimes as high as 400 °F, stabilizes troublesome shales and decreases bore hole erosion, helps seal depleted sands, reduces torque and drag, causes no adverse effects on the flow properties of the drilling fluid properly conditioned and lowers total well costs.

The invention also comprises a product made by combining the components of the composition as well as a product made by the process of adding the composition or product to a drilling fluid. Lastly, the invention comprises a process for controlling HPHT fluid loss in subterranean wells by adding the composition or product into a subterranean well.

Drilling fluids as used in the written description and the claims, include not only conventional drilling fluids or drilling muds including petroleum oil, synthetic oil and fresh water and salt water types as known in the art but also completion fluids and work over fluids.

B. Confi - Trol

It is a natural occurring Gilsonite used for HTHP filtration control in invert oil / synthetic base systems at temperatures above 400 0F (205 0C).

It is compatible to all invert oil / synthetic base systems and can be used both in the initial formulation and for treatment while drilling.

Initial treatment in the range of 2 – 10 lb/bbl (5.71 – 28.53 kg/m3) is recommended, although higher concentrations may be necessary in extreme cases.

Pilot testing should be conducted to determine actual concentration needed in each case. If CONFI-TROL HT is to be added to a newly mixed mud prior to displacement, the addition should be made after all other components have been mixed thoroughly.

C. Asphasol

Gilsonite Asphasol shale inhibitor is a partially water-soluble, sulfonated organic material developed for use in most water-base drilling fluids.Gilsonite Asphasol shale inhibitor contains no surfactants as do most water-dispersible products used in shale-control applications.

Advantages of Gilsonite Asphasol

Contains no surfactants
Premixing is not required
Inhibits swelling and water-wetting of shales
Reduces High-Temperature, High-Pressure (HTHP) fluid loss
Reduces torque and drag
Improves wall cake quality

Typical Physical Properties

Physical appearance: Black, free-flowing powder
ph (2% solution): 7.5 – 9.5
Solubility in water: Minimum 50% by weight

Applications

Gilsonite Asphasol shale inhibitor can be used in most water-base drilling fluids. Gilsonite Asphasol shale inhibitor is a free-flowing powder and can be added directly to the mud system through the mixing hopper. Unlike some shale control additives, it is not necessary to pre-mix the Gilsonite Asphasol inhibitor with oil and it contains no surfactants.

Normal concentrations of Gilsonite Asphasol shale inhibitor range from 2 to 10 lb/bbl
(5.7 to 28.5 kg/m3) for most applications.

Gilsonite additive can provide the following benefits: 

When perforated, it is shatter-resistant.
It does not significantly affect the setting time of cement.
Gilsonite additive can provide higher strength than heavier additives with high water requirements.