US2329878A - Drilling fluid and the method of drilling and lubricating wells - Google Patents

Description

Patented Sept. 21, 1943 UNlTED STAT-ES, PATENT OFFICE panama FLUID AND 'rrm nm'rnon or panama AND women-ruse wens Baruch Cerf, LosAngeles, Callf asslgnor to Graphite Frees Company, Los Angeles, Calif.

No Drawing. Application March 14, 1941,

. Serial No. 383,351

This invention concerns the treatment and lubrication of equipment and tools in the drilling ,of wells and the like, and especially for oil and gas wells, and also the treatment, improvement and conditioning of the circulating fluid, or circulating mud for such wells when earthy materials are suspended in the fluid. For instance, in rotary drilling, mud-laden fluids, or clay-laden fluids, of various nature are introduced to the upper end of the drill stem or pipe under pressure and made to flow to the drill bit where it issues and then passes between the drill 'stem and hole bore to the ground surface for cleaning and inspection. v

Some of the purposes of the circulating fluid, regardless of .the exact ingredients therein, is to remove the cuttings from the hole, provide some lubrication for the bit and stem, prevent freezing or sticking of the bit and stem in the 'hole, reduces gas and other pressures in the hole, and provide a mud-liner, when mud is an ingredient, for the hole so as to avoid liquid absorption along its walls, and reduce cave in hazards, shale slides, etc.

So far as known, there has not been any satisfactory method or means for lubricating'the drilling bit or its connected stem and parts while in the hole and at work. Various suspensoids have been tried in the mud-laden circulatory fluid to make it slick, soapy, etc., so as to reduce friction as much as possible, but a truly effective lubricant with a high degree of wear reducing qualities has not been put to practical use. Many well known lubricants have proven more or less detrimental to the required qualities demanded of the mud, :the required qualities of which could not be sacrificed in favor of a better lubricant.

I have discovered that carbon allotr P raphite and allotroplc forms of carbon added to the mud-laden fluid solved the problem of lubrication and also assisted certain functions of the mud. It was found that the carbon additive not only greatly reduced the destructive attrition and abrasion of the bits and stems used in. drilling, but aflordedstable protection for all the equipment used which came into contact with the carbo-mud fluid, whether in storage or in the outdoor working pipe stacks. This inventive fluid made it possible to increase the speed of the moving equipment, especially rotary bits resulting in the drilling of larger and deeper bores, and the use of longer casingsand drill pipes. Furthermore, the addition of allotroplc carbon to the mud increased the effectiveness of the drill upon the harder formational strata, gave the mud-fluid under the higher pressures and "temperatures encountered at great depths. The

preferred forms of carbon for best results will be revealed later. It is to be understood, that all wells do not necessarily employ a clay based drilling fluid or one which contains earthy materials as the circulatory drilling medium, that such circulatory drilling fluid may be oil based, or oil-water-clay based, and when so oil based,

the fluid may or may not contain earthy mate rials except such earthy materials which may incidentally be entrained in the fluid while it is circulated in the well.

One of the principal objects of this invention is to economically provide new mud-laden circulating fluids for the drilling of wells which provide continuous lubrication to all the moving partsof the drilling equipment and especially to the cones or cutters, their bearing supports and races within the drill hit, all discs and bearings, reamers, stems, and the-formation cutterr drillpipe, bit and easing surfaces necessary to discourage high-speed power losses, lessen torque,

stresses and prevents frictional heating ingeneral.

A-further object is to present the means and methods of improving the circulatory mud-fluids in the drilling of wells and for imparting to the mud-fluids new and useful functions without increased costs or the employment of additional equipment.

A still further object of this invention is to I present the means, products, and methods for description, the foregoing preamble and the carrying out the intent and purposes of this invention. I

Other objects, advantages and features of my invention will appear from reading the following appended claims; a

Applicant is about to disclose one or more forms in which the invention can be practiced,

but it is to be understood that this invention is ,susceptlble of variousother embodiments and that theinventlon is not to be limited in any manner whatsoever, except as limited by the appended claims.

Both the mined and manufactured varieties of graphite possess important lubricating properties. Carbon allotrope graphites are valuable for many diversified uses in industry, and as I have discovered. it is of incalculable value to the industry of drilling oil and gas wells for the lubricating and protection of the sub-surface equipment at any and all deaths.

The properties of graphite differ widely from those of amorphous carbon which has a minimum of lubricating and friction reducing values, and is not comparable to the attributes of graphite or is it ever used as a substituent where graphite is required. Graphite mined and manufactured, (imported and domestic or native) is used in many industries and for many purposes. Selected graphites allocated commercially as #lubrieating graphite" or "for lubricating purposes has high graphitic carbon content, is free from grit and abrasive matter, and has a profound inherent aflinity for metal surfaces and ability to penetrate to and remain at points inaccessible to other lubricants. This graphite is lubricous and has a highly unctuous value of .major importance as a friction reducer. Such a graphite is valuable in this invention.

It is because of its greasy feel, unctuousness and non-coalescent nature that the carbon allotrope graphite is preferred as an additive for mud-laden fluids. Its suitability as a dry lubricant has long been recognized and is often designated a slick to which nothing sticks." It is a solid, chemically inert, highly resistant to oxidation, and stable under conditions that. are deof the graphite used is not of primary importwice. The graphitic carbon content may vary in quantity and purity but should conform to graphite allotted and designated to conform to the requirements of "commercial lubricating graphite.

The exact degree or mesh, measured by riddle, screen, or air float, of fineness of graphite or variant in size of the particles is not of primary structive to fluid and semi-solid lubricants as well as preventive petro-base coatings.

Graphite orients itself easily to metal surfaces and thereby creates what is known as a "slick graphoid siu'face on the metal. particles become intimately combined with the metal of the surface, and this is a desirable attribute since the lubric graphoid surface provides a perfect dry solid lubrication. It has an antisticking quality and an extremely low co-eflicient of friction and acts as a boundary film between the fast rising swirling helical drilling fluid and the faster rotating drill stem. power loss with the additional advantage of resistance to corrosion from drilling chemicals or oxidation by weathering. The graphoid surface consists of a plane of carbon allotrope graphite particles adhering firmly to the metal surface,

tightly linked together and correlated to the finer graphite particles occluded within the pores of the metal, filling in the depressions and levelling the projections of the roughness of the metal surfaces. These entrapped absorbed graphite particles explains the self-lubricating properties of metal so treated and the ability of metal so treated-to run without damage or injury for a considerable period of time, even after a breach or rupture, caused by exceptional conditions, exposes the metal surface. This lubricating quality lasts until restored by the external source of graphite, circulating with the mild through the bore of the well, reaches all parts to renew their surfaces.

,The graphite used may be natural or artifical of the various grades available which have lubricating values, or by selective or blending of one The graphite It discourages or more types of carbon or distinctive allotropic importance, but a substantial portion of them should come within the particle size range generally designated as 200 mesh or finer.

Also, the proportions of graphite used in themud-laden fluid may be varied within wide limits. That is, the requirement of constant circulation of graphite within the bore of the well may be varied in accordance to the frequency of complete drilling fluid changes, replacement thereof and renewals during operations.

There are various methods whereby the graphite can be applied to the equipment and at the same time improve the circulating drilling mud or fluid, all of which must ultimately conform to the requirement of the circulation of the graphite through the well, to lubricate and apply graphoid surfaces to the successive changed bits and additional strings of drill and casing pipe run in, as the bore is deepened.

To conserve against unnecessary loss or waste of graphite, continuous, interrupted of predetermined periods of circulation of the graphite shall refer primarily to operations in wells where complete or semi-renewals of the drilling fluid is often made during operations, where the drilling fluid is discarded after short use or stored to be re-claimed or re-processed for future use and new drilling fluid circulated.

The graphite can successfully be used as follows:

1. By adding the graphite mechanically to the circulating mud-laden fluid so as to circulate through the well and be unified therewith into a single medium so as to lubricate and protect the drilling equipment and generally improve the mud itself.

2. By-circulating the graphite in a continuous manner through the bore by means of a circulating drilling mud or fluid as the dispersing medium.

3. By forming and using a "suspensoid drilling mud or fluid" for circulation through the bore while operating the drillingequipment of which the disperse phase is the solid graphite particles and the disperse medium the drilling mud or fluid.

4. By adding graphite in varying proportions in the dry ground, hydrated or de-hydrated, or in combination with other materials at their point of origin, distribution or at the well, and used thereafter as the integral or as a component part of the drilling fluid or mud circulating in the well.

5. By adding the graphite to the components of the drilling mud or fluid by means of any of the mechanical or hand mixers generally used,

or add directly into the circuitous flow of the drilling mud whether it is in the open pit or in storage. a r

6. By spraying the graphite in dry blast or in a, colloidal or suspended form to the mud or applying it to adhere to the equipment before entering the sub-surface or mouth of the bore, to be followed by circuitous graphite applications by the mudding or flushing fluids circulating through the bore of the well.

' 2,aaa,-s 7s colloidal, electric furnace graphite and graph- Where cost of the material is to be considered, imported graphltes (Mexican phites excluded), principally fiake' and crystallines and certain classes of amorphous (trade connotations) would not be used since-they are cost prohibitive for the purposes of this invention, for they in no way show any advantages or benefits over domestic mined o'r manufactured graphites or Mexican graphites so as to warrant their use for the p p ses of this invention, providing domestic graphite can be secured.

I have found that carbon allotrope graphites and domestic commercial amorphous graphite, mined in the United ,States, contain all the inherent properties and requisites, and when procitized carbon. Amorphous carbon is commercialessed in accordance to this invention, is suitable and adaptable for efllcient functioning and proper correlation and as fitting smoothly into all drilling mud and fluids to carry out the objects of this invention.

As an 'example domestic amorphous graphite" is refined and processed by levigating, grinding, riddling, and/or airfioating until the physical properties show a quantitative 80-85 percent graphitic carbon-that 98 percent of the particles pass through screens of indicated 100 mesh, 80 to 85 percent through 150 mesh, 35 to 40 percent through 200 mesh or finer, free from grit or abrasive matter (tolerance of 5% or less) and of sp. g. 2.25-2.35. These figures may varied within wide limits. 7

As a second example, I make use of graphite of micro crystalline-like minute particles of an intimate blend of levigated airfloated domestic and Mexican amorphous graphites and/or manufactured graphite levigated, ground and airfloated until the physical properties show a quantitative of 85 percent graphitic carbon, when subdivided, reduced and fraotioned to come.

within the particle sizes, designated commercially as 300-325 mesh, sp. g.'-2.25-2.35 lu-v brlcous, highly u'nctuous and non-coalescent. These figures may be varied within wide limits as well as the quantitative of each of the graphites within the blend and within the determinative as shown.

The following proportions have been found very satisfactory: 5% to 5% pounds of processed graphite added to each barrel (42 gallons- 5.6154 cubic feet, oil country calculations, conversion factors) of circulating drilling mud or graphite per barrel may be'as low as 2% pounds.

After the drilling of each 100 cubic feet of bore,

fluid,. or 95 to 100 pounds of processed graphite as shown by the record in the drilling log, the so quantitative determination of graphite circulating should be evaluated by elutriation or through other apparatusused at the well or in-the' laboratory for making tests of quantity of solids in suspension. The graphite should then be replenished to the amount pre-determined to care for the added equipment and for the improvement of the functions of the added drilling fluidwithin the well as the bore deepens. V

Allotropic form of carbon is sometimes designated "Polymorph form. Natural graphite is commercially classified as fiake, crystalline, and amorphous graphite. Black lead and plumbago are mined, whereas manufactured graphite are commercially classified as synthetic, artificial,

ly classified as carbon black, lampblack, wood charcoal, bone black and coke. (Non-crystalline carbon.) "All graphites fundamentallyv are of crystalline formation. The amorphous carbon term is applied to a comparatively large variety of'carbonaceous substances which are not regarded as diamond or graphite. -Though originally intended to imply that these varieties of The properties of graphite differ widely from The those ofcarbon black for industrial uses. carbon black has but. a; minimum of lubricating and friction reducing value. Graphite of less than graphitic carbon is usually not 16-. garded as commerciallubricating graphite be-v cause low in unctuous quality and lacking in an'inherent ability to'orient on metal surfaces and it has an excess of. abrasive and organic matter. Such' graphit'es are generally classified for the foundry and paint industrieaetc. For

this invention, the highly unctuous and lubricating' graphitic carbons are employed.

Carbon capable of orientation upon metal is preferred as an added: property;

This property of graphite isvery important. It enables the carbon molecules to arrange themselves in crystaliine axial positionsupon metal surfaces, thus' a good drilling mud usually has the following ingredients; and properties:

Solids per c ent 30-35 Water do 65-70 Viscosity seconds 25-35 Weight p ound 72-82 pH value 8-10 Filtering properties ml. per hour 10-25 v The amount of graphite to add to such a mudfiuid would depend upon a number of factors, but as anexample:

Variables in the equation ofquantity of the allotropic form of carbon or its generic, "carbon allotrope graphite used as anadjuvant to the drilling fluid depends uponmanyfactors. Itcan be computed on a sliding scalecalculated against the weight of a barrel of the circulating drilling fluid in relation to its pounds per cubicfoot and/or specific gravity (mud weight conversion tables of. relation-between specific gravity and mud-weights in oil country calculations, conversion factors). v

dulating or to be circulated within the bore.

Solids and fluid, with or without applied admix- 2nd fa'ctor.When the sub-surface rotating assembly'is' devoid of graphoid surface.

3rd jactor.-When the sub-surface rotating assembly or any substantial part thereofhad previ-I ous contact in operation or otherwise with carbomud or graphiteand is already eraphoidsm'faced.

4th Jacton-When the casing is'run in the correction is made by lessening the amount of weighting materials which has been-added solely for increasing the weight of the drilling mud.

Using a. conversion scale 01..readings from minus one per cent (-l%) minimum" to five per cent inclusive maximum" with two per cent (2%) indicator as the balance or poisepoint, it is possible to converge in calculations on the poise-point and care for the diverse factors connective or individually.

For example-Underthe combined factors 1-2-5, as set forth above, a 75 pound per cubic foot drilling fluid or mud, pounds per gallon, sp. g.1.20 (a weight commonly utilized for drilling), to each barrel of such fluid (42 gallons- 5.6154 cuuft.) there'would be added 2% to 3% (10 /2 to 12 /2'=lbs.) of graphite i'orv thefirst 1000 lineal feet 'from the' spudding in of the well. Thereafter, the quantity is reduced (V2) one-half of one percent for each additional 1000 lineal feet drilled until a (1%) one percent proportion is reached. This percentage is then used as average until completion of the well.

As a'seco'nd' example-Under combined factors 1--3-5, the normal requirement would start at 2% (8 /2 pounds) of graphite and be reduced in the same proportion and manner for each 1000' lineal feetuntil 1% is reached. This proportion is then maintained until completion of the well. These figures may be varied within wide limits, and tolerances allowed where complete or partial changes of the drilling fluid in weight and character-ismade during operations to meet formation strata requirements.

The slick lubricous allotropic form of carbon is inert and would not in any way be a detriment to a good drilling mud. The lubricous slick clip nature of the unctuous carbon energizes the la of thesluggiest mud flow, and accelerates the circuitous movement of the fluid, eliminates necessity of excessive pressure and induces better circulation. The influence of the lubricous slick surfaces prevents flocculence oi: the physical particles of the drilling mud or fluid. intensifies the hydraulic action of the jetted drilling mud or fluid and thus aids in removing the cuttingsfrom the bit. It prevents the forming of cluster or aggregates of 'the cuttings rising to the surface within the drilling fluid, prevents formation or accumulation of dangerous gas pockets in the ascending drilling mud, prevents blow outs, makes de-gassing of the mud easier, lessens the strain on the drill pipe after the drilling mud has packed and set while at rest in the bore and aids in re-starting the drilling.

Having thus described my invention, what is claimed as new and desired to be secured by Letters Patent is.

I claim:

1. In combination, an aqueous well drilling mud and graphitic carbon.

Further, it

' 2. In combination, an aqueous well drilling mud by the fact that it is a fluid to plastic mixture containing unctuous, non-coalescent graphitic carbon particles of fine mesh.

6. An aqueous well drilling mud containing graphitic carbon having an ailinity for metal surfaces and in which the carbon is of fine mesh of approximately 300 to 325.

7. The art of improving the lubricating of wells while being drilled by adding to the circulatory aqueous drilling mud thereof a proportion of graphite particles having orientation'and slickness characteristics as a suspensoid throughout the mass thereof.

8. The art of improving the lubricating qualities of aqueous well drilling muds by spraying unctuous, metal adhesive type graphite in a dry state onto the muds, and circulating the muds through the bore of the well and into contact with the lower end of the drill bit. while operating in the well.

9. The art of improving the lubrication of well drilling tools while in the well and also the equipment connected with the mud circulatory system of the well by adding graphitic carbon to the aqueous drilling mud of the well, the graphitic carbon filling the pores of the metal parts contacted thereby.

10. The art of circulating an improved aqueous drilling mud through the hole of the well, drill ing stems, cutters and mud channels, etc.', of a well in which fine graphite particles are suspended in the mud, the graphite, as a residue, adhering to the metal parts of the drilling equipment and functioning as a dry lubricant and protective graphoid surfaces, the graphite penetrating to and remaining at points in the drilling equipment inaccessible to other lubricants.

11. The art of reducing friction and equipment wear in the drilling of wells by creating aboundary film of unctuous oriented graphite'particles between the circulating drilling mud and subsurface drilling tools and equipment, and maintaining the film by continually circulating a graphitic treated mud in contact with the tools and equipment.

12. A lubricant and well drilling mud comprising substantially one to five parts in a hundred of graphite and substantially ninety-five to ninety-nine parts in a hundred of clays, and water added to form the fluid to plastic consistency desired.

13. An aqueous well drilling mud comprising about one to five percent graphitic carbon, ninetyfive to ninety-nine percent mud forming ingredients, and sufiicient liquid to allow the mud to flow under desired pressures.

14, A well drilling circulatory substanceof a liquid to plastic consistency containing a liquid, a. proportion of particles dispersed throughout the substance, the particles comprising graphite of fine mesh.

BARUCH CERF.