US3027324A

US3027324A - Water base drilling fluid and method of drilling

Info

Publication number: US3027324A
Application number: US783665A
Authority: US
Inventors: Rosenberg Milton
Original assignee: Gulf Research and Development Co
Current assignee: Gulf Research and Development Co
Priority date: 1958-12-30
Filing date: 1958-12-30
Publication date: 1962-03-27
Anticipated expiration: 1979-03-27

Description

United States Patent 3,027,324 WATER BASE DRILLING FLUID AND METHOD OF DRILLING Milton Rosenberg, Pittsburgh, Pa., assignor to Gulf Research & Development Company, Pittsburgh, Pa., a

corporation of Delaware No Drawing. Filed Dec. 30, 1958, Ser. No. 783,665 23 Claims. (Cl. 252-85) This invention relates to drilling muds and drilling processes and is particularly concerned with water base drilling muds having improved lubricating properties and their use in rotary drilling processes.

In the usual procedure for the rotary drilling of wells, a drill pipe extending down the borehole is rotated by suitable equipment at the well head. A rotary bit at the lower end of the string of drill pipe has cutting cones mounted on bearings to permit their rotation to bring cutting elements on the surface of the cones into contact with the bottom of the hole. A drilling fluid, commonly referred to as a drilling mud, is circulated down through the drill pipe, out its lower end, and then back through the annular space between the drill pipe and the borehole wall to the well head. The drilling fluid serves several purposes among which are carrying cuttings from the borehole and producing a hydrostatic head which prevents the entrance into the borehole of fluids in the formations penetrated during the drilling operation.

During the drilling of a hole for an oil or gas well, it is usually necessary to change the drill bit from time to time. In order to make a change, the entire string of drill pipe is pulled from the hole, the bit attached to the lower end of the drill pipe is replaced, and then the entire string of drill pipe is run back into the hole. It is apparent that changing a bit causes substantial loss of drilling time and is an important part of the cost of drilling a well. Frequently when the bits are changed, the cutting elements are in good condition but changing the bits is necessary because of failure of the bearings on which the cutting cones are mounted.

When drilling wildcat or exploratory wells, it is desirable to avoid the use of drilling mud containing oil to avoid contamination of the cuttings which will interfere with study of the cuttings by geologists. In many areas, the formations drilled are hard and contain no clay or shale. It has been found that the use of a drilling mud which is clear water permits high drilling rates to be attained. In the hard formations, it is commonplace to use drill bits having tungsten carbide inserts for cutting elements. Those drill bits generally fail because of bearing failure. It is particularly desirable when drilling with bits having tungsten carbide inserts in hard formations to use a drilling mud substantially free of clay solids and having good lubricating properties to increase the life of the bearings of the drill bits.

This invention resides in a Water base drilling mud having improved lubricating characteristics and rotary drilling processes employing such drilling muds. The improved water base drilling muds of this invention are obtained by the incorporation in water base muds of a small amount of additives which are sulfurized organic compounds. In a preferred embodiment of this invention, the improved water base drilling mud is substantially free of clay solids,

The term drilling mud" used in this specification refers to any liquid used as a circulating medium in the rotary drilling of wells. The drilling mud may be practically clear water substantially free of suspended solids when pumped down the hole. Such drilling muds are commonly used in drilling the hard formations in West Texas. When wells are drilled through shales, the drilling mud may pick up as much as 40% by weight of natural clays.

' 3,027,324 Patented Mar. 27, 1962 The term drilling mud also includes withinits scope fluids prepared by dispersing in water clays such as bentonite in concentrations up to about 8% bentonite in water.

The term water base is used in describing the drilling muds of this invention to distinguish those muds from oil-in-water emulsion drilling muds and oil base drilling muds. Oil-in-water emulsion drilling muds contain petroleum oils such as crude oil, gas oil, or diesel oil which have been added to a water base drilling mud to alter characteristics of the water base drilling mud. A principal purpose of adding oil to a water base drilling mud to form an oil-in-water emulsion drilling mud is to increase the drilling rate. Hydrocarbon oils have also been added to improve the lubricating characteristics of the drilling mud. The presence of a separate oil phase has been believed to be necessary for a marked improvement in the lubricating properties of the drilling mud to be obtained by the addition of additives. It was believed that the additive causing the improved load carrying characteristic was carried principally in the oil phase and that phase preferentially wet the metal surfaces. It is an important advantage of this invention that water base drilling muds having excellent lubricating properties can be prepared Without adding a hydrocarbon oil to the drilling mud.

The water base drilling muds with which this invention is concerned differ from the oil-in-water emulsion muds in that there is no mineral oil added to form a separate phase and modify the properties of a water base mud. Moreover, the amount of the sulfurized additive, which might be considered an oil phase because of its organic nature, in the water base drilling muds of this invention is ordinarily substantially less than the amount of the oil phase in oil-in-water emulsion drilling muds. Whereas the oil phase in oil-in-water emulsion drilling mud is usually in the range of 5 to 20% by volume of the drilling mud, the total concentration of the organic sulfurized lubricant additives in the drilling muds of this invention is less than 3% and in most instances about 2% or less by volume of the drilling mud. A further difierence in Water base and oil emulsion drilling muds is indicated by the inability of some additives that are effective in oil emulsion drilling muds to improve the load carrying capacities of water base muds. Similarly, some additives that increase the load carrying capacities of water base muds are ineffective in oil emulsion muds.

The water base drilling muds of this invention can contain, in addition to the sulfurized compounds, additives conventionally used to modify the properties of the muds other than their load carrying capacity. Clays may be incorporated in the drilling muds to control their Water loss properties in accordance with the usual practice. Weighting agents can be added to increase the density of the drilling mud. Fresh, brackish, or salt water can be used as the liquid medium in the mud. Conventional thinning agents may be used for control of the viscosity. However, an excessive amount of caustic is to be avoided as it will destroy the load carrying capacity of the drilling mud.

The sulfurized compounds which can be dispersed in water base drilling muds to form the novel drilling muds having improved lubricating properties of this invention are generally sulfurized unsaturated fatty acids, sulfurized rosin acids, sulfurized unsaturated fatty alcohols of high molecular weight, sulfurized esters of the unsaturated fatty acids, and sulfurized unsaturated fatty acid pitches.

Examples of suitable sulfurized unsaturated fatty acids are sulfurized oleic acid, sulfurized linoleic acid, sulfurized linolenic acid and sulfurized ricinoleic acid. Sulfurized mixtures of fatty acids such as occur in the product from the hydrolysis of naturally occurring fats and oils can be sulfurized to produce effective lubricant additives. A preferred sulfurized fatty acid composition for use in this invention is sulfurized tall oil. Sulfurized abietic acid, although difficult to disperse in water, is suitable when incorporated in the drilling mud with an emulsifier to form a stable emulsion. Sulfurized substituted fatty acids, for example the sulfurized hydroxy acids, can be used.

The fatty acid pitches which can be sulfurized to prepare additives capable of increasing the load carrying capacity of a drilling mud are high molecular weight materials usually obtained as by-products in the preparation of fatty acids from animal or vegetable fats. Among the pitches that can be sulfurized are tall oil pitch, which is a bottoms product in the distillation of tall oil from acidified black liquor, cottonseed pitch, and soya pitch.

Preferred esters suitable for the preparation of the novel drilling rnuds of this invention are the triglycerides of high molecular weight fatty acids such as castor oil, cottonseed oil, linseed oil, tallow, lard oil, menhaden oil, soybean oil, etc. Those oils are easily sulfurized to form effective lubricant additives. Sulfurized esters other than the sulfurized triglycerides are also suitable. Glycerolmonooleate can be sulfurized and used successfully in this invention. Sulfurized esters of monohydric alcohols and the unsaturated fatty acids are also suitable. Typical esters which can be sulfurized and used in this invention are stearyl oleate, oleyl oleate, and oleyl stearate. Sulfurized esters of aromatic alcohols, for example sulfurized phenyl oleate also can be used. The esters of the fatty acids listed above and the anhydroalkitols such as sorbitan mono-, di-, and tri-oleate and the pentaerythritol esters of tall oil or oleic acid can be sulfurized and incorporated in Water base drilling muds to improve their lubricating properties.

The unsaturated fatty alcohols that can be sulfurized and used in this invention are high molecular weight alcohols having about 12 or more carbon atoms per molecule. They are generally commercially available in mixtures of several unsaturated alcohols with saturated alcohols such as mixtures of oleyl, linoleyl, and linolenyl alcohols with cetyl, stearyl, and arachidyl alcohols.

Some of the sulfur-containing compounds which have been found to be effective in the preparation of oil-inwater emulsion drilling rnuds do not impart improved lubricating properties to water base drilling rnuds. For example, the sulfurized hydrocarbons such as sulfurized diisobutylene do not, when incorporated in a water base drilling mud, produce a drilling mud with effective lubricating properties. Similarly, the metal sulfides such as lead sulfide or iron sulfide, arsenic sulfide, zinc sulfide, copper sulfide, etc. do not impart extreme pressure lubricating properties to Water base drilling muds.

The sulfurized products useful in this invention are readily prepared by conventional sulfurization techniques. In general, the unsulfurized material is mixed with a sulfurization agent such as sulfur chloride, phosphorus pentasulfide, or elemental sulfur and the mixture heated to a temperature generally below 200 C. while the mixture is stirred. When elemental sulfur, the preferred sulfurizing agent, is used in the sulfurization, the mixture of elemental sulfur and the unsaturated high molecular weight fatty acid compound or alcohol is heated to a temperature above the melting point of sulfur. A temperature of about 160 C. is usually adequate to cause the sulfurization to proceed. Stirring of the mixture at the elevated temperature is continued until sulfurization occurs. Completion of the sulfurization reaction can be determined by observation of a ortion of the reaction mixture on a spatula. A clear mixture free of particles of sulfur indicates completion of the sulfurization. If there is an excess of sulfur, the excess merely precipitates out. The amount of sulfur introduced into the organic compound can be varied within wide limits and may range from about /z% to the maximum amount that can be incorporated in the compound, which may be as much as about 40% by weight of the compound. Usually it is preferred to prepare a sulfurized compound containing about 2 to 5% sulfur.

It has been found that the load carrying capacity of a drilling mud as determined by the Timken Wear and Lubricant Tester gives an excellent indication of the usefulness of the performance of the drilling mud in lubricating bearings of rotary drill bits. A drilling mud having a load carrying capacity above about 30 pounds on the Timken Wear and Lubricant Tester has been found to give satisfactory lubrication of the bearings of rotary drill bits. Many of the lubricant additives described above when incorporated in water base drilling rnuds will result in the mud having a load carrying capacity higher than pounds, the maximum reading on the Timken machine. The higher load carrying capacities are desirable in providing improved lubrication; however, a drilling mud having a load carrying capacity of about 30 pounds will protect the bearings of a drill bit sufficiently to prevent failure of the bearings under conditions usually encountered during the drilling of wells.

The sulfurized additive is incorporated in the water base drilling mud in amounts sufficient to give the mud a load carrying capacity above 30 on the Timken Wear and Lubricant Tester. The amount of additive required will depend upon the particular lubricant additive being used, the sulfur concentration in the additive and the characteristics of the water base mud. Generally, an increase in the sulfur concentration of the additive increases the load carrying capacity of the drilling mud. Water base muds having high concentrations of clay solids or other solid particles will require higher concentrations of the additive than drillingrnuds which are substantially clear water. The concentration of the lubricant additive required for a mud of the desired load carrying capacity is generally about /2 to 3% by volume of the mud. Higher concentrations of the additive can be used but increase the cost of the drilling mud without a corresponding improvement in the lubricating properties of the drilling mud. It is preferred to add the lubricant additive in amounts equal to about 0.5 to 2% of the volume of the water base mud. Even in such low concentrations, the additives dispersed in an aqueous medium are effective in lubricating the bearings of the drill bit Without the addition of a hydrocarbon oil. Heretofore it had been thought necessary to have a separate small volume of a hydrocarbon oil phase in the system such as is present in oil-in-water emulsion drilling muds to concentrate the additive in the oil phase which would preferentially wet the metal surfaces and thereby increase the effective concentration of the additive on the metal surfaces. The effect of concentration of the additive in the drilling mud is illustrated in Table I.

TABLE I Timken Lubricant Tester Load Carrying Capacitics (Pounds) Percent (by vol.) sulfurized Tall Oil in Suspension Fall 5. Pa ss 40. Pass 100 Pass 1'30.

1 Tall oil (crude, Llgro., West Virginia Pulp & Paper Co.) containing 2.9% sulfur.

Most of the sulfurized additives used in this invention are insoluble and difficulty dispersible in water and must be used with an emulsifier to form a stable and uniform dispersion of the additive throughout the water phase.

stable dispersion free of suspended solid particles. Preferred emulsifiers are the non-ionic surface active agents such as DME, an ethylene oxide derivative of nonylphenol. Other suitable emulsifiers are sodium meta- If a stable dispersion is not formed, the additive will sep- 5 borate, trisodium phosphate, the alkylaryl sulfonates, arate out of the water base drilling mud and, for examthe condensation products of ethylene oxide and polyple, float on the surface of the drilling mud in the mud propylene glycol, carboxy methyl cellulose, etc. Mined pits. Thus, the lubricant additive is not effectively lignins, quebracho, starch, and calcium lignosulfonate brought into contact with the metal surfaces to be lubrican also be used- The yp of emulsifier is not critical cated. The Timken machine gives an excellent i di a- 10 it only being necessary that a stable dispersion of the tion of the performance of the drilling mud circulated sulfurized additive in the water be obtained. The amount through the machine if that a d i11i d i pumped of emulsifier required is ordinarily in the range of about down the drill pipe in a rotary drilling operation. How- Pound P barrel of drilling however, If ever, the agitation obtained in th circulatory system f concentrations of calcium ion are present in the drilling the Timken machine may keep sufiicient additive sus- 15 higher eoheellhations 0f emulslfiel' y be required pended in the water base drilling mud to provide efiective to dlspelse the eeleltlh} grease formed; lubrication, even though a stable dispersion of the addi- The Improved h muds Of this Invention can he tive in the water base mud was not formed. If the same P PP before dfllhllg q the Well Commences drilling mud were u ed in th d illi f a ll h addiventional Water base dr lling muds can be treated to obtive would have an opportu it t Separate f the drill ta n the 1n proved drilling muds of this invention while ing mud in the mud pits and would not be circulated to dthhhg 111 P It 15 P e Y Ohtalh a the drill bit. Thu th f r ti of a Stable dispersion stable dispersion of the lubricant additive in the water f h ddi i i h illi mud is essentiaL base drilling mud. This can be accomplished by mixing In most instances where the water base drilling mud e lhhneaht attthttve wtth he dthhhg t h a mud contains suspended clay solids, the clay is efiective in hhxer atehg Y t other edthttvee to the dthhhg forming a stable dispersion of the lubricant additive in e the hh thud 1S ptatfttcahy clear the the aqueous drillin d, Wh h lubricant addi lubricant additive and the emuls fier can be added in the tive is an acid, such as sulfurized tall oil, the presence mhd ditch to e P atl n 0f the drilling of calcium in the water base drilling mud may cause the thud doYvh the h e ahtthack to the th Ptts W f ti of an i l bl curd f ki tauate. The accompl sh the desired dispersion of the add tive. During greasing out of the additive as a result of contamination the thhhhg opetahehi the Improved dthhhg muds are with calcium can be avoided by the incorporation of suitpumped to the ottom of the borehole where they contact bl em l ifi i h mud, For example, the addition the bearings of the drill bit and lubricate the bearings. of an emulsifier such as DME (an ethylene oxide deriv- The drilling mud 1S ell'eulated hack to h Well head ative of nonyl phenol) is effective in preventing greasing. through a Shake! Screen removfll of euthhgs and h Such greasing out ordinarily is not encountered in oil- 10 the mud P in aeeefdahce Wlth the usual Practiceemulsion drilling muds. The prevention of the forma- In the usual operation, the circulation of the drilling mud tion of insoluble curds of calcium soap in drilling muds is down through the drill pipe and back to the well head Contai ing calcium i ns is d s ri d d C i in pthrough the annulus between the drill pipe and the bore- Pheahon Seflal Q 0f igand Sehauh, 40 hole wall. As the drilling proceeds, samples of the drilll y 8, 1959, and ellhfled Composltloh and ing mud are tested from time to time with a Timken ess. tester and if necessary, additional lubricant additive is lthls deslrable.m Songs g h added to the mud to maintain its load carrying capacity g i .arly i g .fi h g eanng above 30 pounds on the Timken machine.

31 mos .Preva en o n W1 a we er ase mu Water base drilling muds containing sulfurized organic which is practically clear water. The absence of clay com ounds were R are d an d the.r 10a d car in ca adt solids from the drilling mud allows a marked increase d t p d b p p t 1 g in the rate of drilling that can be obtained. It is an ime ermme y meheuremen on 6 t en h portant advantage of this invention that water base The shtthttzed t h was theotpetated m the ht drilling muds having excellent lubricating properties and merely y mlXlhg the drllhng hh and d ive containing substantially no clay solids can be prepared. 11! a Warlng h e p f e 0f the dfllhng Those drilling mud are o u d d by dispersing the muds and their load carrying capacities on the Timken lubricant additive in water with an emulsifier to form a machine are presented in Table II.

TABLE H L d l i a Drilling Mud Additive Emulsifier Car ging Capacity 1 6% Bent 0.3% Sulf. oleic acid (16.5% S) 10 2 6% Sulf. oleic acid (16.5% S) 100 3 .0% Sulf. fatty alcohol 4 lb/bbl. Sulf. tall Oil (5% lbJbbl. DME 3 5 .O% Sulf. oleic acid (5% S) 1 lb./bbl. sodium metaborate 100 6 .0% Suit. tall oil (5% S) 1lbJbbl.tris0diumph0sphate 100 7 .0 0 51111. tall oil (2.7% S) lb.[bbl. ethylene oxide deriv- 100 ative of sorbitan trioleate. 2.0 0 Suli. lard oil (17%s) 100 2.0 o Suli. glyceryl trioleate..- 100 QIbJbbLleadsulfide 31b./bbl.CMC 5 F 9lb./bbl. iron sulfide 31b./bb1.CMO- 5 F 1.0% by vol. sulfurized Indusoil M28 4 (10% S) .15% 0M0 100 3.0% by vol. sulfurized Indusoil M28 (2.3% 8)--.. .15% OMO 100 1.0% by v01.su1furized Indusoil M28 (2.3% S) 15% OMO 55 6.5 lb./bbl. suliurized 1ard 100 6lb.[bbl.s11lfuriZedta1l0i1 11b./bb1.sodiummetaborate 100 3.5 lb./bbl. sulfurized tall 0iL 0.2 lb./bbl. DME 100 6 lb./bb1. sulfurized tall oil 0.2lb./bb1. Pluronic F 88 100 See footnotes at end of table.

TABLE IIContinued Example Load No. Drilling Mud Additive Emulsifler Carrying Capacity 19 67 Bent 1 7 sulfurized diisobutylene (407 S) F 6%; Bent oig sulfurized diisobutylene 46% s) 0.5% tall 100 O1 21 Saturated salt water 61b./ bbl. sulfurized tall oil... I 100 22 Water 3 lb,/bbl, sulfurized abietic acid (33% S) 3 lb./bbl. sodium metaboraten 40 1 50 grams of sulfur were added to 200 grams of Unadol 40, an unsaturated fatty alcohol obtained from the Archer Daniels Midland Company containing 85.5% unsaturated alcohols (i.e. oleyl, linoleyl, linolenyl) and 14.5% saturated alcohols (r.e. cetyl.stearyl, and araehidyl) that had been heated to 180 C. The mixture was stirred for 10 minutes at 180 C. and then cooled to roomtemperature.

The resulting liquid contained 4% sulfur.

An ethylene oxide derivative of nonyl phenol marketed by the Aquaness Division of Atlas Powder Company.

a Carboxymethyl cellulose marketed by Hercules Powder Company. 4 Refined tall oil, West Virginia Pulp and Paper Company.

5 A condensation product of ethylene oxide and polypropylene glycol manufactured by Wyandotte Chemical Corporation. 5 A saturated salt water mud containing 6% by weight salt gel plus 35.7% by weight salt in water.

The data presented in Table H show that the addition of small amounts, above about 0.5% of the sulfurized additives of this invention, to water base drilling muds will greatly increase the load carrying capacity of the drilling mud. In most instances the load carrying capacity of the resulting drilling mud is 100 or more, the maximum reading on the Timken machine.

Referring to Table II it will be noticed that the water base drilling muds, unlike oil-in-water emulsion drilling muds, containing metallic sulfides and sulfurized hydrocarbons do not have satisfactory load carrying capacities. The addition of a small amount of tall oil to the drilling muds containing the metallic sulfides or sulfurized hydrocarbons increases the load carrying capacity of the water base mud to the maximum on the T imken scale.

An important advantage of the drilling muds of this invention, in addition to increasing the life of the bearings of the drill bit, is the reduction of the torque required to rotate the drill pipe. The reduced torque reduces the power required in drilling and reduces the danger of twist offs of the drill pipe. The improved drilling muds of this invention also reduce drag of the drill pipe as it is going into or coming out of the hole; hence, danger of struck drill pipe is also decreased.

I claim:

I. A water base drilling mud substantially free of petroleum hydrocarbons and having improved lubricating properties consisting essentially of water, a sulfurized organic compound selected from the group consisting of sulfurized unsaturated fatty acids having more than 8 carbon atoms per molecule, sulfurized unsaturated esters of high molecular weight fatty acids, sulfurized unsaturated high molecular weight alcohols, sulfurized rosin acids, and sulfurized fatty acid pitches, said sulfurized organic compound containing one-half to forty percent sulfur and an emulsifier in concentrations adequate to form a stable emulsion of the compound in the water, the concentration of the sulfurized organic compound being sufficient to impart a load carrying capacity of at least about pounds on the Timken machine to the water base drilling mud.

2. A drilling mud as set forth in claim 1 in which the emulsifier is a clay.

3. A drilling mud as set forth in claim 1 in which the concentration of the sulfurized compound in the drilling mud is in the range of about 0.5 to 3% by volume of the total drilling mud.

4. A drilling mud as set forth in claim 1 in which the sulfurized compound is sulfurized oleic acid.

5. A drilling mud as set forth in claim 1 in which the sulfurized is a sulfurized rosin acid.

6. A drilling mud as set forth in claim 1 in which the sulfurized compound is a sulfurized ester of an unsaturated fatty acid of high molecular weight.

7. A drilling mud as set forth in claim 1 in which the sulfurized compound is a sulfurized triglyceride of a fatty acid of high molecular weight.

8. A drilling mud as set forth in claim 1 in which the sulfurized compound is a sulfurized fatty alcohol of a high molecular weight, said fatty alcohol having at least twelve carbon atoms per molecule.

9. A clear water base drilling mud substantially free of clay solids and having improved lubricating properties consisting essentially of water, a sulfurized organic compound selected from the group consisting of sulfurized unsaturated fatty acids having more than 8 carbon atoms per molecule, sulfurized unsaturated esters of high molecular weight fatty acids, sulfurized unsaturated high molecular weight alcohols, sulfurized rosin acids, and sulfurized fatty acid pitches, and a water-soluble emulsifier in a concentration sufficient to form a stable dispersion, the concentration of the compound being sufiicient to impart a load carrying capacity of at least about 30 pounds on the Timken machine to the water base drilling mud.

10. A water base drilling mud substantially free of hydrocarbon oil and having improved lubricating properties consisting essentially of water, sulfurized tall oil, and an emulsifier, the concentration of the sulfurized tall oil being sufiicient to impart a load carrying capacity of at least about 30 pounds on the Timken machine to the water base drilling mud, and the concentration of the emulsifier being suflicient to form a stable emulsion of the compound in the water.

11. A drilling mud as set forth in claim 10 in which the emulsifier is clay.

12. A drilling mud as set forth in claim 10 in which the sulfurized tall oil contains about /2 to 20% sulfur.

13. A drilling mud as set forth in claim 10 in which the concentration of the sulfurized tall oil is in the range of about 0.5 to 3% by volume of the drilling mud.

14. A drilling mud as set forth in claim 10 in which the concentration of the sulfurized tall oil is in the range of 0.5 to 2% by volume of the drilling mud.

15. A clear water base drilling mud substantially free of hydrocarbon oil and clay solids and having improved lubricating properties consisting essentially of water, sulfurized tall oil, and a water soluble emulsifier, the concentration of the sulfurized tall oil being between 0.5 and 3.0% by volume to form a clear water base drilling mud having a load carrying capacity of at least about 30 on the Timken machine, and the concentration of the emulsifier being sufiicient to form a stable emulsion.

16. A drilling mud as set forth in claim 15 in which the emulsifier is sodium metaborate.

17. A drilling mud as set forth in claim 15 in which the emulsifier is a non-ionic emulsifier.

18. A drilling mud as set forth in claim 15 in which the emulsifier is an ethylene oxide derivative of nonyl phenol.

19. A Water base drilling mud substantially free of hydrocarbon oil and having improved lubricating properties consisting essentially of water, clay solids, a sulfurized organic compound selected from the group consisting of sulfurized unsaturated fatty acids having more than eight carbon atoms per molecule, sulfurized unsaturated esters of high molecular weight fatty acids, sulfurized unsaturated high molecular weight alcohols, sulfurized rosin acids, and sulfurized fatty acid pitches, said sulfurized organic compound constituting about onehalf to three percent by volume of the drilling mud to give the drilling mud a load carrying capacity of at least about 30 lbs. on the Timken machine, the sulfur concentration in the sulfurized organic compound being within the range of one-half to forty percent.

20. A method of drilling a well in which a rotary drill bit is rotated at the bottom of a borehole on the lower end of a drill pipe, said method comprising circulating a water base drilling mud substantially free of hydrocarbon oil and having a Timken load carrying capacity of at least about 30 pounds down the borehole in contact with the-rotary drill bit and back up the borehole to carry cuttings therefrom, said water base drilling mud consisting essentially of water, a sulfurized organic compound selected from the group consisting of sulfurized unsaturated fatty acids having more than 8 carbon atoms per molecule, sulfurized unsaturated esters of Patent No, 3,027,324

Milton Rosenberg It is her-eh; ant requiring correct corrected below.

' Column 4, TABLE I,

UNITED STATES PATENT O FICE 'CERTIFICATE, OF CORRECTION that error appear ii Zia that the said Letters Patent should read as 10 high molecular weight fatty acids, sulfurized unsaturated high molecular weight alcohols, sulfurized rosin acids, and sulfurized fatty acid pitches, and an emulsifier in vquantities to form a stable dispersion of the sulfurized organic compound in the water.

21. A method as set forth in claim 20 in which the sulfurized organic compound is sulfurized tall oil.

22. A method as set forth in claim 20 in which the sulfurized organic compound is sulfurized tall oil and the emulsifier is clay.

23. A method as set forth in claim 20 in which the water base drilling mud is a clear water base drilling mud, and the emulsifier is a water soluble emulsifier.

References Cited in the file of this patent UNITED STATES PATENTS article in The Oil and Gas Journal, September 10, 1956, pages 104, 105, 106 and 107.

s in the above numbered patline 1 of the footnote thereof, for column 5, line 2, for

Li re "Llgmjw dif icultlg columns 5 toS, TABLE T ggHEgluTgCtZI, li es l to 3 8, 91 15 l9 and 2,0 therezof l 21041 for, struck Y lumn 1 u ti ifmil iri s, aft ei sulfurized, first occurrenc rea I insert compound I Signed and sealed this 24th day of July 1962,.

(SEAL) Attest:

ERNEST W SWIDER Attesting Officer DAVID L. LADD Commissioner of Patents UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,027,324

Milton Rosenberg It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 4 TABLE I line 1 of the footnote thereof, for "Ligro" read Liqre column 5, line 2 for "difficulty" columns 5 to8, TABLE II, column 2.

read difficultly for "Bent", each lines- 1 to 3, 8, 9c, 15. 19 and 20 thereof column 7, line 41, for "struck occurrence, read Bent. read stuck line 69 after "sulfurized", first occurrenc insert compound Signed and sealed this 24th day of July 1962.

(SEAL) Anew ERNEST w. SWIDER DAVID LADD Commissioner of Patents Attesting Officer

Claims

1. A WATER BASE DRILLING MUD SUBSTANTIALLY FREE OF PETROLEUM HYDROCARBONS AND HAVING IMPROVED LUBRICATING PROPERTIES CONSISTING ESSENTIALLY OF WATER, A SULFURIZED ORGANIC COMPOUND SELECTED FROM THE GROUP CONSISTING OF SULFURIZED UNSATURATED FATTY ACIDS HAVING MORE THAN 8 CARBON ATOMS PER MOLECULE, SULFURIZED UNSATURIZED ESTERS OF HIGH MOLECULAR WEIGHT FATTY ACIDS, SULFURIZED UNSATURATED HIGH MOLECULAR WEIGHT ALCOHOLS, SULFURIZED ROSIN ACIDS, AND SULFURIZED FATTY ACIDS PITCHES, SAID SULFURIZED ORGANIC COMPOUND CONTAINING ONE-HALF TO FORTY PERCENT SULFUR AND AN EMULSIFIER IN CONCENTRATIONS ADEQUATE TO FORM A STABLE EMULSION OF THE COMPOUND IN THE WATER, THE CONCENTRATION OF THE SULFURIZED ORGANIC COMPOUND BEING SUFFICIENT TO IMPART A LOAD CARRYING CAPACITY OF AT LEAST ABOUT 30 POUNDS ON THE TIMKEN MACHINE TO THE WATER BASE DRILLING MUD.