CA1318494C - Use of polyalphaolefin in downhole drilling - Google Patents

Abstract

ABSTRACT

The composition of matter and application thereof in the present invention relates to the application of a synthetic hydrocarbon compound, a polyalphaolefin liquid, blended in various concentrations with chemical oil and water emulsifiers, thinners and oil and water surface tension reducers, the concentration of polyalphaolefin liquid to that of the remaining portion of the blend being no less than 5%; blending the polyalphaolefin liquid and the emulsifiers in a blending tank containing water base drilling mud; circulating the blend of polyalphaolefin liquid and emulsifier with the water base drilling mud down hole, so that the blend of polyalphaolefin liquid emulsifier and water base drilling mud lubricates the drill string or reduces the differential pressure between the wall of the borehole and the drill string so that the drill string is free to rotate and drilling may be undertaken with less drag or torque. In another application, the polyalphaolefin blended with the emulsifier serves as a spotting fluid in order to unstick drill pipe that has become stuck. In this method, the polyalphaolefin is blended with the emulsifiers; the polyalphaolefin emulsifier blend is introduced into the borehole as a "pill"; the pill is circulated downhole in the mud system through the annulus to the depth at which the pipe is stuck; the polyalphaolefin emulsifier blend acts on the differential forces between the wall mud cake and the pipe to reduce the differential pressure between the pipe and the formation, so that the pipe is freed and drilling is able to resume.

Description

APPLICATION FOR PATENT

INVENTORS: David O. Trahan Mi.chael B. Faulk INVENTION: TEIE USE OF POLYALPHALOLEFIN IN

S ASSIGNEE: COASTAL MUD INCORPORATED
A Louisiana Corporation SPECIFICATION

BACKGROUND OF THE INVENTION
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l. Field of the Invention The present invention relates to downhole lubricants and spotting fluids. More particularly, the present invention relates to the use of a downhole drilling compound used as an additive in water~based drilling fluids to lu~ricate the drill pipe during the drilling process and to fxee the drill pipe that has become stuck during the drilling process. The present invention further r~lates to the use of a synthetic hydrocarbon fluid, in particular polyalphaolefin (PAO) liquid containing no more than 0.5 ~ l - decene mo~omer, blended in a concentration range of at least 5% by volume with emulsifier~; sometimes referred to as the PAO/emulsifier blendO When introduced at a certain volume downhole, the compound performs as a lubricating agent, used particularly for preventing the drag and torque on drill pipe, and as a spotting fluid, fox dislodging stuck drill pipe ~rom the well bore. One distinct advantage of the invention over the previous art in this field, is that the PAO/emulsifier blend is non-toxic to marine life and does not produce a visible sheen when discharged into water bodies.
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2. General Back~round In the drilling of oil and/or gas wells, a drill bit at the end of a rotating drill string or at the end of a drill motor is used ~o penetrate through geologic formations. During this operation a drilling mud is circulated through the drill string, out of the bit and is returned to the surface via the annular space between the drill pipe and the formation. The drilling mud, a Eluid, cools and lubricates the drill string and drill bit and is designed to counterbalance, through hydrostatic pressure, the encountered formation pressures while providing a washing ac-tion to remove the formation cuttings from the wellbore. The drilling mud also forms a friction reducing wall cake between the dril] string and the wellbore.
During the drilling of the well, the drill string may demonstrate a tendency to develop unacceptable rotational torque or in the worse case become s~uck. At this point, the drill string cannot be raised, lowered and rotated.
The most common factors that can lead to this situation are (1) cuttings or slough buildup in the borehole; (2) an undergauge borehole; ~3~ irregular borehole development embedding a section of the drill pipe into the drilling mud wall cake; and ~4) differential formation pressure unexpectedly encountered.
In the case of differential sticking, the hydrostatic fluid pressure of the drilling mud is greater than the permeable pressure of the exposed formation causing the flow of drilling mud into that area of the formation thus lodging the drill pipe against the formation face. When this occurs, the contact area of the drill pipe and the formation is great enough to cause an increase in rotational torque such that it prevents further movement of the drill pipe without a risk of parting the drill pipe string.
Previous publications concerning methods of preventing drill pipe from sticking and/or freeing stuck drill pipe have discussed the common method of using an oil mud or oil or water based surfactant composi-tion, to reduce friction, permeate drilling mud wa]l cake, destroy binding wall cake and reduce diEferential pressure.
Applicant is attaching hereto a statement of the art which is pertinent to the present invention.
There remains a serious need for chemical compositions which can better reduce frictional torque and release stuck drill pipe while demonstrating a low order of toxicity to marine life, more specifically a product to comply with NPDES permit GOM LC50 test, and not produce a surface sheen on the water body. In contrast to prior art developments which incorporated the use of refined crude oil, diesel, kerosene, mineral oil and most recently low polynuclear aromatic mineral oils (as described in International Pat No. WO 83,102,949), it has been discovered that synthetic oils, an iso-paraffinic oil with no aromatic contPnt, in particular a class of synthetic oils known as polyalphaolefin, demonstrate the required fluid properties and provide the necessary low order of t.oxicity to comply with the NPDES permit GOM LC50 to function as the primary composi1:ion of downhole fluid additives, more specifically a lubricant and spotting fluid.
Previous developments in this area deal with the application in oil based mud. This invention specifically pertains to the application of these polyalphaolefin compounds as an additive in water based drilling fluids.
In contrast to the previous use of synthetic oils in lubricating e~gines, mills, etc., this invention does not deal with metal to metal, thin film type of lubrication.
It is specifically the use of a polyalphaolefin li~uid blended with emulsifiers used in a concentration of at least .25~ by volume introduced as an additive into a water based drilling fluid to lubricate the drill pipe while rotating or pulling past a mud filter cake, hard or soft rock, or casing in a well bore, and to unstick drill pipe that has become differentially stucX.

SUMMARY OF THE PRESENT INVENTION
.. . ... _ . ~ . . _ The composition of ma-tter and application thereoE in the present invention relates to the applica-tion of a synthetic hydrocarbon compound, a polyalphaolefin liquid, blended in various concentrations with chemical oil and water emulsifiers, thinners and oil and water surface -tension reducers, the concentration of polyalphaolefin liquid to that of the remaining portion of -the blend being no less than 5%; blending the polyalphaolefin liquid and the emulsifiers in a blending -tank containing water base drilling mud in an amount of at least .25~ by volume;
circulating the blend of polyalphaolefin liquid and emulsifier with the water base drilling mud down hole, so that the blend of polyalphaolefin liquid emulsifier and water base drilling mud lubricates the drill string or reduces the rotational torque or drag between the wall of the borehole and the drill string so that the drill string is free to rotate and drilling may be undertaken with less drag or torque. In another application, the polyalphaolefin blended with the emulsifier serves as a spotting fluid in order to unstick drill pipe that has been stuck. In this method, the polyalphaolefin is blended with the emulsifiers in a concentration of at least 5~ polyalphaolefin; the po:Lyalphaolefin emulsifier blend is intxoduced into the borehole as a "pill"; the pill is circulated downhole in the mud system through the annulus to the depth at which the pipe is stuck; the polyalphaolefin emulsifier blend acts on the wall filter cake reducing the differential pressure bond. For purposes of this invention, the emulsifier, thinner and surface tension reducing additive can, in the case of the spotting fluid, be a blend of modified fatty acid and Amides. In the case of the drilling fluid lubricant, the additive can be described as a blend of sulfurized fatty acids and modified fatty acids. For purposes of this invention7 the polyalphaolefin is a totally hydrogenated alpha-olefin oligomer produced from an alpha-olefin such ~ 3.~
as 1-decene. More particularly, the polyalphaolefi.n relates to an alpha-olefin oligomer comprisecl of dimmer, -trimmer, tetramer and pentamer having a viscosity oE approxima-tely 2 centistokes at 210 degrees Fahrenheit.
Therefore, it is a principal object of the present invention to provide a synthetic hydrocar-bon, more particularly, polyalphaolefin, utilized as a lubricant to be administered in downhole drilling operations for reducing the drag or torque on the drill string during drilling.
It is a further object of the present inven-tion to provide the application of a polyalphaolefin as a spotting fluid in order to unstick pipe that has been stuck downhole.
It is a further object of the present inven-tion to provide the application of a polyalphaolefin-emulsifier blend as a downhole lubricant which is non-toxic to marine life and does not produce a sheen on the water surface when dumped on the water body.
It is still a further object of the present invention to provide a non toxic base fluid that complies with NPDES - GOM - LC50 test, the polyalphaolefin liquid consisting of a low value ~less than 0.5% concentration of 1 decene monomer).
According to one aspect of the invention, there is provided a drilling fluid compound for lubricating drill pipe in a water base mud system during the drilling process, the compound compris-i~g:

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a) a polyalphaolefin liqui.d in a concen-tration of at least 5% by volume o:E the drilling fluid compound, the polyalphaole:Ein liquid containing no more than 0.5% of 1-decene monomer; and b) an emulsi.fier additive in a concentration of 5% -to 30% of -the dri.lling fluid compound;the drilling fluid compound introduced into the water base mud system in a liquid volume concentration of at least 0.25% of the water base drilling mud for serving as a lubricant in the water base drilling mud system.
According to another aspect of -the .invention, there is provided in a process for drilling oil wells, wherein a drill string is rotated in a forma-tion utilizing a water base mud system, the processcomprising the steps of:
a) combining a liquid polyalphaolefin in a concentration of at least 5% by volume with an emulsifier, the polyalphaolefin containing no more than 0.5% of 1-decene monomer;
b) introducing the polyalphaolefin-emulsifier combination into the water base mud system in a liquid volume concentration of at least 0.25% the water base drilling mud; and c) circulating the mud containing the poly-alphaolefin-emulsifier combination down the borehole sufficient to lubricate the pipe to reduce the friction between the wall of the drill pipe and the formation as the drill pipe is rotated.

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According to yet another aspect of the inven-tion, -there is provided a process for uns-ticking dr.ill pipe in a water base mud system, where the drill pipe has become differentially stuck against the formation, the process comprising -the s-teps of:
a) locating a point downhole where the drill pipe has become stuck against the formation;
b) blending a polyalphaolefin in a concentra-tion of at least 5~ by volume with an emulsifier, the polyalphaolefin-emulsifier containing no more than 0.5% of 1-decene monomer; and c) introducing the polyalphaolefin-emulsifier blend downhole as a spotting fluid to the depth of the point of the stuck pipe, the polyalphaolefin-emulsifier blend being introduced into the water base mud system in a liquid volume concentration of at least 0.25% of the water base drilling mud, whereby to displace the water base mud ~ver the entire`stuck interval to unstick the pipe.
According to a further aspect of the inven-tion, there is provided a drilling fluid composition of matter for lubricating drill pipe during drilling, the composition of matter comprising:
a) a water base mud system; and b) a mixture of a polyalphaolefin and an emulsifier added to the water base mud system as a liquid, the polyalphaolefin having a viscosity of approximately 2 centistokes at 210F and containing no more than 0.5~ of 1-decene; the polyalphaolefin-1~ .

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emulsifier mixture being ad.ded to the water base mud system in a liquid volume concentration of at least 0.25% of the water base drilling mud.
According to still a further aspect of -the inven-tion, there is provided in drilling oil wells, wherein ~ drill string is ro-tated in a Eormation, and the drill s-tring has become s-tuck, a process of unsticking the drill string, comprising the steps of:
a) combining a liquid polyalphaolefin contain-ing no more than 0.5% of 1-decene and having a viscosity o-f approximately 2 centistokes at 210F
with an emulsifier;
b) introducing the polyalphaolefin-emulsifier combination into a borehole containing a volume of water base mud, the polyalphaolefin-emulsifier combination being introduced in-to the water base mud in a liquid volume concentration of at least 0.25%
of the water base drilling mud; and c) circulating the mud containing the poly-alphaolefin-emulsifier combination down the borehole sufficient to lubricate the pipe to reduce the friction between the wall of the drill pipe and the formation so that the drill pipe becomes unstuck.
According to still another aspect of the invention, there is provided a process for unstick-ing drill pipe when employing a water base mud system, where the drill pipe has become stuck against a formation due to differential pressure between the formation and the drill pipe, the process comprising the steps of:
a) locating a point downhole where the drill pipe has become stuck against the formation;

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b) combining a li.quid polyalphaolefin contain~
ing no more than 0. 5% of 1-decene and having a viscosity of approxima-tely 2 centis-tokes at 210F
with an emulsifier; and c) introducing the liquid polyalphaolefin-emulsifier combination downhole -to the depth of the point of the stuck pipe, the polyalphaolefin-emulsifier combination being introduced into the water base mud system in a liquid volume concentra-tion of at least 0. 25% of the water base drilling mud, whereby to unstick the pipe.
DETAILEV DESCRIPTION OF THE PREFERRED EMBODIMENT
The preferred embodiment of the combination of matter and the system of application of same of the present invention would utilize a synthetic hydro-carbon fluid, in particular polyalphaolefin (PAO) liquid which would preferably contain no more than 0.5% 1-decene monomer, in a concentration range of at least 5~O by volume with other liquid additives blended in various concentrations; additives such as chemical oil and water emulsifiers, thinners, and oil and water surface tension reducers. The concen-tration of the polyalphaolefin liquid to that of the remaining portion of the blend would be no less than 5~O

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and function as a water base drillirlg mud lubrlcant or a water base drllling mud spotting fluid. When utilized as a water base drilliny luhricant, the blend of polyalphaolefin liquid and additives, presently sold under the registered trademark "COASTALUBE", would have an optimum PAO liquid concentration of 70~ to 95~ and an optimum additive concentration of 30% to 5%. When utilized as a water base spotting fluid, the blend is sold under the registered trademark COASTAL SPOT; likewise, the polyalphaolefin liquid comprising an optimum percentage of 70% to 95~ of the blend, and the optimum additive concentration comprising 30~ to 5% of the blend.
For purposes of this invention, in either case when the PAO liquid - additive blend is either serving as a drilling fluid lubricant, or as a spotting fluid, the emulsifier~ thinner, surface tension reducing additives can be described as a blend of modified fatty acid and amides. The polyalphaolefin liquid is commercially prepared in a number of different methods, but for purposes of this invention the totally hydrogenated alpha-olefin oligomer is produced from an alpha-olefin such as 1 - decene. More particularly, the PAO liquid is an alpha-olefin oligomer comprised of dimer, trimer, tetramer, and pentamer having a viscosity of approximately 2 centistokes at 210 degrees Fahrenheit. Furthermoxe, in order to qualify as a non-toxic base fluid and comply with NPDES GOM LC50 test, the polyalphaolefin liquid must consist of a low value ~less than .5% concentration) of 1 - decene monomer. The various oligomer distributions were determined by gas chromotography. The important feature of the polyalphaolefin liquid application downhole and more particularly offshore, is the fact that it is non-toxic to marine life and does not produce a sheen on the water when the liquid is introduced into the sea water.
Turning now to the manner in which the PAO blend is applied downhole, reference is made to the fact that in a 1.L ,7, water base drilling system, as was discussed earlier, the dri:Ll string may at one point demonstrate rotation throu~h the formation under :increased torque or drag, and lubrication of the drill string is critlcal. Therefore, one woulcl introduce a lubricant into the water base mud system, in order to lubricant the drill string. This lubricant would comprise a polyalphaolefin liquid containing no more than .5~ 1 - decene monomer, at an optimum concentration range of between 70% and 95%
polyalphaolefin liquid to an optimum range of 30% to 5%
additives, more particularly chemical, oil, and water emulsifiers, however, the percentage of of polyalphaolefin liquid would be no less than 5~ of the blend. This polyalphaolefin - additive blend would then be added to the water base mud system, for example by introduction of the polyalphaolefin - additive blend into the mud pit, so that the blend would be in a concentration of at least .25% to 6.0% by volume in the water base drilling mud system. The drilling mud, in the system, during the introduction of the PAO - additive hlend, does not have to be interrupt~d, and the blend would then be mixed into the wa-ter base mud system and introduced downhole. Upon being introduced downhole, the PAO - additive blend would help to lubricate the surface between the wall of the drill pipe and the wall of the surrounding formation, so as to reduce the torque and drag on the drill string during downhole drilling.
Due to the fact that the polyalphaolefin has a con~entration of no more than .5~ 1 - decene monomer, the polyalphaolefin liquid is non-toxic to marine life, and therefore, can be maintained in the mud system during drilling, and the drill cuttings do not have to be recovered and may be discharged. In the previous state of the art, if an oil based lubricant was introduced into the mud system, the entire mud system would have toxic levels above acceptable limits as per the LC50 test and/or would produce a sheen on the water. In order to avoid the possibility of the spreading of the lubricant into the surrounding seawater~ creating a hazard to marine :Life, the drilling fluid and cuttings would necessitate containmen-t. The combination of matter in the present invention would overcome this likelihood and could be maintained in the water base mud system allowing normal discharge of drilling fluids and/or cuttings.
In its second application, the polyalphaolefin liquid/ additive blend, would be utilized ln the same concentration, with the same additives such as emulsifiers, downhole in order to unstick the drill string that has become stuck to the wall of the formation due to various factors including differential pressure downhole.
In this particular application of the invention, the normal circulationof the water base mud system would be altered to allow for a certain volume of the polyalphaolefin liquid/ additive blend to be introduced as a "pill" into the active mud system, which would therefore result in a greater combination of the polyalphaolefin liquid/additive blend being applied at a predetermined point downhole. Following the introduction of the blend into the the borehole5 the blend would then be displaced into the annulus in the borehole at the estimated level that the drill string has become stuck, and the blend would serve as a spotting fluid in order to, for example, replace the water in the mud causing the sticking of the pipe against the wall mud cake due to differential pressure, and wouldl relieve that pressure and rotational torque in order to allow the drill string to resume rotational and vertical movement. Again, in view of the fact that the polyalphaolefin liquid/addîtive blend is non-toxic to marine life, the pill could be maintained downhole and recirculated in the system, which thereafter it would function as a lubricant, and not have to be isolated and removed from the active mud system. At the present time, if an oil-base lubricant mud is introduced downhole as a pill, the EPA may require that 50 barrels of l 3 ,~
mud preceeding and following the pill be retrieved together wi-th -the pill in order to avoid contami.nation of the mud sys-tem by a toxic substance such as the state-of-ar-t oil base spotting fluids.
For purposes of clarification of the present invention, applicant is submi-tting here~1ith the following appendixes attached to this application, which provide evidence of the usefulness and non-toxicity of the present invention.

APPEMDIX A
Appendix A attached hereto i5 a mixing chart of the polyalphaolefin liquid/additive blend being used as a spotting fluid, and the manner in which the composition would operate under varlous required densities.

APPENDIX B
Appendix B is a summary of the result of tests conducted for providing bio-assay data from Coastal Chemical Company on the drilling fluid containing 3%
volume polyalphaolefin.

APPENDIX C
Appendix C is a test and the results of the tests for approximating LC of a base mud containing 10%
of spotting fluid in the sample.

Because many varying and different embodiments may be made within the scope of the inventive concept herein taught, and because many modifications may be made in the embodimen-ts herein detailed in accordance with the descriptive requirement of the law, it is to be understood that the details herein are to be interpreted as illustrative and not in a limiting sense.
What is claimed as invention is:

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COASTAL S~OT
Mlxing C:hart Mix in the following order while agita~n~:
1 ) Clean mixin~ pit to avoid unnec~ssary contaminatior~
2) To Coastal Spot, add th~ water phase 3) Add salt (NaCI ~r CaCI ) continua to agitate for ~0-30 minutes 4) Add t Oppb lim~ and ag~ate well (1 Oppb all densities~

5) Add ~arite and agitate to a smooth blend 6) Add SX-LU8E (25ppb ail densities) and agitats to a smooth blend COMPOSITION BY DESIRED DENSITY
(Makes one 42 gallon barrel) Salt Barite Ib Ib Density Spot Water ~al ~alNaCI or CaCI? w!NaCIor w/CaC!2 8.0 27.6 11.823.6 28.4 4.8 0.0 8.5 27.~ 11.022.0 41.8 34.8 15.0 9.0 27.5 10.521.0 39.9 61.0 42.1 9.~ 27.2 10.020.0 38.0 89.1 71.1 10.0 27.4 9.1 18.2 34.6 118.1 101.7 10.5 27.2 8.6 17.2 32.7 145.6 130.1 tt.O 26.7 8.4 16.8 . 31.9 172.0 156.9 11.5 26.5 7.9 15.8 30.0 199.5 185.3 12.0 26.0 7.7 15.4 29.3 æ5.9 212.1 12.5 25.8 7.2 14.4 27.4 253.4 240.5 13.0 25.6 6.8 13.6 25.8 279.9 267.6 13.~ 25.3 ~.3 12.6 23.~ 308.1 296.7 14.0 24.7 6.2 12.4 23.6 334.1 322.9 1 4.5 24.6 ~.71 1 .4 21 .7 360.~ 350.7 15.0 24.0 5.7 11.4 21.7 386.9 375.7 15.5 24.0 5.0 10.0 1~.0 414.2 405.2 16.0 23.5 4.æ 9.6 13.2 440.6 431.9 16.5 23.2 4.4 8.8 1~.7 467.7 459.8 17.~ 22.8 4.0 8.0 15.2 495.5 ~a8.3 17.5 22.6 ~.6 7.2 13.7 522.0 515.5 18.0 22.5 3.0 6.0 11.4 549.9 544.5 After Coastal Spot ha~ fre~d your stuck ,~ip~, simply leave Caastal Spot in your mud system to give enhanced lubricating characteristios and r~duoe the chancQ of sticking th~ pipQ a~ain.
APPENDIX A
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This evaluation was designed to establish the toxicity level of the Polyalphaolefin Uquid (Coastal Solvent 300) which is the base component for Coastal Spot, CoastaLube. Due to the proprietary n~ture of these initial tests, the name Solvent 300 was given to the PAO.
Coastal Solvent 300 is a high molecular weight syn~hetic hydrocarbon solvent, which has no aromatics, ~xhibits excellent lubricity characteristics, and tha bulk liquid is tharmally stable to >600~ F.
Solvent 300 performs very similar to diesel and mineral oil in water based drilling fluid systems.
See Solvent 300 Acute Toxici~y Test data for additional comparisons to highly refined mineral seal oil.
At a 3% by volume of PAO in the drilling fluid, the results of the NPDES LCso 96HR
Range Finder were:
Solvent30û LCso 96HR RF 1,000,000 REF: Weintritt Testins Laboratories 510-12-6070-C 11/23t87 This test was conducted durin~ product dQvelopment phase.
The results of the approximate LCso test is much greater than the 3û,000ppm SPP
specified in the NPDES permi~.

APPENDIX B
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WEINTRIlll-TESTING LAE3C)RJQTORIES

November 23, 19B7 Project Number: 510-12-6070 C

LC50 APPROXIMATION BY 96 HOUR RANGE FINDER ON A DRILLIN~ FLUID
BONTAINING 3~ BY VOLUME SOLYENT 300 FOR COASTAL CH~ICAI COMPANY

Requested By: Mr. Mike Faulk Coastal Chemtcal Company P.O. Box 8~a Abbeville, LA 70511-0820 Tested By: CalYin Humble Scott Gordon Matt Salmon ~c~
Leslie Lafferty Approved By: Donald J. Weintrit~, PO E.
WIL IS AN I~IDEPE~IDERT UliORAlORr. ANALVSES AND OPINION8 ARE OF I~ATERIAI,S PRESEN~ED ffY OUFI CUSICIIEIIS.
OUSI REPORl~; ARE NOT INTENOD FI~R DlSralhUTlOil TO H011 RELUNCE UPOII BV PEllSONS OTHE 11 TIIAN OUIl CU570iJERS. . ~

TELEPHONE (318~ 9a1~1560 5750 81NTLIFF. SUITE 214. HOUSTON. TX 77036 ~,TELEPHONE 1713~ 952~11.1 ~ ~3 ~ i3 ~

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November 23, 1987 Project Number: 510-12-6070 C

LC50 APPROXI~lATION BY 96 HOUR RANGE FINDER ON A DRILLING FLUID
CONTAINING 3~ ~Y VOLUME S~LYENT 300 FOR COASTAL CHEMICAL COMPANY
INT UCTION

The purpose of this test was to provide approximate bioassay data for Coastal Chemieal Company on a drilling fluid containing 3~ by volu~e Solvent 300.
Custody transfer of the sample occurred on 11-17-87 at WTL, the drilling fluid was immediately placed in a wa1k-in cooler at 4C. A 96 hour range finder was run on 11~18/87-11/22/87.

Prehydrated Aquagel 20 lb/bbl Chrome Free Ligno (QB II) 4 lb/bbl Simulated Drill7ng Solids Marttn #5 Ball Clay 20 lb/bbl Caustic Soda to pH 9.5-10 Drispac, reg. O.5 1b/bbI
Cellex, regO 0.5 Ib/bbl Soda Ash 005 l~/bbl So1vent 300 , 3 vol SUMMARY

APPROXIMATE LC TOXICITY RESULTS
~50 ~
Moving Average Method ke~O ~5~ ~ONFI~ 'I'L
LOWER UPPER

UNCORRECTED ~ 1,000,000 0 Infinity CORRECTED FOR CONTROL I~ORTALITY ~1,000,000 - _ REFERENCE TOXICANT, ppm 15.6 14.5 16.9 .. .

November 23, 1987 Project Number: 510-12-6070 C Page 2 DRILLING FLUID SPP CONCENTRATION DATA

TEST CONC~ENTRATIONTOTAL_NUMBER _ SIDS
(~Dm SPP~ EXPOSED SUPV~VED
__ _ . _ __ __ 10,000 10 10 50~0~0 10 9 100,000 10 9 500.000 10 8 1,000,000 10 5 Complete test results and calculations may be found in the Experlmental Details section.

CONCLUSION

This drilling fluid containing 3% by volume Solvent 300 has an approximate LC50 of about 100~ SPP or much greater than the 3.0% minimum SPP specified in the NPDES permit.

This ;s only an approximate LC50 obtained from a ~6 hour range finder.

RECOMMENDATIONS

To obtain a more accura~e LC50 value, a 96 hour Acute Toxicity test is recommended.

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November 23, 1987 ~ 3~
Project Number: 510-12-6070 C Pa~e 3 The drilling fluid had a pH of 9.04 and did not emit a foul odor. Black spots were not present on the container walls. The sample was identified as follows:

COASTAL CHEMICAL COMPANY
BASE DRILLING FLUID CONTAININ& 3b BY VOLUME SOLVENT 300 The drilling fluid was placed in cold storage upon arrival at 4C in WTL's walk-in-cooler. The drilling fluid was prepared for biolosical testing according to EPA protocol. The drilling fluid was thoroughly homogenized for 30minutes with a high shear mixer. The homogenized material was then combined with artificial seawater (salinity=20ppt~ in a 1:9 ratio by volu~e.

The drilling fluid-seawater mix~u~e, which was charac~erized by a pH of 8.15, was mixed for 5 minutes and a110wed to settle for 1 hour. During the 5 minute mixing period, the pH was adjusted with 0.05 m1 of 6N HCl to within +0.2 units of the seawater tpH - 7.8). Fo110wing the settling period.~ the suspended particulate phase (SPP) was carefully decanted. Measuremen~ of the pH, dissolved oxygen concentration, and temperature was made during a brief mixing period. The SPP had a pH of 8.02 and was adjusted with 0.05 ml of 6N HCl to a pH of 7.80, a dissolved oxygen concentration of 7.1 ppm a temperature of ~0C.

Mysids ~ bahia) used as t~st organisms were 4-6 days old. The test animals were cultured in WTL's bioassay facilities using brood stock originally purchased from commercial suppliers. The test was conducted at 20C I 2C usingartificial seawater (Hawaiian M~rine Mix) adjusted to a salinity of 20 parts perthouxand (ppt) ~ 2 ppt. Myslds were ~ed approximately 50 live Ar~emia (brine shri~p) nauplii per test animal every 96 hours. Tests were canducted with five concentrat~ons of suspended particulate phase and a control (of seawater only) with 10 mysids randomly distributed among each concen~ration. Tests were perfonmed ~n 1770 ml crystallizing dishes which contained 1 liter of test solution. Filtered ar~ificial seawater with a sa1inity of 20 ppt was used to dilute the suspended particulate phase to test concentra~ions and as the controlsolution. A 14-hr l~ght and 10-hr dark photo period was maintained with cool-white fluorescent lights.

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November 23, 1987 Project Number: 510-12-6070 C Page 4 Air was supplied to the test chambers by a col~mercial aquaculture blower and delivered through glass tubing at d rate of between 50 and 140 cubtc centime~ersper minute. At a minimum, the number of survivors were determined at O and 96 hours. remperature, salinity, dissolved oxygen, and pH were measured daily.

The 96 hour reference toxicant test, Sodium Lauryl Sulfate (SLS), for this bioassay was performed according to EPA protocol. The SL5 used was obtained from Fisher Scientific and was from their Lot #~53661. The LC50 obtained with this most recent SLS reference test was 15.6 ppm SLS with 95% CI of 14.5 ppm to 16.9 ppm. Up to this point the mean LC50 for SLS reference toxicant tests run at this lab has been 15.1 with a Standard deviation of 2.7. The LC50 of this 96 hour reference toxicant test is within two standard deviations of the mean an~ therefore can be considered acceptable.

DATA ANO RE5ULr5 Data generated by the 96 hour Range Finder test with mysids are presented in Appendix 8. Greater than 90 percent surviva1 occurred in the control exposure.
Survival data and a copy of the computer print out for the LC50 calculation are included in Appendix A.

The 96 hour approximate LC50 for this sample of drilling fluid was yredter than 1 ,ono ,Doo ppm suspended part~eulate phase (SPP). The 95 percent confidence limits for this approximate LC50 value O - infinity ppm (SPP).

~EFERENCES
.
Stephan, C. E. 1983. Computer program for calculation of LC50 values. U. S.
Environmental Protection Agency, Duluth, Minnesota.

U.S. Environmental Protection Agency, 1985.
Draft t~ethodology: Drilling Fluids Toxicity Test. Industrial Technology Givision of the Office of Water, EPA, Washington, D.C. FR5G, FR34592~ August 26, 19~5. Appendix 3 to the proposed oil and gas extract10n point source category guidelines and new - source standards.

~) November 23, 1987 Project Number: 510-12-6070 C

I

November 23, 1987 ~ 3 l~ ~
~ Project Number: 510-12-6070 C

TA~LE 1: Survival data from 96 hr. Range Finder test with mysids (~ ldops~s bahia) and drilling fluid.

CONCErJTRATION
OF PHASE, PPM~ SURVIVALRFPLICATF O HR 24 HR 48 HR 72 HR96 HR
O (Control) 90 A 10 10 10 9 g 10,000 100 A 10 a a a 10 50,000 90 A 10 a a a 9 100,000 90 A 10 a a d 9 500,000 80 A 10 a a a a 1,000,000 50 A 10 a a d 5 a Visual observation for determining the number of survivors could not be made withou~
disturbing the mysids, ~æ

November 23, 1987 Project Number: 510-12-6070 C

APPENDIX B. RAW BIOASSAY DATA
. _ _ _ _ , . _ . _ .

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.

.

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This evaluation was designed to establish tha toxicity level of a genaric, unw~ighted, laborato~ prepared mud and then again determine the approximate toxicity i0v~1s of thc fluid with the addltion of ~0% concenlration of Coastal Spot, Polyalphaolefin base~ spotting fluld.
This test condi~ion would simulate a 2,000BBL mud system with a 250LBL spot added.
This is believed to be above practical applications, but will cover worse possible case situation, or multiple spot application within the same systern.

At a 10% by volume of Coastal Spot (PAO) in the drilling fluid, the results of th~
NPDES LCso 96HR Range Finder wera:
Mud evaluation LCso g6HR RF1,000,000 Mud evaluation with 10% Coastal Spot LCso 96HR RF iO9,995 REF: Weintritt Testing Laboratories 510-12-5847 B8,D 912187 The abova tast was conducted during product development.
The results of the approximate LCso test is much greater than the 30,000ppm SPP as specifled in the NPDES permit.

APPENDIX C
`

.

WEINTRI~
TESTING LAE31E:~R~TORIES

September 2, 1987 Project Number: 510-12-5847 B & D

APPROXI~MATED LC50 OF A 8ASE MUD CONTAINING 10% OF
SAMPLE ~3 SPOTTING FLUID FOR COASTAL CHEMICAL

Reques~ed 8y: Mr. Mike Faulk Coastdl Chemical Company P.O~ Box 820 Abbevi 11 e, LA 70511-0820 Tested By: Matthew Salmon Calvin Humble Scott Gordon Approved By: Donald J. Weintrltt, P. E.

wn. Lq All U9E?E~EN7 UaORlmaY ANAW9S UID OPINIOOIS ARI~ OF II~ filAlS PaBENTED ~ OUii CUST01~
0UI RWRla M NO~ Itl~D F011 01~1WliUlt0N 7011OR a~NcF UPOD ~ PEI;50NS G~ HAN OUII CUST0UEF18. ~ ' P. O. EIOX 301ii2. 3C5 ANDREW GUIDFIY ROAI~, LAFAYE~TE. LA ioso3 ~ C 5750131NTLIFF. SUITE 214. HOUSTON. ~)~ 77038 SepCember Z, 1987 Project Number: 510-12-5847 B & D

APPROXI~lATED LC50 OF A BASE MUD CONTAINING 10% OF
SA~IPLE ~3 SPOTTING FLUID FOR COASTAL CHEMICAL
INTRODUCTION

The purpose of ~his test was to provide approximate LC50 data for CodStd~
Chemical Company on a base mud con~aining 10% by volume of Sample ~3 sp~tting fluid. Custody transfer of Sample ~'3 occurred on 8/27j87 at '~TL. rhe ~ud ',~dS
mixed according to specifications on 8-28-~7, hot rolled 16 hrs. dt iSGF, immediately placed in a walk-in cooler at 4C. A 96 hour range finder w~s run on 8/29/87-9/2/87.

~ASE MUD PPEPARED FROM NL BAROIO MATERIALS.

Prehydrated Aquagel 20 lb/bbl Chrome Free Ligno (QB II) 4 lb/bbl Simulated Drilled Solids Martin ~5 8all Clay 20 lb/bbl Caustic Soda to pH 9.5-10 Drispac, reg. 0.5 lb/bbl Cellex, reg. 0.5 lb/bbl Soda Ash 0.5 lb/bbl Sample ~3 (Spotting Fluid) 10 vol ,~0 ~ L~

SeptemDer 2, 1987 Projeet Number: 510-12-5847 B & D Page 2 This mud was sent with two others. The approxima~e LC~o values for ~hese Sdmp les will be reported seperately.
SU~ARY
LC, TOXICITY RESULTS
~0 ~
~loving Averaye Method ~ 0 95~ CONFIDENCE LE'/EL
LOWER UPPER
~ . . _ OR ILLING_FLUID, ~Q~
UrlCORRECTED (Sample ~3)109,995 66,024 179,7B2 UNCORREOTED (Base Mud)1,000,000 - -CORREOTED FOR CONTROL ~ORTALITY
(Sample ~3) 109,995 66,024 179,732 (Base Mud) 1,000,000 REFrRENCE TOXICANT, ppm 16.1 14.8 17.7 DRILLING FLUID SPP CONCNTRATION DATA

SAMPLE ~3 8ASE MUD
, . . .. _ _ TEST COIICENTRATION,TOTAL NUMBER MYSIDS TOTAL NUMBL~ MïSIOS
~ EXPOSEDSURVIVED EXPOSb SURVIVED

10,000 10 9 1~ 10 50 ,000 10 10 10 10 100,000 10 6 10 3 500 ,000 10 0 10 10 1,000,000 10 ~ 10 10 SAMPLE ~3 BASE ~UD
TOTAL SUSPENDED SOLIDS, mg/l11,795 30,359 TOTAL DISSOLYED SOLIDS, mg/l12,625 29,575 Complete test resu1ts and calculations may be found in the Experimental Detdi lssection.

~'3 ~fJ~

September 2, 1387 Project Number: 510-12-5847 A & D Page 3 CONCLUSION
.

Sanlple #3 in a concentration of 10~ by volume has an approxima~e LC50 of about 11% SPP or much ~rea~er than the 3.0% minimum SPP specified in the NPDES permi~.
This is only an approximate LC50 obtained from a 96 hour range finder.

RECOMMENDATIONS

To obtain a more accurate LC50 value, a 96 hour LC50 test is recommended.

EXPERIMENTAL DETAILS

The drilling fluid had a pH of 10.4 and did not emit a foul odor. 31ack spots were not present on the container walls. rhe sample was identified as follows:

SAMPL~ ~3 COASTAL CH~`~ICAL COMPANY

The drilting fluid was placed in cold storage upon arrival at 4C in ~TL's walk-in-cooler. The drilling ftuid was prepared for biological testing according to EPA protncol. The drilling fluid was thoroughly homogenized for 30minutes with a high shear mixer. The homogenized material was then combined with artificial seawater (salinity-20ppt) in a 1:9 ratio by volume.

.,~ ~q `eptember 2, 1987 ~ 3 ~ 3 ~
Project Number: 510-12-58~7 B & D Page 4 -SAMPLE ~3 The drilling fluid-seawater mixture, which WdS characterized by d pH of 9.24, was mixed for 5 minutes and allowed to settle for 1 hour. During the 5 minute mixing period, the pH was adjusted with 1.0 ml of 6N ~Cl and 0.05 ml lON NaOH towithin l0.2 units of the seawater (pH 7.8). Following the settling period, the suspended particulate phase (SPP) was carefully decanted. Measurement of the pH, dissolved oxygen concentration, and temperature was made during a brief mixing period. The SPP had a pH of 7.79, a dissolved oxygen concentration of 6.6 ppm, a temperature of ZOC, Total Suspended Solids of 11,79~ mg/l and Total Dissolved Solids of 30,359 mg/l.

~ASE MUD
....
The drilling fluid-seawater mixture, which was characterized by a pH of 8.99, was mixed for 5 ~inutes and allowed to settle for 1 hour. Ouring the 5 minute mixing period, the pH was adjusted with 0.6 ml of 6N HCl and 0.05 ml 10N NaOH tOwithin +0.2 units of the seawalPr (pH - 7.8). Following the settling period, the suspended particulate phase (SPP) WdS carefully decanted. Measurèment of the pH, dissolved oxygen concentration, and temperature was made during a brief mixing period. The SPP had a pH of 8.01 and was adjusted with 0.1 ~1 6N HCl to a pH of 7.87, a dissolved oxygen concPntration of 6.8 ppm, a tempera~ure of 20C, Total Suspended Solids of 1296Z5 mg/l and Total Dissolved Solids of 29,574mg/l.

Mysids ~Mysidopsis bahi3) used as test organisms were 4-6 days old. The test animals were cultured in WTL's bioassay facilities using brood stock originally purchased from commercial suppliers. The test was conducted at 20C ~ 2C usingarti~icial seawater adjusted to a salinity of 20 pdrts per thousand (ppt) + 2 ppt. Mysids were fed ~50 live Artemia (brine shrimp) naup1ii per test animal every 24 hours. Tests were conducted with five concentrations of suspended particulate phase and a control (of seawater only) with 60 mysids randomly distributed among three replicates of each concentration. Tests were performed in 1770 ml crystallizing dishes which contained 1 lit~r of test solution.
Filtered artificial seawater with a salinity of 20 ppt was used to dilute the suspended particulate phase to test concentrations and as the control solution.
3~

~ 3 ~
September 2, 1987 Project Number: 510-12-5847 B ~ D Pd~e 5 A 14-hr light and 10-hr dark photo period was maintained with cool-white fluorescent lights. Air was supplied to the test chambers by commercial aquarium air pumps and delivered throllgh glass tubing at a rate of between 50 and 140 cubic centimeters per minute. At a minimum, the number of survivors were determined dt O and 96 hours. Temperature, salinity, dissolved oxygen, dndpH were measured daily.

The reference toxicant test, Sodium Lauryl Sulfate (SLS), for this bioassa~ was performed according to EPA protocol. The SLS used was obtained from Fisher Scientific and was from their Lo~ ,853661. The LC50 obtained with this most recen~ SLS reference tes~ was 16.1 ppm SLS with 95~ CI of 14.8 ppm to 17.7 ppm. Up to this point the mean LC50 for SLS reference toxicant tests run at this lab has been 15.2 with a Standard deviation of 3.1. The LC50 of this reference toxicant test is within two standard deviations of the mean and therefore can be considered acceptable.

OATA AND RESULTS

Data generat~d by the acute toxicity test with mysids are presented in Appendix B. Greater than 90 percent survival occurred in the contro1 exposure. Survival data and a copy of the computer print out for the LC50 calculation are included in Appendix A.

The appr~ximate LC50 for Sample ~3 was 109,995 ppm suspended particulate phase (SPP). The approximate LC50 for the 3ase Mud was ~ 1,000,000 ppm suspended particulate phase (SPP). The 95 percent confidence limits for Sample ~3 LCSo value were 66,024 - 179,782 ppm (SPP) and values for the Base Mud could not be calcu1ated.

September 2, 1987 ~ 31 ~ Page o REFERENCES
tephan, C. E. 1983. Computer progra~ for calculation of LC50 values. U. S.
Environmental Protection Agency, Duluth, Minnesota.

U.S~ Environmental Protection Agency, 1985.
Draft ~lethodology: Drilling Fluids Toxicity Test. Industrial Technology Division of the O~fice of Water, EPA, Washington, D.C. FR50, FR3~592q August 26, 1985. Appendix 3 to the propos~d oil and gas extraction point source category guidelines and new source standards.
.

~.~

~ 3 ~
Sep~ember 2, 1987 Projec~ Number: 510-12-5847 ~ ~ D

APPENDIX A~ SURVIVAL DATA AND STATISTICAL RESULrS

3`~

SeptPmber 2, 1987 1 3 Project Number: 510-12-5847 B & D

SAMPLE #3 96 HOUR RANGE_FINDER OATA

TEST CONCENTRATION TOTAL NUMBER ~YSrDS
_ __(PPM SPP~ EXPOSED SURVIVED
Control 10 10 10,000 10 9 50 ,OOO 10 10 100,000 10 6 500~00o 10 O
1,000,000 10 0 APPROXIMATE 96 HR. LC50, ppm 109,995 BASE MUD
_ ___ _ TEST CONC_NTRATION IOIiL ~ 8E~ iYSID' (PPM SPP~_ EXPOSEDSURVIVED
Control 11 11 10~000 10 10 50,000 10 10 100,000 . 10 8 500.000 10 10 1,000,000 10 10 APPROXIMATE 95 HR~ LC50, ppm 1~000,000 ,~

3 ~
ieptember 2, 1987 Projecl Num~er: 510-12-5847 B & D
TABLE 1: Sujrlvliyal dlatjadfrom toxicity ~est with mysids ~ bdhia) and SA~!PLE ~3 CONCENTRATION
OF PHASE? PPM ~ SURVIVAL REPLICATE O HR 24 HR 48 HR 72 HR 96 HR
O (Control) 100 A 10 10 10 1O 10 10,000 90 A 10 a a d 9 50,000 100 A 10 a a a 10 100,000 60 A 10 a a a 6 500,000 0 A 10 d a a O
1,000,000 0 A 10 a d a O
~ASE MUD
CONCENTRATION
OF PHASE, PPM ~0 SURVIVAL 2EPLICATE O HR 24 HR 48 HR 7L HR 96 HR

10,000 100 A 10 a a a 10 50,000 80 A 10 d d d 10 ~ 100,000 100 A 10 a a a ~ 500,000 100 A 10 a a d IO
1,000,000 100 A 10 a a d 10 a Vlsual observation for determining the number of survivors could not be made without dlsturblng the mysids.

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September 2, 1987 Project ,~umber: 510-12-58~7 B & D

APP'~D~ W IOASSAY DATA

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Claims (25)

1. A drilling fluid compound for lubri-cating drill pipe in a water base mud system during the drilling process, the compound comprising:
a) a polyalphaolefin liquid in a concen-tration of at least 5% by volume of the drilling fluid compound, said polyalphaolefin liquid containing no more than 0.5% of 1-decene monomer; and b) an emulsifier additive in a concen-tration of 5% to 30% of the drilling fluid compound;
the drilling fluid compound introduced into the water base mud system in a liquid volume concentration of at least 0.25% of the water base drilling mud for serving as a lubricant in the water base drilling mud system.

2. The drilling fluid compound of claim 1, wherein the drilling fluid compound is introduced into the water base mud system in a liquid volume con-centration of 0.25% to 6.0% of the water base drilling mud.

3. The drilling fluid compound of claim 1, wherein the concentration of polyalphaolefin in the drilling fluid compound is about 90%.

4. The drilling fluid compound of claim 1, wherein the concentration of emulsifier additive in the drilling fluid compound is about 10%.

5. The drilling fluid compound of claim 1, wherein the drilling fluid compound is non-toxic to marine life and is a permanent addition to the water base mud system.

6. In a process for drilling oil wells, wherein a drill string is rotated in a formation utilizing a water base mud system, the process comprising the steps of:
a) combining a liquid polyalphaolefin in a concentration of at least 5% by volume with an emulsifier, said polyalphaolefin containing no more than 0.5% of 1-decene mononer;
b) introducing the polyalphaolefin-emulsifier combination into the water base mud system in a liquid volume concentration of at least 0.25% the water base drilling mud; and c) circulating the mud containing the polyalphaolefin-emulsifier combination down the borehole sufficient to lubricate the pipe to reduce the friction between the wall of the drill pipe and the formation as the drill pipe is rotated.

7. The process of claim 6, wherein the polyalphaolefin-emulsifier combination is introduced into the water base mud system in a volume con-centration of 0.25% to 6.0% of the water base drilling mud.

8. The process of claim 6, wherein the polyalphaolefin-emulsifier combination contains about 90% polyalphaolefin and about 10% emulsifier.

9. The process of claim 6, wherein the polyalphaolefin-emulsifier combination is non-toxic to marine life in its application downhole.

10. A process for unsticking drill pipe in a water base mud system, where the drill pipe has become differentially stuck against the formation, the process comprising the steps of:
a) locating a point downhole where the drill pipe has become stuck against the formation;
b) blending a polyalphaolefin in a con-centration of at least 5% by volume with an emulsifier, said polyalphaolefin-emulsifier containing no more than 0.5% of 1-decene monomer; and c) introducing the polyalphaolefin-emulsifier blend downhole as a spotting fluid to the depth of the point of the stuck pipe, said poly-alphaolefin-emulsifier blend being introduced into the water base mud system in a liquid volume concentration of at least 0.25% of the water base drilling mud, whereby to displace the water base mud over the entire stuck interval to unstick the pipe.

11. The process of claim 10, wherein the polyalphaolefin-emulsifier blend is introduced into the water base mud system in a liquid volume con-centration of 0.25% to 6.0% of the water base drilling mud.

12. The process of claim 10, wherein the polyalphaolefin-emulsifier blend is introduced into the mud system as a "pill" separated from the mud in the system.

13. The process of claim 10, wherein the polyalphaolefin-emulsifier blend displaces the water in the formation at the point the pipe is stuck against the formation and lubricates the pipe and wellbore so that rotation and vertical movement of the drill pipe can be reestablished.

14. A drilling fluid composition of matter for lubricating drill pipe during drilling, the composition of matter comprising:
a) a water base mud system; and b) a mixture of a polyalphaolefin and an emulsifier added to the water base mud system as a liquid, said polyalphaolefin having a viscosity of approximately 2 centistokes at 210°F and containing no more than 0.5% of 1-decene;
the polyalphaolefin-emulsifier mixture being added to the water base mud system in a liquid volume con-centration of at least 0.25% of the water base drilling mud.

15. The drilling fluid composition of matter of claim 14, wherein the polyalphaolefin-emulsifier mixture is added to the water base mud system in a liquid volume concentration of 0.25% to 6.0% of the water base drilling mud.

16. The drilling fluid composition of matter of claim 14, wherein the polyalphaolefin is in a liquid state.

17. The drilling fluid composition of matter of claim 14, wherein the drilling fluid compo-sition of matter is non-toxic to marine life.

18. The drilling fluid composition of matter of claim 14, wherein the concentration of poly-alphaolefin in the polyalphaolefin-emulsifier mixture is about 90%.

19. In drilling oil wells, wherein a drill string is rotated in a formation, and the drill string has become stuck, a process of unsticking the drill string, comprising the steps of:
a) combining a liquid polyalphaolefin containing no more than 0.5% of 1-decene and having a viscosity of approximately 2 centistokes at 210°F with an emulsifier;
b) introducing the polyalphaolefin-emulsifier combination into a borehole containing a volume of water base mud, said polyalphaolefin-emulsifier combination being introduced into the water base mud in a liquid volume concentration of at least 0.25% of the water base drilling mud; and c) circulating the mud containing the polyalphaolefin-emulsifier combination down the borehole sufficient to lubricate the pipe to reduce the friction between the wall of the drill pipe and the formation so that the drill pipe becomes unstuck.

20. The process of claim 19, wherein the polyalphaolefin-emulsifier combination is introduced into the water base mud in a liquid volume con-centration of 0.25% to 6.0% of the water base drilling mud.

21. The process of claim 19, wherein the polyalphaolefin-emulsifier combination contains about 90% polyalphaolefin and about 10% emulsifier.

22. The process of claim 19, wherein the polyalphaolefin-emulsifier combination is non-toxic to marine life in its application.

23. A process for unsticking drill pipe when employing a water base mud system, where the drill pipe has become stuck against a formation due to differential pressure between the formation and the drill pipe, the process comprising the following steps:
a) locating a point downhole where the drill pipe has become stuck against the formation;
b) combining a liquid polyalphaolefin containing no more than 0.5% of 1-decene and having a viscosity of approximately 2 centistokes at 210°F with an emulsifier; and c) introducing the liquid poly-alphaolefin-emulsifier combination downhole to the depth of the point of the stuck pipe, said poly-alphaolefin-emulsifier combination being introduced into the water base mud system in a liquid volume concentration of at least 0.25% of the water base drilling mud, whereby to unstick the pipe.

24. The process of claim 23, wherein the polyalphaolefin-emulsifier combination is introduced into the water base mud system in a liquid volume concentration of 0.25% to 6.0% of the water base drilling mud.

25. The process of claim 23, wherein the polyalphaolefin-emulsifier combination is administered downhole as a spotting fluid to replace the water base mud surrounding the point where the drill pipe is stuck against the formation.