DRILLING FLUIDS CONTAINING PHOSPHATE ESTER ACIDS

FLUIDES DE FORAGE CONTENANT DES ESTERS DE PHOSPHATE ACIDIFIES

English Abstract

DRILLING FLUIDS CONTAINING PHOSPHATE ESTER ACIDS
(D#73,131-F)
ABSTRACT
Aqueous drilling fluids containing a minor
amount of alkyl- or alkaryl-polyethyleneoxy phosphate
ester acids are set forth. Such fluids are especially
useful where high lubricity drilling muds are needed.
Another embodiment of this invention relates to a method
of drilling utilizing the above-described fluids.
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Claims

The embodiments of the invention in which an exclusive
property or privilege is claimed are defined as follows:
1. An aqueous drilling fluid comprising an aqueous phase
containing a minor amount of at least one phosphate compound
of the class consisting of compounds of the formula:
(I) <IMG>
wherein n is an integer of 4 to about 50, R is alkyl of
from about 8 to about 12 carbon atoms and Ra is selected
from the group consisting of hydrogen and alkyl of from
about 8 to about 12 carbon atoms; Rb is selected from the
group consisting of hydrogen,
<IMG> ,
wherein R, Ra and n are as previously defined, and M,
wherein M is a monovalent salt forming radical selected
from the group consisting of alkali metal and ammonium
radicals; and wherein Rc is selected from the group
consisting of hydrogen and M as previously defined; and
of the formula:
(II) <IMG>
wherein n is an integer of from 4 to about 50, Rd is
alkyl of from about 8 to 20 carbon atoms; Re is
selected from the group consisting of hydrogen,
Rd(OCH2CH2)n-, wherein Rd and n are as previously defined,
and M, wherein M is a monovalent salt forming radical
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selected from the group consisting of alkali metal and
ammonium radicals and wherein Rf is selected from the group
consisting of hydrogen and M as previously defined.
2. The aqueous drilling fluid of Claim 1 wherein the
said phosphate compound has the formula:
<IMG>
wherein n is an integer of from 4 to about 50, R is
alkyl of from about 8 to about 12 carbon atoms and Ra
is selected from the group consisting of hydrogen and
alkyl of from about 8 to about 12 carbon atoms; Rb
is selected from the group consisting of hydrogen,
<IMG>
wherein R, Ra and n are as previously defined, and M,
wherein M is a monovalent salt forming radical selected
from the group consisting of an alkali metal and ammonium
radicals; and wherein Rc is selected from the group
consisting of hydrogen and M is as previously defined.
3. The aqueous drilling fluid of Claim 1 wherein the said phosphate
compound has the formula:
<IMG>
wherein n is an integer of from 4 to about 50, Rd is
alkyl of from about 8 to about 20 carbon atoms; Re is
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selected from the group consisting of hydrogen,
Rd(OCH2CH2)n-, wherein Rd and n are as previously defined,
and M, wherein M is a monovalent salt forming radical
selected from the group consisting of alkali metal and
ammonium radicals and wherein Rf is selected from the
group consisting of hydrogen and M as previously defined.
4. An aqueous drilling fluid comprising clay dispersed
in an aqueous phase and containing a minor amount of at
least one phosphate compound of the class consisting of
the compounds of the formula:
(I) <IMG> ,
wherein n is an integer of 4 to about 50, R is alkyl of
from about 8 to about 12 carbon atoms and Ra is selected
from the group consisting of hydrogen and alkyl of from
about 8 to about 12 carbon atoms; Rb is selected from the
group consisting of hydrogen,
<IMG> ,
wherein R, Ra and n are as previously defined, and M,
wherein M is a monovalent salt forming radical selected
from the group consisting of alkali metal and ammonium
radicals; and wherein Rc is selected from the group
consisting of hydrogen and M as previously defined; and
of the formula:
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<IMG>
(II)
wherein n is an integer of from 4 to about 50, Rd is
alkyl of from about 8 to about 20 carbon atoms; Re
is selected from the group consisting of hydrogen,
Rd(OCH2CH2)n-, wherein Rd and n are as previously
defined, and M, wherein M is a monovalent salt forming
radical selected from the group consisting of alkali
metal and ammonium radicals and wherein Rf is selected
from the group consisting of hydrogen and M as previously
defined.
5. The aqueous drilling fluid of Claim 4 wherein
the amount of the said phosphate compound employed is
in the range of about 0.01 to about 25 percent by weight.
6. The aqueous drilling fluid of Claim 4 wherein n in the said
phosphate compound is from 4 to about 10.
7. The aqueous drilling fluid of Claim 4 wherein
the said phosphate compound has the formula:
<IMG> ,
wherein n is an integer of from 4 to about 50, R is
alkyl of from about 8 to about 12 carbon atoms and Ra
is selected from the group consisting of hydrogen and
alkyl of from about 8 to about 12 carbon atoms; Rb
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is selected from the group consisting of hydrogen,
<IMG> ,
wherein R, Ra and n are as previously defined, and M,
wherein M is a monovalent salt forming radical selected
from the group consisting of an alkali metal and ammonium
radicals; and wherein Rc is selected from the group
consisting of hydrogen and M is as previously defined.
8. The aqueous drilling fluid of Claim 7 wherein n in
the said phosphate compound is from 4 to about 10.
9. The aqueous drilling fluid of Claim 4 wherein the
said phosphate compound has the formula:
<IMG>
wherein n is an integer of from 2 to about 100, Rd is
alkyl of from about 8 to about 20 carbon atoms; Re is
selected from the group consisting of hydrogen,
Rd(OCH2CH2)n-, wherein Rd and n are as previously defined,
and M, wherein M is a monovalent salt forming radical
elected from the group consisting of alkali metal and
ammonium radicals and wherein Rf is selected from the
group consisting of hydrogen and M as previously defined.
10. The aqueous drilling fluid of Claim 9 wherein n in
the said phosphate compound is from 4 to about 10.
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11. In a method of drilling wells wherein a drilling
fluid is passed through the well in contact with earth
formations during the drilling operation, the improvement
which comprises treating said earth formations with an aqueous
drilling fluid comprising clay dispersed in an aqueous
phase and containing a minor amount of at least one
compound of the class consisting of phosphate compounds
of the formula:
(I) <IMG> ,
wherein n is an integer of 4 to about 50; R is alkyl
of from about 8 to about 12 carbon atoms and Ra
is selected from the group consisting of hydrogen and
alkyl of from about 8 to about 12 carbon atoms; Rb is
selected from the group consisting of hydrogen,
<IMG>
wherein R, Ra and n are as previously defined, and M,
wherein M is a monovalent salt forming radical selected
from the group consisting of alkali metal and ammonium
radicals; and wherein Rc is selected from the group
consisting of hydrogen and M as previously defined; and of
the formula:
(II) <IMG>
wherein n is an integer of from 4 to about 50, Rc
is alkyl of from about 8 to about 20 carbon atoms;
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Re is selected from the group consisting of hydrogen,
Rd(OCH2CH2)n-, wherein Rd and n are as previously defined,
and M, wherein M is a monovalent salt forming radical
selected from the group consisting of alkali metal and
ammonium radicals and wherein Rf is selected from the
group consisting of hydrogen and M as previously defined.
12. The method of Claim 11 wherein n in the said phos-
phate compound is from about 4 to about 10.
13. The method of Claim 11 wherein the said
phosphate compound is a Class II compound in which n
is 7.
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14. The aqueous drilling fluid of Claim 1 wherein
the said phosphate compound is a phosphate ester acid salt.
15. The aqueous drilling fluid of Claim 14 wherein
the said phosphate compound is:
<IMG> .
16. The aqueous drilling fluid of Claim 1 wherein
the said phosphate compound is:
<IMG> .
17. The aqueous drilling fluid of Claim 1 wherein
the said phosphate compound is:
<IMG> .
18. The drilling method of Claim 11 wherein the
said phosphate compound is:
<IMG>
wherein n is an integer of from 4 to about 50, R is alkyl of
from about 8 to about 12 carbon atoms and Ra is selected
from the group consisting of hydrogen and alkyl of from
about 8 to about 12 carbon atoms; Rb is selected from the
group consisting of hydrogen,
18

<IMG>
wherein R, Ra and n are as previously defined, and M, wherein
M is a monovalent salt forming radical selected from the
group consisting of an alkali metal and ammonium radicals;
and wherein Rc is selected from the group consisting of
hydrogen and M is as previously defined.
19. The aqueous drilling fluid of Claim 18 wherein
the said phosphate compound is a phosphate ester acid salt.
19

20. The aqueous drilling fluid of Claim 1 wherein
the said aqueous phase is a brine phase.
21. The aqueous drilling fluid of Claim 4 wherein
the said aqueous phase is a brine phase.
22. The method of Claim 11 wherein the said
aqueous phase is a brine phase.
23. The method of Claim 11 wherein the said
phosphate compound is:
<IMG>
wherein n is an integer of from 4 to about 50, R is alkyl of
from about 8 to about 12 carbon atoms and Ra is selected from
the group consisting of hydrogen and alkyl of from about 8 to
about 12 carbon atoms; Rb is selected from the group
consisting of hydrogen,
<IMG>
wherein R, Ra and n are as previously defined, and M, wherein
M is a monovalent salt forming radical selected from the
group consisting of an alkali metal and ammonium radicals;
and wherein Rc is selected from the group consisting of
hydrogen and M is as previously defined.

Description

D7~ ~ 3, l 31
1049246
m is invention relates to aqueouæ drilling
fluids. More particularly, this invention relates to
~queous drilling fluids having incorporated therein a
minor amount of an alkyl- or alkaryl-polyethyleneoxy
phosphate ester acid. In another embodiment thls inven-
tion is dlrected to an improved drilling operatlon
employing the modified drilling fluids described above.
In a drilling operation, such as ln a rotary
drilling operation, a drllling fluid i6 forced down the
drill string, about the drill blt at the bottom of the
borehole ~nd then back up to the surface. The dril~ing
fluid employed in such a drilling operatlon u~ually is
an aqueous drilling fluid and ls compounded of various
materials in order to impart certain desirable physical
and chemical properties to the drilling fluid. For
example, thére is usually incorporated ln an aqueous
drilling fluid a hydratable clayey material, such as a
; bentonite clay, to impart desirable viscoslty and gel
strength properties to the drllling fluid BO as to better
enable the drilling fluld to carry away the drilling
cuttings from the bottom of the borehole. Other materials
such as weighting agents, e.g., barium sulfate, are
employed to increase the density of the drilling fluid
so as to make the drilling operation more effective
and safer by overcoming the fluid pressure within
the formation being drilled. Other materials
such as water loss improving agents, e.g., carboxy-
methylcellulose, hydrolyzed starch, etc. are added
to reduce the loss of fluid from the drilling fluid
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1049246
into the formation during the drilling operation. Still
other materials such as corrosion inhibltors, bacteri-
clde6 and drill bit lubricants are incorporated in the
drllling fluid in order to impro~e the drllline operatlon
and the drilling fluid.
Although a wide varlety of agueous drilling
rlulds contalnlng materials deslgned to lncrease the
lubrlclty of these fluld~ have been proposed and used
ln the fleld, all of these ~odlfled drllllng flulds
surfer ~rom one or more disadvantages.
In accordance with thls lnventlon an improved
aqueous drilling fiuid is provlded by incorporating
thereln a mlnor amount of a water-soluble phosphate
ester acld or salt thereof Or the class consisting of
compounds of the formula
R 0
(I) ~ -(0CH2cH2)n - 0 - P - ORC
Ra oRb
wherein n is an integer of from 4 to about 50; R le alkyl
of from about 8 to about 12 carbon atoms and Ra 1B
selected from the group conslstlng of hydrogen and
al~yl of from about 8 to about 12 carbon atoms; Rb ls
selected from the group consistlng of hydrogen,
R ~ ~(CH2cH2)n ~
wherein R, Ra and n are a~ previously deiined, and M,
whereln M i8 a monovalent salt ~orming radical selected
from the group consisting of alkali metal and ammonium
radicals; and wherein Rc ls selected irom the group

1049Z46
consisting of hydrogen and M a8 prevlously defined; and
o~ the formula:
o
(II) * (CH2cH2)n ~ - P - OR~
ORe
wherein n is an integer o~ from about 4 to about 50;
~d is an alkyl of from about 8 to about 20 carbon atoms,
Re i8 selected ~rom the group conslsting o~ hydrogen,
Rd(OCH2CH2)n-, whereln Rd and n are as prevlously
defined, and M, wherein M is a monovalent salt formlng
radical selected from the group consisting of alkali
metal and ammonium radlcals and wherein R~ ls selected
from the group conæisting of hydrogen and M as pre-
vlously defined. Use~ul alkali metal salts include
sodlum, lithuim and potassium salts of the abo~e-descrlbed
phosphates. Compounds of the types set out above where
the total number o~ ethyleneoxy units ranges from 4 to
about 20 are especially valuable phosphates ~or use ln
the drilling fluids of this lnvention.
A drilling fluid of this inventlon may be pre-
pared by the addition of a minor amount of at least one
of the water-soluble phosphate ester acid~ or salts
described abo~e to an aqueous drilling fluld or to an
a~ueous drilling fluid containing a clay dispersed~
therein.
Water-soluble phosphate ester acids and salts
o~ the types described above are avallable commercially
~a ~gls~e~ +~
from a number of manufacturers. For example, Antara~
LE-500, LS-500, LM-600, LE-700, LP-700 sold by GAF
Corporation, New York, New York, are typicaL water
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1049246
soluble phosphate ester aclds usefuL in this invention.
m e amount of the water-soluble phosphate ester acid
or salt added to the well drilling fluid may be only
a minor but surflc$ent amount to substantially increase
the lubricity of the said drilllng ~luid ~s measured,
for example, by torque reduction. Pre~erably, the amount
of the water soluble phosphate ester acid or salt added
to the well drilling fluld will be from about 0.01 to
about 25 percent by weight.
It has been found that the drilllng ~lulds of
this invention whlch exhiblt a high degree of lubrlcity
will not cause an abnormal distortion of mud propertles,
nor cauæe foaming o~ a degree that cannot be controlled
by the use of defoamers which are c~mpatible wlth
drllllng fluid systems. The novel drilling flulds of
this invention show tolerance and stability over wider
ranges in pH and electrolyte concentratlons and they
perform satisfactorily in the various mud systems
(i.e., drilling fluid systems) in general use today~
e.g., low and high pH, æea and salt water, as well a~
polymer, nondisper3ed and inhibiti~e mud systems.
Alkylpolyethyleneoxy phosphate ester acid~
and salts useful in the drilling fluids of this inven-
tion include, for example:
O O
ll 11
C8Hl7(0CH2cH2)4-O_l_oH~ (C8Hl7(ocH2cH2)4-o)2-p-oH~
OH
O
Il 11
C8Hl7(ocH2cH2)5-o-i-o~a~ 8 17( 2 2)12
OH OE

1049Z46
o o
CgHlg(OC~CH2)6-O-P-oH~ (C9Hl9(oc~2cH2)lo )2
OH
O O
ClOH21(C~2C ~)5- I-OH, Cl ~21(0CH2CH2)s_o_p_o
OH OL1
O O
C12~25(0CH2CH2)15-0-P-OH, C14H29(0CH2~H2)35
OH OH
O O
(C14H29(0CH2CH2)9 )2 P ~ C14E2g(0CH2C~2)6-O-P-ONa
ONa
(C6H33(ocH2cH2)4-o)2-p-oH~ C16H33(0CH2CH2)5-0-P-OLi
OLi
Ol O
(C20H41(0c~2cH2)lo-o)2 P ~C20H4l(ocH2cx2)18
OLi
Alkarylpolyethyleneoxy phosphate ester acids
and salts which may be employed in the drilllng n uids of
this invention include, for exQmple:
ICgHlg O
CgHlg_ ~ _ (CH2CH2)4 - O - P - OH,
OH
CgHlg O
(CgHlg ~ _-~~~~(CH2cH2)6 - )2 ~ P - OH,

1~49246
9~19 ~ ( 2 2)7 1 ;
( gHlg ~ ~ (OCH2c}i2)5 - )2
(C10~21 ~ _ (0CH2CH2)12 - )2
o
CloH21 -~ ( 2 2)6
C14H29 0
C12~25 ~ - (0CH2CH2)5 - O - P - ONa, and
OH
(CgHl7 - ~ _ (OCH2cH2)3s ~ )2 P OK
C8H17
Mixtures o~ any of the above-deæcribed alkypolyethyleneoxy
and alkarylpol~ethyleneoxy phosphate ester acids and
salts may likewise be utilized in the novel drilling
fluids of this invention.
The following examples which lnclude test data
illustrate the surprising advantages o~ the use of alkyl-
and alkaryl-polyethyleneoxy phosphate ester acids and
salts in conventional drilling fluids and are to be
considered not limitative.

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EXAMPLE I
In this example one pound per barrel of Antara
LP-700, an alkylpolyethyleneoxy phosphate ester sold by
GAF Corporation, New York, New York in which the alkyl
group is a mixture o~ alkyl~ derived from C12-C16
alcohols and in which the number of ethylene oxide units
is about seven, waæ added to a low pH Louisiana Gulf
Coast drilling fluid treated with 6 pounds per barrel o~
ferrochromelignosulfonate. The effect of the addition of
thls phosphate acid ester on the properties o~ the drilling
~luid is set out in Table 1 which follows:
TABLE 1
EFFECT ON DRILLING ~UD PROPERTIES
-
Plaætic Yield API
Treatment Viæcosit ~ Point pH Fluid-Loss(cc)
Base Mud 20.5 0lO.O 9.2
+l lb per bbl 22 0 9.5 8.8
Antara LP-700
+2 lb per bbL 21 0 9.6 8.8
Ant~ra LP-700
+3 lb per bbl 22.5 1.59.6 8.1
Antara LP-700
Plastic Viscosity is obtained by calculation, æub-
~racting the Fann vlscosity reading at 300 rpm from the
600 rpm reading.
Tested in accordance with the procedure o~ API RP13B,
November 1972.
The above results æhown in Table 1 indicate
that there was no adverse effect of the treatment on the
base mud and that there was no foaming.
The e~fect upon torque reduction of this same
mud waæ obtained uæing a drilling mud lubricity tester
and the results are reported in Table 2 which follows:
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1049Z46
TABLE 2
TORQUE MæASUREMæNTSl ON PHOSPHATE
ESTER ACID TREATED DRILLING MUD
1 lb/bbl 2 2 lb/bbl 2
Time Interval Treatment Treetment
Before Treatment
15 min 8~o 7-9
30 min 8.2 7.9
45 min 8.5 8.5
60 min 8.7 8.8
10A~ter Treatment
15 min 7.0 5.8
30 min 7.0 5.6
45 min 6.2 5.6
60 mln 6.1 5.6
% Reduction of Torque 29.9 36.3
lThe values shown are dial readings whlch are directly
proportional to the torque.
Antara LP-700
The data presented in Table 2 show that sub-
stantiaL reductions in torque requirements are achieved
with the above-identified treatment. Very little
~oaming was obser~ed in these tests.
EXAMPLE II
In a well drilling at 19097 ~eet in which an
8.9 lb/gal sodium chloride brine wa~ being used as the
circulation fluid the torque requirements was measured
and found to be 8000 ft. lbs. After two drums of the
same alkyl-polyethyleneoxy phosphate ester acid as
utilized in Example I had been added over a period o~
5.5 hours which represented one complete turnover of
the mud, the torque at the end of 6 hours a~ measured
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.
1049Z46
was 3500 ft. lbs. This treatment corresponds to a 1/2
lb. of phosphate ester acld per bbl. of drilling fluid.
This data indicates the large reduction in torque
achieved with the modi~ied drilling mud.
EXAMP~E III
To a salt water drilling fluid containing
attapulgite clay (11 lbs/gal) in æodium chloride brine
containing barite as a weighing agent belng used ln
drilling a Gulf Coast well at 15,050 feet there is added
over a period of 4.15 hours (one complete turnover of mud)
su~icient phosphate ester acid of the ~ormula:
C9Hl9
~ - (OCH2CH2)5 _ o - P _
CgHlg/ OH
to effect a treatment of 1.42 lb. of phosphate ester acid
per barrel of drilling fluid. After addltion of the
phosphate ester acid it is found that a significant
reduction in torque requirement is achieved~
EXAMPLE IV
To a calcium base driLling ~luid (calclum
hydroxide in a 10 lb/gal sodium chloride brine) being used
in a West Texas well drilllng at 12480 feet there is added
over a period o~ 3.47 hours (one complete mud turnover)
4 barrels o~ a phosphate ester acid salt of the formula:
o
ClOH21 (C~2cH2),5 - O - I - ONa
CloH21(0CH2CH2)5 - O
It is found that the torque requirement for rotation of the
drill stem is substantially reduced on addition of the
above-described phosphate ester acid salt.
_g _

1049Z46
EXAMPLE V
To a freæh water drilling fluid containing
clay, barite and ferrochromelignosulfonate being used in
drilling a Guli Coast well at 14,485 feet there is added
over one circulatlon 4 bbl of phosphate ester acid o~ the
iormula:
o
(C12H25(0CH2CH2)~ )2
~fter addition of phosphate ester acld it is ~ound that
the drill stem torque requirement is slgniiicantly reduced.
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