Note: Descriptions are shown in the official language in which they were submitted.
77~
--1~
AQUEOUS WELLBORE SERVICE FLUIDS
Thi~ invention relates to aqueous wellbore
servire fluids, including drilling fluids, completion
fluids, work over fluids, packer fluids, fracturirlg
fluids and the like, which may be employed in various
well servicing operations. More specifically, it
relates to thic:kened, substantially solids-f:ree high
electro].yte-containing aqueous fluids which are employed
as a base fluid to prepaxe many types of wellbore
service fluids.
Essentially solids-free aqueous 1uids con-
tai~ing electrolytes have some advantages over clay-
based fluids for preparing wellbore service. fluids
because: (a) they do not noxmally contain undesirable
solids which can cause foxmation damage, (b) they
contain hydration inhibiting materials such as pota~-
sium chloride, calcium chloride or ~he like, which are
important to prevent damage to clay containing forma
tions, and (c) they can be prepared over a wide range
of densities.
The viscosity of high electrolyte-containing
aqueous fluids is, however, difficult to control because
of the high elPctrolyte concentration. Thickened fluids
28,986 F
~2
are desirable for carrying solids, e.g. in cleaning
out wells, drilling and the like. Likewise, thickened
fluids resist water loss, which may be damaging to
petroleum producing subterranean formations.
Hydroxy alkyl celluloses have been employed
to thicken electrolyte~containing aqueous fluids to
improve the solid carrying capacity thereof. Likewise,
starch has been em~loyed to aid in water loss control
of these fluids, but with limited success. However,
these materials are difficult to disperse and dissolve
in concentrated electrolytes at ambient temperature;
the viscosity of the resulting solutions tend to de-
crease with an increase in temperature; and the hydroxy
alkyl celluloses are subject to shear degradation under
normal operating conditions.
Certain quaternary ammonium salts have been
shown to impart viscoelastic properties to a~ueous
solution.s, S. Gravsholt "Viscoelasticity in Highly
Dilute ~queous Solutions of Pure Cationic Detergents",
~ournal of Colloid and Interface Science, Vol.57, No.
3, December 1976, pp. 575-577. Gravsholt showed that
cetyl trim~thyl ammonium bromide would not impart
viscoelastic properties to water but that cetyl tri-
methyl ammo~ium salicylate and certain other aromatic
anion-containing guaternary amines would. In U.S.
Patent 3,292,698, a mixture of cyclohexyl ammonium
chloride and undecane-3-sodium sulfate was taught to
induce viscoelastic properties to a formation flooding
liquid containing less than about 3.5 percent by weight
of sodium chloride. Higher levels of sodium chlvride
were said to destroy the viscoelastic properties of the
fluid. In British Patent No. 1,443,244, a specific
28,986-F -2;
~3~ ~ '7'7~
ethoxylated or propoxylated tertiary amine ls employed
to th,icken an aqueous solution of a strong mineral
acid. U.S. Patent 3,917,536 teaches that cer-tain pri-
mary amines may be employed in subterxanean formation
acidizing solu-tions to retard ~he reaction of the acid
on the formatlon. The amine may be more readily dis~
persed into the acid solution wlth the use of a dis-
persing agent such as a quaternary amine.
It is a feature oE the present invention to
provide a high electrolyte-containing aqueous wellbore
service fluid which has improved VisCOSlty character-
istics over a wide range of wellbore conditions; is
easier to prepare at the well site and has better shear
stability and consistent viscosity over a wide tempera-
ture range.
The improved aqueous wellbore service fluidof the present invention can be employed in well-known
wellbore services such as, perforation, clean-up, long
,term shut-ins, drilling, placement of gravel packs, and
the like. These services are well known in the art and
are taught, for example, in U. S. Patent Nos. 3,993,570;
3,176,950; 3,126,950; 2,898,294 and in C. M. Hudgens et
al "High Density Packer Fluids Pay Off in South Louisiana":
World Oil, 1961, pp. 113-119,.
As employed herein, "ppg" means pounds per -
gallon. Also, when "percent" or "%" are employed, khey
mean percent by weight unless otherwise specified.
28,986-F -3-
The present invention comprises an aqueous
wellbore service fluid comprislng:
water, a suffi~ient quantity of at least one water soluble
salt to increase the density of sald fluid to within a
range of from 12 to 21 lbs/gal, and a sufficient quan-
tity of at least one thickener soluble in said fluid to
increase the viscosity of said fluid to at least 50%
over the viscosity of the salt containing fluid, said
thickener being at least one member selected from the
group consis~ing of: (a) an amine correspondlng to the
formula
Rl - N wherein
R3
Rl is at least about a C16 aliphatic group which
may be branched or stralght chained and which may be
saturated or unsa~uratedi
R2 and R3 are each independently, hydrogen or a
Cl to about C6 aliphatic group which can be branched or
st,raigh-t chalned, saturated or unsaturated and ~hich
may be substituted with a group which renders the R2
and/or R3 group more hydrophilic; (b) salts of said
amine corresponding to the formula
R2
Rl - N -H X wherein
R3
., 28,986-F _4_
,, . ,!
.,
-5~ '7~
R1, R2 and R3 are the same as defined hereinbefore
and X is an inorganic or organic salt forming anion;
or (c) a quaternary ammonlum salt of said amlne corres~
ponding to the formula
R N~ R X~ wherein
R3
R1, R2 ~ R3 and X are the same as hereinbefore
defined and R4 independently constitu~es a group which
has previously been set forth for ~2 and R3, none of
R1, R2, R3 or R~ are hydrogen, and the ~2~ R3 and R4
groups of the amine salt and quaternary ammonium salt
may be fo~ned into a heterocyclic S or 6 member ring
structure which lncludes tne nitrogen atom of the
amine.
The aqueous wellbore service fluid may have a
density rangin~ from'as low ~s about 8.5 ppg, preferably
about 12 ppg, to about 21 ppg. It has been found that
the higher density fluids are more difflcult to thic~en
because of the high electroly~e content. It is at
these higher densities, e.g. about 15 ppg and higher,
-that the practice of the present invention is par-ticu-
larly useful. However, advantages are also achieved in
the lower density flui.ds.
The density is achieved by dissolving one or
more water soluble inorganic salts in water to provide
a substantially solids-free fluid. Naturally occurring
brines and seawater can be employed if desired. Prefer-
ably, the aqueous wellbore service fluid contains at
28,986-F -5-
6~ 16,~
least about 3 percent of a water soluble salt of potassium,
calcium or sodlum. In addition, the aqueous fluid may
contain other soluble salts of, for example, zinc,
lithium, chromium, iron, copper, and the like. Preferably
inorganic chlorides and/or bromides are employed because
of the high denslty which can be achieved, but other
salts such as sulfates, nitrates, etc. can be employed.
The only restriction is that the sâlts must be compatible
with the particular thickening agent employed to thicken
the aqueous fluid. By compatible it is meant, for
example, that the salt does not detrimentally interfere
with the ~thickening function of the thickening agent
and/or undesirable quantities of precipitates are
formed. As examples of useful water soluble salts,
reference may be had to Table I, Column 3, of U. S.
Patent No. 2,898,294
28,986-F -6-
-7~
One preferred agueous wellbore service fluid
contains a mixture of at least calcium bromide and zinc
bromide to provide an aqueous solution having a density
of at least about 15 ppg. The solution may also contain
other water soluble salts such as calcium chloride and
th~ like.
A preferred aqueous solution for use in deep
wells reguiring a fluid having a density greater than
about 15 ppg is one which contains, as percent by
weight:
ZnBr2 about 5% to about 35%;
CaBr2 about 25% to about 45%;
CaCl2 about 5% to about 20%;
water about 30% to about 40%; and
thickener about 0.5% to about 2%.
A preferred thickening agent for the above
d~ined ~luid having a density of above about 16.5 ppg
i8 a tertiary amine of the formula C18H35N(CH2CH2OH)2.
The thickening agent employed in the inven
tion comprises at least one of the thickening agents
defined h~reinbefore under Summary of the Invention.
It is found that with certain solutions, a mixture of
two or more thickeners may be preferred.
Preferaoly, X is an inorganic anion such as
a sulfate, nitrate, perchlorate or halide. A halide,
(C1, Br or I) is preferred, Cl and Br being most pre
ferred. X may also be an aromatic organic anion such
as salicylate, naphth~lene sulfonate, p and m chloro-
benzoates, 3,5 and 3,4 and 2,4~dichlorobenzoates,
28,986-F 7-
t butyl and ethyl phena~e, 2,6 and 2,5~dichlorophenates,
2,4,5~trichlorophenate, 2,3,5,6~tetrachlorophenate,
p-methyl phenate, m-chlorophenate, 3,5,6 trichloropico-
linate, 4-amino-3,5,6-trichlorpicolinate, 2,4-dichloro-
phenoxyacetate, toluene sulonate ~,~ naphthols,
p.plbisphenol A. The thickening agent should be chosen
such that the anion is compatible with the electrolyte
present in the aqueous solution such that undesirable
precipitates are ~ot formed. Also, the specific anion
chosen will depend to some clegree on the specific amine
structure.
The thickening agent is employed in an amount
which is sufficient to increase the viscosity of the
aqueous fluid at least 50 percen~ ov~r the viscosity
thereof without the addition of the thickener as meas~
ured on a Haake Rotovisco Viscometer at about 20C and
a shear rate of 160 sec 1
The exact quantity and specific thickener or
m.ixture oE thickeners to be employed will vary depending
on the concentration o and specific soluble salt~s)
employed to make up ~he solution, the viscosity de-
sired, the temperature of use, the p~ of the solution,
and other similar factors. The co~centration of the
thickener can range from about 0.05 to about 5 percent,
preferably from about 0.2 to about 3 percent of the
aqueous wellbore service fluid. Simple laboratory
procedures can be employed to det~rmine the optimum
conditions for any particular set of parameters. For
example, when a non-protonated amine is employed as the
thickener, the pH of the aqueous fluid can affect to
some degree the effectiveness of particular amines.
More acidic solutions are required for some amines to
be dissolved therein. It is thought that this is
28,986-F -8-
~5~
_g _
because the amine must become protonated before it
will become effectively dissolved in the fluid.
~ pecific wellbore service fluids found to be
useful in the practice of the invention are set forth
in the following Table I.
28,986-F 9-
~ ~ 7~
h O
rl
3 ~ ~ ~
~-1 a) ~1
~ ~3 O
O U~ ~ ~
O ~q ~t
O #
a) o t.) o ~ ~ ~ ~I t` a) ,i r~ co . ,
O u~ h rl o ~D ~ r` ~ Ln o ~ o ~D ~ ~ ~ ~
V O
V~
U~ Nl C`l N N N N N N ~ N ~
h h ~ ~I h ~ N N N N
q~ m a: m u m o ~ m v m m ,~ h
m
3 ::1 V U V V UV V N O V N
o
~q
O h
U~ r~
h ~ ~ ~1 0 o o oo o C` o ~
O rl ~1
H ~ l U
~! C) o~
a) o a~
h~
P~ ~ O
~1 ~
,1 ~ o
h ~ tn
O ~
m~
3 0
V o ~ _ o o o ~) o o V
o
g o
~o
U~
28, 986-F -10-
35~o9~
N
h ~ ~ O 0 ~
O U~ U~ N ~ N ~ N ~ ~ t")
~ ~ ~ U~
~ O ~ #
rl ~7 0 ~ O O d' O O ~ O O ~ O ~
O p.~ ~) Lt') ~ N r l ~ N r-l ~ N ~I tr~ N O
O Lt)
~1 ~1 N ~J M N N ~1 N N N ~1 N N S-l
3 C) C~ C~ N C.) ~) ~ ~ C~ M U V M X
~
~ o ~ ~ ~ ~ ~
o ~ ~
~ ~ o o c~ o o
~ o ~ ~o
C) O P~ h p~ ~3 ~:/ O
~ o u~ ~ o a~
C ~ r ,~ U
~ ~ ~ ~ O O
N~ Ln
rl
c~ o
o ~ e
o ~
O
o *
28, 986-F
-12-
Examples of other thickeners which can be
employed include oleyl methyl bis~hydroxyethyl) ammonium
chloride; octadecyl methyl bis(hydroxyethyl) ammonium
1 bromide; octadecyl tris(hydroxyethyl3 ammonium bromide;
and octadecyldimethylhydroxyethyl ammonium bromide
cetyldimethyl hydroxyethyl ammonium bxomide; cetyl
methyl bis(hydroxyethyl~ammonium salicylate; cetyl
methyl bis(hydroxyethyl)ammonium 3,4-dichlorobenzoate;
cetyl tris~hydroxyethyl)ammonium iodide; bis(hydroxy-
ethyl) soyaamine; N~methyl, N-hydro~yethyl tallow
amine; bis(hydroxyethyl)octadecylamine; cosyl dimethyl-
hydroxyethyl ammonium bromide; cosyl methyl bis(hydroxy-
ethyl) ammonium chloride; cosyl tris(hydroxyethyl)
ammonium bromide; docosyl dimethylhydroxyethyl ammonium
bromi.de; docosyl methyl bis(hydroxyethyl~ammonium
chloride; docosyl tris(hydroxyethyl)ammonium bromide;
hexadexyl ethyl bis(hydroxyethyl)ammonium chloride,
hexadecyl isopropyl bisthydroxyethyl)ammonium iodide;
N,N-dihydroxypxopyl hexadecylamine, ~-methyl, N-hydroxy-
ethyl hexadecylamine; N,N-dihydroxyethyl octadecylamine,
N,M-dihydroxypropyl oleylamine; N,N-dihydroxypropyl
soya amine; N,N-dihydroxypropyl tallow amine; N-butyl
hexadecyl amine; N-hydroxyethyl octadecylamine; N-hydroxy-
ethyl cosylamine; cetylamine, N-octadecyl pyridinium
~5 chloride; N-soya-N-ethyl moxpholinium ethosulfate;
methyl-l-oleyl amido ethyl-2-oleyl imidazolinium~methyl
sulfate; methyl-1-tallow amido ethyl-2-tallow imidazo-
liniwn-methylsulfate.
It has been ound that as the concentxation
of the soluble salt in the aqueous solution increases
the thickener should be more hydrophilic. This can be
achieved by employing thickeners having a specific
combination of Rl and R2-R~ groups to provide such
28,986-F ~12-
-13-
hydrophillic character. It has also been found that
the X component of the thickener affects, to some
degree, the effectiveness of the thickener in specific
a~ueous solutions. For example, organic anions ~x )
generally are found to function more effectively in
lower density fluids, e.g., less than 49% CaBr2, because
of their solubility. Thickeners having an inorganic
anion cons~ituent are generally more effective over a
broader density range than are thickeners containing an
organic anion.
To prepare the a~ueous wellbore service fluid
of the present invention, the thickener is added to an
aqueous solution to which has been dissolved a quantity
of at least one water soluble salt to pxovide a solution
having a desired density. Standard mixing procedures
known in the art can be employed since heating of the
solution and special agitation conditions are normally
not necess~ry. Of course, if used under conditions of
extreme cold such as found in Alaska, normal heatin~
procedures should be employed. It has been found in
som~ instances preferable to dissolve the thickener
into a lower molecular weight alcohol prior to mixing
it with the aqueous solu~ion. The lower molecular
weight alcohol (e.g., isopropanol) functions as an
aid to solublize the ~hickener. Other such agen~s can
also be employed. A defoaming agent such as a poly-
glycol may be employed to preven~ undesirable foam
during the preparation of the service fluid.
In addition to the water soluble salts and
thickening agents described hereinbefore, the aqueous
wellbore service fluid may contain other co~ventional
constituents which perform specific desired functions,
28,986-F -13-
-14-
e.g., corrosion inhibitors, propping agents, fluid loss
additives, and the like.
The 1uids defined herein can be employed in
standard wellbore treatment services employing tech~
niques and equipment well known in -the art. They may
be used to control a well during certain wellbore
operations such as durins the pex~oration of liners
and the like. They can also be employed as packer
fluids, drilling fluids and the like.
The following examples are illustrative o
aqueous wellbore service fluids of the present invention.
ExamE~e_l
The rheological behavior of 0.5 percent oleyl
methyl bis(2-hydroxyethyl) ammonium chloride in a 53%
aqueous CaBr2 wellbore service fluid over a shear rate
range of 0.6-3900 sec l was determined. The fluid was
prepared by combining
0.21 g of C18~35N ~CH~C~20H)~ Cl
CH3
(added as 0.29 g of commercially available 75%
active Ethoquad 0/12) with 39.63 g of 53~ CaBr2
aqueous soLution.
The solution was prepared by adding the
Ethoguad 0/12 to the 53% CaBr2 solution and shaking on
a mechanical shaker overnight at room temperature. A
clear, very viscoelastic solution with a layer of
stable foam on top resul-ted from this procedure.
The viscosity of -the so prepared fluid was
measured at three temperatures (approx. 23C, 43C and
28, 986-F -14~
-15-
60C) as a f~mction of shear rate. The lowest shear
rate (0.66 sec 1) measurement was determined employing a
Brookfield LTV viscometer with a UL adaptox. Twenty
milliliters (ml) of solution were slowly removed from
the bottom of a sample bottle to avoid introducing foam
into the annulus between the rotating cylindrical bob
and the stationary cup wall. The calculated viscosities
at the shear rate of 0.6 rpm (0.66 sec 1) are tabulated
below in Table II for the three temperatures. The
readings changed with time so the viscosity in centi-
poise ~cps) is reported in Table II as a range and not
as a single value. This characteristic indicates the
elastic, non-Newtonian nature of the solution.
TABLE II
Temperature No. of Viscosity
C_ Readings (cps)
23 4 470 - 620
43 3 720 - 750
59.S-60 3 370 - 530
The viscosity of samples taken at higher shear
rates were measured on a Haake Rotovisco using the NV
double~gap cup system. The rotor is a hollow cylinder
wh.ich fits over a stationary cylindrical stator on the
inside with the othex cylindrical stator being the inside
wall of the stainless steel cup containing the sample
solution. The eight ml of fluid required for the test
were delivered from a hypodermîc syringe. Torque is
recorded on a single pen strip chart at successively
increasing shear rates. Shear rate is increased
stepwise by increasing the rotor xpm.
28,986-~ -15-
16-
Individual torque readings were taken at
three temperatures. The t~mperature, shear rat~ and
calculated viscosities are set forth in the following
Table III.
TABLE III
Teml~. She~r Rate (sec 1) Viscosity ~cps)
25C 5.4 54
" 10.8 81
" 21.6 58.5
" 43.1 45
" ~6.2 32.6
" 173 26.4
" 345 20.3
" 690 16.6
" 1380* 13.9
" 1380* 17.0
" 2760 14.0
" 173 26.4
43.1 5.4 169
" 10.8 117
" 21.6 g9
" 43.1 86.3
" 86.2 60.~
" 173 37.1
~5 " 345 21.9
" 690 16.1
" 13~0* 12.2
" 1380* 13.4
" 2760 ll.g
" 173 38.5
61.6 10.8 99
" 21.6 67.5
" 43.1 56.3
" 86.2 40.5
" 173 28.4
" 345 20.5
" 690 14.5
" 1380* 10.5
" 1380* 12.3
" 2760 8.5
" 173 28.7
* Duplicate readings at different head scales of the
instrument.
28,986~F -16
-17
Example 2
A 40.3% aqueous CaBr2 solution was thickened
with 1% of cetyl trimethyl ammonium salicylate, ~C16-
H33(CH3)3N salicylate ] as follows:
0.131 g of salicylic acid was mixed with 9.47
g of 0.1 M C16H33N (CH3)30H solution and the resulting
solution mixed with 30.4 g of a 53% aqueous CaBr2
solution.
Af~er dissolu~ion, a clear, slightly yellow
solution of high viscosity was formed.
Viscosity measurements were made on a Brook
field LTV viscometer with UL adaptor and the results
are tabulated below:
TABLE IV
15Shear Rate Temp.No. ofViscosity
(~ec 1~ C ~eadin~ s~ _
. _
0.33 23 3524 - 4g2
0.66 23 Off Scale
0.66 27.5 3 317 - 307
~00.66 37.5 3 lg5 - 144
0.66 50 3 62 - 66
Example 3
A quaternary ~mmonium salt of the formula:
C18H35N -~CH2CH20H)2 Cl (Ethoquad 0/12
CH3
28,986-F -17-
--18--
was employed to thicken an agueous electrolyte solution
as follows.
A solution was prepared by mixing 0.33 g
Ethoquad 0/12 with 49.67 g of a solution containing
17.2% CaC12/43.7% CaBx2/39.1% H20, having a density of
about 15 ppg. After dissolving by mechanically
shaking, there was some foam. The aqueous solution
also contained 0.4 perce~t by weight of a corrosion
i~hibi~or comprising a mixture of N-octyl pyridinium
bromide and ammonium thiocyanate. Using the pro-
cedures of Example 1, the rheolo~y of the fluid was
measured on the Haake Rotovisco NV system and the
calculated viscosity and shear rate da~a is set forth
in the following Table V.
28,986-F -18-
--19--
TABLE V
Shear Rate ( sec 1 ~
2S.3C 43.1 49.5
~I 86.2 47 3
" 173 ~4 7
" 3~5* 40.8
" 345* 41. ~
" 690 43.6
" 1380* 38 5
" 1380* 36 ~
" 2760 33.6
" 3902* 32.3
" 3902* 31.5
" 13~0 37 4
" 690 44 6
" 6gO 3~ 1
~' 345 gl 1
" 173 44.4
Il 86.2 47-3
20 45.5 21.6 75.6
" 43 ~ 1 72
" 86.2 60.8
" 173 50.1
" 345 40 8
" 3~5 36 5
" 690 35.2
" 1380 29.4
" 2760* 26.1
" 2760* 24.8
" 3902 23.1
" 1380 30.3
" 690 33.9
" 345 40.9
" 173 50.1
3~ " 86.2 60.8
62.7 10.~ 126
" 21.6 105.3
" ~1.6 117
" 43.1 94.5
" 86.2 77.4
" 173 63.5
" 345* 47.3
" 345* ~9.6
" 690 35.7
" 1380 25.8
28,986 F -19-
-20~
TABLE V (Continued)
Tem~. Shear Rate (sec ~ Viscositx (cps)
62.7 2760 19.4
" 3902* 18
7~ 3gO2* 17.3
" 13~0 26.1
" 690 35.2
" 345 45.9
" 173 ~4.5
" 86.~ 82.1
" 43.1 105.3
85.7 21.6 75.6
" ~3.1 71.1
" 86.2 61.4
" 173 48.9
" 345* 37.5
" 345* 3g.1
~90 , 30
" 1380 21.9
" ~760 16.6
" 3902 13.7
" 1380 21.3
" 69~ 29.7
" 3g8 37.9
" 173 51.1
" 86.3 64.4
" 43.1 76.5
* Duplic~te readings at different head scales of the
instrument~
Example 4
An agueous solution was made up at room
temperature containing 0.33 g of Ethoguad 0/12 (Example
1) in 49.67 g of a 15.5 ppg aqueous solution containing
15.1% CaCl2, 40.7% CaBr2, 6.8% Zn~r2 and 37.4% water.
The resulting solution was clear and viscous. Viscosity
measurements are set forth in the following Table VI.
A similar solution was prepared at room
temperature as a~ove except that a mixture of amines
was employed. The solution contained 0.25 g of
28,986~F -20~
-21~
Ethoquad 0/12, 0.13 g of C16H3~N ~C~3)3 Cl ( qu
16-50/50% active) and 49.62 g of the 15.5 ppg density
aqueous solution defined directly hereinbefore. The so
prepared solution was viscous and clear. Viscosity
measurements were made as described directly herein-
before and are set forth in the following Table VII.
The solution containing the mixture of
thickening agents demonstrated higher viscosities than
did the solution containing the single thickener. This
demonstrates the fl xibility of being able to control
the viscosity of high density aqueous ~luids by the
practice of the present inven~ion.
28,986-F -21
~ t7~
- 22 -
TABLE VI
Temp . C Shear Rate ( sec l ~ Viscosity ( c~s
10.8 133
" 21. . ~ 113
" 43.1 93.9
" 86.~ 80.8
" 173 68.5
" 345* 44.4
" 345* 47.
" 690 2g .7
" 13~0 21.2
" 2760 16.6
" 3902 15.0
" 13~0 21.5
" 345 4~.5
" 173 75 ~ 7
" 21. ~ 111.9
21.6 82.9
" 43.1 74.3
" 86.2 63.8
" 173 54.2
" 345* 4~ .3
" 3~5* 40.5
" 6~0 27.3
" 1380 1~ .4
" 2760 12.9
" 3902 ~1.4
" 345 40.0
~3.1 26.6
" 86.2 27.4
" 173 27.4
" 345 24.6
" 690* 19.8
" 690* 20.0
" 1380 14.9
" 2760 10.9
Il 3902 9 7
87 173 4.4
" 3*5 4.2
" 690 4.4
" 1380 5.0
" 2760 6.8
" 3902 7.2
" 2760 6.5
" 138~ 5.6 5.1
* Duplicate readings at different head scales of the
instrument .
28,986-F ~22
~35~
-23-
TABLE VII
Temp. CShear Rate (sec_1~ Viscoslty (cps)
10.8 344
21.6 260
43.1 164
86.2 102
173 63.8
345* 42.1
345* 48.7
10 " 6~0 37.8
' 138Q 31.1
~760 23.7-20.3
3902 18.6~26.3
15'' 1385 375 7
173 105
86 173
~6 153
55.2 10.8 266
20~' 21.6 167
32.7 128
86O2 101
" 172* 79.2
Z5,, 172* 867 56
690 43.3
1380 40.5
2760 34.7
3902 33 5
345 62.2
" 173 69.4
89 10.8 117
35'' 32 7 47-3
" 86.2 31.3
" 173 22
345 12.5
690 7.8
40'' 1380 5,5
2760 4.1
" 3902* 4-3
,. 3902* 4-3
" 690 4.3
5 * Duplicate readings at different h~ad scales of the
instrument.
28,986-F -23-
7~9
~24-
The following illustrates the fact that the
amount of thickener and mixtures thereof which are
effective can vary and that preliminary screening tests
should be made prior to field use. The same thickening
agent was employed as in the immediately preceding
Example 4 except in different proportion: 0.17 g of
Ethoquad 0/12 and 0.25 g Arquad 16-50 were mixed with
49.58 g of the same 15.5 ppg density solution defined
in Example 4 hereinbefore. A very thick and viscoelastic
fluid was formed. However, there was some insoluble
materials ~loating on top. Upon heating to 70C, the
viscosity became low and the solution became unstable
and formed two distinct phases. ~he fluid would not
find general utility as a wellbore service fluid as
contemplated herein.
Example 5
A variety of different thickeners were screened
to determine their effectiveness to thicken an aqueous
solution containing 53% by weight o~ CaBr2. The char-
actexistics of the resulting fluids are tabula~ed in thefollowing Tables VIII, IX and X. When viscosity data is
shswn, it was calculated employiny data generated on a
Haake Rotovisco NV system as described hereinbefore and
set forth in one o~ the following Tables IX and X.
28,986-F 24-
~~ o
-u~ o
u~ h
a)u~
O
R ~
OO ~ r~ O O ,1 0 0
:~ N . u~ u2 N :1 ~
O ~1 0 ~ O O p~l O O
U~ O ~ tQ U~
~_1 ~1~~ lQ ~ ~ ~ h. ~ )~ ~
q~ ~O N ~ O ~ a)~ ~ ~1) 0
O ~I h rl rl ~ ~ r~
~ U
U~ ~ O
O 3a.~ 5 H ~ ~_~
tl3 o~ o ~ o c~
~10 U IU O u~ O rt l--t rt
E3 m t~ u~ o ,~
Ort OO~
H
~t
C) ~ E~ Ll~
O O O
~t O O O Il-) O O c:~ O
m
~t ~
tr~l
~ ~ +Z~ a +z~
~ U~ ~ ~P ~ ~
.,, . ~ ~ ~ ~ P: = CO
rt ~Dh 0
~R ~ ~ ~ V
U ~ V ~
o
~)
~: m v a
28, 986- F -25-
~57~7~
--26--
tn
a)
N
S~ O O
. ~
~ ~ ~ O O
~1 h ~ h S-l
C) 3 V V
O ~
,_ c) Q~ O a
~ t~ ~ ~1
'~ ~ ~ ~
,~ ~ h E~
~v~
p: = _
+~_~
~ Lr~ ~
U .
S~
28, 986-F 26-
~27-
TABLE IX
Temp. C Shear Rate ~ec ll* Viscoslt~ (cps)*
5-4 492~6**
" 10.8 3~9.2
" 21.6 219
" 43.1 1~7.
" 8~.2 300.1
" 172.5 273.1
il 345 1~6.~
" 689.9 106.9
5.4 2728.9
" 21.6 1131.3
" ~6.2 S33.3
" 172.~ 3~8~2
" 345 1~5.1
" 689.9 129.3
" 1379.8 73.7
" 2759.7 39.9
5.4 1278.2
" 10.8 1035
~1.6 794 5
" 86.2 347.6
" 172.5 211.6
~ 689.9 73,7
" 1379.8 44.7
" 2759.7 23.3
* Da~a as printed out from computer interfaced wi-th
Rotovisco NV.
** Since thickener was not entixely in solution, the
lower viscosities were expected.
28,986-F -27-
-28-
TABLE X
Tem~. CShear Rate (sec 1)*Visco~it, (rps~
~.4 1830.8
" 21.6 561.3
5 " 86.2 161.g
" 172.5 86.4
" 345 57.2
" 1379.~ 15.7
5.4 12~7.S
10" 10.8 676.5
" 43.1 215.5
" B6O2 455.5
" 172.5 281.7
" 6~9.9 9~.~
15" 1379.8 56.5
90.3 5.4 1555.~
~' 10.8 125g.8
" 21.6 872.2
i' 8~.~ 261.2
20" 172.5 149
" 689.9 47.5
" 1379.8 27.9
2759.7 17.1
" 3902.~ 13.7
2 5 * Data as printed out from compu~er inter~aced with
~otovisco NV.
Ex, ~ mparative Tests
~n electrolyte solution of about 16 ppg
density was prepared containing 1~ ZnBr2; 37% CaBr2;
30 12% CaC12 and 37% water. The fluid los~ property of
this fluid was determined employing a thickener as
described hereinafter. A particulate ~luid loss
additive was also employed in some of ~he tests. The
particulate fluid loss additive comprised a mixture of
particulate aliphatic hydrocarbon resins~ A comparative
series of ~ests were run employing hydroxy e~hyl cellu-
lose as a fluid loss additive. The fluid loss tests
28,986-F -28~
-29-
were run on Brea Sandstone according to the API-RP39
standard fluid 105S test using 1 inch by 1 inch Brea
sandstone instead of filter paper. All the tests were
I conducted at 150F and 600 psi. The thickener con-
5 sisted of Ethoquad 0/12 (Example 1). To each 300 ml
fluid sample containing the thickener, one drop of
polypropylene oxide was added to control foaming. As a
comparison, several solutions containing hydroxyethyl
cellulose were tested in the same manner~ The hydroxy-
ethyl cellulose was a commercially available product
purchased under the trademark Vatrosol 250HHR~ The
results of ~hese ~ests are set for~h in the following
Table XII. This data illustrates the favorable fluid
loss properties achieved by the practice of the
invention.
28,986-F -2g-
-30-
TABLE XII
_ _ _ _
Time (Minutes~Fluid Loss (milliliters)
ke
~ 2.6
54 6.
9 12.6
16 21.2
32.6
39.0
B. Test Solution-1% Thickener and 0.5~ Particulate
Fluid Loss Additive
__ _ _,_ _ , ... _ . _ ..... __
1.0
4 1.6
g 2.0
1516 2.6
3.0
3.~
Test Solution (0.22%3 Hydroxyeth ~ Cellulose
1 4.6
204 14.0
9 30.0
16 57.0
95.0
Not measured
28,986-F -30~
~31-
D. Test Solution-1.5 lb/gal (0.22%~ Hydro~yethyl Cellulose
~us 5~QParticulate Fluid Loss Additi e
1 3.6
4 8.0
9 11.0
16 12O2
13.0
13.2
E. Test Solut_on-0.2~_Thlckener
1 ~.
4 7.0
g 15.6
16 27.0
~5 47.0
15 30 Sg.0
F~ Test Solution-0.2% Thickener plus 1.5% Particulate
Fluid Loss Additive
_~
1 .0
47.0
~0 9 3.2
4.8
Z5 . 7~2
8.4
Example ?_and Comparative Tests
Several thickening agents were evaluated
for use in a~ueous fluids having densities of greater
than 15 ppg. In each example (data set forth in the
following Table XII), 0.9 ml of a thickener was
added to 35 ml of the indicated high density fluid.
The thickener was employed as a 75 percent active
solution in isopropanol. The resulting mixtures
28,9g6-F -31-
-32-
were shaken on a mechanical shaker for 3 hours and
thr~e days later the viscosities were measured at
room temperature ~about 75F) employing a Brookfield
viscometer at a shear rate of 60 rpm employing a
number 2 or 4 spindle. The data employing th number
4 spindle is marked with an asterisk. The data indi~
cates that ~he thickening agents were more effective
in the higher density fluids.
The results are tabulated in the following
Table XII.
TABLE XII
_Vlscosity (cps)
15.5 pp~16.5 ppg 17.5 ppg
Thicken n~ Agent ~ 3) ~ L___
bis(2-hydroxyethyl)- 45 3250* 850*
oleylamine
bis(2-hydroxyethyl)- 40 2500* 550*
soyaamlne
bis(2-hydroxyethyl)~ 40 1900* 420
tallowamine
bis(2-hydroxyethyl)- 45 300* 60
octadecylamine
~one 28 25 25
none 50* 40* 40*
(2) Solution contained 15% CaCl2; 41% CaBr2; 6% ZnBx2
and 38% H20.
(3 ) Solution contained 10% CaC12; 34% Ca~r2; 20% ZnBr2
and 36% H20.
( 4 ) Solution contained 6% CaCl2; 28% CaBr2; 33% ZnBr2
and 33% H20.
28,986-F 32--
33-
Example 8
A solu~ion was prepared by dilution of a 40 g
sample of 1.5% solution ~0.6 g of C22H46(CH3)2N C2H4HB
+ 39.4 g of 17.5 ppg f~uid) with 80 g of 17.5 ppg fluid
to prov1de ~.5% of the surfactant in the solution. The
17.5 ppg fluid contained 6% CaCl; 28% CaBr2; 33% ZnBr2,
and the remainder water. The sample was heated to
approximately 85C with occasional shaking to produce a
clear, homogeneous solution which was hazy at room
temperature. The viscosity was measuxed in a ~aake
Rotovisco as described in Example 1. These data axe
tabulated in Table XIII and show good thickening at
room and intermediate tempexatures, and falling off at
8~C. The viscositiPs are from a computer printout
inter~ace with the Haake Rotovisco.
28,986-F ~33~
-34~
TABLE XIII
Temp- C Shear Rate (sec 11 .15co~iLy Ir~5
26 5.4 1025
" 10.~ 789.7
" 21.6 439.~
" ~3.1 241.7
86.2 149.7
" 172.5 107.1
" 345 67.6
10 ~I 689.9 48.9
" 1379.8 38.7
" 2759.7 31.~
" 3902.4 29.6
54 5.4 635
15 ~' 10.8 436.7
" ~1.6 31705
" 43.1 ~05.3
" 86.2 166.6
" 172.5 64.9
20 ~' 3~5 35.7
" 689.9 25.1
" 1379. a 17
" 2759.7 14.1
ll 3902.~ 13.2
25~5~.5 86.2 10.1
~' 172.5 9-3
" 345 8.7
" 689.9 8.4
" 1379.~ 8.4
30 ~' 2759.7 7.1
" 2759.7 9.7
" 3902.4 10.4
28,986 F 34-
-35-
Example 9
A solution was prepared by diluting a 50 g
sample of 1-5% solution ~0.75 g of C20H41(CH3)2N C2H40HBr
~ 49.25 g of 19.2 ppg fluid) with 50 g of 19.2 ppg
fluid to provide 0.75% of the thickening agent in the
fluid. The fluid contained 56~ ZnBr2~ 19% CaBr2 and
25% H20. The sample was heated to 85C to provide
rapid dissolution. The appearance at this temperature
was a clear viscous solution which was also clear
when cooled to xoom temp~rature (21-22C). After
standing a number of days, the sample tended to be-
come hazy although warming (approximately 30-35C3
restored the original clear appearance. The viscosity
of the fluid was determined as a function of shear
rate on a ~aake Rotovisco with a computer printout
as previously described. The results are set forth
in the following Table XIV.
28,986-F -35-
-36-
TABLE XIV
Temp. C Shear Rate (sec 1) Vi _OI~EL~
27 10.8 104.~
" 21.6 116.8
" 43.1 87.8
" 86.2 66.5
" 172.5 50.1
" 345 39.
" 689.9* 34.3
" 689.9* 34.3
" 1379.8 29.5
" 27~9.7 25.8
" 3902.4 24.5
5 4 4 13~.6
" 10.8 125.7
" 5.4 13~.6
" 10.~ 12~.7
" 21.6 123.3
" 43.1 117.2
" 86.2 99.3
" 172.5 79.1
" 345 63.8
689.9 4~-5
" 1379.8 35.7
" 275~.7 27.6
" 3902.4 24.~
~1.6 50.8
" 43.1 47.1
" 86.2 g4.3
" 172.5 42.6
" 345 3g.1
" ~89.9* 36.8
" 68g.g* 36.8
" 1379.8 31
" ~75g-7 25.6
" 3902.~ 22.9
* Duplicate readings at different heat scale of
instrument.
28,g86-F ~36-
