close

Вход

Забыли?

вход по аккаунту

?

Патент USA US3070553

код для вставки
he
_
3,70,543
Patented Dec. 25, 1962
2
3,070,543
LOW SQLES DRELLENG FLUID
Platho P. Scott, .112, Tulsa, 81th., assignor to Pan Ameri~
can Petroleum Corporation, Tulsa, Okla, a corporation
of Delaware
No Drawing. Filed Mar. 25, 1960, Ser. No. 17,484
12 Claims. (Cl. 25.2-55.5)
EXAMPLE I
Various concentrations of bentonite were dispersed in
‘fresh water and the drilling ?uid properties were measured.
These properties were compared with those of the same
bentonite dispersion containing several concentrations of
the preferred polymer with and without soda ash. The
results are presented in Table I. The plastic viscosities
and yield values were measured with a multi-speed Faun
This invention relates to low solids drilling ?uids. More
viscosirneter. The instrument and method of use are
particularly, it relates to an additive for giving a drilling 10 described in detail in the article “Meter Aids Exact Mud
?uid some of the properties of a high-solids mud while
Control,” by J. C. Melrose and W. B. Lillenthal on page
having a drilling rate close to the high rate which is ob
136 of the July 1, 1952, issue of World Oil. The funnel
tainable with water.
viscosities, ?uid losses and Stormer viscosities were
For several years, clear water or Water containing a low
measured by the equipment and methods described in the
solids content has been used as the circulating ?uid in well
API Recommended Procedure 29. The polymer in these
drilling operations because of the high drilling rate which
tests was the copolymer of vinyl acetate and maleic anhy
results. Two of the difficulties are low viscosity, which
dride containing between 1 and 11/2 times as many moles
results in failure to lift bit cuttings e?iciently, and high
?uid loss, which results in excessive loss of Water to the
drilled permeable formations. Obviously, it would be
desirable to have a drilling ?uid possessing the higher
viscosity and lower ?uid loss properties of high solids
muds, but retaining most of the high drilling rate proper
ties of clear water. Preferably, the drilling ?uid should
of vinyl acetate as maleic anhydride and containing suffici
ent lime to form a partial calcium salt of the polymer.
When concentrations are stated in pounds per barrel, a
42 gallon barrel is intended.
Table I
Concentration of polymer (lb/bbl)
include means for preventing the accumulation and sus
pension of a high concentration of drilled solids in the
drilling ?uid. Preferably also, the drilling ?uid should
be compatible with and responsive to treatment with or
dinary drilling ?uid additives.
An object of this invention is to provide a drilling ?uid
having a high drilling rate, high viscosity, and a low
?uid loss. Another object of the invention is to provide an
additive for water to form such a drilling ?uid. An object
of the invention is also to provide a method which will
permit high drilling rates, but which will effectively re
move cuttings and prevent excessive loss of water to for
mations drilled.
In general, I accomplish the objects of my invention by
the use of a particular type or" clay together with a poly
mer. The clay must be of the montmorillonite class.
Preferably it should be bentonite. The polymer is a
vinyl-maleic copolymer. In the copolymerization the
vinyl radical may be introduced through compounds such
0
0.025-
0.05
0.10
0.20
Gouc. soda. ash (lb./
bbl.) ______________ __
0
1
0
1
0
1
0
1
0
1
3 percent bentonite:
Plastic vis. (cus.)_
Yield value (lb./
100 51ft.) ____ _-
Funnelvis.(scc.)_
2 __._
4
8
4.5
9
45
9
6
9
2
12
1
14
2
14
3
6
30 _.-. 33
39
32
41
33
45
37
45
22
32
16
.-__
‘
1.5
.___
Fluid loss (er/3O
min.) _________ __
Stormervis.(cps.)_
26
6
____ -___ ____
23
..__ ____ 28 __.__
25
3O
17
_.___
16
33,
4 percent bentonite:
Plastic vis. (cps)-
4
6
10
11
12
12
10
16
13
22
10081112.) ____ __
1
13
15
25
10
31
6
32
18
27
Funnel vis. (sec).
32
43
48
56
49
66
45 126
55
292
Yield value (lb./
Fluid loss (cc./30
5 percent bentonite:
6
7
15
25
18
19
18
19
26
34
as the ester or ether, for example, vinyl acetate or vinyl
100811.03.) ____ ._
2
23
30
40
22
57
15
64
22
54
Funnel vis.(sac.)_
34
50
99
176
111
270
methyl ether. The maleic radical may be introduced
through compounds such as maleic acid, maleic anhydride
Fluid loss (co/30
19
20
..__
22
____
._-_
or salts or amides. Preferably, the ratio of vinyl to maleic
radicals is one to one. The amount of vinyl radicals may,
however, be as much as about 1.5 times the amount of
maleic radicals on a molar basis. The preferred copoly
mer for my purposes is the copolymerization product of
equal molar amounts of vinyl acetate and maleic anhy
dride prepared as further described in US. Patent 2,476,
474 Baer. As described in more detail in the Baer patent,
Plastic vis. (CDS.)_
Yield value (lb./
ruin.) _________ __
86 ____ _-_. ____.
Stormer vis.(cps.).
6 percent bentonite:
Stormervis.(cps.)_
-___
____.
____
__--_
._._
.._-
...
A comparison of the properties of the 3 percent
bentonite slurry containing 0.20 pound per barrel of the
polymer, but no sodium carbonate, to the properties of
the, 5 percent bentonite slurry containing no treatment
should be made. It will be apparent that by substitut
ing 0.2 pound per barrel (0.06 percent) of the polymer
the polymerization should be carried to such an extent as to
for 2 percent bentonite about the same or slightly im
produce a viscosity between about 1 and 3 centipoises at
proved drilling ?uid properties are obtained. It is well
25° C. when in solution in water at a concentration of
known in the art that a reduction of 40 percent in the
bentonite concentration provides a substantial increase
in drilling rate. Further data on this point are found in
0.4 percent by weight. This polymer may be used either
unneutralized or as a salt, preferably the calcium salt.
Example Vll and VIII.
Tests of 4 percent bentonite slurries containing no
treatment,
containing 1 pound per barrel of soda ash,
most clays, but will bene?ciate montmorillonitic clays, and
that it be water-dispersible to an extent of at least about 65 and containing the soda ash plus 0.025 pound per barrel
of polymer demonstrate how the polymer enhances the
0.5 pound per 42 gallon barrel of water. When the term
treating action of the sodium carbonate. Looking at it
“water-soluble copolymer” is used hereinafter, a copoly
another way, the data show how the sodium carbonate
mer being water-soluble or water-dispersible to at least
enhances the action of the polymer. Additional informa
this degree will be intended. My invention will be better
tion on this point is presented in Example IV. Data
understood by consideration of the following data which 70 on the effects of the polymer on the action of other treat
for purposes of convenience are presented in the form of
ing chemicals are presented in Example V. The com
examples.
binatione?ects of soda ash and the polymer are claimed
The principal requirements of the copolymer are that
it be polymerized to such an extent that it will ?occulate
‘3,070,543
4
3
in U.S. patent application Serial Number 17,481, ?led
March 25, 1960, by Paul E. Robertson.
It will be apparent from the data in Table HI that
oil is not only compatible with the polymer and bentonite,
The data show that the concentration of bentonite in
the drilling ?uid should be at least about 3 percent by
weight if the polymer is to produce very much effect.
The data also show that the amount of bentonite should
not be very much greater than 5 percent by weight or
the eifect may be too great. Obviously, this range can
be extended somewhat by using large amounts of poly
but serves to produce an additional viscosity increasing
effect.
EXAMPLE IV
Samples of a 3 percent bentonite suspension contain
ing 0.05 pound per barrel of the polymer described in
Example I were treated with various amounts of sodium
carbonate. The Stormer viscosities of the resulting drill
mer with a low concentration of bentonite or a small 10 ing ?uids are reported in Table IV.
amount of polymer with a high concentration of benton
Table IV
_
ite. The practical limits, however, are about 2 and 7
Stormer
percent of bentonite. The lower limit is set by the high
viscosity
cost of the large amount of polymer required to obtain
(c.p.s.)
good effects. In addition, high concentrations of the 15 Concentration of sodium carbonate (lb./bbl.):
0 _.._'__________________________________ __ 20
polymer tend to decrease the drilling rate. The upper
1A ____________________________________ __ 24
limit is set by the decreased drilling rate which occurs
1/2 ____________________________________ __ 28
when higher concentrations of bentonite are used.
BA ____________________________________ .._ 29
The amount of polymer should be at least about 0.01
1 _____________________________________ __ 30
pound per barrel of drilling ?uid even with high con 20
1% ___________________________________ __ 30
centrations of bentonite. The amount of polymer should
11/2 ___________________________________ __ 32
not ordinarily be much greater than about 0.3 pound per
barrel, principally for economic reasons. Under special 7
It will be apparent that use of from about 1/2 to about
circumstances, use of up to about 0.5 pound per barrel
11/2 pound per barrel of soda ash, preferably about 1
or even more, may be advisable. Preferably about 0.1 25 pound per barrel seems advisable.
pound per barrel of polymer and about 4 percent by
weight of bentonite should be used, particularly if soda
EXAMPLE V
ash is also used in a concentration of about 1 pound per
The stability and response of 5 percent bentonite sus
barrel.
30 pensions to ordinary drilling fluid treating agents with
EXAMPLE II
and without the polymer and soda ash are shown in
To determine the applicability of vinyl-maleic copoly
Table V.
'
mers other than the preferred calcium salt of the reac
tion product of vinyl acetate and maleic anhydride, the
Table V
effects of two copolymers identi?ed in Table II were
35
tested. Results of the tests are presented in Table II.
Table II
Treating agent
PVA/MA 1
Properties
Treatment
PVM/MA 2
Cone.
(l‘o./bbl.)
40
Cone. (lb./bbl.) _________________________ __
M
M
Plastic viscosity (cps.)__._.
Yield value (lo/100 Sq. ft).
15
10
10
10
Fluid loss (co/30 min.) _____ -_
17
18
None ________________________ _.
Plastic
vis.
Yield value
(lbJlOO
(cps)
sq. ft.)
A1
B2
A1
B2
14
18
38
53
14
10
Fluid loss
(co/30
min.)
A1
14
B1
16
Quebracho..
Quebracho___
Quebraeho.
X PVA/MA is the same polyvinyl acetate/maleic anhydride copolymer
Caustic .... __
as in Example I except that no lime is added to form the calcium salt.
2 PVM/MA is the ammonium salt of the half amide of the copolymer
Caustic ____ __
of vinyl-methyl other and maleic anhydride.
It will be apparent that the unneutralized copolymer of
Calcium ligncsulfo
polyvinyl acetate and maleic anhydride is quite satisfac
tory. It will also be seen that the quite different am
lignosulim
monium salt of the half amide of the copolymer of vinyl 50 Calcium
nate _____________ __
Caustic ____________ __
methyl ether and maleic anhydride is also operative for
Modi?ed lignosulio
Caustic ____________ ._
nate _____________ __
Caustic ____________ __
my purposes.
1
1
natc _____________ __
EXAMPLE III
Oil is frequently used in Water-base drilling ?uids.
Caustic ____________ __
Modi?ed lignosulfo
55
To determine the effects of oil on a drilling ?uid con
nate _____________ __
Caustic ____________ _.
1
Mangrove bark ____ __
taining bentonite and my polymer, the tests reported in
Table III were run. In this case the polymer was the
same as that described in Example I. The oil was num
Caustic ____________ __
Mangrove bark ____ __
Caustic ____________ __
ber 2 diesel fuel. The viscosity values are plastic viscos
ity as determined on the variable speed Fann viscosim
eter. The yield values are in pounds per 100 square
inch and the fluid loss values are in units of cubic cen
1 A=5% bentonite suspension.
2 B=5% beutonite~polymer suspension (0.1 lb./bbl. polymer and 1.0
timeters per 15 minutes, as determined With the appara
lb./bbl. soda ash).
tus and method described in API Recommended Pro
65
cedure 29.
The eifect of the polymer on the e?ectiveness of the
Table III
treating agents shown in Table V is much the same as with
sodium carbonate. That is, the polymer seems to en
Drilling ?uid properties
hance the effectiveness of the treating agents, making pos
Polymer,
Oil,
Suspension
(lb./bbl.) percent
sible the use of much smaller quantities of the agents.
(vol.)
Vise. Yield Fluid 70
In some cases, the combination of the polymer and treat
value
loss
ing agents can obviously be used to obtain results not
obtainable with the treating agents alone. In all cases it
6% bentonite
8
7
10
D
.
20
22
7
40
38
7
is apparent that the polymer is compatible with the treat
75 ing agents.
6
v.
polymer is acting’to increase the viscosity of the bentonite
slurry, it also acts to prevent disintegration and dispersion
EXAMPLE VI
To determine the effects of salts on bentonite suspen
of drilled shales and clays since these are almost always
non-bentonitic. This means the bit cuttings remain sul?
percent bentonite slurries were prepared and tested as 5 ciently large to be removed by the shale shaker or to
shown in Table VI.
settle in the mud pits. Even those small particles or bit
sions treated with polymer and soda ash, 5 percent and 3
Table VI
_
_
Suspension
Contaminant
Cone.
Yield
Plastic
value
Funnel
(lb./bbl.) vis. (cps) (lb/100 vis.(sec.)
v
5% Bentonite.
_. ___
D0
Sodium chloride_____
D0
Calcium sulfate. ._._
3% Bentonite.
3% llilentonite 0.025 lb./bbl. polymer, 1.0 lbjbbl. soda
as
_
‘,é
1
_
__
Sodium chloride-_.._
sq. ft.)
Fluid
loss
(ed/30
mm)
6
7
6
18
45
5
18
38
46
17
52
3
3
33
24. 5
19
tr’;
8
9
42
26
1A
y;
iii
8
8
8
8
8
8
41
42
42
26
27
25. 5
10
6
43
.
Do
D0
Do
____.d"
___---(10
_..__(10
Do
__._.do
Do
_....do _____________ __
Do
Calcium sulfate. ___-
_
The polymer and soda ash seem to stabilize the vis
1
30
IV:
1
37
28
cuttings which were not removed remain in a particle size
cosity and yield value properties against the effects of
range above the colloidal range. It has been previously
sodium chloride, but the ?uid loss begins to become ex 25 found that those particles in the colloidal range are most
cessive at salt concentrations above about 1 or 11/2 lb./bbl.
detrimental to drilling rates.
(3,000 to 4,500 ppm). Use of the polymer in brines
When the term “consisting essentially of” is used herein
containing more than about 5,000 parts per million of
after in connection with a composition, it will be under
alkali and alkaline earth metal chlorides and sulfates is not,
stood that this term is intended to indicate a composition
therefore, ordinarily recommended.
30 which may contain not only the named ingredients, but
also other materials, such as drilled solids, treating chemi
EXAMPLE VII
cals and the like, Which do not substantially adversely
The effects of the polymer on drilling rates was deter
aifect the properties of the composition for its intended
mined with a 31/2 inch diameter 3-cone rock bit and
blocks of Berea sandstone using a laboratory drilling ap
paratus.
use.
35
In one case, a 3 percent bentonite suspension
treated with polymer and soda ash and having a Stormer
viscosity of 20 centipoises was used. In the other case,
a 5 percent bentonite dispersion having a Stormer vis
The polymer, soda ash and bentonite may be added
separately, if desired. The polymer and soda ash can be
added as solid powders or they can be ?rst dissolved
or dispersed in Water. Dispersion of the polymer in Water
can sometimes be facilitated by mixing the polymer ?rst
cosity of 14 centipoises was used. In spite of the higher 40 with a little alcohol or oil to separate the particles before
viscosity of the treating suspension, it drilled 12.5 per
they contact Water. The same effect can be obtained by
cent faster than the untreated bentonite slurries. It will
be apparent that the small amount of polymer and soda
ash does not substantially affect drilling rates in spite of
the increase in viscosity.
45
EXAMPLE VEI
Upon completion of laboratory tests, a ?eld test of the
polymer was conducted in Martin County, Texas. The
premixing the polymer with the sodium carbonate,
bentonite or both.
The polymer, the bentonite, and the other drilling fluid
additives can be added in any order. It is generally most
convenient, however, to add them simultaneously.
It
is best to start with clear Water in preparing a drilling
?uid so any drilled solids do not have a chance to
disintegrate and disperse into the colloidal range before
higher drilling rates experienced in the laboratory with 50 the polymer is added. It is possible, however, to add
polymer-treated bentonite suspensions were substantiated
the polymer to a drilling fluid containing several percent
in the ?eld test. In one Well a 4 percent bentonite slurry
of drilled solids to cause ?occulation and precipitation of
containing 0.05 lb./bbl. of polymer and 1.0 lb./bbl. of
soda ash was used in drilling the 900 feet from 11,110
these solids before the bentonite is added. Some of the
advantages of the invention can be obtained by adding
both the bentonite and the polymer to drilling ?uid con
to 12,000 feet. In an oil-set location, a drilling ?uid was
used having 9 percent bentonite and native solids with no
taining drilled solids. The drilling fluid should ordinarily
polymer or soda ash. Rotating time for drilling the in
be diluted with water in such cases, before adding the
terval of 900 feet was 142 hours, using the treated drill
bentonite and polymer, to decrease the solids content.
ing fluid, and was 192 hours, using the untreated drilling
In some cases, as when the solids content is low, however,
?uid. The drilling fluid properties of the two muds were 00 no dilution is required.
approximately the same. The drilling time in the case
As usual, a small amount of polymer and bentonite
of the treated mud, however, was about 25 percent less.
should be added intermittently or continuously during
The reduction in rotating hours equals about 5 days of
drilling operations to make up for losses to the formation,
rig time or a saving of about $5,000. Costs for the treated
when cleaning the settled solids from mud pits, and the
mud were about 8 percent less, bit costs were essentially 65 like. A high ratio of polymer to bentonite should be
the same. No unusual problems were experienced in the
used in this make-up-stream. The reason is to compen
application of the polymer.
sate for losses of the polymer on bit cuttings which were
In the drilling operation in the ?eld, there was, of
separated in the mud pits. The polymer is thought to
course, some accumulation of drilled solids in the drilling
prevent disintegration of bit cuttings, principally by be
fluid. These drilled solids did not seem to decrease the 70 coming adsorbed on the surfaces of such solid particles.
drilling rate in the presence of the treating materials.
When the cuttings are separated in the mud pits, some of
This is thought to be because of the ?occulating action
the polymer is lost from the system. The excess polymer
of the polymer on non-bentonitic clays. The polymer has
is to make up for this loss.
the unusual ability to fiocculate most clays, but to bene
A convenient concentrate or additive for forming or
?ciate bentonitic clays. Therefore, at the same time the 75 treating drilling fluids is a mixture of the polymer and
3,070,543
S
bentonite. For forming drilling ?uids from fresh water,
polymer, said copolymer containing from about 1 to
the concentrate should contain about 100 times as much
about 1.5 times as many vinyl radicals as maleic radicals
and being polymerized to a degree such that a 0.4 percent
bentonite as polymer.
For make-up addition during
paring drilling ?uids containing high concentrations of
by weight aqueous solution has a viscosity of between
about 1 and about 3 centipoises at 25° C.
6. The drilling ?uid of claim 5, in which said clay is
bentonite, as high as 1000 times as much bentonite as
bentonite.
drilling operations, the additive may contain as little as
10 times as much bentonite as polymer. For use in pre
polymer may be used. Since the polymer is lost from
the system on bit cuttings, as previously noted, it is
ordinarily best to use an additive containing about 100
times as much bentonite as polymer and then add polymer
unmixed with bentonite to increase the ratio of polymer
to bentonite.
7. The drilling ?uid of claim 5 in which said copolymer
is prepared from vinyl acetate and maleic anhydride.
8. The drilling ?uid of claim 7, in which said clay is
bentonite and said copolymer contains suf?cient calcium
hydroxide to form at least a partial calcium salt of said
copolymer.
9. A method of drilling a well comprising operating a
The polymer may be used alone to ?occulate drilled
solids and maintain clear water for drilling. In this case, 15 bit in the bottom of said well to drill the well deeper
and thus produce bit cuttings and circulating in said well
a small amount will remain in the water when it is decided
the drilling ?uid of claim 5, whereby a fastdrilling rate
to mud up. Theoretically, this amount may be taken
is maintained due to the low solids content of the drilling
into account in calculating the quantity of polymer to add
?uid which results from ?occulation of drilled clay solids,
with the bentonite. Actually, however, this amount al
but the loss of the drilling ?uid to porous formations
ready in solution can be ignored since it is so small com
penetrated by the Well is maintained at a low value and
pared to the quantity required for bene?ciating the
su?icient viscosity is maintained to remove the bit cut
bentonite.
tings from the well.
One advantage of the polymer is that it can be used
10. A method of drilling a well comprising operating
with poor grades of bentonite to increase the e?ectiveness
a bit in the bottom of said well to drill the well deeper
of such material to a point comparable to that expected
and thus produce bit cuttings and circulating in said well
for good grades of bentonite. This can be particularly
the drilling ?uid of claim 6, whereby a fast drilling rate
important in relatively inaccessible areas having readily
is maintained due to the low solids content of the drilling
available poor grades of bentonite, but no high-quality
?uid which results from ?occulation of drilled clay solids,
clays. There may be some question Whether a clay which
does not greatly increase the viscosity of water is a poor- ° but the loss of the drilling ?uid to porous formations pene~
trated by the well is maintained at a low value and su?i
quality of bentonite, or is some other type of clay. This
cient viscosity is maintained to remove the bit cuttings
can be simply determined by mixing some of the clay
from the well.
into the water and adding a little of the polymer. If the
11. A method of drilling a well comprising operating
clay is simply a low-grade bentonite, the viscosity will
be increased by the polymer. If the clay is of another ' a bit in the bottom of said well to drill the well deeper
and thus produce bit cuttings and circulating in said well
the drilling ?uid of claim 7, whereby a fast drilling rate
By use of the polymer, the viscosity of water contain
is maintained due to the low solids content of the drilling
ing a very low concentration of bentonite can be in
?uid which results from ?occulation of drilled clay solids,
creased and the ?uid loss can be decreased to increase the
e?iciency of the water when used as a fracturing ?uid. 4-0 but the loss of the drilling ?uid to porous formations
penetrated by the well is maintained at a low value and
Due to the low concentration of bentonite, there is less
sufficient viscosity is maintained to remove the bit cuttings
tendency for the fracture to become plugged by the clay
from the well.
'
When the well is put back on production. The same ad
12. A method of drilling a well comprising operating
vantage applies to dilute clay slurries used opposite zones
a bit in the bottom of said well to drill the well deeper
to be perforated with bullet or jet perforators.
and thus produce bit cuttings and circulating in said well
Still other advantageous applications of my invention
the drilling ?uid of claim 8, whereby a fast drilling rate
will be apparent to those skilled in the art.
is maintained due to the low solids content of the drilling
I claim:
?uid which results from ?occulation of drilled clay solids,
1. An additive for increasing the viscosity of water
but the loss of the drilling ?uid to porous formations
consisting essentially of a mixture of montmorillonitic
penetrated by the well is maintained at a low value and
clay and a water-soluble vinylmaleic copolymer, said co
su?icient viscosity is maintained to remove the bit cut
polymer containing from about 1 to about 1.5 times as
tings from the well.
many vinyl radicals as maleic radicals and being polym
erized to a degree such that a 0.4 percent by weight aque
References Cited in the ?le of this patent
ous solution has a viscosity of between about 1 and about
3 centipoises at 25° C., the weight of said clay being
UNITED STATES PATENTS '
from about 10 to about 1000 times the weight of said
2,702,788
Dawson _____________ .__ Feb. 22, 1955
type, it will be ?occulated and precipitated by the polymer.
copolymer.
2. The additive of claim 1, in which said clay is ben
60
tonite.
3. The additive of claim 1, in which said copolymer
is prepared from vinyl acetate and maleic anhydride.
4. The additive of claim 3 in which said clay is
bentonite and said copolymer contains su?icient calcium
hydroxide to form at least a partial calcium salt of said 65
copolymer.
5. A low solids drilling ?uid consisting essentially of
‘water containing no more than about 5000 parts per mil
2,718,497
2,948,678
Oldham et al _________ __ Sept. 20, 1955
Turner et al ___________ .._ Aug. 9, 1960
725,460
517,883
553,011
Great Britain _________ __ Mar. 2, 1955
Canada ______________ __ Oct. 25, 1955
Canada _____________ __ Feb. 11, 1958
FOREIGN PATENTS
OTHER REFERENCES
McGhee: New Oil Emulsion Speeds West Texas Drill
ing, article in the Oil and Gas Journal, Aug. 13, 1956.
pages ll0—1l2.
lion by weight of alkali and alkaline earth metal chlorides
Mallory: How Low Solids Muds Can Git Drilling
and sulfates, from about 2 to about 7 percent by weight 70
Costs, article in the Petroleum Engineer, April 1957, pages
of a montmorillonitic clay, and from about 0.01 to about
B21, B22, B23, B24.
0.5 pounds per barrel of a water-soluble vinyl-maleic co
Документ
Категория
Без категории
Просмотров
0
Размер файла
682 Кб
Теги
1/--страниц
Пожаловаться на содержимое документа