Note: Descriptions are shown in the official language in which they were submitted.
`` ~iL~3~ S
BACKGROUND OF THE INVENTION
-
1. F Irl D OF IHI :U~u,roN: Thls invention relates to a
process for enhancing the recovery of petroleum and bitumen
from subterranean strata and petroliferous rocks or sands.
~ore specifically, it relates to new and improved aqueolls
flooding processes wherein the improvement comprises the util-
ization of a thin film spreading agent composition of an
acylated polyether polyol which facilitates the displacement of
petroleum and bitumen from the source rock.
2. DESCRIPTION OF THE PRIOR ART: It has long been known
that the natural forces operating to cause flow of oil from
source rocks into bore holes penetrating the rock are relative-
ly inefficient in producing the oil. After the completion of
such "primary" production, as much as 60~ to 95~ of the origin-
al oil in place may remain in the reservoir stratum.
For this reason, so-called "secondary" and "tertiary"
recovery processes are usually applied to the reservoir at some
point. Such processes include steam injection to provide
additional reservoir energy for subsequent oil production and
numerous other re¢overy methods which have been proposed where-
in various fluids are injected into the oil-bearing formation
to effect removal and recovery of additional oil from treated
wells or from adjacent wells communicating with the reservoir.
Such displacement methods are generally referred to as "flooding"
and have utilized steam, water, brines, gas, caustic solutions,
acidic solutions, aqueous solutions of detergents, high viscos-
ity aqueous solutions of very high molecular weight polymers,
oil solutions of detergents, micellar solutions, emulsions,
liquefied carbon dio*ide and combinations of such methods.
In some instances, one fluid may be injected for a time and is
then followed by another and perhaps less costly fluid, such a~
X ~..
_____.__ ______._ __________=_.. ______ __._.. _.. _ ", .. .. _ ;~. . . ; ~ , , ~ b
3~;3~95
water or brine. All such procedures are aimed at removing
petroleum trapped in minute pores of the reservoir rock.
Removal of petroleum from its source rock is believed to
be a complex process involving the flow of two or more phases
through a permeable solid phase. Many variables affect the
results. For example, pore size in the rocks, viscosity of
fluids, temperature, pressure, wettability characteristics of
the rock, the composition of the oil phase and numerous other
properties all apparently play a part in the dynamics of petro-
leum production.
Much of the oil left in the rock formation during primary
production appears to be trapped by forces of adhesion between
oil and rock. Although not fully understood, most reservoir
rocks appear to be "preferentially" wet by water, meaning that
the contact angle between water and rock, measured through the
water phase, is smaller than the contact angle between crude
oil and rock, similarly measured. It is believed that the
polar constituents contained in most crude petroleum oils, such
as asphaltenes and other complex compounds, become absorbed on
the polar rock surfaces to form ~hick, viscous, hydrophobic
films which cause the rock to be wettable or partially wettable
by the oil, prevent the close approach of and wetting by any
aqueous phases and hinder the displacement and flow of the oil.
Even in the presence of interstitial (connate) water or of
injected aqueous fluids, only limited water wetting of the form-
ation with displacement of the oil is effected.
Micellar solution flooding systems which are miscible with
the petroleum, all of its dissolved companents and water, were
first disclosed and proposed for oil recovery in U.S. Patent
2,356,205, dated August 22, 1944, to Chas. M. Blair, Jr., and
Sears Lehmann, Jr., entitled "Process For Increasing Product-
ivity of Subterranean Oil-Bearing Strata". These systems are
. ~. , . ... . . .. .. . .. . . ..... , ~
` ~.3~;~9S
capable of dissolving and removing such trapped oil as they can
contact, but have not yet proven to be generally feasible
because of the hlgh cost of chemicals, solvents and hydrotropic
agents involved.
Aqueous flooding fluids containing acids, bases or deter-
gents solutes have been employed to improve oil recovery by
lowering oil-water lnterfacial tenc;ion sufficiently to lessen
back pressure from dynamic surface and interfacial tension
(Jamin) effects or to bring about emulsification of oil in the
aqueous fluid, but with only limited improvement over the re-
sults of ordinary water flooding.
None of these methods has clearly attempted to effect more
complete water wetting of the formation by chemical means. In-
deed, the use of water- or brine-soluble surfactants, such as
detergents, for decreasing oil-water interfacial tension are
generally ineffective in decreasing oil wetting or, alterna-
tively, increasing water wetting of highly polar surfaces.
Classical wetting theory shows quite generally that the work of
adhesion for displacement of oil by water on a rock surface is
decreased by lowering the oil/water interfacial tension and,
as a consequence, the tendency of the water to displace oil is
actually decreased.
Indirectly, aqueous caustic may reduce the oil wettability
of rock by reaction with crude oil constituents and reduction of
their oil wetting action. However, this method typically re-
quires from ~% to 3~ of caustic, and sometimes as much as 15~,
to reduce the oil-wetting ability of the petroleum. Such high
concentrations are costly and, in addition, being about re-
actions with injected water or interstitial brine to form plug-
ging precipitates of inorganic compounds such as calciumcarbonate, strontium
... j,O _ 5
, .~ I
. , ~,
:
~3~i3~5
1 carbonate and m.~nesium hydroxide, thllS st:opping or ~-rcatly
.
reducing the fluid inj'ection pr'ocess,
.... .... ..
' BRIEF DESC~'IPTION OF THE DRAWINGS
Fig. lA is a vert'ical, cylindr'ical section taken throu~h the
reservoir rock' 1, its layer of adhering oil (or bi~umen) 2, and
the'adi'acent connate (or added~ water phase 3. At this stage,
which'is the'instant before the altera~ion of any interfacial
conditions in the'reservoir resulting from the introduction of
the acylated polyether polyol, the ch'emical has already been
incorporated into the wa'ter phase but has not yet contacted or
migrated into the''oil phase.
, Following i~troduction of the acylated polyether polyol, it
may then' migrate to the'rock surface and spread to displace the
thick adsorbed oil wetting layer. Simultaneously, it will be
adsorbed a~ the oil-water interfa.ce where it spreads similarly
with'displacement of any emulsifier film formed there by ad-
sorption of emulsifying agents from the oil, leaving a system as
depicted in Fig. lB.'
Fig. lC depicts the final stage of water wetting of the
reservoir rock with displacement of the adhering oil layer, now
containing the displaced.'emulsifier and the acylated polyether
polyol, as a droplet suspended in the water phase.
,.:
SUMMARY OF THE Il'l~ENTIO~
This invention provides an improved flooding process leading
to enhanced oil recovery.
It also provides a pretreating flood of a th~n film spreading
agent composition having present therein an acylated polyether '~
polyol~ to improve the recovery of oil by subsequent flooding with.
water or other aqueous systems such as viscous, aqueous polymer
solutions, caustic solutions and detergent solutions.
~ 6-
::
. . .
~-:31 3~3~Si
I have found that the ability of crude oil to wet and
adhere to rock surfaces in the presence of water can be substan-
tially reduced by injection of certain classes of organic
compositlons, not previously described for such use, into the
petroleum or bitumen reservoir and that, by suitable application
of these compounds ahead of or in conjunction with water and
other aqueous fluids, significant increases in the recovery of
the petroleum is effected.
I believe that the composition used in the present method,
hexeinafter referred to as a "Thin Film Spreading Agent", or
"TFSA", probably acts by adsorbing preferentially at the
petroleum-rock interface where it is spread to displace the
thick, semi-solid film of previously adsorbed, naturally occur-
ring oil-wetting agen~ from the petroleum, forcing it back into
solution or dispersion in the oil phase, leaving in its place a
very thin, mobile, monomolecular, semi-polar adsorbed film.
The tendency of the oil to adhere to or wet the rock is thereby
reduced. As aqueous fluids are pumped into the reservoir, the
oil is then more readily pushed away. Also, since the TFSA
forms such thin layers on mineral surfaces, it permits close
approach of the mineral and aqueous flooding fluids surfaces,
sufficiently close, indeed, to permit the powerful short range
molecular forces of attraction between polar molecules to
become effective and to bring about wetting of the rock by -the
aqueous fluid. As this oil displacement and water wetting
process proceeds, the temporary film of TFSA, itself, is dis-
placed just as the aqueous phase displaces the petroleum phase
on the rock, and becomes dispersed in the oil or the flood
water to be carried forward toward the untreated portions of
the formation. Contact of displaced petroleum with petroleum
masses adhering to the rock downstream permits the TFSA to
become adsorbed again between oil and rock and to effect further
- 7 -
- : .,.. , . ~
13~3~9S
oil displacement by aqeuous flooding fluids.
Besides adsorbing on rock surfaces, the asphaltenes and
other complex polar constituents in the crude petroleum oil
adsorb strongly at interfaces between the oil and water or
brine, forming thick, viscous layers which resist flow forces,
stabilize viscous emulsions within the flooded rock zone and
inhibit oil displacement~
The invention also replaces such viscous interfacial films
with very thin, mobile films of the TFSA and thereby lessen the
viscosity of the interstitial oil and water fluids, decrease
flow resistance, minimize the formation of interstitial emul~
sions and increase the production of petroleum oil.
Regardless of any theory or proposed mechanism for the
function of the TFSA composition and method, the utility of
these products for removal of oil from sand bodies has been
clearly established by experiments described below. However,
for its possible scientific interest and bearing on the process
the steps visualized as occurring in the water wetting of
reservoir rock initially wet with a film of oil or bitumen when
brought in contact with TFSA are presented in the Figs.
The TFSA compound may be introduced as a minute dispersion,
a micellar solution or an emulsion in the flood water from ~:
which it may migrate and diffuse into the oil phase or spread
; after adsorption on rock surfaces adjacent to the oil-wet
surfaces. Although, as pointed out below, the TFSA compounds
are not "soluble" in the conventional macroscopic sense in
~ water or in hydrocarbons of low solubility parameter, they are
: soluble to some very small microscopic extent sufficient to
: permit some diffusion through the water phase to the oil,
especially at the elevated temperatures found in underground
reservoirs. Additionally, contact of minute dispersed parti-
cles of, or micelles containing, TFSA with the oil
- 8 -
~13~3~S (`
1 ~ phase as the result of flow of tlle wa~er ph~se thlou~h ~he rockwill facilitate t~ansfer to the oil phase, as will the active
spreading of the 'I~FSA at water-oil interfaces. Still further,
the T~SA may actually be introduced as a preliminary batch or
"slug" dissolved in an organic solvent for the material to be
pushed along by the following flow of injected water.
- Referring to Fig. lB, the water and rock surfaces are now in
condition to adhere when they approach closely. In the dynamic
process of water injectionj the fluid pl~ases of water and oil in
the rock can and will undergo some ~overnent and displacement
sufficient to bring about the requ;red water-rock contacts from
time-to-time.
In order to better visualize the energy changes involved in
this process, it is assumed that the cross sections shown are one
square centimeter in area and that the oil droplet in Fig. lC has
a s~rface area of about 1 cm2. This last assumption would be
true for an original adhering oil film which was 0.1 cm thick, a
rather thick section for most reservoir rocks and, thus, a con-
servatively high value for the new oil water interfacial area
generated during displacement and of the concomitant energy
requirement for its generation.
The energy changes involved are shown on the lower part of
the Figs. ~ere, Tl, T2 and T3 are the solid, oil and water
; ~ specific surface energies, respectively. They are numerically
equal ~o the surface tensions. SPE is the interfacial spreading
pressure of the naturally occurring oil wetting ~aterial in the
oil and SPsA is the spreading pressure of the T~SA at oil-r~ck
and oil-water interfaces,
The t~tal energy change for the process is shown in Equation
1, as follows:
_g_
.
- :
li363~5
1 , ,' 'E~'~at';on l
~ E = T3 - T2 - 2SPE + SPSA
In deriv;ng thi's; it ;s assulned that interfacial tensions
' betwe'e'n pure'phases' are'numerically equal to the difference in
inter'facial tensions of the phases involved, as in ~ntonoff's
Rule. I~hile it is known that this asswnption is not ex'act, since
dispersion forces s'omet'imes lead to somewhat di~ferent values of
interfacial energy (or tension) than predicted by Antonoff's
Rule, the' minor errors introduced by the assumption are a'Lmost
wholly eliminated in tak;ng the energy differences involved in
the process.
To obtain a numerical est'ima~e of the energy change, ~E> in
Equation 1, the approx'imate values of the surface energy value
involved are needed. Surface energy values for solids are not
easily obtained. However, Tl, the surface energy value for the
rock surface, does not appear in Equation 1 and, thus, does not
affect the ener'gy change involved during the process of oil
displac'ement. - -
; T2, the surface energies of petroleum oils`are ~enerally
about 30 ergs or less per cm2 at 25C T3, the surface tension
~ of water, is about 72. Inserting these and other appropriate
; values into Equation 1, the following is obtained:
E = 72 - 30 - 2(25) + 30 = 22 ergs per cm2
This indicates a very favorahle free energy change for the
oil displacement process. In actual practice it would be ex-
pected that an even more favorable free energy change would occur
since it is assumed that an unusually large volume of oil is dis-
placed per unit area of rock. Porè sizes of natural oil sand
deposits would indicate much smaller volumes whic~ are also ex-
pected to coales'ce, leading to a' maximum ener~y change value,
when ignoring the area' of the oil-water interface of
- ~ ÉmaX = 2~T3 - T2 ~ SPE
.. .
-10-
, . . . .
~,
: . .
- 1136395
l ; . IJsi?~g the previously estilnated (rlergy val~es, the ollowing
equation is obt'aine'd:
~'Emax = .34 elgs .per c~2
In su~nary, a favorable'o~erall thermodyn'alnic effect of
'5 betwe'en aboùt 22 and 34 er~s per. cm2 Of rock surface is obtained
during displ'ac'e'ment of typical oils.
~owever, in order to dete-r~ine whether the condition de-
.
picted ;n ~ig. lB' can pr'oceed.t.o that of Fig. lC, the free enérgy
change in this step' must be ex'amined Unless it is negative, the
displacement'process rnay stop at the state of Fig. lB, leaving
oil adhering to the' r'ock.
'Eq'uati'o'n 2
A EBC Tl - 2 T2 + T3 - 2SPSA - T1 ~ T2 ~ SPSA
= T3 - T2 ~ SPSA
15- Inserting the previously used typical surface energies into
Equation 2, the ollowing equation is obtained:
- A EBC = 12 ergs per cm2
' If the ~inal oil-water interfacial. area is ignored, this
becomes 24 ergs per cm2. These results indicate that the thermo-
dynamics generally will strongly favor .the displacement process
in preference to the intermediate state of Fig. lB.
. Most petroleum reservoirs have temperatures above 25C, de-
- pend;n~ upon depth, the nature of the formation and, perhaps, to
the extent of cooling effected by prior treatment. Surface and
~5 interfacial ener~y decline with increases in temperature, so the
actual free energy decrPase to be expected in actual reservoirs
sho~ld be s'omewhat less than indicated above or a temperature ~f
' 25C, but since the r'actional decline~s in surface and inter-
- facial energies' with temperature are similar, the free energy
decline will remain positive.
,
-~i -i1-
.
,
.
~3~3~S
DESCRIPTION OF THE PREF~RRED EMBODIMENTS
._ _ _ _ _
The compositions which have been found to be an effective
TFSA in the practice of the invention have the following prop
erties:
1. Solubility in water and isoctane at Z5C is less
than about 1% hy volume;
2. Solubility parameter at 25C i5 in the ranye of about
6.9 to about 8.5 with a preferred range of about
7.0 to about 7.9; and
3. Spread at the interface between distilled water and
refined mineral oil to form films which have a
calculated thickness no greater than about 20
Angstroms (0.0020 micrometers) at a spreading
pressure of about 16 dynes per cm (0.016 Newton per
meter).
Products meeting these requirements are generally organic
polymers or sèmi-polymers with average molecular weights be-
tween about 800 and 30,000 and have structures which allow
~ orientation on polar surfaces with much or most of the elements
; of the molecule in a thin plane. To be effectively adsorbed
at oil-water or oil-rock interfaces, they must generally con-
tain constituents which give them highly distributed hydrophile
and hydrophobe character, and without such concentrations of
either hydrophilic or hydrophobic groups as to produce water
solubility or oil solubility, in the ordinary macroscopic sense.
e compositions appear not to be effective micelle-forming
compounds in the manner of detergents, soaps and the surfac-
tants such as those previously used in aqueous floods. They
also appear to differ from formerly used surfactants in that
their effects on oil-water interfacial tensions as a function
of concentration are limited. While spreading efficiently at
such interfaces to form thin films with spreading pressures up
- 12 -
~36~3~95
to about 35 to ~0 dynes per cm, addition of larger amounts of
TFSA have relatively little effect on interfacial tension. ~lso,
the present ayents, in contrast to formerly used surfactants,
have relatively little or no tendency to stabilize either oil-
in-water or water-in-oil emulsions when present in normal use
amounts,
Usually the compositions applicable to the practice of the
invention are organic molecules containing carbon, hydrogen and
oxygen, although in some instances they may also contain sulfur,
nitrogen, silicon, chlorine, phosphorous or other elements.
Small amounts of inorganic material such as alkalies, acids or
salts may appear in the compositions as neutralizing agents,
catalyst residues or otherwise. The critical requirements for
the compositions are not so much compositional as structural
and physical. They must be made up of hydrophilic tpolar)
moieties, usually ones capable of forming hydrogen bonds, such
as hydroxyl, carbonyl, ester, ether, sulfonium, amino, ammonium,
phospho or similar hydrogen bonding groups, connected by or to
hydrophobic groups, such as alkylene, alkyl, cycloalkyl, aryl,
arylene, aralkyl, polyalkylene, polyalkylyne, combinations of
such groups and such groups containing relatively non-polar -
substituents, such as hydrocarbon, chlorine, fluorine and the
like. Sometimes the hydrophobic moieties are larger and con-
tain more atoms than the polar groups in the molecule, having a
minimum of two carbon atoms in each group and up to as many as
36 carbon atoms, although the actual ratio of sizes depends
greatly on the structure o~ the hydrophilic moiety. Most
commonly the hydrophobic groups will contain 14 to 22 carbon
atoms and will have linear or sheet-like conformations allowing
for relatively flat orientation on surfaces.
Polar moieties other than hydrogen bonding onas are not
excluded ~rom these compositions and, indeed, may be deliberately
- 13 -
~L~3~;3~5
included in some structures to i~prove adsorption and inter-
facial
:
;
.~
: `:
.
~ - 13a -
.. . . .
1~3~3~S
1 ' spreading ten'de'~cies'. For'ex'ample,' quaternary 'alr~oniu~ gro~ps,
while'inca'pable'of fo'l~ning hydrogen bonds, can 'improve spreading
and interfacial adsorption in .some'applications by way of their
.
hi'ghI'y ioni~ed fo'rm wh'i'ch ~imparts' cationic character to the
molec'ules in wh'ich'they.'o'ccur and, via coulombi.c re;pulsion
effects;' can 'improve'spreading in a film
Generally, the compositions wlll contain at least ~wo each
- of the req'uîred'hydrophil'i.c (polar) and hydrophobic moieties per
'molecule'and' commonly wi'll' contain'many more of each. r~he effec-
tive'products; hbwe'ver,'rnust have the three .properties described
above.' . '' .'
The'products usef~l in the process res'emble products which
have been found effective'for breaking petroleum 'emulsions, but
for most applications for oil recovery the products will tend to
be somewhat more'or less hydrophobic than the demulsifier actually
used on the water-in-oil emulsion produced from the formation to
.. . .
be treated. However, the'actual product to be used for a given
system is best sel'ected ~y laboratory tests to be described below
rather than by.its' chem'ical s'imilarity to demulsifiers or other
surface-active agents which may have been used in the system.
~ While,' as pointed out above, the effective TFSA may be
; derived from a wi'de variety of ch'emical reactants and may contain
numerous different groups or moieties, I.have found that particu-
'~ larly effective products are those which are described as:
I 25 ~ O(A)jH~n
.. ~, .
~ NRl~(A)kH]~ m
wherein: '
A is an alkylene oxide group, -CiH2iO-;
0 is oxy~en;
i is a positive integer from 2 to about 10 inclusive;
:
--i4--
,
~li36i3~5
j is a positive integer no greater than about 100;
k is a positive integer no greater than about 100;
N is nitrogen;
R is one of hydrogen, a monovalent hydrocarbon group cantain-
ing less than about Cll, or [ALH~;
L is a positive integer no greater than about 100;
R is a hydrocarbon moiety of a polyol, a primary or secondary
amine, a primary or secondary polyamine, a primary or
secondary amino alcohol, or hydrogen; and
m ~ n is no greater than about 4 when R is other than hydrogen
and one of m and n is zero and the other is unity when R
is hydrogen~
said acylated polyether polyol being the reaction product of
said polyether polyol and a member selected from the class
consisting of mono- and polybasic carboxylic acids, acid an-
hydrides, and iso-, diiso-, and polyisocyanates, said acylated
polyether polyol at about 25C: ~a) being less than about 1%
by volume soluble in water and in isooctane; (b) having a
: solubility parameter in the range of between about 6.9 and about
8.5; and (c) spreading at the interface between distilled water
and refined mineral oil to form a film having a thickness no
greater than about 20 Angstroms at a film pressure of about 16
; dynes per cm. These compositions must conform to the physical
property parameters set forth above.
Alternatively, the TFSA compositions may be described as
acylated polyether polyols wherein said polyether polyols are
derivable by reaction of an alkylene oxide containing less than
about 10 carbon atoms with a member of the group consisting of
polyols, amines, polyamines and amino alcohols containing from
about 2 to about 10 active hydrogen groups capable of reaction
with alkylene ox:ldes and the acylating agent b~ing a member
selected from the class consisting of mono- and polybasic
carboxylic acids, acld anhydrides and iso-, diiso , and poly-
~r
- 15 -
_ . __,.,~ .. _ , . . . _ , . . . . ... ... .. .
39S
1 ' isocyanates As described above, sl~itable acylate~ polyether
polyols'must, at about 25C: .(1) be soluble'in water and in
isooctane:to the'extent of les's than .1%'by volu~ie; (2? have a
solubility parameter in tlle'range'of between about..6.9 and about
8.'5; and (3) spread at the interface between distilled water and
. .
refined ~ineral ~il to fo'rm a fi'l~ having a.thi'ckness no greater
than about 20 Angstroms at a film pressure of about 16 dynes per
'cm.
' ' Compositions incorporated within the scope of the fo'rrnula
set forth above contain an average of about l~ or more hydroxyl .
groups per;mol'ecule'and are generally. composed of a cogeneric
mixture'of products obt'aine~.by condensing alkylene oxides with
. sma'ller'mol'ec'ules' co'ntaining two or more reactive hydrogens as
'~ part of hydroxyi or amino groups.
15. Representative of these compositions is polypropylene glycol,
~ having an average molecular weight of about 1,200, to which about
: 20% by weight of ethylene oxide has been added. Such a polyether
: ' glycol is theoret'ically obtainable by condensing about 20 moles
of propylene'oxide with'about one mole of water, followed by
addition of about six moles of ethylene oxide. Alternatively,
one may condense'about 20~moles of propylene oxide with a pre-
viously prepared polyethylene glycol of about 240 average molec-
ular weight.
' Alkyiene oxides suitable for use in preparing the polyether
polyols used in synthesizing the compositions used in the present
process include ethylene oxide,.propylene oxide, butylene oxide,
2-3-epoxy-2-methy'L butane, trimethylene oxide, tetrahydrofuran,
glycidol and sîmi'Lar oxides containing less than about 10 carbon
.
atoms. Becausè'o their reactivity and rel.atively.low cost, the
preferred alkylene oxides for.prepa~ing effective TFSA are the
1,2-.alkylene oxides (oxiranes'~ exemplified b~ ethylene oxide,
"
. ~ . ..
-16- .
- ~' I
6i395
1 propylene oxide and butylene oxide In the preparation of rnany
TFSA's, more than one'alkylen'e'oxide'may.be 'employed either as
mixtures of oxides or sequentially...to .form block'additions of
individuaL alkylene'oxide'gr~ups. '
Othe'r suitable'dihydric alcohols ma~ be obtained by condens-
ing alkylene'oxides' or'mixtures of oxides''or in su'ccess.ive steps
.
(b~ocks') with'difunctional (with respect to oxide addition) com-
pounds, such'as ethy'lene'glycol,'methy'l amine, propylene glycol,
hexamethy'lene'glycol, ethyl ethanolamine, analine, resorcinol,
10 hydro~uinone and.the like.'
Trihydric ether alcohols may be pxepared by condensation of
ethylene, propylene or butylene oxides with, for ex'ample, ~lycerin,
ammonia, triet~anol'amine,' diethanolamine, ethyl ethylene diamine
or similar smaller ~ol'ec'ules' containing three hydrogens capabie
of reacting with alkylenP oxides. Similarly, polyether alcohols
with'a.ml~ltipl'icity of hydroxyl groups' may be obtained by con-
: densing alkylene oxides with multireactive starting compounds,
' such 2s pentaerythritol, gl'ycerol, N-monobutyl ethylene diamine,
- ' trishydroxymethyl'amin'omethane, ethylene diamine, diethylenetri-
amine, diglycerol, hexamethylene ~iamine, ~ecylamine and cyclo-
hexylamine. DeGroote', in~V.:S..Patent No. 2,679,511, describes .a
number of amino derived polyols which he subsequently esterfies.
Product 15-200,'manùfactured and sold by the Dow Chemical Company,' .
and derived.by axyalkylation of glycerol with a mixture of
ethylene and propylene oxides, is an examp~e of a commercially
available'polyol of the kind contemplated herein.
Generally, these compositions will have average molecular
weights of 15,000.or less and.will be derived from reactive
hydrogen'c'ompounds having 18 or fewer carbon atoms and 10 or
fewer reactive hydrogens.
Othe'r' general descriptisns of suitable.'compounds.c'oming
' within the'scope'of'the' structure'detailed above, alon~ with'
.~ , . , ~ . .......................................... . . . .
-17
.
... ~,........
~ I
i~ 113~;3~
,~
1 methods for' carrying out the'actuaL'malltl~Ac~uring steps, ~re dis-
closed in "H~gh Polymers,.Vol..X~II, .Polyethers," edited by N. G.
.. . . .. .
Gaylor'd, 30hn Wile~'& Sons,..New;York, 1963. ' .
Effective ~FSA wi'th'improved performance'may be prepared by
.5 acylation of the polyether polyol.described above with a mono- or
.' polybas'ic' carb'oxylic acid, acid.anhydride, isocyanate, dliso-
' cyanate'or other polyisocyanate. . ~n especially. useful.TFSA may
be'made by re'acting an approx'imately difunctional polyether polyol
with'a'dif~inctional; carboxylylic 'acid, acid anhydride or iso-
10, cyanate to form a pol~meric ester or urethane. .However,.poly-
mer;zation`is not always required, and where effected is usually .~ ' not carr.ied to the'point of including a very large number of
monomer units in the molecule Frequently, effective reagents
are obtained where'res'idual,. unreacted hydroxyl or carboxyl groups
remain in the product or, where a polyisocyanate is used, one or
' more residual isocyanate groups or amino or substituted ur~a
groups wh'i'ch'result from reaction of residual end groups with
water, followed by decarboxylation, may remain.
Examples of acylating agents suitable for preparing usefùl
esters include'acetic acid, acetic anhydride, butyric acid,
. benzoic acid, abietic acid, adipic acid., diglycollic acid,
phthallic anhydride, f~naric acid, hydroxyacetic acid, it~conic
acid, succinic 'acid, dimerized fatty acids and the like. I have,
found the most generally useful acylating agents to be the di-
and mono-basic acids and anhydrides containing less than'13 ca~bon
.- atoms..
. Examples of isocyanates. useful ~or the acylation.of a poly-
ethe'r polyol to produce an effective TFSA include'methylisocyanate,
phenyl isocyanate, cyclohexylmethylene isocyanate, and.the like,
Espec'ially useful reactants are'polyis'ocyanates containing two
or mor'e'is'ocyana~e'groups and including phenylene di;socyanate,
-18- -
.
.
, ~
L3639~ji
l toluene diisocyanate, diphenylmethane diisocyanate, hex'arnethylenediisocyanate, 1,5-NaphthaleIIe'diisocyanate and polymethylene-
polyphenyl isocyanates.
Followi'ng acylation re'actions of polyethe~ polyols with
polyisocyanates', where a stoichiometric excess of the latter re-
actant is employed,' remaining isocyanate groups'may be left ~s
such'or'may; by appropriate addition of water or monohydric
alcohol, be''converted to' carb'amic acid ~roups, which 'i~ediately
undergo decarboxylation to yiel'd xesidual amino groups, or
carbamate'groups.
Examples' of 'acylated'polyether polyols and their'mamlfac-
turing pr'ocedures are well known to the art, as disclosed in
, . . . . .
V.S'. Patent No. 2,4~4',808, issued November 30, 1948, to
Kirkpatrick, U.S'. Patent No. 2,562,878, issued August 7, 1951,
to Blair,-U.S. Patent No. 2,679,511, issued May 25, 1954, to
DeGroote, U.S. Patent No; 2,602,061, issued July 1, 1952, also '
to DeGroote,' "Ch'emical Process Industries" by R. N. Shreve,
McGraw Hill Publishing Co.','''1967,~page 654 et seq., and "High
' Polymers", Vol. XIII, edited by N. G. Gaylord, ~ohn Wiley &
Sons, 1963, page 317 et seq.
; All flnal compositions useful in the present invention must
; ha~e the previously recited properties: -
l. Solubility in water and in isooctane at about 25C is
less than about 1% by volume.
Solubility tests may be run by placing a 1 ml
' sample'(or the we'ight of solid product calculated to
have'a volume of 1 ml~'in a graduated cylinder of the
type'wh'i'ch''may be''closed wi'th'a ground glass stopper.
Place'100 ml of water in cylinder, close, pl'ace in a
.
~1~3~39S
1 ~ 25C water bath until thermal equilibrium is reached,
r'emove'fr'om the bath'and shake vi.go-rously ~or one
' 'hour.---: Return to.thb bath for five''minutes and then
~ . . . . . . . . .
repeat the'''shaking pr`ocedure. Finally, return to the
' ba'th'and allow to stand yuiet'ly for one hour, Examine
the''cylinder' contents carefully. Any cloudiness or
' . opacity of the liquid phase or the appearance of any
sediment or undissolved material in the cylin.der indl-
: . ' cates that the product satisfies the'requlr'ement for
~ 10~ insolubility in water.
.
- ' ' Isooctane'solubility.is determined s'imilarl~ by
- subs'tituting this hy'dr'ocarbon for the wat'er used above.
. 'The'solubility'parameter (S.P.)'at about 25C is from
between about'6.9.to about 8.5, inclusive.
. 15 . '' Met~o'ds of determination of solubility.parameter
are di'sclosed in Joel.H. Hildebrand, "The Solubility o'f
Nonel'ectrol~.tes," Third Edition~ pages 425 et se~.
. . .
- Howe'ver, a s'implified procedure, sufficiently accurate
: for qualification:of.useful TFSA products, may be
utilized,' Components of a given solubility parameter
- arè'generally .i~soluble in hydrocarbon (non-hydrogen-
~ . bonding) solvents of lower solubility parameter than: themselves. Therefore, the present compositions should~
all be soluble in a hydrocarbon solvent of a solubility
25. parameter of about'8.5 and insoluble or incompletelysoluble in one having a solubility parameter of about
- 6.8, Since the solubility parameter of mixtures of
solvents is an additive function of. volume percentage
; . of components in the` mixture, test solutions of the
des'ire'd solubili~y par'ameters may be easily prepared by
:
,: ~ : . ,- ' .
2~
3~ii39S
,
1 '~ '' blending,.or ex'ample, benzene (S.P. 9 153 and isooc~ane
(:S.P'. '6.85)'or perfluoro-n-heptane (S.P.:5.-7).
' - ' A mixture of about .72 parts o benzene with about
.
. 28 parts o~ iso'octane will provide a solvent having an
;5 S.P. of about 8.5 at ro'om .t'e~perature:(a~out 25C).
. Perfluoro-n-heptane has an.S.P'. of.5.7 at 25C, so a
' mi~ture'of 68 parts of this solvent with 32 parts of
_ . .
:benzene provides a solvent with an S..P. of 6.8, or
. isooctane'o S.P'. 6'.85'may be used.
!' ' ' When S ml of c'ompositions useful in.the present
pr'oces's are'mixed with'95'ml of ~he'8..5 S.P'. solvent at
room temperature, a clear solution should result. When
'-5 ml of composition'is mixed wi'th'the 6'.85 S.P. solvent,
' a cloudy'mixture'or one showing phase separation should
'- res'ult.' So.lvent' mixtures of S.P. 7.0 and 7.9 may be
- prepared as described above and utilized in a similar''
. test pr'ocedure.
' ' . In interpreting the solubility parameter and other
t'es'ts, .it should be recognized.that in preparing the
polymeric' compositions use~ul in the present invention,
.the~'resulting end product consists not of a single
material'or compound b~t a cogeneric mixture of products
. containing a ran~e of.prod~cts of molecul.ar weîghts
distributed around the average molecular weight and
. 25 even containing small amounts of the starting compounds
''employed in the synthesis.
As a result, in running solubility'and solubility
' parameter .tests.'~ery slight appearances of cloudiness
- or lack of absolute'clarity should not be'interprete~d
as a pas~ or'a failure'to pass the''criteriaO.-. The
.. . . . .
.' - ` ' ., ~ ~ .
, . ; .-. . ~ .. ....
. ............. .. -21- .
'~'
, .
1~3Çi3~5 ;
.
l ' intent'of ~he test is to ensure that ~he bulk of the
cogener'ic'm;xture,' say 75V/~ or'm~re,~ meets the requi.re-
'ment. When.'the'res'ult.is in doubt thé'solubility .tests
' may'be'run in centrifuge tubes allowing subsequent
rapid phase'separati.on.by' centrifuging, ater which the
- sep'arated n~n-solvent phase' can be r'emoved, any solvent
- . contained in it' can be'evaporated and the actual weight
' - or volume.of separated phase can be determined.
- 3. .The'product should sprea'd at the'interface between
' : distilled water and'refined mineral.oil to fo'rm films
- ' . "wi'th'th'i'ckness no greater.than about 20 ~ngstroms
. - (0.'0020 micr'omet'er~ at a film pres'sure of about 16
dynes' per' cm (0.0l6 Newton per meter~.
. - ` Suitable''methods'of determining film pressure are
15' ' disclosed in N. K. Ad'am, ''Physics and Chemistry of
-- Surfaces," Third Edition, Oxford University Press,
' London, L941, pages 20 et seq.. , and C. M. Blair, Jr.,
'Interfacial Fi'lms Affecting.The Stability Of Petro'leum
: Emulsions";''Ch'e'mi's!t'ry''and''In'd'us'tr.y, 1960, pages 538 et
; 20 ' '- seq. Film th'ickness is' calculated on the assumption
~: ' tha~ all of thé composition remains on the area ~f
~ ~ interface between distilled water and refined mineral '
: ' oiI on which'the product or its solution in 'a volatile
solven~ has been placedn
' ~ 'Since spreading pressure is numerically equal to
the change in interfacial tension resulting from spread-
' ing of the ilm, it i6 conveniently. determined by making
inter~acial .tension measurements beore and after adding
a known amount of.TFSA to an interface of known area.
30 ' ' Alternatively, one~may utilize an interfacial film
' . balance'of the ~an'gmuir.. type.such'as that de'scri4ed by
~ .' ' '' . ', ~ ' .
: -22~
, . ~ . .
-, '.. ,, ' ' .'...... . .
. .
~3~i3~5
l' ' J. H. Brooks and B. A. Pethica,' Tran'sa'c't'ions''of'the
.. .... .. . .. .... ..
. '' Fa'r'a'da~ S'o'c'i'ety, 1964,'page 208, et seq., or other
'rnet~o'ds wll'ich ~ave bee'n ~ualified for such'interfacial
' spre~'ding pres'sure'det'e'rminations.
In deter~nining the interfacial spreading pressure
~f the'TFSA products, it is preferred to use as the oil
phase'a fairly available and reproducible oil such as a
- ' clear, refined mineral oil. Such oils are derived from
~ petrolet~ snd have been trea~ed with sulfuric acid and
'-' other agents to r'emove non-hydrocarbon and aromati.c
` -'''const'ituents. Typical'of such'oils is "Nujol'', dis-
tributed'by Plough-,' Inc. This oil ranges in density
from'about 0;85 to about 0.89 and usually has a solu-
- bi'lity par'ameter between about 6.9 and about 7.5.
Numerous s'imilar oils of greater or smaller density and
viscosity are'c'ommonly available from chemical supply-~
` houses' and pharmacies.
' Other- essentially aliphatic or naphthenic hydro-
~ carbons of low volatility are equally usable and will
yield s'imilar values of spreading pressure. Suitable
hydrocarbon oils`appear in commercial trade as refined
"white oils"7 '"textile lubricants'', ''paraffin oil", and
the'like.' Frequently they may contain very small
' quantities of alpha-tocopherol (vitamin E) or similar
- antioxidants w~ich are oil soluble and do not inter~ere
' with'the'spreading measurements.
- The'invention is further illustrated in the following
examples: ' '
'EXAMPLE I
-- * ,.
In an apparatus sïmilar to that of Example I of my co-pending
application'~iled on'even date her'ewith'and entitled "Method Of
* Trade Mark . -'
, -23- ' `
~, .
-. ~
13~3~S
**Example I of an applicat:Lon entitled "Method of Recovering
Petroleum From A Subterranean Reservoir Incorporating A
Polyether Polyol"
EXAMPLE I
To an autoclave equipped wi~h a means of mechanical s~ir-
ring heating and cooling, 4.7 parts of dipropylene glycol and
0.25 parts potassium hydroxide were added. The contents of the
autoclave were heated to 125C. At this temperature, 1,2-
propylene oxide was slowly introduced from a transfer bomb
which contained 200 parts of 1,2-propylene oxide. Cooling was
applied during the addition to maintain the temperature belo~
130C with a pressure of 60 - 75 psi. Approximately two hours
were required to introduce the 1~2-propylene oxide. The
reaction mass was maintained at 130C for four hours to ensure
that the unreacted 1,2-propylene oxide was at a minimum. E'ive
parts of ethylene oxide were then added from a transfer bomb
at such a rate that the temperature was maintained between
150 - 160C with a pressure of 60 - 75 psi. After all of the
ethylene o*ide had been added, the temperature was held at
150C for an addltional hour to complete the reaction. The
molecular weight of the final product was approximately 4,000.
This product is insoluble in water and diisobutylene, has
a solubility parameter of 7.2 and spreads at the distilled
water-mineral oil interface to yield a spreading pressure of
21 dynes per cm at a calculated thickness of 10 Angstroms.
~ - 23(a) -
. ., .. ~ ., .. ....... .. . . . , .................. ~ .
,~ , . .... . .
; ~136i;~5
Recovering Petroleum From A Subterranean Reservoir Incorporat-
ing A Polyether Polyol", Serial No. 353,250, 9.2 parts of
glycerol were reacted with 275 parts o~ a mixture of 225
propylene oxide and 50 parts of ethylene oxide, using the same
procedure as that employed in Example II*** of my co-pending
application filed on even date herewith, entitled "Method Of
- Recovering Petroleum From A Subterranean Reservoir Incorporat-
ing Resinous Polyalkylene Oxide Aclducts", Serial No. 353,232.
The final product was a clear, almost colorless viscous oil
having a molecular weight of about 3,000.
3,000 lbs. of this product were placed in a 1,000 gal.
stainless steel reaction vessel equipped with a ~as-fired heat-
er, an overhead outlet pipe connected through a condenser to a
steam eductor and having an efficient, heavy duty stirrer.
220 lbs. of adipic acid were added after which the vessel was
closed, the stirrer was started and heating was initiated. The
temperature was gradually increased to 140C and held at this
; point for 3 hours during which about 28 lbs. of water were
distilled over from the reaction vessel and condensed. The
steam ejector system was then activated and adjusted to main-
tain a vacuum of about 26 inches of mercury while heating was
continued at 140C for another 1~ hours. About 4 lbs. of
additional water condensate were collected~ The final product
was a pale, viscous oil having an acid number of 14 and was
found to meet the three speading and solubility criteria as
set forth above.
; EX~MPLE II
Using the apparatus of Example I, above, with the con-
denser arranged for reflux, 750 lbs. of the product of
Example I and 2,250 lbs. of commercial mixed xylene were
placed in the reactor. The mixture was stirred to effect
solution of the polyether
24 -
1136.'39Si
*** Example II of an application entitled "Method of Recovering
Petroleum Fxom A Subterranean Reservoir Incorporating
Resinous Polyalkylene Oxide Adducts"
EXAMPLE II
Into a 4,000 gal. stainless steel reactor, equipped with
steam heating and cooling coils, stirrer, reflux and tak.e-off
condensors, steam vacuum jet and inlet feed lines, were placed:
High boiling aromatic solvent 5,200 lbs.
Paraformaldehyde 120 lbs.
Para-tertiary amyl phenol 4,600 lbs.
After warming to 55C while stirring, 68 lbs. of 50%
aqueous caustic soda solution were introduced. A mildly exo-
thermic reaction ensued. The condensor was opened to a de-
canter, the steam jet was activated and a vacuum of 26 inches
of mercury was held on the vessel for a period of 2~ hours
during which the temperature was gradually raised to 165 C.
At this point resin formation is essentially complete.
150 lbs. of additional 50% caustic soda were then intro-
duced and a full vacuum applied while continuing heating for
one hour. The vessel was then closed, cooled to 135C and
then was introduced:
Ethylene Oxide, 3,050 lbs. at a rate which maintained
a temperature of about 1~5 - 130C.
Aromatic Solvent, 3,000 lbs. were then added, the
batch was cooled and filled into drums.
A sample, after vacuum distillation to remove aromatic
solvent, met the three required tests, set forth above.
Selection of the best TFSA product for use in a given
ield application is bes~ done by laboratory test procedures
which have been found to have predictive value for other
enhanced recovery methods. For disclosures of such procedures,
reference is made to procedures given in "Oil-in-Water Emul-
sions and Their Flow Properties in Porous Media," by
~`r
: - 24(a) -
- -~ il3~3~S
C. D. McAuliffe, Journal of Petroleum Technolo~, June 1973,
p. 727, et seq., and to U.S. Patent 3,163,214, entitled
"Solvent-Waterflood Oil Recovery Process," issued December 29,
1964, to Csaszar,
Among such procedures, one which has been found useful in
selecting a suitable TFSA involves a determination of oil dis-
placement efficiency from prepared oil-containing rock cores in
equipment described below. A tube of glass or transparent poly-
methacrylate ester, having an inside diameter of about 3.5 cm
(1~ inches) and a length of about 45 cm (18 inches), is fitted
with inlet connections and appropriate valves at each end. The
tube is mounted vertically on a rack in an air bath equipped
with a fan, heater and thermostat which allows selection and
maintenance of temperatures in the range of between about 25
130C
To select the most efficient TFSA for use in a given oil
: formation, samples of the oil, of the producing rock formation
and of the water to be used in the flooding operation were
obtained. The formation rock is extracted with toluene to re-
move oil, is dried and is then ground in a ball mill to the
point where a large percentage passes a 40 mesh sieveO The
fraction between 60 and 100 mesh in size is retained. The tube
described above is removed from the air bath, opened and, after
insertion of a glass wool retainer at the lower end,is packed
with the ground Eormation rock. The tube is tapped gently from
time-to-time during filling to ensure close packing and i5
visually inspected to assure absence of voids.
The tube is then returned to the air bath, connected to
the inlet tubing, the temperature is adjusted to the oil forma-
tion temperature and oil from such formation is admitted slow-
ly through the bottom line from a calibrated reservoir in an
amount just sufficient to fill the packed rock plug in the
- 24(b) -
1~3~3~5
tube. This volume is determined from the calibrations and isreferred to as the "pore volume", being that volume of oil just
sufficient to fill the pores or interstices of the packed plug
o f rock.
The tube is now closed and left in the air bath at the
selected temperature for a period of from one to, perhaps, five
days to allow establishment of equilibrium between the ground
formation rock and the oil with respect to adsorption of oil
constituents on the rock and lowering of interfacial tension.
The time allowed for equilibrium may be varied widely. At
higher temperatures, the time required to reach equilibrium is
probably reduced. Usually, for comparative tests, three days
are allowed to age the oil-rock plug. Results with this pro-
cedure closely simulate work with actual cores of oil-bearing
rock.
The oil and water samples used for test purposes are
preferably taken under an inert gas such as high purity nitro-
; gen, and are maintained out of contact with air during all
manlpulations in order to prevent oxidation of the oil and
concomitant introduction of spurious polar, surface-active
constituents in the oil. At this point, the rock-oil system
simulates the original oil formation before primary production
~; of oil was commenced and well before any secondary waterflood
operation.
The upper inlet line to the tube is now connected to the
sample of water used in the flooding of the oil formation and,
by means of a syringe pump or similar very small volume
positive displacement pump, the ~ater is pumped into the sand
body from the top to displace fluids out of the bottom tubing
connection into a calibrated receiver. The pumping rate is
adjusted to one simulating the rate of flood water advance in
an actual operation, which is usually in a range of 1 to 50 cm
- 2~(c) -
:-.
39S
per day. Pumping is maintained at this rate until several pore
volumes of water have been pumped through the sand.
The volumes of fluids collected in the receiver are
measured and the relative amount oE oil and water displaced
from the rock sample are determined and recorded. Of special
interest is the volume of oil disp:Laced as a fraction of the
original pore volume. This information may be viewed as an
indication of the approximate percentage of oil originally
in place which is produced by natural water drive following
drilling of a well into the rock formation followed by the
primary phase of field production.
Following this step, several additional pore volumes of
water containing the TFSA composition to be tested are pumped
slowly through the plug and the volumes of additional oil and
water displaced are determined. Alternatively, the TFSA com-
position dissolved in a relatively small volume of organic
solvent or emulsified in a relatively small volume of water,
may be pumped into the plug and followed with several pore
volumes of flood water. Typically, where such an initial "slug"
of TFSA is introduced it may be contained in a volume of fluid
ranging from 1% to 100~ of the pore volume, but most frequently
it will be in a slug volume of 10% to 50% of pore volume.
After this final displacement step, the produced oil and
water are again measured. By comparing the amount of oil pro-
duced by this additional injection of water containing, or pre-
ceded by a solution, of TFSA with the amount produced when the
same volume of water containing no TFSA is injected, one can
- evaluate the effectiveness of the particular TFSA composition
used for enhancing the recovery of additional oil over and
above that obtained by ordinary waterflooding alone.
~ -,r
-- - 24 (d)
li3~395
1 ~ gIycol in the xylene while the te~pera~ure was brought to about
80C. An inlet feed line:to .the re'actor was then opened and a
10% solution in xylene of to.luene'diis'ocyanate was pumped slowly
through'the line to the'reactor at a rate'to deliver 1,100 lbs.
of solution du~ing a 2~ hou~ peri.od. The tempe~ature was main-
tained at 80C d~ring this.addition... The valve was then closed
and the't'emperature brought to 140C where it was held unti'l a
sample'of re'a'ction product taken from the' ves'sel was ound to
have a'vi'scosity within the range of 2,500 to 3,500 centipoises
10 at a temperature'of 100C'; At this point, hea~ing was dis-
continued and cooling water was' c;rculated through'the interal
coils. of the re'actor to br.ing about rapid cooling of the pro'duct.
' The final product met the three required tests for. a TFSA com-
.~ pound, as set forth'above,' being soluble to an exten~ of less
than 1% in water and isooctane, ha'ving a solubility para~eter of
8.4 and spreading at.the interface be~ween distilled water and
refined mineral oil to give a spreading pressure of 20 dynes per
cm when ~he'amount on the surface has a thickness of 17 Angstroms.
. : - 'EXAMPLE''III
150 lbs. o~ maleic anhydride were substituted for the 220 lbs.
of adipic aci`d in'Example.I,.while' maintaining the same operating
procedure. '~nly about.7 lbs.~..of aqueous.distillate were obtained
in this case. The product was a vis.cous, slightly yellow oil.
Selection of the best TFSA product for use in a given field
application is best done by laboratory test procedures which have
been found to have predictive value for other enhance'd recovery
metho'ds. For di'sclosures of such procedures, reference is'made
to procedures' given in ''Oil-in-~ater Emulsions and Their rlow
Properties' in Porous Med'ia," by C; D. McAuliffe,' Jo'u'r'n'al''of
.... .... . .... ... ....
~e't`r'ol'e'um Te-c~'nolo'gy, June'19.73,.p.. 727, et seq., and.to U.~. '
Patent 3,'163,214,. entitled "Solvent-Waterflood Oil' Recovery
,.. .., , ., : ,, ~ . -
25- ' ' `~' ' ; -
.
~13~3~5i
Process," issued December 29, 1964, to Csaszar.
Among such procedures, one which has been found useful inselecting a suitable TFS~ involves a determination of oil dis-
placement efficienc~ from prepared oil-con~aining rock cores in
equipment described below. A tube of glas~ or transparent poly-
methacrylate ester, having an inside diameter of about 3.5 cm
(l~ inches) and a leng~h o~ about 45 cm (18 inches), is fitted
with inlet connections and appropriate valves at each end. The
tube is mounted vertically on a rack in an air equipped with a
fan, heater and thermostat which allows selection and mainten-
ance of temperatures in the range of between about 25 - 130C.
To select the most efficient TFSA for use in a given oil
formation, samples of the oil, of the producing rock formation
and of the water to be used in the flooding operation were
obtained. The formation rock is extracted with toluene to ~e-
move oil, is dried and is then ground in a ball mill to the
point where a large percentage passes a 40 mesh sieve. The
fraction between 60 and 100 mesh in size is retained. The tube
described above is removed from the air bath, opened and, after
insertion of a glass wool retainer at the lower end, is packed
with the ground formation rock. The tube is tapped gently from
time-to-time during filling to ensure packing and is visually
inspected to assure absence of voids.
The tube is then returned to the air bath, connected to
the inlet tubing, the temperature i9 adjusted to the oil forma-
tion temperature and oil from such formation is admitted slowly
through the bottom line from a calibrated reservoix in an amount
just sufficient to fill the packed rock plug in the tube. This
volume i5 determined from the calibrations and is referred to as
the "pore volume", being that volume of oil just sufficient to
fill the pores or interstices of the packed plug of rock.
_ 26 -
i~3~39~;
.
1 ' The tube'is now closed and left in the air bath at the
selected t'emper'a~ure'for a per'iod of fr'om one Lo, perhaps, five
days to.a~low'establ'ishment of..equi.librium between'the ground
. formation'rock and the oil wi'th'res'p'ect to adsorption of oil
constituents on.the'r'ock and.lowering of interfacial tension.
The't'ime allow'ed for.~equilibri'um.may be'varied widel'~. ~t higher
temperatures; the't'ime required to re'ach equilibr.ium is probably
reduced.: Usually,. for c'omparative tests, three'days are allowed
to age the'oil-r'ock'plug.'' Results with'this procedure closely
10 ' simulate wo'rk wi'th 'actual' cores'of oil-bearing rock.
The oil and wa'ter samples used for:tes't purposes are prefer-
ably taken under an inert gas .such'as high'purity nitrogen, and
are'maintaine'd:out'of contact with air during all'manipulations
in order to prevent oxidation of.the'oil and concomitant intro-
duction of spurious polar, surface-active constituents in the
. oil. At this point, the rock-oil system simulates the original
oil formation before pr'imary production of oil.was commenced and
well before any s'ec'ondary'waterflood operation.
The'upper inlet line to the .tube is now connected to the
sample of water used'in the flooding of the oil formation and, by
means of a syringe pump-or similar very small volume positive
displacement pump, the water.is pumped into the sand body from
the top to displace fluids out of the bottom tubing connection
.~ into a calibrated receiver. The pumping rate is adjusted to one
'simulating the rate of flood water advance in an actual operation,
which is usually in a range of 1 to 50 'cm per day. Pumping is
maintained at this rate'until several pore volumes of water have
- been pumped thro~gh the sand.
The volumes of fluids' collected in the'rec~iver are measured
and the rel'ative'amount of oil and.water displ'aced from the rock
sample'are'det'e'rmined'and recor.ded. O spec'ial..interest i~ the
:. - . ~. i , , . . . : .,
. ~ -2~
;3~5
1 voll~e of oil. displaced as a fraction of the original p~re volume.
Thi's information'may be'v.iewe'd.as an indica~ion.o the approxi-
'mate'pe'rcentage'of oil originally in pl'ace wh'ich is produced by
.natural water drive'followi'ng drilling of a well into the rock
fo'rmation followed by the'prïmary phase of field prod~ction.
.Following thi's step', several addit;onal pore volumes of
water' containing the TFSA cornposition to be tested are pumped
slowly through'the''plug and the volumes of additional oil and
water displ'aced are det'e'rmined.. .Alternatively,..the TFSA composi-
10 tion dissolved in a relatively smal.lvolume'of organic sol~ent or
emulsified 'in''a'rel'a~ively small volume of water,'may be pumped
into the'plug'and followed with s.e~eral pore volumes of flood
water, Typically, wh'ere'such'an.initial ''slug'' of TFSA is intro-
duced it'may be' contained in a volume of fluid ranging from 1% to
15 100% o~ the'pore'volume,' but most frequently it will be in a slug
volume of 10% to 50% of pore volume. . .
After'~thi's fîna~ displacement step, the produced oil and
'water are again'measured.:. By comparing the amount of oil pro-
: duced by this addit;onal injection of water containing, or pre-
ceded by a solution, of TFSA with the amount produced when the
same volume'of water co~taining no TFSA is injected, one can
evaluate the'effectiveness of.the particular TFSA composition
used for enhancing the recovery of additional.oil over and above
that obtained by ordinary waterflooding alone.
: ' EXAMPLE IV
A core from an'oil-producing East Texas field was ground and
packed as described'in the'.test description above. Oil from the
same'fieId was used.to saturate the gro~md rock after which it
was held for two days at.-50C~ . The pore volume was found to be
- 30 121'ml. Thr'ee'pore.'volumes .o.f water used in this iel'd for
floo'ding of the-'zone were'pumped.through'and the'yolume of.`dis- . ¦
pl'ace'd oil was 'recor'd~d.~.'This is cal-ed "pr'imary" production.
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~13~3~5
.
1 '' Aliquotes of 0.05 ml and O.l'ml of ~the product of Example II,
above, were then dispersed by vigorous stirring into 0.2 pore
volume'of water wh'ich was slowly pumped into the'rock samples and
then followed by 3.8 pore'volumes.of water.containing no addi-
tional TFSA agent. Pumping was at a rate to complete the in-
jec'tion in 30 hours. The additional oil produced in this step,
re'ferred to as ''secondary'' production, was recorded.
A test, s'imilar to the above in all respects, except that no
TFSA was used, was then run.. The difference in oil volume procluced
in the first run minus the volume produced in the second (blank)
run is a measure of the increase in.production effected through
use of the TFSA compound. .The numerical res~lts of this test are
shown in'Table I. The final results are shown as percentage
increase in oil produced based on the pore volume of oil originally
in place in the rock column.
. Where the TFSA composition was introduced into the system in
the form of an emulsion, the blank (comparison) run was always
conducted with the same amount of emulsifier or of solvent as
- that used with 'the TFSA'composition in order that effects of the
latter should be'clear~y defined.
' All tests were run with the equipment and procedure described
above.
Use of a properly selected TFsA composition is seen to
provide very significant increases in the amount of oil produced
over that obt~in~b~e by ordinary waterfloodin
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1 '. " ' IMPLEM~NTA'rION OF THE ~I~EM'rION
As indicated above, introduction of the TFSA compositioninto the'waterflood pr'oces's' may.be accomplished in numerous ways.
Simples't, perha'ps, is the''continuous introduction, with rapid
. dispersion such'as may be'obtained through a centrifugal pump,
into the''flood'water strea~. The~amount required varies with the
formation being treated, the character of the oil and water and
the'sp'ecific TFSA composition used, but will generally be within
the range of from betwe'en about 5 to about .300 ppm o ~lood water
injected. O'ccasionally., wi'th 'especially viscous and refractory
oils of hi'gh.'aspha'ltene contënt or where lower reservoir t'empera-
tures' are encountered,.somewhat higher concentrations of up to
500 to 2,000 parts per` million may be more efecti~e.
An especialiy useful'and effective'means of application is
that of introducing the TFSA composition into the water stream as
an emulsion. The compositions generally may be emulsified with:'
- one of numerous commercially available emulsifying agents, either
cationic., anionic or nonionic or mixtures thereof. The composi-
tions may also be incorporated into micellar or transparent
' emulsions of e~tremely small size for injection into the water
stream. The previously cited U.S. Patent 2,356,205, dated August
27, 1944, to Blair and Lehmann shows numerous micellar emulsion
formulae into which TFSA compositions may be incorporated by
~ relatively minor changes in formulation.
- Rather than introduce the compositions continuously into the
flood water, one may, often with greater effect and lower cost,
introduce a higher concentration .of compound for only a part of
- the time. Commonly, this takes the form of batch or slug treat-
" ~ ment early in the history of the flooding operation usually to be
continued for a period of t'ime covering up to 1% to about 20% o~
the 'est'imated totàl time of water injection. O'ccasions ~ay arise
wher'e two or more periods of ba'~ch treatments are'util ized.
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' : ~ ' ' -31- I
; ~13t;39S
1 Where slllgs'o~ bal:c}7es' are employed, the concen~rat;on of
TFSA composltion injec'ted is higher than for the continuous
injection' case,' very rou~hly in proportion to the'ratio o the
total volume of water to be'inj'ected to the volume of the slug.
Gener'ally, howe'ver,' it has been found that results eql~ivalent to
those obtained with''continuous txeatment can be accolnplished with
les's TFSA if an early or "ront end" slug is introduced.
Instea'd of int~od'ucing an aqueous slug one ~ay inject a
solution of the TFSA' in a suitable organic solvent. Such sol-
vents include hydrocarbons wi'th solubility parameters equal to orabove that o the sel'ected TFSA, such as, or ex'ample, benzene,
' xylene;' toluene;' certain aromatic petroleum fractions, t~rpentine,
~` tetralin and the like. Alternatively, polar or semipolar solvents
in wide variet'y may be used. Satisfactory solvents for most TFSA
compositions i'nclude hexan~l, cresol, butanol, diisobutyl ketone
and mixtures of such'solvents with hydrocarbons. It is preferred
to use solven'ts wi'th rel'atively low water solubility. These,
too, are usually the' most readily available and econo-mic solvents
to use. In some applications it may be~highly desirable to
incorporate viscosity increasing agents into the organic solution
slugs in order to better distribute the fluid into the formation
- being flooded and to lessen excessive penetration into more
permeable or "thief" strata.
Effective "thickening'' or viscosity increasing agents in-
clude polybutylene, polyisoprene, polyacrylic acid esters and
- other high molecular weight polymers which are soluble in organic
solvents;
The improve~ents in oil recovery possible from use of TFSA
compositions is not l'imited to ordinary waterfloods. Positive
3~ enhanc'ement of res'ults are also obtainable:in conn'ection with'
othe'r so-called "chemical'.' or "surfactant" waterfloods, inc~uding
, .
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-32-
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~ il3~5
1 ' polymer or pusher floods, whe're water-soluble polymers of high
molecular we'ight' are dissolved in the water ~o 'impart higher
viscosity and improved distributio'n; micellar floods, such as
those'describe'd previously;' caust'ic floods; silicate floods;
detergent floods; emulsion floods; c~mine floods; and others
wher'ein s'ome 'soluble'additive'is added to the flood water.
In all s~ch appl'ications the range of concen~rations and use
rates of the sel'ected TFSA is about the same as with s'imple
waterflooding. In most of these appl'ications ~he use of a ront
~end slug t~ea'tment is des'i.rable, possibly excepting the case of
polymer or pushe'r' floods where the injection of at least some
polymer ahead o~ the' selected TFSA may be indicated by reservoir
characteristics.
In general, it is highly desirable to institute the use of
the TFSA composition as soon as possible after waterflooding,
pressure maintenance or any such water injection program is '
; started. Ear~y cont'act of reservoir oil with the TFSA facili-
tates its prod~ction by natural as well as artificial water
drive.
Nevertheless, since'most ordinary secondary waterflood _
operations leave'a large fraction of the oil in the producing
strata, it is often economically feasible to carry out a second
~' waterflooding operation (tertiary recovery) utilizin~ the present
;' invention for the recovery of additional oil.
25~ Other variat;ons and combinations of enhanced recovery
; procedures employ;ng the present invention will be apparent to
those skilled in the art o~ petroleum and bitumen production.
For example, large deposits of viscous oils are known to exist in
.
the United States, Venezuela and elsewhere in extensive shallow,
cool, sand formations where little reservoir energy exists to
produce flow of the oil into bore holes. Such formations a'ppear
: . '
-33-
,'' , , '' ~
~L13~;3~Si
1 , amenable to flood;ng w~'th ~ot ~ater which can be further enhanced
in effectivenes's by addit;on of a properly selected TFSA composi-
.
tion in 'accorda'nce with'this invention.
' Altho'ugh the inven'tion has been described in terms of speci-
-5 fied 'embodiments wh'ich'are'set forth ;n detail, it should be
understood that this is by illustration only and that the inven~
t';on is not n'ecessarily l'imited thereto, since alternative
embodiments and operating t'echni~ues will become apparent to
those skilled in the'art in view of the disclosure, ~ccordingly,
mo'difications are'cont'empla~ed wh'ich''can be made without depart-
ing from the spirit of the described invention.
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'_34~
