Note: Descriptions are shown in the official language in which they were submitted.
X~ 3~3~3~
HOECHST A~TIENGESELLSC~T HOE 89/F 900 Dr. GL/nu
Gendorf Work6
Process for stimulating oil and gas well~ in oil and gas
production from subterranean formation~, and ~timulant
for this purpose
Description
The invention relates to a proces~ for stimulating oil
and ~as wells in oil and gas production from subterranean
formations, the oil/gas-containing formation being
contacted in the region of the well with a stimulant from
the group comprising the fluorosurfactants. The inven-
tion also relates to a stimulant.
The reduced production and the pressure decline in oil
and gas production wells can have various ca~e~.
Deposits of organic substances such as asphaltenes, waxes
and paraffins, inor~anic precipitates, swelling clay
minerals or moving ~and grains, can reduce the perme-.
ability of the reservoir, in particular in the region of
the well. The damage to the oil/gas-bearing formation
can also be caused: by retained componen~s of, for ex-
ample, mud fluids, which haYe made the capillaries in the
pore space of the for~ation imperviou~.
It is known that stimulating fluids are used for over-
coming this problem, which increa~e again the perme-
ability of the reservoir, in particular in thesurroundings of the production and in~ection wells.
These fluids contain surface-active compounds which
reduce the interfacial:tension at the pha~e boundaries
and favorably~ affect the wetking p~opertie~ of the
reservoir rock. ~ost recently, fluorine-containing
surfactants have above all been recommended as surface-
active compounds (stimulants). ~h~s, in US Patent~
4,425,242, 4,460,791 and 4,594,200, fluorosurfactants
having a relatively long polyalkylene glycol ether group
:
- 2 ~ t3~
in ~he molecule are de~cribed as a stimulating agent
which is introduced into the subterranean formation to be
treated.
The rçduction in the abovementioned interfacial tension
values, achieved by mean~ of the known fluoro~urfactanks,
still leaves something to be desired. The effectivene~s
of the fluorosurfactants is also xeduced to a greater or
lesser extent by adsorption losse~ during con~acting with
the formation which i~ to be treated. There is thus
~0 still a demand for suitable and highly effective fluoro-
surfactants for the purpose in guestion.
To meet this demand, it has been found that fluoro-
surfactants with a very narrow range with xespect to the
carbon atoms in the perfluoroalkyl radical and with the
specific qroup -N(CH2CH2OH)2 in the mole~ule are advan-
tageous and unexpectedly effective stimulants for the
treatment of the formation~ in question.
The proces~ according to the invention for stLmulating
oil and ga~ wells in oil and gas production from sub-
terranean formation~, the oil/gas-containing formation
being contacted in the region of the well with a stimu-
lant from the group comprising the fluorosurfactants,
comprises using as the stimulant at least ona fluoro-
surfactant of the following formulae (1) to ~3),
F~-CF=CHCH2N(C2H4H) 2 ( 1 )
R'f-CONHC3~6N(C2H4H)2 (2)
R~y~CONHC3H6~(c2H4O~)2 (3~
o
in which Rf, R~r and R"~ are a perfluoroalkyl radical
having 5 to 8 carbon atoms, preferably having 7 carbon
atoms~
~he perfluoroalkyl radicals R~, R'~ and R"~ are preferably
straight-chain. The particularly preferred compounds of
_ 3 ~ r~3~
the formulae (1) to ( 3 ) are thus
n-C7Fl5CF=C~ICH2N ( C2~[40H ) 2
n-C7Fl5CON~C3H6N ( C2H4OH ) 2
n-C7Fl5CONHC3H6N ( C 2H40H ) 2
0
The fluoro~urfac~ants to ~e used according to ~he inven-
tion have been described in the printed publications
German Offenlegungsschrift 20749,331, US Patent 3,836~552
and US Patent 3l562,lS6, but there i~ no indication or
suggestion at all to the effect that precisely these
fluorosurfactants would be advantageous and effective
means for stimulating hydrocarbon-bearing formation3.
These fluorosurfactant~ represent more or le~s vi~cous to
pasty substances. The fluorosurfactants of the formula
(1) can be prepared by reaction~ accordin~ to the follow-
ing e~uations, in which a particular fluorine compound i~
used as an ex~mple:
C8Fl~CH2CH2I + Nat CH3 ~ > CaFl7CEI~CH2 +
NaI + CH30H
CsF17CH=CH2 + NH(~2~4H)2 ----> HF +
C7F15CF=CHCH2N ( C2H4H ) 2
The fluorosurfactants of the formula (2) can be prepared
by a reaction according to the following equa ion, in
which again a particular fluorine compound i8 used a~ an
example:
C7F1sC~C2Hs + H2~(CH2)3N(~2H40H) 2 ~ >
o
C7F1sC~NH(CH2)3N(~2H4~) 2 + C2H50H
~he fluorosurfactants of the formula (3) can be prepared
by a reaction according to the following equation:
o ~ 3~
C7F15C-~H(CH2)3N(C2H4OH) 2 ~ H22
C7F1s~-NH(cH2)3N(c2H~oH) 2 + H20
O
In other re~pects, reference may ba made to the cited
printed publications.
The effectiveness of the fluorosurfactant~ according to
the invention is~ surprisingly, increased considerably if
they are u~ed in a mixture with certain non-fluorinated
nonionic ~urfactan~, namely with alkoxypolyethylene
glycol ethers which contain 6 to 18 carbon atoms, prefer-
ably 8 to lS carbon atoms, in the ~lko~y moiety and 3 to
15 ethylene o~ide units, preferably 6 to 12 ethylene
oxide units, in the polyethylene glycol ether moiety; for
example octyl polyglycol ether having 10 ethylene oxide
units, decyl polyglycol ether having 6 ethylene oxide
units and isotri~ecyl polyglycol ether having 8 ethylene
oxide units, or with alkylphenoxypolyethylene glycol
ethers which contain 6 to 18 carbon atoms, preferably 8
to 12 carbon atoms, in the alkyl moiety and 3 to 15
ethylene oxide units, preferably 6 to 12 ethylene oxide
units, in the polyethylene glycol ether moiety, for
example octylphenol or isooctylphenol polyglycol ether
having 10 ethylene oxide units, nonylphenol polyglycol
ether having 10 ethylene oxide units and dodecylphenol
polyglycol ether having 8 ethylene o~ide unit~. The non-
fluorina~ed nonionic ~urfactants men~ionQd are thus
selected fatty alcohol ethoxylates and alkylphenol
ethoxylates having the indicated nu~ber of carbon atoms
in the hydrophobic radical and having the indicated
number of ethylene oxide units. The fluoro~uractant~ to
be u~ed according to ~he invention are preferably
combined with one or more (as a rule one) fatty alcohol
ethoxylate or with one or more ( d8 a rule one) alkyl-
phenol ethoxylate, the combination with a fatty alcohol
ethoxylate being preferred. These stimulant~ composed of
- 5 ~ r~3~
fluorosurfactant ~nd fatty alcohol ethoxylate or alkyl-
phenol ethoxylate contain the two mix~ure components
preferably in a weight ratio of 1 . 1 With particular
preference, th~ indicated fluorosurfactants are u3ed
together with fatty alcohol ethoxylate and with al~yl-
phenol ethoxylate. In these mixtures of three
components, the weight ratio of the component6 i~ prefer-
ably 1 : 1 : 1. The ~timulant~ according to the invan-
tion in the form of the fluorosurfactants of the formul~e
(1) to (3) or in the form of the mixtures de~rribed of
these fluoro~urfactants and the indicated alkoxypolyethy-
lene glycol ethers and/or alkylphenoxypolyethylene glycol
ethers are particularly effective, in particular those
having the three ~aid component~, which i~ probably the
result of an unexpectedly large synergistic effect.
The stLmulant composed of the said three components i8
novel. The invention therefore also relates to an agent
for stimulating oil and ga~ wells in oil and gas produc-
tion from subterranean formation~. The ~timulant accoxd-
ing to the invention i8 composed essentially of a) atleast one fluoro~urfactant of the formulae (1) to (3)
described, b) at least one alkoxypolyethylene glycol
ether having 6 to 18 carbon atoms, preferahly B to
15 carbon atoms, in the alkoxy moiety and 3 to 15 ethy-
lene oxide units, preferably 6 to 12 ethylene oxideunits, in the polyethylene glycol ether moiety, and of
c) at least one alkylphenoxypolyethylene glycol ether
having 6 to 18 carbon atoms, preferably 8 to 12 carbon
atoms, in the alkyl moiety and 3 to 15 ethylene o~ide
unit~, preferably 6 to 12 ethylene oxide units, in the
polyethylene glycol ether moiety, the three component~ a)
to cj being pre~ent in a weight ratio of preferably
~ 1. A3 a rule, only one representative of each
component is used. In other respect~, the above comments
apply to the three components. The stimulant~ according
to the invention are produced by mixing the component~
together, advantageously with stirring, at a temperature
of preferably 20 to 50C.
The stLmulants according to the inYention, 1.e. both the
fluorosurfactants of the formulae (1) to (3) and the said
mixtures of the fluorosurfactan~s and the said ethoxy-
lates, are as a rule soluble in w~ker. ~o improve the
ease of handling (pourahility), they are in general
blended with an appropriate quantity of water and/or with
lower alcohols, such as methanol, e~hanol~ propanol,
isopropanol and/or e~hylene glycol.
The contac~ing of the stimulant~ to be used according to
~0 the invention with the hydrocarbon-bearing ffubterranean
reservoir can be carried out by the methods known per ~e.
Accordingly, the ~timulant i~ preferably u~ed in a
carrier fluid (dissolv~d or dispersed) which, in the
present case, advantageou~ly i8 essentially composed of
waterO The concentration of ~timulant in the carrier
fluid can vary within wide limits, and this is 0.001 to
10 % by weight, preferably 0.05 to 5 % by weight, the
percentages by weight relati~g to the weight of the
carrier fluid. The carrier fluid containing the stimu-
lant is introduced into the reservoir to be treated undera high pressure, which may be at a higher or lower level,
until the desired increase in hydrocarbon production has
been reached again. Lower alcohol6 (methanol or iso-
propanol), ~alts and/or acids or alkalis for adjusting
the pH of the fluid to an advantageous value can be added
to the aqueous carrier fluid; by means of these methods
likewise known per se, a better distribution of the
stLmulant in the reservoir can be achieved if neces~ary
(the carrier fluid i6 thus under~tood to mean the fluid
medium and all further additiv2s, with the e~ception of
the stimulant).
.
The stimulants according to the invention have a number
of advantages. AB already mentioned, they are particu-
larly effective and therefore lead to a pronounced
increase in the production rate of gas and oil. ~hey are
also active even in a low concentration. Because of
their special surfactant properties, a high recovery rate
- 7 ~ J7~
of the ~tLmulant fluid i8 al80 obtained; in view of the
high price of fluoro~urfac~ant~, thi~ i~ a further
particular advantage.
~ he invention will now be explained in greater dstail by
reference to ~xamples:
As a measure of the effectiveness of the stimulants
described, their adsorption behavior on Oklahoma No. 1
~and i~ testedO This test method (which i~ analogous to
that de~cribed by Henry B. Clark et al. in Journal of
Petroleum Technolo~y, July 1982, pages 1,565 to 1,569) is
indicated in detail below:
The ~dsorption te~ts are carried out in a burette
(length: 350 mm, internal diameter: 19 mm) which has been
filled with 50 g of Oklahoma No. 1 sand between two pad~
of glass wool. The test solutions are prepared as
follows: initially, a solution of 50 % by wsight of
isopropanol, 49 % by weight of distilled water and 1 % by
weight of stLmulant is prepared. 1 ml of this 1 % by
weight solution is dissolved in 250 ml of a 2 % by weight
aqueous ~Cl solution (i.e. about 40 mg of stLmulant per
liter). 11 ml of the test solution thu~ obtained are
filled into the burette and then ~ub~ected for 1 to
2 hour~ to a pressure of 35,150 Pa. The solution iB then
forced out by opening the cock of the burette and apply-
ing a pressure of 105,450 Pa, and its surface tension i8
measured by the Du Nouy method (DI~ 53 914). This
procedure is repeated five tLmes in the same burette,
with the ~ame ~and filling, using 11 ml of test solution
each time. The surface tension value of the thlrd test
solution forced out of the burette (i.e. the third
eluate) should be less than 35 m~/m, preferably le~s than
30 mNtm.
The following stLmulants to be u~ed according to ~he
invention were tested:
'7~
Example 1
The stimulant is a mixture of
n-C7Fl5CF=CHCH2N ~ C2H40H ) 2 1 i~otridecyl polyglycol ether with
8 ethylene oxide units and
nonylphenol polyglycol e~her wikh 10 ethylena oxide units
in a weight ratio of 1 : 1 o 1.
E~a~pl~ 2
The stimulant is a mixture of
n-C7Fl5CONHC3H6N ( C2H40H ) 2, isotridecyl polyglycol ether with
1~ 8 ethylene oxide units and
nonylphenol polyglycol ether with 10 ethylene oxide units
in a weight ratio of 1
Example 3
The stimulant is a mixture of
n-C7Fl5CONHC3H6N t C2H40H )
isotridecyl polyglycol ether with 8 ethylene oxide unit~
and nonylphenol polyglycol ether with 10 ethylene oxide
units in a weight ratio of 1
Comparison example
Example 1 was repeated, the fluorine compound used being
the fluorosurfactant Fluorad~ Well Stimulation ~dditive
FC-750 from Minne60ta Mining and ~anufacturing (3M~
Company, USA (~ = regi~tered trademark of 3M), which i5
commercially available and described a~ particularly
effective; this fluorosur~actant is a fluorinated quater-
nary alkylammonium iodide.
The mixtures (stimulants) from Exzmple~ 1 to 3 according
to the invention and the compari~on example were prepared
by mixing the three components at room temperature.
3~:3~3~
g _
In the table which follow~ e ~urface ~ension valua~ of
the first to fifth eluates of th2 ad~orption test de-
scribed are indicated:
. . .~
Stimulant Surface tension (mN/m~ of the
test solutions and of the
1st to 5th eluates
_ Test solution l~t. 2nd. 3rd. 4th. 5th.
Example 1 l9 41 30 29 28 26
Example 2 22 39 35 29 29 29
Example 3 23 37 32 28 28 27
Comparison
example 22 51 51 48 41 40
. _ _ _
As the examples show, the stimulant~ according to the
invention pa~s the demanded test and are therefore very
effective in oil and gas production from hydrocarbon--
bearing subterranean formations. Above all, they hare a
particularly advantageous ad~orption behavior, i.e. the
loss of fluorosurfactant due to adsorption proce~ses is
small. The same result was al~o obtained ~hen isooctyl-
phenol polyglycol ether with lO ethylene oxide units was
used in place of nonylphenol poly~lycol ether with
10 ethylene oxide units.
