Method for drying out rock containing immobile formation water within the encroachment area of natural gas deposits and gas reservoirs

The invention relates to a process for drying out rock containing immobile formation water in the intake radius of natural gas wells and gas storage wells which deliver less than 50 l of water per 1000 m.sup.3 (S.T.P.) of natural gas produced, in which a dispersion comprising the components PA1 A) a water-repellent active compound, PA1 B) hydrophilic water-miscible dispersion medium, with or without PA1 C) a dispersant renders the water-containing rock hydrophobic.

The invention relates to a process for drying out rock containing immobile 
formation water in the intake radius of natural gas wells and gas storage 
wells, in which water-repellent active compound in dispersed form renders 
the water-containing rock hydrophobic. 
In the vicinity of production wells in natural gas fields, formation water 
in the pore cavities of the rock prevents the flow of gas to the 
production well. If the formation water has a high salt content, the 
evaporation of water causes the solubility limit to be exceeded, and in 
particular chloride salts crystallize out. Since salt water is 
continuously drawn into the pore cavities by capillary forces, the salt 
crystals constantly grow until the flow channels are closed to the point 
of impermeability to natural gas. 
Salt deposits occur not only in the pore cavities, but also form on well 
casings and other pipes, and on storage and further processing facilities, 
such as piping, valves, heating coils and heating tubes and separators, 
which are involved with handling the gas produced and the formation water 
which is separated off. When a deposit forms, the extraction rate 
decreases and finally the entire operation ceases. Furthermore, the heat 
transfer is decreased. 
The customary process for enhancing the productivity of natural gas wells 
is the hydraulic generation and stabilization of fractures in the vicinity 
of the well. The additional drainage areas produced by this means and the 
high gas flux density in the fractures leads to an elevated production 
rate of the well. However, this process is highly expensive. Fracture 
formation can be controlled only to a very restricted extent. 
The salt deposits, in particular chloride salts, can be eliminated by 
flushing with fresh water. Since the salt deposits continue to reform, 
these flushing operations must be carried out at regular intervals, which 
causes frequent losses of production. 
A process for removing salt deposits in wells is described in U.S. Pat. No. 
5,051,197. There, the wells are treated with an aqueous composition of 
aminopolycarboxylic acid and water-soluble organosilane. However, 
water-soluble organosilanes generally have a high volatility and a low 
flashpoint, hydrolyze rapidly and release toxic and highly flammable 
products in the presence of water. Thus, chlorosilanes form HCl, 
methoxysilanes form methanol and ethoxysilanes form ethanol. Therefore, 
these compositions can only be kept for a short time and are difficult to 
handle. In addition, a process for removing salt deposits is described 
here, and not a process for preventing salt deposits. 
A process for preventing salt deposits in wells is described in U.S. Pat. 
No. 3,682,831. There, the wells are treated with water-soluble 
glycol-silicone copolymers which contain SiOC bonds which are highly 
sensitive to hydrolysis. However, the action of this process is too poor. 
U.S. Pat. No. 3,653,442 describes a process for removing water by means of 
micellar dispersions, which achieves the increase in gas or oil flow 
through removal of a water block. 
Database WPI, week 9311, AN-93-091996 and SU-A-1 724 854 describe a seating 
material for natural gas and oil boreholes which is claimed to block 
mobile ingressing water. 
U.S. Pat. No. 4,074,536 describes a process for hydrophobicizing rock 
formations using organosilicon compounds with regard to preparation of the 
rock and prevention of dissolution of the rock in the presence of water. 
The object was therefore to provide a means which drys out immobile 
formation water in the rock and which provides durable prevention of salt 
deposits in the pore cavities of the rock in the vicinity of natural gas 
production wells in natural gas fields. 
The water-repellent active compounds (A) used according to the invention 
are readily dispersible in the formation water and can therefore be 
distributed homogeneously over the entire rock surface and then break 
there. By this means, the water-repellent active compounds (A) cover the 
rock surface in a very thin layer. 
If natural gas is then produced, decreasing the gas field pressure causes 
additional uptake of water in the natural gas. Since, in the vicinity of 
the well, in the rock zone rendered hydrophobic, the capillary action for 
water is greatly decreased, the treated region gradually dries out by 
evaporation of the water. 
The drying out of the rock improves the gas permeability, since gas can 
then again flow through the entire pore cavity without hindrance by water. 
Since, at the same capillary pressure, the water saturation in 
low-permeability rock having narrow capillaries is greater than in 
high-permeability rock, the process is particularly suitable for gas 
fields of low permeability. In addition, in the case of heterogeneous gas 
field rock having variable permeability, use of the process leads to 
homogenization of the flow profile in the vicinity of the well. 
Drying out the rock in the vicinity of the well prevents blockage of the 
rock capillaries, and prevents salt deposits on equipment for production, 
storage and further processing. 
The process has significantly lower costs in comparison with hydraulic 
generation of fractures in the vicinity of the well. The process requires 
lower injection pressures and leads to a considerably lower risk of 
damaging the well. Wells treated by fracture formation can have a 
supplementary treatment with the process according to the invention. Wells 
whose equipment is not suitable for hydraulic generation of fractures can 
also be treated by the process according to the invention. 
The dispersion is chemically inert to the rocks and salt solutions present 
in the gas fields, the natural gas and the production equipment. 
The water-repellent active compound (A) is preferably soluble to at most 1% 
by weight, in particular to at most 0.1% by weight, in water at 20.degree. 
C. 
In the process according to the invention, as water-repellent substances 
(A), use can be made of, for example, inorganic substances which have been 
rendered hydrophobic or unfluorinated or fluorinated waxes, paraffins, 
carboxylic salts, organic or organosilicon polymeric compounds. 
Examples of suitable inorganic substances which have been rendered 
hydrophobic are pyrogenic and precipitated silicic acid and 
silicon/aluminum mixed oxides. Said inorganic substances can be rendered 
hydrophobic, for example, by treatment with organosilanes or 
organosiloxanes or by etherification of hydroxyl groups to give alkoxy 
groups. Preference is given to pyrogenic and precipitated silicic acids, 
since these are readily dispersible. 
Suitable waxes are, for example, natural waxes, such as vegetable waxes, 
e.g. candellila and carnauba wax; animal waxes, e.g. beeswax and lanolin; 
mineral waxes, e.g. ceresin and ozokerite; chemically modified natural, in 
particular fluorinated, waxes and synthetic waxes, e.g. polyethylene waxes 
and silicone waxes. 
Suitable carboxylic salts are, in particular, the salts of monobasic or 
polybasic carboxylic acids having 8 to 50 carbon atoms per carboxyl group. 
Preference is given to the salts of fluorinated carboxylic acids, in 
particular when these have a perfluoroalkyl radical having at least 4 
carbon atoms. Examples of preferred monobasic fluorinated carboxylic salts 
are the alkali metal salts of arylcarboxylic acids, such as benzoic acids 
or naphthoic acids having one or two perfluoroalkyl radicals having 
preferably 4 to 18 carbon atoms. 
Fluorinated organic polymeric compounds which can be used in the process 
according to the invention are, for example, all compounds of the type 
which also have been able to be used or have been used hitherto for 
rendering organic substances water repellent, such as organic fibers, and 
inorganic substances. Examples of compounds of this type are polymers 
which have been prepared from at least partly fluorine-containing 
monomers, such as polytetrafluoroethylene, copolymers of 
tetrafluoroethylene and hexafluoropropylene, poly(vinyl fluoride), 
poly(vinylidene fluoride), polytrifluorochloroethylene, copolymers of 
trifluorochloroethylene and other monomers, such as vinylidene fluoride, 
vinyl chloride, vinyl acetate, methyl methacrylate or styrene; and 
fluorinated acrylic resins, such as homopolymers and copolymers of 
perfluoroalkyl-containing acrylic and methacrylic esters with acrylic acid 
and methacrylic acid and their derivatives. 
Preferred examples of fluorinated acrylic resins are 
poly(1,1-dihydroperfluorobutyl acrylate) and mixed polymers of n-butyl 
acrylate, N-methylol acrylamide and at least 35% by weight of 
1,1,2,2-tetrahydroperfluoro-C.sub.1 to C.sub.16 -alkyl methacrylate having 
a linear alkyl chain. 
Further examples of fluorinated acrylic resins of this type are the alkali 
metal salts of the copolymers of the above listed acrylates, 
methacrylates, acrylic acid and methacrylic acid which preferably have a 
fluorine content of at least 20% by weight. 
Other examples of fluorinated organic polymeric compounds are organic 
synthetic polymers which have been fluorinated after polymerization, such 
as poly(vinyl chloride), polyethylene, polypropylene, poly(vinyl acetate), 
poly(vinyl alcohol), polycarbonate, polyacrlate, polymethacrylate, 
poly(methyl methacrylate), polystyrene, polyacrylonitrile, poly(vinylidene 
chloride), poly(vinyl fluoride), poly(vinylidene fluoride), 
poly(vinylidene cyanide), polybutadiene, polyisoprene, polyethers, 
polyesters, polyamide, polyurethane, polyimide, silicones, 
polyvinylpyrrolidone, polyacrylamide, poly(ethylene glycol) and their 
derivatives which are fluorinated in the side chains or in the main 
chains. The polymers which have been fluorinated after polymerization 
preferably have a fluorine content of at least 10% by weight. Particular 
preference is given to polyurethane resins having a fluorine content of 
25-35% by weight. 
In particular, preference is given as water-repellent active compound (A) 
to organosilicon compounds, since these are thermally stable at 
temperatures of 130.degree. C. and significantly above which frequently 
prevail in gas fields. The action on the rock surface rendering it 
hydrophobic persists for a long period. 
Preferably, the organosilicon compound (A) is made up of units of the 
general formulae (I) to (VII) 
##STR1## 
where R denotes monovalent hydrocarbon radicals having 1 to 18 carbon 
atoms, which are optionally substituted by halogen atoms, cyano, amino, 
alkylamino, quaternary ammonium, mercapto, epoxy, anhydrido, carboxylato, 
sulfonato, sulfato, phosphonato, isocyanato or polyoxyalkylene groups, 
R' denotes monovalent hydrocarbon radicals having 1 to 30 carbon atoms and 
hydrogen atoms, which are optionally substituted by halogen atoms, cyano, 
amino, alkylamino, quaternary ammonium, mercapto, epoxy, anhydrido, 
carboxylato, sulfonato, sulfato, phosphonato, isocyanato or 
polyoxyalkylene groups. 
Examples of hydrocarbon radicals R and R' are alkyl radicals, such as 
methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, 
n-pentyl, isopentyl, neopentyl and tert-pentyl; hexyl radicals, such as 
n-hexyl; heptyl radicals, such as n-heptyl; octyl radicals, such as 
n-octyl, and isooctyl radicals, such as 2,2,4-trimethylpentyl; nonyl 
radicals, such as n-nonyl; decyl radicals, such as n-decyl; dodecyl 
radicals, such as n-dodecyl; octadecyl radicals, such as n-octadecyl; 
alkenyl radicals, such as vinyl, allyl and 5-hexene-1-yl; cycloalkyl 
radicals, such as cyclopentyl, cyclohexyl, cycloheptyl and 
methylcyclohexyl; aryl radicals, such as phenyl, naphthyl, anthryl and 
phenanthryl; alkaryl radicals, such as o-, m-, p-tolyl, xylyl and 
ethylphenyl; aralkyl radicals, such as benzyl and alpha- and 
.beta.-phenylethyl [sic]. 
Examples of substituted radicals R and R' are cyanoalkyl radicals, such as 
.beta.-cyanoethyl [sic], and hydrocarbon radicals which have been 
halogenated by fluorine, chlorine or bromine atoms, for example haloalkyl 
radicals, such as 3,3,3-trifluoro-n-propyl, 
2,2,2,2',2',2'-hexafluoroisopropyl, 8 heptafluoroisopropyl [sic], and 
haloaryl radicals, such as o-, m- and p-chlorophenyl. 
Preferably, at least 90 mol% of the radicals R are methyl, ethyl or phenyl, 
in particular methyl. 
Examples of polyoxyalkylene-substituted radicals R and R' are the radicals 
of the general formula (VIII) 
EQU --R.sup.1 --[O(CR.sup.2.sub.2).sub.c ].sub.d OR.sup.3 (VIII) 
where 
R.sup.1 denotes a divalent C.sub.1 - to C.sub.6 - alkylene radical, 
R.sup.2 denotes hydrogen atoms, or monovalent C.sub.1 - to C.sub.6 
-hydrocarbon radicals, 
R.sup.3 denotes hydrogen atoms, monovalent C.sub.1 - to C.sub.6 
-hydrocarbon radicals, C.sub.1 -C.sub.8 -acyl radicals, ethyl ether 
radicals or silyl radicals, 
c denotes values 0, 1, 2, 3, 4 or 5, preferably 2 or 3 and 
d denotes integers from 1 to 100, preferably 1 to 10. 
Examples of the divalent radicals R.sup.1 are saturated linear or 
branched-chain or cyclic alkylene radicals, such as methylene and ethylene 
or propylene, butylene, pentylene, hexylene, 2-methylpropylene, 
cyclohexylene, or unsaturated alkylene radicals such as propenylene and 
hexenylene. 
Examples of the monovalent radicals R.sup.2 and R.sup.3 are listed under 
the above examples for R and R'. Examples of acyl radicals are acetyl, of 
ethyl ether radicals tetrahydropyranyl, and of silyl radicals, 
trimethylsilyl. 
Further examples of polyoxyalkylene-substituted radicals R and R' are the 
radicals of the general formula (IX) 
##STR2## 
where R.sup.2, c and d have the meanings given above for the general 
formula (VIII). 
Preferably, at most 20 mol% of the units of the organosilicon compound (A) 
have the general formulae (V) to (VII). 
Preferably, the organosilicon compound (A) contains at least 50% by weight, 
in particular at least 80% by weight, of organopolysiloxanes (A1), which 
consist of at least 90 mol%, in particular 95 mol%, of units of the 
general formula (II). Furthermore, preference is given to the 
organopolysiloxane (A1) having an average viscosity of 5 to 2,000,000 
mPa.multidot.s, in particular 350 to 60,000 mPa.multidot.s at 25.degree. 
C. 
Preferably, the organosilicon compound (A) contains at least 2% by weight, 
in particular at least 5% by weight, and preferably at most 70% by weight, 
of organopolysiloxane resins (A2) which consist of at least 90 mol%, in 
particular 95 mol%, of units of the general formulae (I), (IV) and (V). 
The organopolysiloxane resins (A2) can, for example, be solid at room 
temperature and exhibit 0.25 to 1.25 units of the general formula (I) per 
unit of the general formula (IV). These preferred organopolysiloxane 
resins (A2) can contain up to a total of 5% by weight of Si-bonded alkoxy 
radicals or hydroxyl groups resulting from their preparation. The 
organopolysiloxane resins (A2) are generally not completely miscible with 
polydimethylsiloxanes. 
Although not cited in the general formulae (I) to (III), some of the 
radicals R can be replaced by hydrogen atoms directly bonded to silicon 
atoms. However, this is not preferred. 
Although furthermore not cited in the general formulae (I) to (III), 
water-insoluble organosilanes can also be used as organosilicon compounds 
(A). 
However, cross-linking organosilicon compounds (A) are also suitable. Thus, 
for example, aqueous siloxane dispersions which contain cross-linking 
siloxanes, can also be used. However, organosilicon compounds which 
spontaneously form a dispersion in the dispersion medium (B) without 
dispersants (C), so-called self-dispersing organosilicon compounds, in 
particular organopolysiloxanes, are also suitable. 
Preferably, at least 10 parts by weight, in particular at least 50 parts by 
weight, of the hydrophilic water-miscible dispersion medium (B) are 
preferably miscible with 100 parts by weight of water. As hydrophilic 
water-miscible dispersion medium (B), preference is given to polar 
substances, for example aliphatic monoalcohols, such as methanol, ethanol, 
n-propanol and i-propanol, glycols, ethers, such as dioxane and 
tetrahydrofuran, dimethylformamide and, in particular, water. 
Dispersants (C) which are suitable are a multiplicity of active compounds 
which are expediently classified into surface-active dispersants, such as 
nonionic, anionic, cationic and ampholytic dispersants, into partially 
surface-active dispersants, such as high-molecular-weight substances and 
natural products, and into dispersants generally having low surface 
activity, such as inorganic and special dispersion aids. An overview view 
is cited in Ullmans Encyklopadie der technischen Chemie [Ullmans 
Encyclopedia of Industrial Chemistry], Verlag Chemie Weinheim, 4th Edition 
1975, Volume 10, pp. 449-473. 
Preferably, the dispersant (C) is selected from the following dispersion 
aids below: 
1. Alkyl sulfates, for example having a chain length of 8-18 C atoms, alkyl 
ether sulfates having 8 -18 C atoms in the hydrophobic radical and 1-40 
ethylene oxide (EO) or propylene oxide (PO) units. 
2. Sulfonates, e.g. alkyl sulfonates having 8-18 C atoms, alkylaryl 
sulfonates having 8-18 C atoms, esters and half esters of sulfosuccinic 
acid with monohydric alcohols or alkylphenols having 4-15 C atoms; if 
appropriate these alcohols or alkylphenols can also be ethoxylated with 
1-40 EO units. 
3. Alkali metal salts and ammonium salts of carboxylic acids and 
poly(alkylene glycol)ether carboxylic acids having 8-20 C atoms in the 
alkyl, aryl, alkaryl or aralkyl radical and 1-40 EO or PO units. 
4. Partial phosphoric esters and their alkali metal salts and ammonium 
salts, e.g. alkyl and alkaryl phosphates having 8-20 C atoms in the 
organic radical, alkylether phosphates or alkarylether phosphates having 
8-20 C atoms in the alkyl or alkaryl and 1-40 EO units. 
5. Alkyl polyglycol ethers, preferably those having 2-40 EO units and alkyl 
radicals of 4-20 atoms. 
6. Alkylaryl polyglycol ethers having 2-40 EO units and 8-20 C atoms in the 
alkyl and aryl radicals. 
7. Ethylene oxide/propylene oxide (EO/PO) block copolymers having 8-40 EO 
or PO units. 
8. Fatty acid polyglycol esters having 6-24 C atoms and 2-40 EO units. 
9. Fatty esters of glycerol, sorbitol and pentaerythritol. 
10. Alkylpolyglycosides of the general formula R""--O--Z.sub.c, where R"" 
denotes a linear or branched, saturated or unsaturated alkyl radical 
having on average 8-24 C atoms and Z.sub.o denotes an oligoglycoside 
radical having on average o=1-10 hexose or pentose units or mixtures 
thereof. 
11. Polar-group-containing linear organopolysiloxanes having alkoxy groups 
and up to 24 C atoms and/or up to 40 EO and/or PO groups. 
12. Salts of primary, secondary and tertiary fatty amines having 8-24 C 
atoms with acetic acid, sulfuric acid, hydrochloric acid and phosphoric 
acids. 
13. Quaternary alkyl- and alkylbenzylammonium salts, whose alkyl groups 
have 1-24 C atoms, in particular the halides, sulfates, phosphates, 
acetates and hydroxides. 
14. Alkylpyridinium, alkylimidazolinium and alkyloxazolinium salts whose 
alkyl chain has up to 18 C atoms, especially in the form of their halides, 
sulfates, phosphates and acetates. 
15. High-molecular-weight substances such as polymers, e.g. poly(vinyl 
alcohol) and mixed polymers, such as vinylacetate/ethylene polymers. 
16. Natural substances and their conversion products, such as 
polysaccharides or cellulose and cellulose derivatives, such as cellulose 
ethers. 
A dispersant, or else mixtures of a plurality of dispersants, can be used. 
Dispersants which are particularly preferred are the dispersants listed 
above under 1, 2, 3, 5, 6, 7 and 8, 12, 13, 15, 16, in particular the 
dispersants listed under 2, 3, 5, 6 and 13. 
Preferably, 2.5 to 250, preferably 5 to 150, in particular 10 to 70, parts 
by weight of dispersant (B) are used per 100 parts by weight of 
water-repellent active compound (A). 
As additives (D), the dispersion can contain, for example, fillers, 
fungicides, bactericides, algicides, biocides, odorants, corrosion 
inhibitors, native oils, thickeners, crosslinking agents, cosurfactants 
and organic solvents. 
The dispersions may contain small amounts of organic solvents depending on 
the preparation method. In particular in the case of the preparation of 
organopolysiloxane resins, organic solvents or native oils are frequently 
used. If the dispersion contains organic solvents, their content is 
preferably at most 50 parts by weight, in particular 5 to 20 parts by 
weight, based on 100 parts by weight of water-repellent active compound 
(A). 
The content of filler is preferably up to 20 parts by weight, in particular 
2 to 8 parts by weight per 100 parts by weight of water-repellent active 
compound (A). 
The preparation of the dispersions is known to those skilled in the art. 
For the ready-to-use dispersion, the sum of the components water-repellent 
substances (A), dispersion medium (B), dispersants (C) and, if 
appropriate, additives (D) is preferably 0.01 to 25% by weight, 
particularly preferably 0.05 to 10% by weight, in particular 0.1 to 2% by 
weight, based on the weight of the dispersion used. 
The mean particle size of the dispersion is preferably at most 1000 .mu.m, 
in particular 5 nm to 250 .mu.m. 
The compositions, particle sizes and concentrations of the dispersions can 
be matched to the types of rock and conditions, such as temperature and 
salt content, prevailing in the gas fields, so that the dispersions are 
injectable even under extreme conditions. The particle size is preferably 
selected in such a manner that the pore size of the rock is not reached. 
By means of the high content of the components water-repellent substances 
(A), dispersion medium (B), dispersant (C) and, if appropriate, additives 
(D) in the dispersion, the dispersion medium introduced into the rock can 
be kept small. The concentration of the dispersion can be matched to rock 
properties, such as permeability and depth of penetration. In the case of 
high permeabilities, smaller amounts of more coarsely disperse dispersions 
having higher contents of the components water-repellent substances (A), 
dispersion medium (B), dispersant (C) and, if appropriate, additives (D) 
can be used. In the case of low rock permeabilities, greater amounts of 
finely dispersed dispersions having lower concentration are used. 
Substances are also suitable which do not form a water-repellent substance 
(A) in a dispersion medium (B) in which they were previously soluble until 
use conditions are achieved. Examples of these which may be mentioned are 
nonionic surfactants or glycol-functional silicone oils, which are soluble 
in polar dispersion media such as water, but then, at elevated 
temperatures, reach a cloud point and become water-repellent. 
The water present in the natural gas is principally condensation water. 
Preferably, the natural gas wells and gas-storage wells treated by the 
present process deliver at most 40, in particular at most 20, 1 of water 
per 1000 m.sup.3 (S.T.P.) of natural gas produced. 
In the examples below, unless stated otherwise, 
a) all amounts given are based on weight; 
b) all pressures are 0.1013 MPa (absolute); 
c) all temperatures are 20.degree. C.; 
d) the following abbreviations have been used 
dem. demineralized 
PDMS polydimethylsiloxane 
Me methyl radical; 
S.T.P. (volume at) standard temperature and pressure (0.degree. C., 0.1013 
MPa (absolute)) 
e) the amine number has been given as the number of ml of 1 N HCl which are 
necessary to neutralize 1 g of organopolysiloxane.

EXAMPLES 
The examples below were carried out on sample cores of the middle mottled 
sandstone of the gas field in Barrien, northern Germany. The cylindrical 
sample cores had lengths and diameters of 3 cm each. 
Examples 1 to 5 
The following measures were carried out with the sample cores: 
a) The sample cores were dried overnight at 90.degree. C. 
b) The dry sample cores were placed in a vacuum-tight container and the 
container was evacuated. When vacuum was reached, the container was 
isolated from the vacuum pump by closing a valve and dem. water was drawn 
into the container via a second connection. After the sample cores were 
completely immersed in dem. water, the container was vented. 
The sample cores were weighed to determine m.sub.V. 
c) The sample cores were dried overnight at 90.degree. C. and then weighed 
to determine m.sub.1. 
d) The dry sample cores were each rolled up in one absorbent filter paper 
strip of width 7 cm and length 19.2 cm in such a manner that the core was 
wrapped round twice and the paper projected approximately 4 cm on one 
side. The filter paper was pressed onto the cylinder surface by an elastic 
latex tube. In an environment saturated with water vapor, the projecting 
paper was placed in dem. water in such a manner that the end of the paper 
dipped into the water, but the core was situated above the water surface. 
After seven hours, the core was unwrapped and weighed to determine 
m.sub.F1. 
e) Using the equation 
##EQU1## 
the reference value for dem. water having spontaneous imbibition 
Sw(sp).sub.ref was calculated. The spontaneous imbibition describes the 
displacement of the non-wetting phase by the wetting phase. 
f) The sample cores were dried overnight at 90.degree. C. 
g) In a similar manner to measure b), the sample cores were impregnated 
with organopolysiloxane dispersion which contained organopolysiloxanes (A) 
as active compound for rendering hydrophobic in a 10% strength 
concentration. To remove excess dispersion, the cores were blasted with 
nitrogen. 
h) The sample cores were dried for 17 h at 90.degree. C. and weighed to 
determine m.sub.2. 
i) In a similar manner to measure d), the dry sample cores were wrapped in 
filter paper strips and placed in dem. water. After seven hours, the core 
was unwrapped and weighed to determine m.sub.F2. 
j) Using the equation 
##EQU2## 
the spontaneous imbibition Sw(sp).sub.1 after treatment of the cores with 
dispersion was calculated. 
k) The sample cores were dried again at 90.degree. C. Measures i) and j) 
were carried out again. The procedure was repeated several times. 
The 5 organopolysiloxane dispersions below were studied in Examples 1 to 5: 
TABLE 1 
__________________________________________________________________________ 
Dispersion 
FG* in 
for Example % Active compound Emulsifier system/cosolvent 
__________________________________________________________________________ 
1 39 35% of a trimethylsilyl-end-capped PDMS having 4% isotridecyl 
polyglycol ether having 10 EO 
a viscosity of 12,500 mPa .multidot. s units 
Kathon as preservative 
2 100 Silicone microemulsion concentrate, prepared by the following 
process: 
With stirring, to a mixture of 0.2 g of KOH in 4 g of methanol and 
500 g of a hydroxyl-end- 
capped dimethyl polysiloxane having a mean molecurlar [sic] weight of 
about 4000 g/mol, 150 g 
of N-(2-aminoethyl)-3-amino-propyltrimethoxysilane and heat the 
resulting mixture to reflux 
for 6 hours; then cool it to 30.degree. C. and mix in 2.5 ml of 10% 
strength hydrochloric acid. 
Finally, distill off the methanol by heating to up to 140.degree. C. 
and free the resulting organopoly- 
siloxane from KCl by filtration. The organopolysiloxane contains 2.9% 
of basic nitrogen, based 
on its weight. 
Mix 40 g of this organopolysiloxane containing basic nitrogen with 5 
g of glacial acetic acid, 
80 g of the organopolysiloxane of the empirical formula CH.sub.3 
Si(OC.sub.2 H.sub.5).sub.0.8 O.sub.1.1 and of the mean 
molecular weight of 600 g/mol and 10 g of i-octyltrimethoxysilane and 
heat the mixture to 
90.degree. C., to form a clear mixture. 
3 53 40% i-octyltriethoxysilane 
2.7% Glukopon .RTM. 225 from Henkel KGaA, 
5% of an organopolysiloxane of the 
empirical Dusseldorf, a fatty alcohol 
C8-C10 glycoside 
formula CH.sub.3 Si(OC.sub.2 H.sub.5).sub.0.8 O.sub.1.1 having a mean 
in aqueous solution 
molecular weight of about 650 g/mol and a 0.3% Genamin .RTM. 200 from 
Hoechst AG, Frankfurt, 
viscosity of about 20 mPa .multidot. s a reaction product of stearylam 
ine and 
5% of a condensation product of a ethylene oxide 
a,w-dihydroxymethylpolysiloxane having one Si- 
bonded hydroxyl group at each terminal unit 
and N(-2-aminoethyl)-3-aminopropyltrimethoxy- 
silane in the presence of KOH having an amine 
number of about 0.3, a viscosity of about 
1500 mPa .multidot. s at 25.degree. C. and a residual methoxy 
content of less than 5 mol %, based on 
the 
methoxy groups initially present in 
N(-2-aminoethyl)-3-aminopropyltrimethoxysilane 
__________________________________________________________________________ 
Dispersion 
FG* in 
for Example % 0.06 Emulsifier system/cosolvent 
__________________________________________________________________________ 
4 50 33% of an amino-functional silicone oil of the 5% diethylene 
glycol monobutyl ether 
formula x.sup.1), with the amine number being 0.15, 11% isotridecylpol 
yglycol ether having 5 EO 
the viscosity 5000 mPa .multidot. s and R = OH units 
1% fatty alochol polyglycol ether having a 
saturated alkyl group (C.sub.16 -C.sub.18) and 25 EO 
units 
Benzalkylammonium chloride as preservative 
5 39 30% by weight of a trimethylsilyl-end-capped 8.2% by weight of 
hexadecyltrimethylammonium 
PDMS having a viscosity of 35 mPa .multidot. s chloride 
30% by weight of an end-capped PDM having a 0.8% by weight of 
isotridecylpolyglycol ether 
viscosity of 150 mPa .multidot. s having 10 EO units 
40% by weight of a resin having a ratio of Formaldehyde as preservativ 
e 
Me.sub.3 SiO.sub.1/2 /SiO.sub.4/2 of 0.65 and an OH content 
of about 0.3% by weight and OC.sub.2 H.sub.5 content 
of about 2.0% by weight 
__________________________________________________________________________ 
*Solids content 
EO unit = --(CH.sub.2 --CH.sub.2 --O)-- 
.sup.1) Formula x: 
RSiMe.sub.2 O [SiMe.sub.2 O].sub.m [SiMeR'O].sub.n SiMe.sub.2 R 
where R' = (CH.sub.2).sub.3 NH--CH.sub.2 --CH.sub.2 --NH.sub.2 
The spontaneous imbibition Sw(sp).sub.1 decreases sharply after 1 to 2 days 
in the case of the cores treated with organopolysiloxane dispersion, since 
rendering the cores hydrophobic greatly decreases the capillary action for 
water. 
In Table II below, the values for the spontaneous imbibition Sw(sp).sub.1 
after different drying times are given as the sum of the drying times in 
measures h) and k) in comparison with the reference Sw(sp).sub.ref. 
TABLE II 
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Spontaneous water imbibition S.sub.w (sp) 
after total drying time [days] 
S.sub.w (sp) 
S.sub.w (sp)1 
Example ref 1 2 5 10 13 17 
______________________________________ 
1 0.64 0.06 -- 
2 0.67 0.07 -- 
3 0.58 0.05 0.04 0.06 -- 
4 0.71 0.69 0.07 0.03 -- 
5 0.65 0.36 0.3 0.22 0.14 0.07 0.04 
______________________________________ 
Example 6 
The spontaneous imbibition SW(SP).sub.ref of a sample core was determined 
in a similar manner to Example 1 by measures a) to f). Subsequently, the 
measures below were carried out: 
l) The sample core was impregnated with salt water in a similar manner to 
measure b). The salt water roughly corresponds in salt content to the 
formation water and contains, per liter, 28.5 g of NaCl, 18.5 g of 
CaCl.sub.2, 1.6 g of MgCl.sub.2 and 1.4 g of KCl, in total, 5% salt 
content. 
m) The sample core impregnated with salt water was flooded at 140.degree. 
C. with the organopolysiloxane dispersion from Example 5 at a rate of 10 
ml/h up to constant pressure. About 3 to 4 pore volumes of 
organopolysiloxane dispersion were used in the course of this treatment. 
n) The sample core was kept at 140.degree. C. for 3 days. 
o) The organopolysiloxane dispersion was flushed out of the sample core 
with salt water. The salt water was then displaced with nitrogen. 
p) The sample cores were dried by slowly reducing the pressure from 0.44 to 
0.1 MPa in 6 h and subsequently keeping them for 17 hours at 90.degree. C. 
and were weighed to determine m.sub.3. 
q) In a similar manner to measure d), the dry sample cores were wrapped in 
filter paper strips and placed in salt water. After seven hours, the core 
was unwrapped and weighed to determine m.sub.F3. 
r) Using the equation 
##EQU3## 
the spontaneous imbibition Sw(sp).sub.2 was calculated. s) The sample 
cores were dried again for 17 h at 90.degree. C. Measures q) and r) were 
carried out again. The process was repeated several times. 
Table III below gives the values for the spontaneous imbibition 
Sw(sp).sub.2 after different drying times as the sum of the drying times 
in measures p) and s) in comparison with the reference Sw(sp).sub.ref. 
TABLE III 
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Spontaneous imbibition S.sub.w (sp) 
after total drying time [days] 
S.sub.w (sp)ref Sw(sp)2 
______________________________________ 
2 17 
0.61 0.3 0.25 
______________________________________ 
The spontaneous imbibition with salt water Sw(sp).sub.2 also decreases 
sharply after storage at high temperatures in the case of the cores 
treated with organopolysiloxane dispersion. The capillary action of the 
salt water is greatly decreased under conditions which prevail in natural 
gas fields gas fields [sic].