Earth boring – well treating – and oil field chemistry – Earth boring – Contains intended gaseous phase at entry into wellbore
Reexamination Certificate
1998-09-22
2001-01-09
Tucker, Philip (Department: 1721)
Earth boring, well treating, and oil field chemistry
Earth boring
Contains intended gaseous phase at entry into wellbore
C507S202000, C507S112000, C507S113000, C507S120000, C507S121000, C507S129000, C507S135000, C507S222000, C507S226000, C516S010000, C516S012000, C516S015000
Reexamination Certificate
active
06172010
ABSTRACT:
This invention relates to an aqueous foam composition that consists of an optimized combination of surfactants and polymers that are water-soluble. The applications of such a foam according to this invention vary widely, for example for body care, farming applications, fire-fighting, underground works, such as soil consolidation and operations in wells that are drilled into the subsoil: drilling, treatment of reservoirs, production of hydrocarbons.
The use of an aqueous foam to replace a well fluid that circulates through a pipe lining that goes down into a well which is drilled into the ground is known. In some cases, the density of the aqueous fluid that is used is too high for the type of rock, creating an excessive hydrostatic pressure compared to the fracturing resistance of the rock zones through which the drilling passes. The choice is then made to use aqueous fluids with densities that are reduced by the introduction of gas, and it is attempted to make the thus lightened fluid homogeneous by creating the most stable foam possible so that it will have at least adequate power for cleaning the cuttings.
Document US-5513712 describes a drilling process in which a foam that comprises a polymer such as non-cross-linked acrylamide and a surfactant is used, but it does not describe a foaming composition that is stable and optimized by achieving synergy between a specific polymer and a specific surfactant.
Thus, this invention relates to a water-based foaming composition that comprises at least one surfactant and a polymer. The surfactant and the polymer comprise charges of opposite sign.
The applicant has demonstrated that, surprisingly, it was possible to control the production of a stable foam from a composition that is optimized in terms of surfactant concentration if a polymer or a copolymer with a charge that is opposite in sign to that of the charge of the surfactant is combined with said surfactant. A cationic polymer or copolymer is combined with an anionic surfactant; an anionic polymer or copolymer is combined with a cationic surfactant.
The surfactants that can conceivably be used in this invention include all the standard anionic surfactants, such as the anionic group, or:
carboxylates:
soaps of alkaline metals, alkyl or alkyl ether carboxylates,
N-acylamino acids,
N-acylglutamates,
N-acylpolypeptides,
sulfonates:
alkylbenzenesulfonates,
paraffin sulfonates,
&agr;-olefin sulfonates,
petroleum sulfonates,
lignosulfonates,
sulfosuccinic derivatives,
polynaphthylmethanesulfonates,
alkyl taurides,
sulfates:
alkyl sulfates,
alkyl ether sulfates,
phosphates:
monoalkyl phosphates,
dialkyl phosphates
phosphonates.
As cationic surfactants, it is possible to cite:
alkylamine salts,
quaternary ammonium salts of which nitrogen:
comprises a fatty chain, for example, alkyltrimethyl or trimethylammonium derivatives, alkyldimethyl benzylammonium derivatives,
comprises two fatty chains,
forms part of a heterocycle, for example, the derivatives of pyridinium, imidazolinium, quinolinium, piperidinium, morpholinium.
All the standard anionic polymers can be used according to this invention, for example:
synthetic polymers or copolymers that are derived from:
anionic monomers that contain carboxylate or sulfonate or phosphate or phosphonate groups, such as the monomers acrylate, methacrylate, itaconate, 2-acrylamido-2-methyl-propane, sulfonate, 2-methacryloxy ethane sulfonate, 3-acrylamido-3-methyl butanoate, styrene sulfonate, styrene carboxylate, vinyl sulfonate, and maleic acid salts.
synthetic copolymers that are derived from:
an anionic monomer, for example in those that are described above and a neutral monomer, for example, acrylamide, acrylic acid, vinyl pyrrolidone, ethylene oxide, propylene oxide, maleic anhydride, vinyl alcohol, hydroxyethylacrylate, . . .
natural polymers such as:
cellulose derivatives that are modified negatively, such as CMC,
polysaccharides such as xanthanum, alginate,
starches that are modified negatively,
galactomannanes that are modified negatively.
All the standard cationic polymers can be used according to this invention, for example:
synthetic polymers or copolymers that are derived from standard cationic monomers, i.e., of the following general formula:
R1
C══CH2
R2 where R1 or R2 comprises at least one N atom,
polyethylene imines,
polyamide amines,
polyamines,
synthetic copolymers that are derived from:
cationic monomers and neutral monomers (described above),
natural polymers:
starches that are modified positively, chitosans,
galactomannanes that are modified positively,
cellulose derivatives that are modified positively.
The surfactant can be cationic at a concentration that is less than about 5 10
−3
mol/l, and the polymer can be anionic.
The surfactant can be anionic at a concentration that is less than about 5 10
−3
mol/l, and the polymer can be cationic.
The anionic polymer can be a copolymer such as AM/AMPS, of which the level of the charged portion can be between 5 and 40%, and preferably between 10 and 25%. The surfactant can be of the DoTAB type.
The anionic polymer can be a natural polymer that is modified negatively, for example such as CMC.
The cationic polymer can be a copolymer such as AM/MAPTAC, of which the level of the charged portion can be between 5 and 40% and preferably between 10 and 25. The surfactant can be of the SDS type.
The invention also relates to a process for producing a foam from water, at least one surfactant, and at least one polymer. In the process, a surfactant and a polymer or a copolymer of opposite charge are combined, and the polymer concentration is determined to obtain a stable foam with as low a surfactant level as possible.
The polymer concentration can be determined based on the charge level of the polymer and the concentration of surfactant that is used. Considering the electrostatic nature of the interactions between polymer and surfactant, their respective concentrations can be a function of the ionic force of the medium.
The foaming solution can, like well fluid (drilling, completion and workover), also contain solids (cuttings, neutral colloids, . . . ) or other non-charged water-soluble polymers, anti-corrosion additives, . . . .
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Argillier Jean-Francois
Audibert-Hayet Annie
Zeilinger Sabine
Institut Francais du Pe'trole
Millen White Zelano & Branigan
Tucker Philip
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