RHEOLOGICAL AGENT, PREPARATION METHODS AND USES THEREOF
The present invention relates to a method to prepare a rheological agent comprising the polymerization of the following monomers: (a) at least one styrene-based monomer, (b) at least one (meth)acrylate-based monomer or butadiene, and (c) optionally a copolymerisable surfactant containing an optionally substituted vinyl function and moieties derived from propylene oxide and/or ethylene oxide, optionally in the presence of a non polymerisable surfactant containing moieties derived from propylene oxide and/or ethylene oxide, and optionally in the presence of another surfactant, wherein at least the copolymerisable surfactant or the non polymerisable surfactant is present during the said polymerization, as well as a rheological agent obtainable by said method, an oil-based drilling fluid containing such a rheological agent, the use of such a rheological agent as a thixotropic agent in an oil-based drilling fluid and a method of drilling using an oil-based drilling fluid containing such a rheological agent.
1 - 15 . (canceled)
16 . A method to prepare a rheological agent comprising the polymerization of the following monomers:
(a) at least one styrene-based monomer substituted on the phenyl moiety,
(b) optionally at least one (meth)acrylate-based monomer or butadiene, and
(c) a copolymerisable surfactant containing an optionally substituted vinyl function and moieties derived from propylene oxide and/or ethylene oxide,
optionally in the presence of a non polymerisable surfactant containing moieties derived from propylene oxide and/or ethylene oxide, and
optionally in the presence of another surfactant.
17 . The method according to claim 16 , wherein the copolymerisable surfactant is chosen among anionic and non-ionic surfactants.
18 . The method according to claim 16 , wherein the non polymerisable surfactant is chosen among anionic and non-ionic surfactants.
19 . The method according to claim 16 , wherein the styrene-based monomer is styrene substituted on the phenyl moiety with one or more substituents chosen among (C 1 -C 15 )alkyl, (C 2 -C 6 )alkenyl, (C 5 -C 8 )cycloalkyl, aryl and aryl-(C 1 -C 6 )alkyl.
20 . The method according to claim 19 , wherein the styrene-based monomer is a (C 1 -C 6 )alkyl-styrene.
21 . The method according to claim 19 , wherein the styrene-based monomer is chosen among para-tert-butyl-styrene (PTBS), para-methyl-styrene (PMS) and mixtures thereof.
22 . The method according claim 16 , wherein monomer (b) is present and is at least one (meth)acrylate-based monomer corresponding to the following formula:
wherein:
R a represents a hydrogen atom or a methyl group, and
R b represents a (C 1 -C 15 ) saturated hydrocarbon group.
23 . The method according to claim 22 , wherein monomer (b) is at least one (meth)acrylate-based monomer chosen among isobornyl methacrylate (IBOMA), isobornyl acrylate (IBOA), isobutyl methacrylate (IBMA), 2-ethylhexyl acrylate (2-EHA) and mixtures thereof.
24 . The method according to claim 16 , wherein the ratio by weight of monomer (a) to monomer (b) is comprised between 100:0 and 10:90.
25 . The method according to claim 24 , wherein the ratio by weight of monomer (a) to monomer (b) is comprised between 100:0 and 50:50.
26 . The method according to claim 25 , wherein the ratio by weight of monomer (a) to monomer (b) is comprised between 100:0 and 70:30.
27 . The method according to claim 16 , wherein the copolymerisable surfactant has the following formula:
CHR′═CRL-(O—CHR 7n —CHR 8n ) n —X 1
wherein:
L represents a single bond or a linker,
R and R′ represent, independently of each other, H or a (C 1 -C 25 )alkyl,
n represents an integer of at least 1,
each R 7n and each R 8n represent, independently of each other, a hydrogen atom or a methyl group but R 7n and R 8n cannot both represent a methyl group, and
X 1 represents an —O-(optionally substituted aryl), —O(C 1 -C 25 )alkyl, —O—(C 1 -C 6 )alkanediyl-SO 3 H, —OH, —S(O) 2 (OH), —O—P(O)(OH) 2 or —O—S(O) 2 (OH) group, or a salt thereof.
28 . The method according to claim 27 , wherein:
R and R′ represent, independently of each other, H or a (C 1 -C 6 )alkyl, and
n represents an integer comprised between 3 and 120.
29 . The method according to claim 28 , wherein:
R and R′ represent, independently of each other, H or a methyl, and
n represents an integer comprised between 5 and 70.
30 . The method according to claim 29 , wherein:
R and R′ represent, independently of each other, H, and
n represents an integer comprised between 5 and 40.
31 . The method according to claim 27 , wherein X 1 represents an —O-(optionally substituted aryl), —O(C 1 -C 25 )alkyl, —O—(C 1 -C 6 )alkanediyl-SO 3 H, —OH, —S(O) 2 (OH), —O—P(O)(OH) 2 or —O—S(O) 2 (OH) group, or a sodium, potassium or ammonium salt thereof.
32 . The method according to claim 16 , wherein the non polymerisable surfactant has the following formula:
X 3 —(OCH 2 CH 2 ) q —X 2
wherein:
q represents an integer comprised between 1 and 60,
X 3 represents a (C 8 -C 25 )alkyl chain or an aryl optionally substituted with a (C 1 -C 25 )alkyl, and
X 2 represents an —OH, —S(O) 2 (OH), —O—P(O)(OH) 2 or —O—S(O) 2 (OH) group, or a salt thereof,
33 . The method according to claim 32 , wherein
represents an integer comprised between 3 and 20.
34 . The method according to claim 32 , wherein X 2 represents an —OH, —S(O) 2 (OH), —O—P(O)(OH) 2 or —O—S(O) 2 (OH) group, or a sodium, potassium or ammonium salt thereof.
35 . The method according to claim 16 , wherein the polymerization is carried out in the presence of a crosslinking agent.
36 . The method according to claim 16 , using 0.5 to 10 wt % of copolymerisable and non polymerisable surfactants relatively to the total weight of the rheological agent on a dry basis.
37 . The method according to claim 36 , using 1 to 7 wt % of copolymerisable and non polymerisable surfactants relatively to the total weight of the rheological agent on a dry basis.
38 . A rheological agent obtainable by the method according to claim 16 .
39 . An oil-based drilling fluid comprising a rheological agent according to claim 38 .
40 . The oil-based drilling fluid according to claim 39 , containing 0.1 to 10 ppb (0.285 to 28.5 kg/m 3 ) of the rheological agent.
41 . A method of drilling using an oil-based drilling fluid according to claim 39 .