Ultra-high molecular weight (UHMW) branched block copolymer viscosifier for water based drilling fluids

A drilling fluid composition comprising:

• a base fluid;
• and
• a viscosifier comprising a branched multi-block polymer having the following structure,
• where “Z” is selected from the group consisting of a hydrogen, chlorine, sulfur, oxygen, a substituted or unsubstituted alkyl or substituted or unsubstituted aryl radical, a substituted or unsubstituted heterocycle, a substituted or unsubstituted alkylthio radical, a substituted or unsubstituted arylthio radical, a substituted or unsubstituted alkylselenium radical, a substituted or unsubstituted arylselenium radical, a substituted or unsubstituted alkoxy radical, a substituted or unsubstituted aryloxy radical, a substituted or unsubstituted amino radical, a substituted or unsubstituted hydrazine radical, a substituted or unsubstituted alkoxycarbonyl radical, a substituted or unsubstituted aryloxycarbonyl radical, a substituted or unsubstituted acycloxy or carboxyl radical, a substituted or unsubstituted aroyloxy radical, a substituted or unsubstituted carbamoyl radical, a cyano radical, a dialkyl- or diarylphosphonato radical, a dialkyl-phosphinato or diaryl-phosphinato radical, and a polymer chain;
• where “R” is a substituted or unsubstituted alkyl, a substituted or unsubstituted acyl, a substituted or unsubstituted aryl, a substituted or unsubstituted aralkyl, a substituted or unsubstituted alkenyl or a substituted or unsubstituted alkynyl group;
• a saturated or unsaturated aromatic, a substituted or unsubstituted carbocycle or a substituted or unsubstituted heterocycle or a polymer chain, where the polymer chain is hydrophilic;
• where “A” is selected from the group consisting of (meth)acrylate monomer units carrying a COOH or COO— group, fumaric acid or monoethylenically unsaturated C4-C10 and C4-C6 dicarboxylic acid monoesters, ((meth)acrylate/(meth)acrylamide) units having phosphate, phosphonate or phosphinate groups, and sulfonic acid or sulfonate functional group;
• “B” is selected from the group consisting of (meth)acrylate monomer units carrying a COOH or COO— group, unsaturated C4-C10 and C4-C6 dicarboxylic acid monoesters, and ((meth)acrylate/(meth)acrylamide) units having phosphate, phosphonate or phosphinate groups, sulfonic acid or sulfonate functional groups;
• “C” is selected from the group consisting of acrylamide, meth(acrylate) and meth(acrylamide) monomers with ammonium groups, meth(acrylate) and meth(acrylamide) with C20-C30 alkane diols or poly(ethylene glycol), 2-chloroethyl(meth)acrylate, tetrahydrofurfuryl acrylate, vinylacetamide, vinylpyrrolidone, N-vinyl piperidone, N-vinyl caprolactam, N-vinyl-5-methyl-2-pyrrolidone, N-vinyl-5-ethyl-2-pyrrolidone, N-vinyl-6-methyl-2-piperidone, N-vinyl-6-ethyl-2-piperidone, N-vinyl-7-methyl-2-caprolactam, and N-vinyl-7-ethyl-2-caprolactam;
• “D” being selected from the group consisting of vinyl aromatic, (meth)acrylate, and (meth)acrylamide crosslinkers;
• “E” being selected from the group consisting of alkyl (meth)acrylate monomer having C2-C40-alkyl esters of acrylic acid, C1-C40-alkyl esters of methacrylic acid, vinyl aromatics, fluorinated alkyl (meth)acrylates, and vinyl aromatic units;
• and
• “F” being any monomer, or combination of monomers for monomers “A” −“E”;
• where “t” is from 3-500 units, “u”, “v”, and “w” are from 3-260000 units, “x”, and “y” are from 0-260000 units, “m” and “n” are from 1-10 units, and “p” is from 0-10 units, where at least one of “x” and “y” are not equal to 0, and when “y” is not equal to 0 “p” is not equal to 0.