Sequenced polymers for monitoring the filtrate and the rheology

Abstract

The present invention relates to the use of a sequenced polymer as an agent for monitoring the filtrate and the rheology of a fluid injected under pressure into an oil rock, wherein the fluid comprises solid particles and/or is brought into contact with solid particles within the oil rock after being injected, the polymer comprising: a first block which is adsorbed onto at least some of the particles; and a second block having a composition other than that of the first block and a mean molecular weight of more than 10,000 g/mol, for example mom than 100,000 g/mol, and which is soluble in the fluid.

1 . A fluid (F) for injecting under pressure into a subterranean formation, comprising a fluid loss control and rheology agent, wherein the fluid loss control and rheology agent is a block polymer (P) comprising:
 a first block (A); and   a second block (B) with a composition distinct from that of said first block (A), with a weight-average molecular weight of greater than 10 000 g/mol, and which is soluble in the fluid (F).   
     
     
         2 . The fluid claimed in  claim 1 , wherein the polymer has a weight-average weight of greater than 500 000 g/mol. 
     
     
         3 . The fluid claimed in  claim 1 , wherein the polymer has a weight-average weight of less than 200 000 g/mol and reduces the viscosity of the fluid while providing a fluid loss control effect. 
     
     
         4 . The fluid claimed in  claim 1 , wherein the fluid (F) does not comprise solid particles (p). 
     
     
         5 . The fluid claimed in  claim 1 , wherein the fluid (F) comprises particles (p) combined with the polymer (P), the polymer being advantageously employed as dispersing and stabilizing agent for the dispersion of the particles (p). 
     
     
         6 . The fluid claimed in  claim 1 , wherein the fluid (F) is an aqueous fluid and wherein the block (B) is a block at least predominantly composed of monomer units selected from the group consisting of the monomer units U1 to U5 defined below, and the mixtures of these monomer units:
 monomer units U1: monomer units comprising an acrylamide functional group,   monomer units U2: monomer units comprising a sulfonic acid or sulfonate functional group,   monomer units U3: neutral monomer units,   monomer units U4: monomer units carrying ammonium groups,   monomer units U5: acrylate monomer units carrying a COOH or COO— group,   optionally, block (B) comprises hydrophobic monomers in small proportions.   
     
     
         7 . (canceled) 
     
     
         8 . The fluid claimed in  claim 1 , wherein the fluid (F) is an oil cement grout which comprises the polymer (P) as additive. 
     
     
         9 . The fluid claimed in  claim 8 , wherein:
 the block (B) comprises monomer units U1 comprising an acrylamide functional group, and optionally units U2 comprising a sulfonic acid or sulfonate functional group; and   the block (B) has a weight-average molecular weight of between 150 000 and 750 000 g/mol.   
     
     
         10 . The fluid claimed in  claim 1 , wherein the fluid (F) is a drilling fluid or a fracturing fluid which comprises the polymer (P) combined with particles (p). 
     
     
         11 . The fluid claimed in  claim 1 , wherein the polymer (P) is a polymer prepared by controlled radical polymerization. 
     
     
         12 . The fluid claimed in  claim 5 , wherein the first block (A) is adsorbed on at least a portion of the particles (p). 
     
     
         13 . The fluid claimed in  claim 5 , wherein the polymer reduces or inhibits the sedimentation of the particles while providing a fluid loss control effect. 
     
     
         14 . The fluid claimed in  claim 6 , wherein the monomer units U3 are esters of α,β-ethylenically unsaturated mono- or dicarboxylic acids with C2-C30 alkanediols or polyethylene glycols, tetrahydrofurfuryl acrylate, vinylacetamide, vinylpyrrolidone, N-vinylpiperidone, N-vinylcaprolactam, 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 or N-vinyl-7-ethyl-2-caprolactam. 
     
     
         15 . The fluid claimed in  claim 6 , wherein the monomer units U4 are amides of α,β-ethylenically unsaturated mono- or dicarboxylic acids with diamines having at least one primary or secondary amine group; N,N-diallylamines or N,N-diallyl-N-alkylamines. 
     
     
         16 . The fluid claimed in  claim 6 , wherein block (B) comprises hydrophobic monomers in a proportion of 0.05% to 10% by weight, with respect to the total weight of monomer units in the block (B). 
     
     
         17 . The fluid claimed in  claim 9 , wherein block (B) comprises dimethylacrylamide DMA units. 
     
     
         18 . The fluid claimed in  claim 9 , wherein block (B) comprises acrylamidomethylpropanesulfonic acid (AMPS) units. 
     
     
         19 . The fluid claimed in  claim 9 , wherein block (B) has a weight-average molecular weight of between 200 000 and 700 000 g/mol. 
     
     
         20 . The fluid claimed in  claim 5 , wherein:
 the particles (p) are particles of calcium carbonate or cement; and   the block (A) is at least predominantly composed of monomer units U5 and/or U3 and/or U6; and   the block (B) is at least predominantly composed of units U1 and/or U2; or   the particles (p) are particles of carbonate of silica or sand; and   the block (A) is at least predominantly composed of monomer units U3 and/or U4 and/or U7; and   the block (B) is at least predominantly composed of units U1 and/or U2 and/or U5; or   the particles (p) are particles of clay; and   the block (A) is at least predominantly composed of monomer units U4 and/or U6; and   the block (B) is at least predominantly composed of units U1 and/or U2; or   the particles (p) are particles of carbon black; and   the block (A) is at least predominantly composed of hydrophobic monomer units U8; and   the block (B) is at least predominantly composed of units U1 and/or U2 and/or U5;   wherein:
 monomer units U1 are monomer units comprising an acrylamide functional group, 
 monomer units U2 are monomer units comprising a sulfonic acid or sulfonate functional group, 
 monomer units U3 are neutral monomer units, 
 monomer units U4 are monomer units carrying ammonium groups, 
 monomer units U5 are acrylate monomer units carrying a COOH or COO— group, 
 monomer units U6 are monomer units carrying phosphate, phosphonate or phosphinate groups, in the free acid form and/or in the saline form, 
 monomer units U7 are (meth)acrylate units functionalized by polydimethylsiloxanes, 
 monomer units U8 are hydrophobic units.