Preformed particle gel for conformance control in an oil reservoir

Abstract

Expandable and hydrophilic polymeric particles may be made in a non-emulsion system, and with controllable hardness and delay in their time to swell in a fresh or salt water environment. These particles are prepared from combining monomers, controlled monomers, stable cross-linkers, initiators, and other agents, in aqueous solution. The controlled monomers induce kinetically controllable decomposition, degrading over time, thus inducing a desired time delay in particle swelling. The delay and degree of the swelling of the particles is controlled by selection of controlled monomer, stable cross-linking agents, monomers, and process conditions. These preformed particle gels are made to an initial particle size of 0.1 micron in diameter or larger via different grinding techniques. This composition is used for modifying the permeability of subterranean formations and thereby increasing the recovery rate of hydrocarbon fluids present in the formation.

1 . A method of conformance control for oil and gas production by using gel-forming materials comprising preformed particles, wherein the particles have a controlled delay time before forming a gel and expanding significantly. 
   
   
       2 . The method of  claim 1 , wherein the size of the preformed particles ranges from 10 microns to 5 millimeters in diameter. 
   
   
       3 . The method of  claim 1  wherein the preparation of gels further comprises forming cross-linked expandable polymeric particles. 
   
   
       4 . The method of  claim 1 , wherein said method further comprises polymerizing one or more polymerizable monomers, in concentrations of from about 5 to 60 % of reactants, under free radical initiator-forming conditions in the presence of about 0.01% to 30% of controlled monomers and 0 to about 5% of stable cross-linkers in aqueous solution. 
   
   
       5 . The method of  claim 4 , wherein said method further comprises agents selected from the group consisting of: bases, reducing promoters, regulators, stabilizers, chelating agent, thermal agents, chain-transfer agents, oxygen scavengers, pH adjusters, and gel strength modifiers, in amounts of from 0 to about 60%. 
   
   
       6 . The method of  claim 4  wherein the monomer is selected from the group consisting of: nonionic monomer, anionic monomer, cationic monomer, zwitterionic monomer, betaine monomer, and amphoteric ion pair monomer. 
   
   
       7 . The method of  claim 4  wherein the nonionic monomers are selected from the group consisting of: vinyl amide, acryloylmorpholine, acrylate, maleic anhydride, N-vinylpyrrolidone, vinyl acetate, N-vinyl formamide and their derivatives. 
   
   
       8 . The method of  claim 4  wherein the nonionic monomers are selected from the group consisting of: hydroxyethyl (methyl) acrylate CH2=CR—COO—CH2CH2OH (I) and CH2=CR—CO—N(Z1)(Z2) (2) N-substituted (methyl)acrylamide (II), wherein R═H or Me; Z1=H or 5-15C alkyl; 1-3C alkyl substituted by 1-3 phenyl, phenyl or 6-12C cycloalkyl (both optionally substituted) and Z2=H; Z1 and Z2 are each 3-10C alkyl; (II) is N-tert. hexyl, tert. octyl, methylundecyl, cyclohexyl, benzyl, diphenylmethyl, triphenyl Acrylamide; and their derivatives. 
   
   
       9 . The method of  claim 4  wherein the anionic monomers are salts of unsaturated organic acids, including acrylic acid, methacrylic acid, maleic acid, itaconic acid, acrylamido methylpropane sulfonic acid, vinylphosphonic acid, styrene sulfonic acid and their derivatives. 
   
   
       10 . The method of  claim 4  wherein the cationic monomers include quaternary ammonium and acid salts of vinyl amide, vinyl carboxylic acid, methacrylate and their derivatives. 
   
   
       11 . The method of  claim 4  wherein the controlled monomers include:
 a. [CR 1 R 2 ═CR 3 —CO-]n esters of di, tri, tetra alcohols (I);   b. [CR 1 R 2 ═CR 3 —O-]n esters of di, tri, tetra functional acids (II);   c. [CR 1 R 2 ═CR 3 —CR 4 R 5 —O]n esters of di, tri, tetra functional acids (III);   d. [CR 1 R 2 ═CR 3 —CO-]m amides (IV);   e. [CR 1 R 2 ═C R 3 —] 2  of bisazo (V);   f. [CR 1 R 2 ═C R 3 —CR 4 R 5 —] 2  of bisazo (VI); and, the derivatives of (I)-(VI), wherein R 1 ═H or Me, R 2 ═H or Me, R 3 ═H or Me, R 4 ═R 5 ═H or Me, n=2, 3, or 4, and m=2, 3, or 4.   
   
   
       12 . The method of  claim 4  wherein the stable cross-linkers include aluminum salt, zirconium salt, chromium salt and organic cross-linkers such as methylenebisacrylamide, hexamethylenetetramine, and phenol aldehyde. 
   
   
       13 . The method of  claim 4  wherein the aqueous solution includes water, buffer solvent, or other non-oil and non-surfactant solutions and their derivatives. 
   
   
       14 . The method of  claim 4  wherein the initiators are selected from the group consisting of: ammonium persulfate, potassium persulfate, sodium persulfate, sodium bromate, sodium bisulfite, and mixtures thereof. 
   
   
       15 . The method of  claim 5  wherein the bases are selected from the group consisting of: sodium carbonate, sodium bicarbonate, sodium hydroxide and their derivatives. 
   
   
       16 . The method of  claim 5  wherein the reducing promoters are selected from the group consisting of: potassium metabisulfite, sodium sulfite, thionyl chloride, thionyl bromide and their derivatives. 
   
   
       17 . The method of  claim 5 , wherein said regulators comprise organic alcohols. 
   
   
       18 . The method of  claim 5 , wherein the stabilizers are selected from the group consisting of: phenol, m-dihydroxybenzene, and hydroquinone. 
   
   
       19 . The method of  claim 5  wherein the chelating agents are selected from the group consisting of: ethylene diamine tetra acetate (EDTA) and the like. 
   
   
       20 . The method of  claim 5  wherein the thermal agent comprises 2-acrylamido-2-methyl propane sulfonic acid and their derivatives. 
   
   
       21 . The method of  claim 5 , wherein the chain-transfer agents are selected from the group consisting of: thiols, formic acid and alkali metal formates. 
   
   
       22 . The method of  claim 5  wherein the oxygen scavengers are selected from the group consisting of: sodium sulfite, sodium bisulfite, sodium thiosulfate, sodium lignosulfate, ammonium bisulfite, hydroquinone, diethylhydroxyethanol, diethylhydroxylamine, methylethylketoxime, ascorbic acid, erythorbic acid, and sodium erythorbate. 
   
   
       23 . The method of  claim 5  wherein the pH adjusters are selected from the group consisting of: sodium hydroxide and potassium hydroxide. 
   
   
       24 . The method of  claim 5  where the gel strength modifiers comprise clays, and more preferably comprise clays selected from the group consisting of: diatomite, bentonite, lignocellulose, bentonite, montmorillonite, kaolinoite, and mixtures thereof. 
   
   
       25 . A method of using mechanical or physical processes to grind controlled particle gel to sizes ranging from about 0.1 micron to 500 micron in diameter for the purpose of conformance control in oil and gas production. 
   
   
       26 . The method of  claim 25  wherein the mechanical processes are selected from: fluid energy or jet mills, stirred media mills, ball mills, colloid mills, vibrating mills, rotor mills, cutting mills, disc mills, jaw crushers, and mortar grinders, to grind particle gels to desirable particle sizes. 
   
   
       27 . The method of  claim 25  wherein processes can be performed under dry or wet conditions. 
   
   
       28 . The method of  claim 25  wherein said process can be repeated in multiple circulations, until the desirable particle size is achieved. 
   
   
       29 . The method of  claim 25  wherein the physical processes further comprises spray drying.