| 摘要 |
1. Drilling fluid used in the presence of water wherein it comprises cellulose nanofibril composition or dispersion containing at least 80% of cells with primary walls with a degree of crystallinity less than or equal to 50% and with a surface charged with carboxylic acids and acidic polysaccharides, alone or as a mixture, the composition obtained from the drying of a nanofibril dispersion in the presence of carboxycellulose, natural polysaccharides, polyol as an additive, alone or as a mixture. 2. Drilling fluid according to claim 1 wherein the carboxylic acids are uronic acids or their salts, and the polysaccharides are pectins, alone or as a mixture with hemicelluloses. 3. Drilling fluid according to any one of claims 1, 2 wherein a degree of crystallinity of the nanofibrils is less than 50%. 4. Drilling fluid according to any one of claims 1 to 3 wherein the section of the nanofibrils is from 2 to approximately 10 nm, preferably from 2 to approximately 4 nm. 5. Drilling fluid according to any one of claims 1 to 4 wherein the additive is a carboxycellulose, preferably carboxymethylcellulose, with a degree of substitution of less than or equal to 0.95. 6. Drilling fluid according to any one of claims 1 to 4 wherein the additive is a carboxycellulose in salt or acid form with a degree of substitution of greater than 0.95. 7. Drilling fluid according to any one of claims 1 to 5 wherein the said composition is obtained from the drying of a nanofibril dispersion in the presence of the said additive and co-additive, which are chosen from a group of the following compounds: saccharide monomers or oligomers, the compounds of formula (R<1>R<2>N)COA wherein R<1> or R<2> which may be identical or different represent hydrogen or a C1-10alkyl radical, preferably a C1-5alkyl radical, A represents hydrogen, a C1-10alkyl radical, preferably a C1-5alkyl radical, or the group R<'1>R<'2> wherein R<'1> and R<'2> which may be identical or different represent hydrogen or a C1-10alkyl radical, preferably C1-5alkyl radical, cationic or amphoteric surfactants alone or as a mixture. 8. Drilling fluid according to any one of claims 1 to 4 and 6 wherein the said composition is obtained from the drying of a nanofibril dispersion in the presence of the said additive and co-additive, which are chosen from a group of the following compounds: carboxycellullose with a degree of substitution of less than or equal to 0.95, preferably carboxymethylcellulose, saccharide monomers or oligomers, the compounds of formula (R<1>R<2>N)COA wherein R<1> or R<2> which may be identical or different represent hydrogen or a C1-10alkyl radical, preferably a C1-5alkyl radical, A represents hydrogen, a C1-10alkyl radical, preferably a C1-5alkyl radical, or the group R<'1>R<'2> wherein R<'1> and R<'2> which may be identical or different represent hydrogen or a C1-10alkyl radical, preferably C1-5alkyl radical, cationic or amphoteric surfactants. 9. Drilling fluid according to any one of claims 7 to 8 wherein the content of additive and co-additive is less than 30% by weight relative to the weight of the nanofibrils and of additive and of co-additive. 10. Drilling fluid according to any one of claims 1 to 9 wherein the content of cellulose nanofibrils is between 0.05 and 2%, preferably between 0.05 and 1%, relative to the total weight of fluid. 11. Drilling fluid according to any one of claims 1 to 10 wherein the composition is obtained from the drying at temperature which restricts decomposition of carboxylic acids, acidic polysaccharides, hemicelluloses and/or said additives and co-additives. 12. Drilling fluid according to claim 11 wherein the said temperature is in the range of from 30 to 80 degree C, preferably from 30 to 60 degree C. 13. Drilling fluid according to any one of claims 1 to 12 wherein it comprises an agent adsorbed by rock on the wells walls and reducing liquid diffusion through the walls, in an amount of up to 1% relative to the total weight of the fluid. 14. Drilling fluid according to claim 13 wherein the said agent is chosen from polyacrylamides, high molecular weight polyacrylates, succinoglycans, native starch or its derivatives and charcoal, alone or in combination. 15. Drilling fluid according to any one of claims 1 to 14 wherein it comprises a thinning or dispersing agent in an amount of up to 1% relative to the total weight of the fluid. 16. Drilling fluid according to claim 15 wherein the thinning or dispersing agent is chosen from polyphosphates, tannins, lignosulphonates, lignin derivatives, peats, lignites, polyacrylates, polynaphthalene sulphonates, alone or as a mixture. 17. Drilling fluid according to any one of claims 1 to 16 wherein it comprises an oxygen scavenger in a content of up to 0.25% relative to the total weight of the fluid. 18. Drilling fluid according to any one of claims 1 to 17 wherein it comprises a weighting compound chosen from sulphates, carbonates and alkaline-earth metal silicates, alkaline-earth metal or zinc bromides and iron oxides. 19. Drilling fluid according to any one of claims 1 to 18 wherein it comprises at least one mineral colloid chosen from a group containing attapulgite, baryta and bentonite, alone or as a mixture. 20. Drilling fluid according to any one of claims 1 to 19 wherein it comprises inorganic salts. 21. Drilling fluid according to claim 20 wherein inorganic salts are chosen from halides, sulphates, carbonates, bicarbonates, silicates and alkali metal phosphates, alone or as a mixture. 22. Drilling fluid according to either of claims 20 and 21 wherein the inorganic salts content is between 0.01 and 2% relative to the total weight of the fluid. |
