# US 2020/0399523 A1 · Drilling fluids that include water-insoluble acid catalyst precursors or reaction products of such and uses for such drilling fluids > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2020/0399523 A1 - Document ID: US20200399523A1 - Status: Published application - Kind: A1 - Application number: 16/449,996 - Filed: 2019-06-24 - Published: 2020-12-24 - Earliest claimed: 2019-06-24 - Assignees: Saudi Arabian Oil Company - Applicants: Saudi Arabian Oil Company - Inventors: Vikrant Wagle; Abdullah Al-Yami; Abdulaziz Alhehal - Web page: https://patentgrep.com/patent/US20200399523A1 ## CPC - C09K 8/24: Polymers - C09K 8/508: macromolecular compounds {(C09K8/512 takes precedence)} - C04B 26/12: Condensation polymers of aldehydes or ketones - C04B 26/125: {Melamine-formaldehyde condensation polymers} - C04B 26/28: Polysaccharides or derivatives thereof - C04B 28/02: containing hydraulic cements other than calcium sulfates - C09K 8/035: Organic additives - C09K 8/34: Organic liquids - C09K 8/502: Oil-based compositions - C09K 8/5086: {obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds} - C09K 8/512: containing cross-linking agents - E21B 21/003: {Means for stopping loss of drilling fluid (plastering the borehole wall E21B33/138)} - E21B 33/138: Plastering the borehole wall; Injecting into the formation - C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE - C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS ## Abstract In accordance with one or more embodiments of the present disclosure, a drilling fluid may include a base fluid and one or more formaldehyde-based resins. The drilling fluid may further comprise one or more water-insoluble acid catalyst precursors or the reaction products of such water-insoluble acid catalyst precursors. The present disclosure also describes sealed subterranean petroleum formations that include such drilling fluids and methods for sealing subterranean wellbores by utilizing such drilling fluids. ## Claims ### Claim 1 A drilling fluid comprising: a base fluid comprising an aqueous or non-aqueous solution; one or more formaldehyde-based resins, where the weight ratio of the one or more formaldehyde-based resins to the base fluid is from 1:100 to 50:100; one or more water-insoluble acid catalyst precursors or the reaction products of such water-insoluble acid catalyst precursors, the weight ratio of the sum of the one or more water-insoluble acid catalyst precursors and the reaction products of such water-insoluble acid catalyst precursors to the total drilling fluid is from 0.5:100 to 20:100. ### Claim 2 (depends on 1) The drilling fluid of claim 1, where the one or more formaldehyde-based resins comprise melamine-formaldehyde resin, urea-formaldehyde resin, phenol-formaldehyde resin, or combinations of these. ### Claim 3 (depends on 1) The drilling fluid of claim 1, where the one or more water-insoluble acid catalyst precursors comprise a water-insoluble hydrolysable polyester. ### Claim 4 (depends on 1) The drilling fluid of claim 1, where the water-insoluble acid catalyst precursor comprises one or more of polylactide, polyhdroxylakanoates, polyglycolide, polylactoglycolide, polycaprolactone, or combinations of these. ### Claim 5 (depends on 1) The drilling fluid of claim 1, where the reaction products of the water-insoluble acid catalyst precursor comprise carboxylic acids. ### Claim 6 (depends on 1) The drilling fluid of claim 1, where the base fluid comprises an aqueous solution. ### Claim 7 (depends on 1) The drilling fluid of claim 1, where the base fluid comprises a non-aqueous solution. ### Claim 8 (depends on 1) The drilling fluid of claim 1, where the drilling fluid comprises one or more weighting agents, where the weight ratio of the one or more weighting agents to the base fluid is from 10:100 to 300:100. ### Claim 9 (depends on 1) The drilling fluid of claim 1, where the drilling fluid has a density of from 50 pounds per cubic foot to 160 pounds per cubic foot. ### Claim 10 (depends on 1) The drilling fluid of claim 1, where the drilling fluid is in a gelled state such that the apparent viscosity at 300 rpm and 25° C. of the drilling fluid is greater than or equal to 50,000 centiPoise. ### Claim 11 (depends on 1) The drilling fluid of claim 1, where the drilling fluid comprises polyvinyl alcohol or vinyl alcohol copolymers and the weight ratio of the polyvinyl alcohol or vinyl alcohol copolymers to the total weight of the drilling fluid is less than or equal to 1.5:100. ### Claim 12 (depends on 1) The drilling fluid of claim 1, where the drilling fluid comprises latex and the weight ratio of the latex to the total weight of the drilling fluid is less than or equal to 10:100. ### Claim 13 A sealed subterranean petroleum formation comprising: a subterranean wellbore positioned adjacent a subterranean petroleum formation; and a drilling fluid positioned in the subterranean wellbore, the drilling fluid comprising: a base fluid comprising an aqueous or non-aqueous solution; one or more formaldehyde-based resins, where the weight ratio of the one or more formaldehyde-based resins to the base fluid is from 1:100 to 50:100; one or more water-insoluble acid catalyst precursors or the reaction products of such water-insoluble acid catalyst precursors, where the weight ratio of the sum of the one or more water-insoluble acid catalyst precursors to the total drilling fluid is from 0.5:100 to 20:100. ### Claim 14 (depends on 13) The sealed subterranean petroleum formation of claim 13, where the drilling fluid is in a gelled state such the apparent viscosity at 300 rpm and 25° C. of the drilling fluid is greater than or equal to 50,000 centiPoise. ### Claim 15 (depends on 13) The sealed subterranean petroleum formation of claim 13, where the drilling fluid comprises latex and the weight ratio of the latex to the total weight of the drilling fluid is less than or equal to 10:100. ### Claim 16 A method for sealing a subterranean wellbore, the method comprising: introducing a drilling fluid into a subterranean wellbore, the subterranean wellbore positioned adjacent to a subterranean petroleum formation, where the drilling fluid comprises: a base fluid comprising an aqueous or non-aqueous solution; one or more formaldehyde-based resins, where the weight ratio of the one or more formaldehyde-based resins to the base fluid is from 1:100 to 50:100; introducing one or more water-insoluble acid catalyst precursors to the drilling fluid, where the water-insoluble acid catalyst precursor is converted to an acid catalyst in the drilling fluid in an amount operable to transition the drilling fluid from a liquid state to a gelled state. ### Claim 17 (depends on 16) The method of claim 16, where the ratio of the one or more water-insoluble acid catalyst precursors to the total weight of the drilling fluid after the contacting step is from 0.5:100 to 20:100. ### Claim 18 (depends on 16) The method of claim 16, where the one or more water-insoluble acid catalyst precursors are initially contacted with the drilling fluid outside of the subterranean wellbore. ### Claim 19 (depends on 16) The method of claim 16, where the pH of the drilling fluid prior to the addition of the water-insoluble acid catalyst precursors is from 8 to 12. ### Claim 20 (depends on 16) The method of claim 16, where the drilling fluid comprises latex and the weight ratio of the latex to the total weight of the drilling fluid is less than or equal to 10:100.