# US 10,865,337 B1 · Multi-functional weighting agent for drilling fluid and preparation method thereof, and water-based drilling fluid and use thereof > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,865,337 B1 - Document ID: US10865337B1 - Status: Granted - Kind: B1 - Application number: 16/675,765 - Filed: 2019-11-06 - Published: 2020-11-26 - Granted: 2020-12-15 - Earliest claimed: 2019-05-20 - Assignees: Southwest Petroleum University - Applicants: Southwest Petroleum University - Inventors: Yang Bai; Pingya Luo; Yan Cheng; Jinsheng Sun; Guancheng Jiang - Web page: https://patentgrep.com/patent/US10865337B1 ## CPC - C09K 8/03: Specific additives for general use in well-drilling compositions - C08F 120/56: Acrylamide; Methacrylamide - C09K 8/12: containing synthetic organic macromolecular compounds or their precursors - C08K 3/30: Sulfur-, selenium- or tellurium-containing compounds - C08K 2003/3045: {Sulfates} - C08L 33/26: Homopolymers or copolymers of acrylamide or methacrylamide - C09K 2208/28: Friction or drag reducing additives - C09K 2208/34: Lubricant additives - C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE - C08F: MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS - C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09) - C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06) ## Abstract The invention relates to the field of drilling fluid, and provides a multi-functional weighting agent for drilling fluid and preparation method thereof, and water-based drilling fluid and use thereof, wherein the multi-functional weighting agent is an polyacrylamide/modified barium sulfate composite multi-functional weighting agent prepared by sequentially dropwise adding acrylamide and ammonium persulfate to a mixture of modified barium sulfate and deionized water in a presence of an initiator. ## Claims ### Claim 1 A multi-functional weighting agent having a composite structure, comprising polyacrylamide, and modified barium sulfate, wherein the modified barium sulfate and the polyacrylamide are in a ratio by weight in a range of from about 4:5 to about 5:2. ### Claim 2 (depends on 1) The multi-functional weighting agent of claim 1, wherein the polyacrylamide is cross-linked. ### Claim 3 (depends on 1) The multi-functional weighting agent of claim 1, wherein the modified barium sulfate and the polyacrylamide are in a ratio by weight being about 3:2. ### Claim 4 (depends on 1) The multi-functional weighting agent of claim 1, wherein the modified barium sulfate comprises modified barium sulfate A, modified barium sulfate B and modified barium sulfate C; wherein the modified barium sulfate A has an average particle diameter of 0.05-0.45 μm, the modified barium sulfate B has an average particle diameter of 0.5-3 μm, and the modified barium sulfate C has an average particle diameter of 15-25 μm. ### Claim 5 (depends on 4) The multi-functional weighting agent of claim 4, wherein a weight ratio of the modified barium sulfate A, the modified barium sulfate B and the modified barium sulfate C is (0.4-0.6):(0.4-0.6): 1. ### Claim 6 (depends on 5) The multi-functional weighting agent of claim 5, wherein the multi-functional weighting agent is white round particles with an average particle diameter of 8-20 μm, and has a surface lubricating coefficient Kf within a range of 0.05-0.1 and a compressive strength ranging from 9×104 Pa to 10×104 Pa. ### Claim 7 (depends on 1) The multi-functional weighting agent of claim 1, wherein the modified barium sulfate has a density ranging from 4.2-4.8 g/cm3. ### Claim 8 (depends on 1) A water-based drilling fluid, comprising the multi-functional weighting agent of claim 1; wherein the multi-functional weighting agent is in an amount of 150-170 g, based on a total weight of 100 mL water-based drilling fluid. ### Claim 9 (depends on 1) A method for preparing the multi-functional weighting agent of claim 1, wherein the method comprises: (1) mixing a modified barium sulfate with deionized water to obtain a mixture; (2) heating the mixture and adjusting a pH of the mixture at a presence of an initiator; (3) sequentially dropwise adding acrylamide and ammonium persulfate to step (2) for carrying out reaction; (4) washing, drying and grinding the reaction product of step (3). ### Claim 10 (depends on 9) The method of claim 9, wherein mixing conditions in step (1) include: stirring the mixture at a stirring rate of 300-400 r/min for 0.2-1 h and then standing still for 3-5 h; wherein heating conditions in step (2) comprise: a temperature within a range of 70-90° C., and a pH ranging from 4-6; wherein reaction conditions in step (3) comprise: a temperature within a range of 70-90° C., and a dropping rate ranging from 0.5-6 mL/min. ### Claim 11 (depends on 9) The method of claim 9, wherein the modified barium sulfate is used in an amount of 5-20 parts by weight, the acrylamide is used in an amount of 5-15 parts by weight, and the ammonium persulfate is used in an amount of 0.3-6 parts by weight, based on 100 parts by weight of deionized water. ### Claim 12 (depends on 11) The method of claim 11, wherein the modified barium sulfate is used in an amount of 8-15 parts by weight, the acrylamide is used in an amount of 6-10 parts by weight, and the ammonium persulfate is used in an amount of 0.5-5 parts by weight, based on 100 parts by weight of deionized water. ### Claim 13 (depends on 9) The method of claim 9, wherein the modified barium sulfate comprises modified barium sulfate A, modified barium sulfate B and modified barium sulfate C; wherein the modified barium sulfate A has an average particle diameter of 0.05-0.45 μm, the modified barium sulfate B has an average particle diameter of 0.5-3 μm, and the modified barium sulfate C has an average particle diameter of 15-25 μm. ### Claim 14 (depends on 9) The method of claim 9, wherein the initiator is dimethyl azobisisobutyrate and/or sodium sulfite, in an amount of 0.1-4 parts by weight based on 100 parts by weight of deionized water. ### Claim 15 (depends on 14) The method of claim 14, wherein a weight ratio of the modified barium sulfate A, the modified barium sulfate B and the modified barium sulfate C is (0.4-0.6):(0.4-0.6):1. ### Claim 16 (depends on 9) The method of claim 9, wherein the method for preparing the modified barium sulfate comprises the following steps: (S1) contacting an aqueous solution containing barium carbonate with diethylenetriamine pentaacetic acid (DTPA) to form a complexing system; (S2) dropwise adding potassium sulfate into the complexing system to carry out reaction to produce a barium sulfate precipitate; and (S3) washing, drying and grinding the barium sulfate precipitate. ### Claim 17 (depends on 16) The method of claim 16, wherein conditions of the contacting in the step (S1) comprise: the temperature is 40-60° C., the pH is within a range of 5-7, and the time is 1-1.5 h; wherein conditions of the reaction in the step (S2) comprise: a temperature of 40-60° C., a time ranging from 3-10 h, and a dropping rate within a range of 0.5-5 mL/min. ### Claim 18 (depends on 16) The method of claim 16, wherein the diethylenetriamine pentaacetic acid is used in an amount of 0.2-2 parts by weight, and the potassium sulfate is used in an amount of 1-3 parts by weight, based on 0.5-3 parts by weight of barium carbonate. ### Claim 19 (depends on 9) The method of claim 9, wherein the modified barium sulfate has a density greater than or equal to 4.2 g/cm3, or in a range of 4.2-4.8 g/cm3.