Multi-functional weighting agent for drilling fluid and preparation method thereof, and water-based drilling fluid and use thereof

Patent metadata

Field	Value
Publication number	US-10865337-B1
Application number	US-201916675765-A
Country	US
Kind code	B1
Filing date	Nov 6, 2019
Priority date	May 20, 2019
Publication date	Dec 15, 2020
Grant date	Dec 15, 2020

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.

First claim

The invention claimed is:

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.

2. The multi-functional weighting agent of claim 1 , wherein the polyacrylamide is cross-linked.

3. 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.

4. 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.

5. 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.

6. 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 K f within a range of 0.05-0.1 and a compressive strength ranging from 9×10 4 Pa to 10×10 4 Pa.

7. The multi-functional weighting agent of claim 1 , wherein the modified barium sulfate has a density ranging from 4.2-4.8 g/cm 3 .

8. 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.

9. 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).

10. 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.

11. 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.

12. 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.

13. 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.

14. 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.

15. 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.

16. 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.

17. 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.

18. 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.

19. The method of claim 9 , wherein the modified barium sulfate has a density greater than or equal to 4.2 g/cm 3 , or in a range of 4.2-4.8 g/cm 3 .

Assignees

• Univ Southwest Petroleum

Inventors

• Bai Yang
• Luo Pingya
• Cheng Yan
• Sun Jinsheng
• Jiang Guancheng

Classifications

• C08F120/56

  Acrylamide; Methacrylamide · CPC title

• C08L33/26

  Homopolymers or copolymers of acrylamide or methacrylamide · CPC title

• C09K2208/34

  Lubricant additives · CPC title

• C09K2208/28

  Friction or drag reducing additives · CPC title

• C09K8/12

  containing synthetic organic macromolecular compounds or their precursors · CPC title