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CN-121991648-A - Plugging agent, oil-based drilling fluid and preparation method and application thereof

CN121991648ACN 121991648 ACN121991648 ACN 121991648ACN-121991648-A

Abstract

The invention discloses a plugging agent, oil-based drilling fluid and a preparation method and application thereof, and belongs to the technical field of drilling fluid. In order to solve the problem that plugging agents in oil-based drilling fluids are easy to aggregate, the method carries out iron loading on common calcite, forms a complex on the surface of the calcite by utilizing interaction of tannic acid and iron ions, and then loads graphene oxide on the surface of the calcite by utilizing electrostatic adsorption of the iron ions and carboxylic acid groups on the surface of the complex. On one hand, the complexes have certain repulsive interaction due to the existence of iron ions, and on the other hand, calcite cannot be close to aggregation due to the limited domain effect of graphene oxide, so that the dispersion performance of modified calcite serving as a plugging agent in drilling fluid is improved. The modified calcite is used as a plugging agent in the drilling fluid, so that the drilling fluid can effectively enter into a crack, the plugging performance is improved, and the collapse prevention capability of a well wall is improved.

Inventors

  • WANG XUDONG
  • LI WENZHE
  • CHEN YE
  • WU PENGCHENG
  • LI ZHENGTAO
  • WAN XIUMEI

Assignees

  • 中国石油天然气股份有限公司

Dates

Publication Date
20260508
Application Date
20241105

Claims (20)

  1. 1. The preparation method of the plugging agent is characterized by comprising the following steps: Adding an alkali solution into calcite powder to obtain a first mixture, adding a ferric salt-containing solution into the first mixture to obtain a second mixture, separating solids in the second mixture to obtain iron-containing calcite, mixing graphene oxide with water to obtain a dispersion liquid, sequentially adding tannic acid, ferric salt and an acid solution into the dispersion liquid to obtain a first mixed solution, adding the iron-containing calcite into the first mixed solution to obtain a second mixed solution, and carrying out hydrothermal reaction on the second mixed solution to obtain the plugging agent.
  2. 2. The preparation method according to claim 1, wherein the mass ratio of the calcite powder to the alkali solution is 5:5-9, and the concentration of the alkali solution is 1-5mol/L when preparing the first mixture.
  3. 3. The method according to claim 1, wherein the alkali solution is selected from one of sodium hydroxide, potassium hydroxide, ammonia water and sodium bicarbonate.
  4. 4. The preparation method according to claim 1, wherein the mass ratio of the iron-containing salt solution to the calcite powder is 1-4:5, and the concentration of the iron-containing salt solution is 0.5-1.1mol/L, based on the mass of the calcite powder, when preparing the second mixture.
  5. 5. The method according to claim 1, wherein the iron-containing salt solution is selected from one of ferric nitrate, ferric ammonium citrate, ferric acetate, ferric chloride, ferric sulfate, ferrous nitrate, ferrous acetate, ferrous amine citrate, ferrous chloride, or ferrous sulfate.
  6. 6. The method according to claim 1, wherein the mass ratio of graphene oxide to water is 7-10:50 when the dispersion is prepared.
  7. 7. The preparation method according to claim 1, wherein the mass ratio of tannic acid to ferric salt to acid solution is 20-25:5-15:5-15, and the concentration of the acid solution is 0.5-0.95mol/L.
  8. 8. The method according to claim 1, wherein the first mixed solution is prepared from a solution of ferric chloride, ferric nitrate or ferric sulfate, and the acid solution is a solution of hydrochloric acid, nitric acid or sulfuric acid.
  9. 9. The method according to claim 1, wherein the mass ratio of the iron-containing calcite to tannic acid is 4:4-5 based on the mass of tannic acid when the second mixed solution is prepared.
  10. 10. The method of claim 1, wherein the hydrothermal reaction is at a temperature of 80-90 ℃.
  11. 11. An oil-based drilling fluid, characterized by comprising, by mass, 100 parts of base oil, 15-25 parts of the plugging agent prepared by the preparation method according to any one of claims 1-7, 4-12 parts of organoclay, 1-7 parts of emulsifier, 13-21 parts of inhibitor, 3-9 parts of filtrate reducer, 1-8 parts of alkaline regulator and 15-36 parts of weighting agent.
  12. 12. The oil-based drilling fluid according to claim 11, which comprises, by mass, 100 parts of base oil, 18 to 20 parts of the plugging agent prepared by the preparation method according to any one of claims 1 to 7, 5 to 9 parts of organoclay, 2 to 6 parts of emulsifier, 15 to 20 parts of inhibitor, 4 to 8 parts of filtrate reducer, 2 to 6 parts of alkaline regulator and 20 to 35 parts of weighting agent.
  13. 13. The oil-based drilling fluid according to claim 11 or 12, wherein the base oil is selected from one of white oil or diesel oil.
  14. 14. The oil-based drilling fluid according to claim 11 or 12, wherein the organoclay is selected from one of bentonite or montmorillonite.
  15. 15. The oil-based drilling fluid according to claim 11 or 12, wherein the emulsifier is selected from one of calcium naphthenate, naphthenic acid amide, stearic acid ester, sorbitol fatty acid ester, polyoxyethylene ether or alkylbenzene sulfonate.
  16. 16. The oil-based drilling fluid according to claim 11 or 12, wherein the inhibitor is selected from one of potassium chloride, sodium chloride, polyethylene glycol, tetrabutylammonium bromide or sodium polyacrylate.
  17. 17. The oil-based drilling fluid according to claim 11 or 12, wherein the fluid loss additive is selected from one of polyphenylethylbenzene, sodium carboxymethyl cellulose, sulfonated asphalt, or phenolic resin.
  18. 18. The oil-based drilling fluid according to claim 11 or 12, wherein the alkalinity regulator is selected from one of sodium hydroxide, potassium hydroxide, calcium oxide, sodium carbonate or ammonia water.
  19. 19. The oil-based drilling fluid according to claim 11 or 12, wherein the weighting agent is selected from one of barite, limestone, ilmenite, hausmannite or hematite.
  20. 20. Use of an oil-based drilling fluid as defined in any one of claims 11-19 for leak-proof and lost circulation of a well.

Description

Plugging agent, oil-based drilling fluid and preparation method and application thereof Technical Field The invention relates to the technical field of drilling fluid, in particular to a plugging agent, oil-based drilling fluid and a preparation method and application thereof. Background The instability of the well wall is a serious engineering problem which puzzles the field of drilling fluid and needs to be solved for many years. Unstable well walls can cause complicated well descending conditions such as well collapse, drill sticking, well leakage and the like, and well drilling quality and progress are seriously affected. The well wall instability of the stratum mainly occurs in a hard and brittle shale stratum containing cracks, and the stratum mostly has closed or opened stratums and microcracks, so that the acting force of a capillary tube is strong. Under the action of positive pressure difference and capillary pressure, drilling fluid is easy to invade, so that shale is cracked along a crack surface or a bedding surface and continuously develops longitudinally and transversely along the crack surface, and the phenomenon of well wall instability is increased. For the instability of the well wall of the stratum, only by adding the plugging material into the drilling fluid, filling the cracks and forming a blocking layer on the well wall, the pressure transfer process caused by the invasion of the well bore fluid into the stratum can be effectively blocked, and the purpose of stabilizing the well wall is achieved. However, the plugging materials commonly used at present are easy to aggregate when in use, so that the plugging materials cannot effectively enter the inside of a crack, namely the drilling fluid loses the anti-collapse plugging effect. For example, the patent CN113088268a, "oil-based drilling fluid composition, oil-based drilling fluid, and methods for preparing and using the same," provides a modified nano calcium carbonate as a plugging agent, but does not solve the problem that the plugging agent is easy to aggregate. For another example, the patent with publication number CN112048288a provides an oil-based drilling fluid filtrate loss blocking agent, which has better filtrate loss prevention performance, stabilizes the well wall, prevents cracking, has better reagent blocking compression resistance, enhances the stability of oil-based drilling fluid performance, effectively blocks micro-scale cracks with micro-scale particle size, has good plugging effect while drilling, but still does not solve the problem of easy aggregation of the plugging agent. Disclosure of Invention In order to solve the technical problems, the invention provides the plugging agent with good dispersion performance, so that the plugging agent can effectively enter into cracks, and the plugging performance is improved. The invention provides an anti-collapse oil-based drilling fluid for deep shale, which comprises, by mass, 100 parts of base oil, 15-25 parts of plugging agent prepared by the preparation method according to any one of claims 1-7, 4-12 parts of organoclay, 1-7 parts of emulsifying agent, 13-21 parts of inhibitor, 3-9 parts of filtrate reducer, 1-8 parts of alkaline regulator and 15-36 parts of weighting agent; Preferably, the components comprise, by mass, 100 parts of base oil, 5-9 parts of organoclay, 2-6 parts of emulsifier, 15-20 parts of inhibitor, 4-8 parts of filtrate reducer, 2-6 parts of alkaline regulator, 20-35 parts of weighting agent and 18-20 parts of plugging agent. The preparation method of the collapse-preventing oil-based drilling fluid for deep shale comprises the steps of stirring base oil, and sequentially adding bentonite, an emulsifying agent, an inhibitor, a filtrate reducer, an alkaline regulator, a weighting agent and a plugging agent into the base oil in the stirring process to obtain the collapse-preventing oil-based drilling fluid for deep shale. Wherein the plugging agent is modified calcite; the base oil is selected from one of white oil or diesel oil; the organic clay is selected from bentonite or montmorillonite; The emulsifier is selected from one of calcium naphthenate, naphthenic acid amide, stearate, sorbitol fatty acid ester, polyoxyethylene ether or alkylbenzene sulfonate; The inhibitor is selected from one of potassium chloride, sodium chloride, polyethylene glycol, tetrabutylammonium bromide or sodium polyacrylate; The filtrate reducer is selected from one of sulfonated asphalt, polystyrene, sodium carboxymethyl cellulose or phenolic resin; The sulfonated asphalt is selected from one of calcium sulfonate asphalt or potassium sulfonate asphalt; The phenolic resin is selected from one of dihydroxydiphenyl methane resin, m-cresol formaldehyde resin or phenol formaldehyde resin; The alkaline regulator is selected from one of sodium hydroxide, potassium hydroxide, calcium oxide, sodium carbonate or ammonia water; the weighting agent is selected from one of barite,