CN-122011276-A - Oil reservoir deep profile control and flooding combined particle, and preparation method and application thereof

CN122011276ACN 122011276 ACN122011276 ACN 122011276ACN-122011276-A

Abstract

The invention discloses oil reservoir deep profile control and flooding combined particles, a preparation method and application thereof. The profile control and flooding combined particles comprise large-particle-size pre-crosslinked particles which are formed by polymerizing main agent acrylamide and acrylic acid under the combined action of a conventional crosslinking agent and a metal crosslinking agent, and small-particle-size pre-crosslinked particles which are formed by polymerizing main agent acrylamide and acrylic acid under the combined action of a conventional crosslinking agent and a decomposable crosslinking agent. The invention has the advantages that the large-grain-diameter pre-crosslinked particles swell when aged at a certain temperature, the metal crosslinking agent coated inside the large-grain-diameter pre-crosslinked particles is gradually released, the decomposable crosslinking agent of the small-grain-diameter pre-crosslinked particles can break the chain to release carboxylate radicals when aged at a certain temperature, intermolecular complexation is carried out between the decomposable crosslinking agent of the small-grain-diameter pre-crosslinked particles and the metal crosslinking agent released by the large-grain-diameter pre-crosslinked particles, the particles are crosslinked into a network structure to form weak gel, the deep blocking strength of the existing pre-crosslinked particles is greatly improved, the deep retention capacity of a system is improved, and the aim of high-efficiency deep profile control is finally realized.

Inventors

SHAN JINCHENG
WANG TIANHUI
ZHOU RI
LIU NING
LV GUOSHENG
WANG HUANAN

Assignees

中海石油（中国）有限公司天津分公司

Dates

Publication Date: 20260512
Application Date: 20260306

Claims (10)

1. The utility model provides a deep profile control of oil reservoir combination granule which characterized in that includes: Large-particle-size pre-crosslinked particles with the particle size of 120-150 mu m are polymerized by a main agent consisting of acrylamide and acrylic acid under the combined action of a conventional crosslinking agent and a temperature-salinity double-response coated metal crosslinking agent; the small-particle-size pre-crosslinked particles are 50-70 mu m in particle size, and are prepared by polymerizing a main agent consisting of acrylamide and acrylic acid under the combined action of a conventional crosslinking agent and a temperature-sensitive decomposable crosslinking agent; The mass ratio of the large-particle-size pre-crosslinked particles to the small-particle-size pre-crosslinked particles is 9:1-3:1.
2. The oil reservoir deep profile control and flooding combination particle according to claim 1, wherein in the large-particle-size pre-crosslinked particle, the mass ratio of acrylamide to acrylic acid is 100:0-80:20, the total amount of the conventional cross-linking agent and the temperature-salinity dual-response coated metal cross-linking agent is 0.1% -1% of the mass of the main agent, and the mass ratio of the conventional cross-linking agent and the temperature-salinity dual-response coated metal cross-linking agent is 4:1-1:4.
3. The oil reservoir deep profile control and flooding combination particle according to claim 1, wherein in the small-particle-size pre-crosslinked particle, the mass ratio of acrylamide to acrylic acid is 80:20-60:40, the total amount of the conventional crosslinking agent and the temperature-sensitive type decomposable crosslinking agent is 0.1% -1% of the mass of the main agent, and the mass ratio of the conventional crosslinking agent and the temperature-sensitive type decomposable crosslinking agent is 4:1-1:4.
4. The oil reservoir deep profile control and flooding combination particle according to claim 1 is characterized in that the preparation method of the temperature-salinity dual-response coated metal cross-linking agent comprises the steps of taking the metal cross-linking agent, adding a modified chitosan and low-methoxy pectin composite coating material, wherein the total dosage of the composite coating material is 20% -30% of the mass of the metal cross-linking agent, stirring a mixed system at a high speed of 300-500r/min for 15-20min, simultaneously dropwise adding 5% calcium chloride solution at a speed of 1-2mL/min, and then transferring to a vacuum condition of 40-50 ℃ and minus 0.08MPa for drying for 2-3h.
5. The oil reservoir deep profile control combined particle according to claim 4 is characterized in that the metal cross-linking agent is any one of chromium acetate, zirconium acetate, aluminum citrate, zirconium citrate and chromium lactate, the mass ratio of modified chitosan to low methoxy pectin is 2:1-4:1, and the addition amount of calcium chloride is 3% -15% of the mass of the metal cross-linking agent.
6. The oil reservoir deep profile control combined particle according to claim 1 is characterized in that the preparation method of the temperature-sensitive decomposable cross-linking agent comprises the steps of mixing polyethylene glycol diacrylate and itaconic anhydride according to a mass ratio of 2:1-8:1, adding 0.8% -1.2% of azodiisobutyronitrile accounting for the total monomer mass, heating to 65-75 ℃ under the protection of nitrogen, reacting at constant temperature for 3-4h, cooling, adding 10% sodium hydroxide solution to adjust pH to 6.5-7.5, and filtering to remove unreacted impurities.
7. The oil reservoir deep profile control composite particle as claimed in claim 1, wherein the conventional cross-linking agent is N, N-methylenebisacrylamide and/or divinylbenzene.
8. A method for preparing the oil reservoir deep profile control composite particles as claimed in any one of claims 1 to 7, comprising the following steps: preparation of large particle size pre-crosslinked particles: A. adding acrylic acid monomer into deionized water, stirring uniformly, adding acrylamide monomer, stirring uniformly; B, adding a conventional cross-linking agent and a first initiator into the mixture obtained in the step A, and uniformly stirring; C. Adding a second initiator at 10-40 ℃ after introducing nitrogen for 30min, continuously introducing nitrogen for 2-3min, and sealing; D. Reacting for 2-4h at 55-65 ℃, standing for 1-5h at room temperature after the reaction is finished, shearing, drying and granulating to obtain large-particle-size pre-crosslinked particles with the particle size of 120-150 mu m; Preparation of small particle size pre-crosslinked particles: a. Adding acrylic acid monomer into deionized water, stirring uniformly, regulating pH to 7.0-9.0 with NaOH, adding acrylamide monomer, and stirring uniformly; b. Adding a conventional cross-linking agent and a first initiator into the mixture obtained in the step a, and uniformly stirring; c. adding a second initiator at 10-40 ℃ after introducing nitrogen for 30min, continuously introducing nitrogen for 2-3min, and sealing; d. Reacting for 2-4h at 55-65 ℃, standing for 1-5h at room temperature after the reaction is finished, shearing, drying and granulating to obtain small-particle-size pre-crosslinked particles with the particle size of 50-70 mu m.
9. Use of the oil reservoir deep profile control composite particles of any one of claims 1-7 as a profile control agent in oilfield exploitation.
10. The method according to claim 9, wherein the large-particle-size pre-crosslinked particles and the small-particle-size pre-crosslinked particles are dissolved in water to form the profile control solution, and the total amount of the large-particle-size pre-crosslinked particles and the small-particle-size pre-crosslinked particles is 700-1400 mg/L.

Description

Oil reservoir deep profile control and flooding combined particle, and preparation method and application thereof Technical Field The invention relates to the technical field of offshore oilfield exploitation, in particular to oil reservoir deep profile control and flooding combined particles, a preparation method and application. Background Along with the water flooding development of the oil fields in China, each dominant oil field sequentially enters the oil extraction stage in the later stage of high water content or extra-high water content. Due to the heterogeneity of the plane and the longitudinal direction of the oil reservoir, the difference of the viscosity of oil and water and the unbalance in an oil-water well group, the contradiction between layers is outstanding, the contradiction between the oil reservoir development is further aggravated along with the continuous deep development of water injection, the large pore canal of the oil reservoir has serious problems, the water content of the oil reservoir is accelerated, the development effect is poor, and the water flooding recovery ratio is reduced. At present, a pre-crosslinked gel particle profile control and flooding technology used in an oil field becomes an effective means for improving recovery ratio of an oil reservoir with high water content and extra-high water content in the oil field. The pre-crosslinked gel particle profile control technology is a method for improving recovery efficiency developed in the last decade. It is not simply by means of profile control and water shutoff to reduce water-containing bottom hole treatment measure, but belongs to a method for regulating in-situ or inter-layer contradiction and increasing swept volume to raise petroleum recovery ratio. The basic principle of the method is that the water flow channel of the hypertonic zone is blocked by injecting the pre-crosslinked gel system, so that the water flow is forced to redirect to the position or the layer with more residual oil, the swept volume is effectively enlarged, and the recovery ratio of crude oil is improved. The pre-crosslinking system acts mainly as a "plug" and a "turn". The gel is used for blocking the high permeable layer, and the gel is used for forcing the fluid to change the flowing direction and turn to the position or the layer with more residual oil, so that the contradiction between layers is regulated while the contradiction between layers is regulated. The main problems of the existing pre-crosslinking system are that the strength and flexibility of the system are difficult to meet the field requirement, and the performance of the system is poor under the high-temperature and high-salt condition. Currently, conventional gel particles useful in pre-crosslinked systems suffer from significant drawbacks. The particles have high water absorption rate and are already expanded by water absorption before being injected into the stratum, so that the injection process becomes complex, and the particles are difficult to enter the deep part of the stratum. Meanwhile, the strength of the particles after water absorption is low, the mechanical property is poor, shearing and crushing are easy to cause, and the particles are easy to degrade, so that the profile control effect is lost. To solve the problems of poor shearing resistance and low viscosity in the profile control and flooding process, the conventional cross-linking agent and cross-linking system are required to be changed, so that particles slowly expand after absorbing water, have small shearing action by stratum, enter the deep part of the stratum, crosslink into a reticular structure among the particles through intermolecular complexation, and the viscosity of a gel particle dispersion system is increased to form weak gel, thereby playing a role in deep profile control and flooding. In view of the above, it is desirable to provide a combination particle for deep profile control of oil reservoirs and a preparation method thereof to overcome the above problems. Disclosure of Invention The invention aims to solve the technical problems and provides oil reservoir deep profile control combined particles, a preparation method and application thereof. In a first aspect, the invention provides a combination particle for oil reservoir deep profile control, which is realized by adopting the following technical scheme. An oil reservoir deep profile control composite particle comprising: Large-particle-size pre-crosslinked particles with the particle size of 120-150 mu m are polymerized by a main agent consisting of acrylamide and acrylic acid under the combined action of a conventional crosslinking agent and a temperature-salinity double-response coated metal crosslinking agent; the small-particle-size pre-crosslinked particles are 50-70 mu m in particle size, and are prepared by polymerizing a main agent consisting of acrylamide and acrylic acid under the combined action of a conventional c