Particulate profile control agent self-adaptive to pore throat size of stratum and preparation method for particulate profile control agent

Abstract

The invention discloses a particulate profile control agent self-adaptive to a pore throat size of a stratum and a preparation method for the particulate profile control agent. The particulate profilecontrol agent is prepared from the raw materials in percentage by mass: 0.04%-0.2% of main agent, 0.005%-0.01% of coagulation agent, 0.002%-0.04% of cross-linker, 0.005%-0.01% of additive and the balance of water. The preparation method for the profile control agent comprises the steps of proportionally adding the main agent into the water, carrying out uniform stirring, and then, sequentially adding the additive, the cross-linker and the coagulation agent, thereby forming the profile control agent. Colloidal particles can be formed in situ through pumping the profile control agent into the stratum and carrying out a reaction for a period of time at an oil reservoir temperature, and thus, a high-permeability layer can be plugged. The particulate profile control agent and the preparation method therefor have the advantages that the preparing of the profile control agent is simple and convenient in operation and low in cost; a system is low in initial viscosity and good in injectivity;the particulate profile control agent can react in situ to produce colloidal particles highly matched with pores and cracks of the stratum, the strength of plugging is high, and the reaction time is controllable; and the particulate profile control agent is wide in oil reservoir adaptability and good in colloidal particle viscoelasticity, has the ability for deep migration and can perform pluggingin the oil reservoir step by step, and thus, the recovery ratio of crude oil is remarkably increased.

Description

technical field [0001] The invention relates to a particle profile control agent adaptive to formation pore-throat size and a preparation method thereof, belonging to the technical field of oil field chemistry. Background technique [0002] After a short period of elastic energy extraction, the oil field enters the stage of supplementary energy development. Water flooding is still the preferred technology for oilfield development. The water flooding stage endows other functions besides replenishing formation energy and has become a hot topic in the world's oil industry. After many years of water injection development, the oilfield has entered a stage of high water cut and high water production. At the same time, the contradictions in various layers of the reservoir are prominent, water channeling is serious, and it is difficult to stabilize production. Laboratory research and field tests have proved that the profile control technology is an important strategic technology to ...

AI Technical Summary

Problems solved by technology

[0009] Among them, polymer microspheres have attracted extensive attention due to their good injectability, strong migration ability and good stability. The construction process of the microspheres is simple, and they can be easily dispersed in aqueous solution and injected into the formation. The large pores in the formation are blocked by mechanical trapping and adsorption. For example, the patent CN105778016A discloses a polymer microsphere for oil field profile control and water plugging and its preparation method, which includes a cationic core, an intermediate oil-wet shell, The outer anionic hydrophilic shell has a three-layer structure, the particle size ranges from 1 to 500 μm, and the size can be controlled. After fully expanding, the size can reach 30 to 1500 μm. It has good expansion performance and strong plugging performance; however, this type of microsphere also has swelling The speed is too fast, and the ability to block large pores is weak, especially after it migrates into the deep formation, it is easy to reduce the strength due to expansion, degradation, etc., and the bridging and sealing ability of large pores is weakened, so the effect in practical application restricted

[0010] The bulky particle size can be adjusted according to different reservoir conditions, and the expansion multiple and strength are less affected by the salinity of formation water. For example, patent CN105368422A discloses a pre-crosslinked bulky particle profile control agent and its preparation method , consisting of 90-110 parts of acrylamide, 2-4 parts of 2-acrylamido octadecylsulfonic acid, 2-4 parts of N, N-methylenebisacrylamide, 0.02-0.04 parts of ammonium persulfate, 0.08- It is prepared from 0.2 parts of tetramethylethylenediamine and 300-400 parts of deionized water. The compressive strength of the profile control agent after absorbing water is greater than 3MPa. The product has high compressive strength and high elasticity in the bottom layer, which can maintain Larger particle size is conducive to blocking large pores, but the bulky particle size is larger, and its injectability and deep migration ability are poor

[0011] The flexible particles can withstand high temperature and high salt, and the texture is soft after absorbing water, which can produce temporary plugging in the formation, and continue to migrate through deformation under pressure. For example, patent CN106632835A discloses a flexible particle for profile control and its preparation method. The phase material and the oil phase material are formulated according to the weight ratio of 35:65~25:75. It has the characteristics of small particle size, good swelling and salt resistance, high expansion multiple, high content of separable solids, and fast dispersion. The expansion speed is too fast, resulting in the poor injectability of flexible particles with large particle size, which is easy to cause blockage in the wellbore or near the wellbore

[0012] After deeply analyzing the advantages and disadvantages of various traditional profile control agents, the present invention proposes a new type of colloidal particle profile control agent that is adaptive to the size of formation pore throats. This system is formulated under ground conditions to form a profile control agent. Cross-linked under reservoir conditions to form viscoelastic colloidal particles, which can not only seal high-permeability layers and fractures in the near-wellbore zone, divert the fluid flow, but also migrate to the deep through deformation under a certain pressure. The formation of step-by-step plugging can solve the problems of traditional profile control agents such as poor injectability, low or even no gel formation after shearing, and inability to meet profile control and oil displacement at the same time

Images