CN112094629A

CN112094629A - Plugging agent suitable for fractured oil reservoir

Info

Publication number: CN112094629A
Application number: CN202010926874.5A
Authority: CN
Inventors: 孟祥海; 刘长龙; 代磊阳; 张晓冉; 李彦阅; 张璐; 张丽平; 兰夕堂; 符扬洋; 牟媚
Original assignee: China National Offshore Oil Corp CNOOC; CNOOC China Ltd Tianjin Branch
Current assignee: China National Offshore Oil Corp CNOOC; CNOOC China Ltd Tianjin Branch
Priority date: 2020-09-07
Filing date: 2020-09-07
Publication date: 2020-12-18
Anticipated expiration: 2040-09-07
Also published as: CN112094629B

Abstract

The invention provides a plugging agent suitable for a fractured reservoir, which comprises a main agent, a cross-linking agent, a curing agent, a reinforcing agent and water; the composition comprises, by mass, 0.1 to 1.0% of a main agent, 0.1 to 2% of a crosslinking agent, 0.1 to 1.0% of a curing agent, 0.1 to 1% of a reinforcing agent, and the balance of water; the blocking agent is a high-strength blocking agent formed by the cross-linking reaction of a polymer and a cross-linking agent; the plugging agent has controllable gelling speed, high and adjustable strength and strong shearing resistance, can establish effective plugging in the stratum and is effective for a long time.

Description

Plugging agent suitable for fractured oil reservoir

Technical Field

The invention belongs to the technical field of oil and gas exploitation, and particularly relates to a plugging agent suitable for a fractured reservoir.

Background

The existence and development degree of the cracks have double effects on water injection development of the fractured oil reservoir, and on one hand, a high-permeability channel is provided, so that the water absorption capacity of a water injection well and the production capacity of a production well can be improved; on the other hand, directional water channeling can be caused, the oil production well is exposed to water too early and even submerged by violent water, and the water content of the oil well rises rapidly. But a large amount of residual oil exists in the non-fracture direction part, and the oil recovery rate is low. Therefore, how to fully utilize and transform the fracture is the key of the development of the low-permeability sandstone oil field with fracture, and gel water plugging is one of effective technologies for utilizing and transforming the fracture.

The requirements for the gel of the bottom water coning fracture type oil reservoir are more severe. The gel forming strength is required to be high, the stability time is required to be long, the viscosity retention rate is high, however, the oil reservoir oil well water plugging agents meeting the conditions in the existing oil field material supply market are rare, the existing chromium gel has high gel forming speed, the injection pressure is easy to rise too fast, and the injection amount cannot be completed smoothly. On the other hand, the chromium jelly has poor stability, short validity period and easy failure at the formation temperature, especially when the reservoir temperature is higher.

In order to achieve the effect of water plugging and bottom water coning control, the applicant researches a polymer gel system formed by using partially hydrolyzed polyacrylic acid as a polymer gel main agent, a phenolic resin cross-linking agent and other auxiliary agents so as to achieve the aim of applying a water plugging technology aiming at bottom water coning under the condition of a fractured reservoir.

Disclosure of Invention

The invention aims to provide a plugging agent suitable for a fractured reservoir to solve the technical problem of applying the plugging agent aiming at bottom water coning under the condition of the fractured reservoir.

In order to achieve the purpose, the specific technical scheme of the plugging agent suitable for the fractured reservoir is as follows:

the plugging agent suitable for fractured reservoirs comprises a main agent, a cross-linking agent, a curing agent, a reinforcing agent and water; the composition comprises, by mass, 0.1 to 1.0% of a main agent, 0.1 to 2% of a crosslinking agent, 0.1 to 1.0% of a curing agent, 0.1 to 1% of a reinforcing agent, and the balance of water.

The plugging agent suitable for fractured reservoirs is described above, wherein the main agent is polyacrylamide; the cross-linking agent is a phenolic cross-linking agent which is a phenolic resin pre-condensation polymer; the curing agent is sodium bisulfite or sodium thiosulfate; the reinforcing agent is nano silicon dioxide; the water is tap water.

The plugging agent suitable for the fractured reservoir has the following advantages: the plugging agent is continuous gel; forming a high-strength plugging agent through a crosslinking reaction of a polymer and a crosslinking agent; the plugging agent has controllable gelling speed (50-120 hours), high and adjustable strength (2-9 ten thousand mPa.s) and strong shearing resistance, can establish effective plugging in the stratum and is effective for a long time.

Detailed Description

In order to better understand the purpose, structure and function of the invention, the plugging agent suitable for fractured reservoirs of the invention is further described in detail.

Example (b):

weighing 0.5g of polyacrylamide, 1g of phenolic resin pre-condensation polymer, 0.5g of sodium bisulfite, 1g of nano silicon dioxide and 97 g of tap water, stirring uniformly, heating to 60 ℃ for reaction, and reacting for 60 hours to obtain the finished product of the plugging agent.

The prepared plugging agent is injected into a stratum with a storage space and a percolation channel of a storage layer mainly being cracks through equipment such as an injection pump and the like, and the gel can be formed after the reaction for 5 to 10 days under the stratum condition, so that the stratum is plugged.

The invention is suitable for evaluating the performance of the plugging agent of the fractured reservoir:

1. gelling experiment (gelling time and strength)

Weighing main agents, cross-linking agents, curing agents and reinforcing agents in different proportions, adding the main agents, the cross-linking agents, the curing agents and the reinforcing agents in different proportions into tap water, sampling after preparing the plugging agents in different proportions, placing a sample in a high-temperature environment at 80 ℃, measuring the viscosity of the sample by adopting a viscosity meter, testing the viscosity once every 3 hours, determining the gelling time, the initial gelling strength and the highest strength of the sample, and obtaining results shown in table 1.

Table 1 shows the gelling time and strength of the plugging agent samples with different proportions

The results of the experiments in table 1 show that the gelling time of the samples in different proportions is over 99 hours, the smooth injection of the system can be effectively ensured, the highest strength is over 2.5 ten thousand mPa · S, the strength can be controlled by adjusting the formula, and the method has high adaptability.

2. Temperature resistance test

Three different formulas of plugging agents were selected, aged at 60 ℃, 70 ℃, 80 ℃ and 90 ℃ for 90 days, the viscosity of the formula after aging for 90 days was measured, the viscosity retention was calculated, and the results are shown in table 2.

TABLE 2 viscosity Retention at different temperatures for samples of different ratios

As can be seen from the experimental data in Table 2, after the samples in different proportions are aged for 90 days at different temperatures, the viscosity retention rate gradually decreases along with the increase of the temperature; with the reduction of the polymer in the formula, the viscosity retention rate is reduced, and the minimum value is more than 78%, which shows that the system can effectively ensure the stability at different temperatures.

3. Shear test

3 plugging agents with different formulas are selected, a shearing instrument is adopted to respectively shear for 2 minutes, 3 minutes, 4 minutes and 5 minutes, the gelling time and the highest strength of each sample are tested, and the obtained results are shown in table 3.

TABLE 3 shear test of plugging agent samples of different proportions

Watch with watch³The experimental data show that the gelling time of the plugging agent samples with different proportions is prolonged to different degrees after the plugging agent samples are sheared to different degrees, the gelling strength is not changed greatly, and the plugging agent has high viscosity retention rate and shear resistance, so that the performance of the product under the stratum condition can be effectively ensured.

The content that is not described in this embodiment is the prior art, and therefore, the description thereof is omitted.

The plugging agent suitable for the fractured reservoir, disclosed by the invention, has the characteristics that the polyacrylamide adopted as a main agent is in an emulsion state, the initial viscosity is low, and the effective injection in the application process can be ensured; in addition, the polyacrylamide has the characteristics of high strength and long stable period, and can effectively ensure the use effect.

The cross-linking agent is an oligomeric polyphenol cross-linking agent formed by polymerization reaction of various phenols, aldehydes and amines, has a plurality of active hydroxymethyl groups and amino groups, and can react with polyacrylamide at 60-150 ℃ to form gel. The gel has adjustable strength, adjustable gel forming time, delayed gel forming at high temperature, good gel stability, high chemical bond C-N bond energy of the cross-linking agent and the polymer through covalent bonds, so that the cross-linking agent is not easy to break when heated and has strong thermal stability, and meanwhile, a structural unit 'benzene ring' with large volume and large rigid group is introduced on the cross-linking agent, thereby improving the temperature resistance and salt resistance of the gel.

It is to be understood that the present invention has been described with reference to certain embodiments, and that various changes in the features and embodiments, or equivalent substitutions may be made therein by those skilled in the art without departing from the spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

1. The plugging agent suitable for fractured reservoirs is characterized by comprising a main agent, a cross-linking agent, a curing agent, a reinforcing agent and water; the composition comprises, by mass, 0.1 to 1.0% of a main agent, 0.1 to 2% of a crosslinking agent, 0.1 to 1.0% of a curing agent, 0.1 to 1% of a reinforcing agent, and the balance of water.

2. The plugging agent suitable for fractured reservoirs according to claim 1, wherein the main agent is polyacrylamide; the cross-linking agent is a phenolic cross-linking agent which is a phenolic resin pre-condensation polymer; the curing agent is sodium bisulfite or sodium thiosulfate; the reinforcing agent is nano silicon dioxide; the water is tap water.