CN118126692A - Marine medium-low temperature oil reservoir sea water-based nonmetallic ion quick crosslinking gel and preparation method thereof - Google Patents

Abstract

The invention discloses a marine medium-low temperature oil reservoir marine water-based nonmetallic ion quick crosslinking gel and a preparation method thereof. The gel comprises the following raw materials in percentage by mass: 0.3 to 0.6 percent of salt-tolerant polymer, 0.3 to 0.8 percent of cross-linking agent, 0.3 to 0.6 percent of gel promoter, 0 to 0.2 percent of pH regulator and the balance of seawater or simulated seawater which is close to the mineralization degree of the seawater. The invention provides a marine medium-low temperature oil reservoir marine water-based nonmetallic ion quick crosslinking gel system, which solves the problems of slow low-temperature gel forming time, low gel forming strength or non-gel forming in a conventional nonmetallic ion system. The gel system is suitable for oil reservoirs with the temperature of 50-70 ℃ and the mineralization degree of 3 multiplied by 10 ⁴ mg/L, the gel forming time is controllable, the gel forming strength is adjustable, the long-term stability under the condition of medium and low temperature is good, the core plugging rate reaches more than 95%, and the plugging adjustment requirement of the sea water filling medium and low temperature oil reservoir is met.

Description

Marine medium-low temperature oil reservoir sea water-based nonmetallic ion quick crosslinking gel and preparation method thereof

Technical Field

The invention relates to the technical field of oilfield chemistry, in particular to a marine water-based nonmetal ion quick crosslinking gel for an offshore medium-low temperature oil reservoir and a preparation method thereof.

Background

With the continuous development of offshore oilfield water flooding, the problems of injection water injection, poor water flooding effect and the like of all large oilfields are caused by the addition of the reasons of strong reservoir heterogeneity, large oil-water viscosity ratio and the like. Profile control and water shutoff are effective techniques to solve this problem. Most of the sand prevention of the screen pipes in offshore oil fields causes that most of the particle plugging agents cannot be used, and the gel is used as a main agent system in the profile control and water plugging technology at present, so that the gel is applied to various offshore oil fields and achieves obvious oil and water increasing and reducing effects.

From the application type of the gel, the phenolic aldehyde crosslinked gel system for the medium-high temperature oil reservoir with the temperature of more than 70 ℃ is mature, and the gel has been applied in oil fields in large scale. Aiming at a low-temperature oil reservoir below 50 ℃, the Chinese patent application with publication number CN103980872A provides an environment-friendly gel plugging agent suitable for the low-temperature oil reservoir, wherein the plugging agent consists of 0.2 to 0.6 percent of amphoteric polyacrylamide, 0.5 to 2.0 percent of organic zirconium cross-linking agent and the balance of water, and the gel plugging agent is used for deep water plugging construction of the low-temperature oil reservoir at 25 to 35 ℃. The Chinese patent application with publication number of CN1896176A proposes a low-temperature oil layer blasthole plugging agent which is a granular plugging agent and consists of micro-fibers of ultra-high molecular polypropylene, superfine expansive cement, tricalcium silicate, active microcrystal reinforcing agent and yellow tannin. The plugging agent has high density, poor injectability and poor sieving pipe performance, is only suitable for plugging blastholes, and is not suitable for deep plugging operation of sand control wells of screen pipes of offshore oil fields. The Chinese patent application with publication number of CN102304354A provides a low-temperature deep gel profile control water shutoff agent and a preparation method thereof, wherein the profile control water shutoff agent consists of a polymeric flocculant, a dicyandiamide modified urea formaldehyde resin delayed crosslinking agent, industrial sodium carbonate, m-aminophenol and water, and is suitable for oil reservoirs at 20-50 ℃. The Chinese patent application with publication number of CN86108877A provides a zirconium gel water shutoff agent which consists of polyacrylamide or methylene polyacrylamide and inorganic zirconium, and has short construction time (within 4 h) and high construction risk. The Chinese patent application with publication number CN113136185A proposes an organic water shutoff gel for low-temperature high-mineralization oil reservoir, and the gel shutoff agent consists of anionic polyacrylamide, phenolic resin, an accelerator, a regulator and thiourea, and is suitable for oil reservoir at 40-50 ℃.

However, for the middle-low temperature section of 50-70 ℃, especially for the middle-low temperature oil reservoir filled with seawater, no mature gel system exists at present. Therefore, for the seawater injection oil reservoir at 50-70 ℃, a quick crosslinking gel system suitable for the offshore medium-low temperature seawater injection oil reservoir is urgently needed.

Disclosure of Invention

The invention aims to solve the technical problems and provides a marine medium-low temperature oil reservoir marine water-based nonmetallic ion quick crosslinking gel and a preparation method thereof.

In a first aspect, the invention provides a marine medium-low temperature oil reservoir marine water-based nonmetallic ion quick-crosslinking gel, which is realized by adopting the following technical scheme.

The marine medium-low temperature oil reservoir marine water-based nonmetallic ion quick crosslinking gel comprises the following raw materials in percentage by mass: 0.3 to 0.6 percent of salt-tolerant polymer, 0.3 to 0.8 percent of cross-linking agent, 0.3 to 0.6 percent of gel promoter, 0 to 0.2 percent of pH regulator and the balance of seawater or simulated seawater which is close to the mineralization degree of the seawater.

Furthermore, the salt-tolerant polymer is an AMPS copolymer, and the effective content is 40%.

Furthermore, the cross-linking agent is a nano reinforced phenolic prepolymer composite cross-linking agent.

Furthermore, the gel accelerator is an amine gel accelerator.

Furthermore, the amine type gel accelerator is one or a combination of more of ethylenediamine, triethanolamine and hexamethylenetetramine.

Further, the pH regulator is weak acid pH regulator.

Further, the weak acid pH regulator is one or a combination of more of silicic acid, acetic acid and bicarbonate.

By adopting the technical scheme, the gel provided by the application consists of a salt-tolerant polymer, a cross-linking agent, a gel promoter, a pH regulator and seawater or simulated seawater with the mineralization degree close to that of the seawater, and the components react to form a three-dimensional network-shaped cross-linked structure, so that the system structure strength is high. Salt-tolerant polymers belong to AMPS copolymer polymers, contain 40% of AMPS groups and can enhance the salt tolerance of the polymers; the cross-linking agent is a nano reinforced phenolic prepolymer composite cross-linking agent, contains phenolic hydroxyl groups, and can perform cross-linking with amide groups of polyacrylamide to form a three-dimensional network structure; the gel accelerator is an amine gel accelerator, and consists of one or more of ethylenediamine, triethanolamine or hexamethylenetetramine, so that the gel forming reaction can be promoted; the pH regulator is weak acid pH regulator, and consists of one or several kinds of silicic acid, acetic acid or bicarbonate, and the pH value of the polymer cross-linking solution is regulated to reach optimal reaction condition.

In a second aspect, the invention provides a preparation method of a marine water-based nonmetallic ion quick-crosslinking gel for an offshore medium-low temperature oil reservoir, which is realized by adopting the following technical scheme.

The preparation method of the marine water-based nonmetallic ion quick crosslinking gel for the marine medium-low temperature oil reservoir comprises the following steps:

S1, weighing a specified amount of seawater or simulated seawater with the mineralization degree close to that of the seawater, and stirring at the rotating speed of 300-500 rpm;

S2, weighing a specified amount of salt-resistant polymer, adding the salt-resistant polymer into the sea water stirred in the step S1 or the simulated sea water with the mineralization degree close to that of the sea water, and keeping stirring for 1-1.5 h to completely cure the sea water;

s3, continuously adding a prescribed amount of cross-linking agent, a gel promoting agent and a pH regulator in sequence under the stirring condition;

S4, after all the components are stirred and dissolved, placing the mixture at the oil reservoir temperature to carry out crosslinking reaction for 10-72 h, so as to form the gel.

Further, the reservoir temperature is 50-70 ℃.

The application has the following beneficial effects.

(1) The marine medium-low temperature oil reservoir water-based nonmetallic ion quick crosslinking gel system is suitable for oil reservoirs with the temperature of 50-70 ℃ and the mineralization degree of 3 multiplied by 10 ⁴ mg/L, can block large pore canals of stratum, improves the heterogeneity of stratum, and further improves the development effect of water-driven oil reservoirs;

(2) The viscosity of the working solution before gel formation is 80 mPas-500 mPas, the viscosity is larger, the starting pressure in the middle-low permeable layer is high, so that the gel can enter stratum large pore canals preferentially, a non-flowing high-strength gel system is formed under the condition of an oil reservoir, the large pore canals are blocked, the subsequent injected water is turned to enter the middle-low permeable layer, and the development effect of a water displacement reservoir is further effectively improved;

(3) The gel of the invention has the advantages of gel forming time of 10-72 h, controllable gel forming time, adjustable gel forming strength of 50000-150000 mPa.s, good long-term stability under medium and low temperature conditions, and core plugging rate of more than 95%, and meets the plugging adjustment requirement of a low-temperature oil reservoir in sea water injection.

Detailed Description

The present application is further illustrated below with reference to examples.

The experimental methods used in the following preparation examples and examples are conventional methods unless otherwise specified; materials, reagents and the like used in the following preparation examples and examples are commercially available unless otherwise specified.

AMPS copolymer in the following examples of the present application was purchased from the eastern City, severe polymerization chemical Co., ltd., model SL-1;

the nano reinforced phenolic prepolymer composite cross-linking agent in the following examples of the application is purchased from victory oilfield victory chemical industry Limited company, model SG-3.

Example 1

Adding 0.3gAMPS copolymer slowly and uniformly into 99.1g of seawater under stirring, adding 0.3g of nano reinforced phenolic prepolymer composite cross-linking agent, 0.3g of hexamethylenetetramine and 0g of acetic acid into the polymer solution under stirring after stirring for 1h, and continuing stirring to make the mixture uniform to form a cross-linked polymer working solution with the viscosity of 345 Pa.s. The gel system comprises, by mass, 0.3% of AMPS copolymer, 0.3% of nano reinforced phenolic prepolymer composite cross-linking agent, 0.3% of hexamethylenetetramine, 0% of acetic acid and 99.1% of seawater, wherein the gel system has a gel forming time of 72 hours at 50 ℃ and the gel strength is 52145 mPa.s.

Example 2

Adding 0.4gAMPS copolymer slowly and uniformly into 98.75g of seawater under stirring, stirring for 1h, sequentially adding 0.4g of nano reinforced phenolic prepolymer composite cross-linking agent, 0.4g of hexamethylenetetramine and 0.05g of acetic acid into the polymer solution under stirring, and continuing stirring to uniformly obtain a cross-linked polymer working solution with the viscosity of 491mPa.s. The composition of the gel system comprises, by mass, 0.4% of AMPS copolymer, 0.4% of nano reinforced phenolic prepolymer composite cross-linking agent, 0.4% of hexamethylenetetramine, 0.05% of acetic acid and 98.75% of seawater, and the gel system has a gel forming time of 60 hours at 50 ℃ to form gel with a strength of 78654 mPa.s.

Example 3

Adding 0.5gAMPS copolymer slowly and uniformly into 98.3g of seawater under stirring, stirring for 1h, sequentially adding 0.6g of nano reinforced phenolic prepolymer composite cross-linking agent, 0.5g of hexamethylenetetramine and 0.1g of acetic acid into the polymer solution under stirring, and continuing stirring to uniformly obtain a cross-linked polymer working solution with the viscosity of 604mPa.s. The composition of the gel system comprises, by mass, 0.5% of AMPS copolymer, 0.6% of nano reinforced phenolic prepolymer composite cross-linking agent, 0.5% of hexamethylenetetramine, 0.1% of acetic acid and 98.3% of seawater, and the gel system has a gel forming time of 60 hours at 50 ℃ to form gel with a strength of 102544 mPa.s.

Example 4

Slowly and uniformly adding 0.6gAMPS copolymer into 97.8g of seawater under stirring, stirring for 1h, sequentially adding 0.8g of nano reinforced phenolic prepolymer composite cross-linking agent, 0.6g of hexamethylenetetramine and 0.2g of acetic acid into the polymer solution under stirring, and continuously stirring to uniformly form a cross-linked polymer working solution with the viscosity of 798mPa.s. The composition of the gel system comprises, by mass, 0.6% of AMPS copolymer, 0.8% of nano reinforced phenolic prepolymer composite cross-linking agent, 0.6% of hexamethylenetetramine, 0.2% of acetic acid and 97.8% of seawater, wherein the gel system has a gel forming time of 55h at 50 ℃ and the gel strength is 140250 mPa.s.

Example 5

Adding 0.3gAMPS copolymer slowly and uniformly into 99.1g of seawater under stirring, adding 0.3g of nano reinforced phenolic prepolymer composite cross-linking agent, 0.3g of hexamethylenetetramine and 0g of acetic acid into the polymer solution under stirring after stirring for 1h, and continuing stirring to make the mixture uniform to form a cross-linked polymer working solution with the viscosity of 345 Pa.s. The gel system comprises, by mass, 0.3% of AMPS copolymer, 0.3% of nano reinforced phenolic prepolymer composite cross-linking agent, 0.3% of hexamethylenetetramine, 0% of acetic acid and 99.1% of seawater, and the gel time is 64h at 60 ℃ to form gel with the strength of 68447 mPa.s.

Example 6

Adding 0.4gAMPS copolymer slowly and uniformly into 98.75g of seawater under stirring, stirring for 1h, sequentially adding 0.4g of nano reinforced phenolic prepolymer composite cross-linking agent, 0.4g of hexamethylenetetramine and 0.05g of acetic acid into the polymer solution under stirring, and continuing stirring to uniformly obtain a cross-linked polymer working solution with the viscosity of 491mPa.s. The composition of the gel system comprises, by mass, 0.4% of AMPS copolymer, 0.4% of nano reinforced phenolic prepolymer composite cross-linking agent, 0.4% of hexamethylenetetramine, 0.05% of acetic acid and 98.75% of seawater, and the gel system has a gel forming time of 48 hours at 60 ℃ to form gel with a strength of 80559 mPa.s.

Example 7

Adding 0.5gAMPS copolymer slowly and uniformly into 98.3g of seawater under stirring, stirring for 1h, sequentially adding 0.6g of nano reinforced phenolic prepolymer composite cross-linking agent, 0.5g of hexamethylenetetramine and 0.1g of acetic acid into the polymer solution under stirring, and continuing stirring to uniformly obtain a cross-linked polymer working solution with the viscosity of 604mPa.s. The composition of the gel system comprises, by mass, 0.5% of AMPS copolymer, 0.6% of nano reinforced phenolic prepolymer composite cross-linking agent, 0.5% of hexamethylenetetramine, 0.1% of acetic acid and 98.3% of seawater, and the gel system has a gel forming time of 46h at 60 ℃ to form gel with a strength of 114223 mPa.s.

Example 8

Slowly and uniformly adding 0.6gAMPS copolymer into 97.8g of seawater under stirring, stirring for 1h, sequentially adding 0.8g of nano reinforced phenolic prepolymer composite cross-linking agent, 0.6g of hexamethylenetetramine and 0.2g of acetic acid into the polymer solution under stirring, and continuously stirring to uniformly form a cross-linked polymer working solution with the viscosity of 798mPa.s. The composition of the gel system comprises, by mass, 0.6% of AMPS copolymer, 0.8% of nano reinforced phenolic prepolymer composite cross-linking agent, 0.6% of hexamethylenetetramine, 0.2% of acetic acid and 97.8% of seawater, and the gel system has a gel forming time of 40 hours at 60 ℃ to form gel with a strength of 145217 mPa.s.

Example 9

Adding 0.3gAMPS copolymer slowly and uniformly into 99.1g of seawater under stirring, adding 0.3g of nano reinforced phenolic prepolymer composite cross-linking agent, 0.3g of hexamethylenetetramine and 0g of acetic acid into the polymer solution under stirring after stirring for 1h, and continuing stirring to make the mixture uniform to form a cross-linked polymer working solution with the viscosity of 345 Pa.s. The gel system comprises, by mass, 0.3% of AMPS copolymer, 0.3% of nano reinforced phenolic prepolymer composite cross-linking agent, 0.3% of hexamethylenetetramine, 0% of acetic acid and 99.1% of seawater, wherein the gel system has a gel forming time of 24 hours at 70 ℃ and the gel strength is 81226 mPa.s.

Example 10

Adding 0.4gAMPS copolymer slowly and uniformly into 98.75g of seawater under stirring, stirring for 1h, sequentially adding 0.4g of nano reinforced phenolic prepolymer composite cross-linking agent, 0.4g of hexamethylenetetramine and 0.05g of acetic acid into the polymer solution under stirring, and continuing stirring to uniformly obtain a cross-linked polymer working solution with the viscosity of 491mPa.s. The composition of the gel system comprises, by mass, 0.4% of AMPS copolymer, 0.4% of nano reinforced phenolic prepolymer composite cross-linking agent, 0.4% of hexamethylenetetramine, 0.05% of acetic acid and 98.75% of seawater, and the gel system has a gel forming time of 18 hours at 70 ℃ to form gel with a strength of 92331 mPa.s.

Example 11

Adding 0.5gAMPS copolymer slowly and uniformly into 98.3g of seawater under stirring, stirring for 1h, sequentially adding 0.6g of nano reinforced phenolic prepolymer composite cross-linking agent, 0.5g of hexamethylenetetramine and 0.1g of acetic acid into the polymer solution under stirring, and continuing stirring to uniformly obtain a cross-linked polymer working solution with the viscosity of 604mPa.s. The composition of the gel system comprises, by mass, 0.5% of AMPS copolymer, 0.6% of nano reinforced phenolic prepolymer composite cross-linking agent, 0.5% of hexamethylenetetramine, 0.1% of acetic acid and 98.3% of seawater, and the gel system has a gel forming time of 12 hours at 70 ℃ to form gel with a strength of 120110 mPa.s.

Example 12

Slowly and uniformly adding 0.6gAMPS copolymer into 97.8g of seawater under stirring, stirring for 1h, sequentially adding 0.8g of nano reinforced phenolic prepolymer composite cross-linking agent, 0.6g of hexamethylenetetramine and 0.2g of acetic acid into the polymer solution under stirring, and continuously stirring to uniformly form a cross-linked polymer working solution with the viscosity of 798mPa.s. The composition of the gel system comprises, by mass, 0.6% of AMPS copolymer, 0.8% of nano reinforced phenolic prepolymer composite cross-linking agent, 0.6% of hexamethylenetetramine, 0.2% of acetic acid and 97.8% of seawater, and the gel system has a gel forming time of 10 hours at 70 ℃ to form gel with a strength of 149954 mPa.s.

Example 13

Adding 0.5gAMPS copolymer slowly and uniformly into 98.3g of seawater under stirring, stirring for 1h, sequentially adding 0.6g of nano reinforced phenolic prepolymer composite cross-linking agent, 0.5g of hexamethylenetetramine and 0.1g of acetic acid into the polymer solution under stirring, continuously stirring to uniformly form a cross-linked polymer working solution, placing the cross-linked polymer working solution in an incubator at different temperatures, continuously taking out periodically after the cross-linked polymer working solution is gelled, and observing dehydration conditions of the cross-linked polymer working solution. The dehydration rate formula is η=v ₂/V₁ ×100%, wherein V ₁ is the volume of the gel, V ₂ is the dehydration volume of the gel, and the volumes are all measured at room temperature. The results are shown in Table 1. The invention shows that the marine medium-low temperature oil reservoir sea water-based nonmetallic ion quick crosslinking gel system has better long-term stability.

TABLE 1 long term stability of gels

Two artificial cores, namely 1# and 2# are taken, water is respectively driven to pressure stability, the permeability k ₁ before blocking is measured, then the crosslinked polymer working solution in the example 13 of 0.3V _p (core pore volume) is reversely injected, a sand filling pipe is sealed, the sand filling pipe is placed in a baking oven at 60 ℃, water is driven to pressure stability again after gel formation, the permeability k ₂ after blocking of the core is measured, and the core blocking rate is calculated according to the formula F= (k ₁-k₂)/k₁ multiplied by 100%, and the result is shown in Table 2.

TABLE 2 blocking Properties of gels

Artificial core	Permeability before plugging mD	Permeability after plugging mD	Plugging rate%
				1#	1521	43	97.17
2#	3569	164	95.40

The experimental results show that: the marine medium-low temperature oil reservoir marine water-based nonmetallic ion quick crosslinking gel system has good plugging performance, and can effectively plug a stratum high permeable layer, so that the sweep efficiency is improved, and the purpose of improving the water flooding development effect is achieved.

The embodiments of the present invention are all preferred embodiments of the present invention, and are not intended to limit the scope of the present invention in this way, therefore: all equivalent changes in structure, shape and principle of the invention should be covered in the scope of protection of the invention.

Claims (9)

1. The marine medium-low temperature oil reservoir marine water-based nonmetallic ion quick crosslinking gel is characterized in that: comprises the following raw materials in percentage by mass: 0.3 to 0.6 percent of salt-tolerant polymer, 0.3 to 0.8 percent of cross-linking agent, 0.3 to 0.6 percent of gel promoter, 0 to 0.2 percent of pH regulator and the balance of seawater or simulated seawater which is close to the mineralization degree of the seawater.

2. The marine medium and low temperature oil reservoir marine base nonmetallic ion rapid crosslinking gel as claimed in claim 1, wherein: the salt-tolerant polymer is AMPS copolymer.

3. The marine medium and low temperature oil reservoir marine base nonmetallic ion rapid crosslinking gel as claimed in claim 1, wherein: the cross-linking agent is a nano reinforced phenolic prepolymer composite cross-linking agent.

4. The marine medium and low temperature oil reservoir marine base nonmetallic ion rapid crosslinking gel as claimed in claim 1, wherein: the gel promoter is an amine gel promoter.

5. The marine medium and low temperature oil reservoir marine base nonmetallic ion quick crosslinking gel as claimed in claim 4, wherein: the amine type gel accelerator is one or a combination of more of ethylenediamine, triethanolamine and hexamethylenetetramine.

6. The marine medium and low temperature oil reservoir marine base nonmetallic ion rapid crosslinking gel as claimed in claim 1, wherein: the pH regulator is weak acid pH regulator.

7. The marine medium and low temperature oil reservoir marine base nonmetallic ion quick crosslinking gel as claimed in claim 6, wherein: the weak acid pH regulator is one or several of silicic acid, acetic acid and bicarbonate.

8. A method for preparing the marine water-based nonmetallic ion quick-crosslinking gel of the marine medium-low temperature oil reservoir according to any one of claims 1-6, which is characterized in that: the method comprises the following steps:

S1, weighing a specified amount of seawater or simulated seawater with the mineralization degree close to that of the seawater, and stirring at the rotating speed of 300-500 rpm;

S2, weighing a specified amount of salt-resistant polymer, adding the salt-resistant polymer into the sea water stirred in the step S1 or the simulated sea water with the mineralization degree close to that of the sea water, and keeping stirring for 1-1.5 h to completely cure the sea water;

s3, continuously adding a prescribed amount of cross-linking agent, a gel promoting agent and a pH regulator in sequence under the stirring condition;

S4, after all the components are stirred and dissolved, placing the mixture at the oil reservoir temperature to carry out crosslinking reaction for 10-72 h, so as to form the gel.

9. The method for preparing the marine medium-low temperature oil reservoir marine water-based nonmetallic ion quick-crosslinking gel according to claim 8, which is characterized by comprising the following steps: the reservoir temperature is 50-70 ℃.