Preparation method of plugging agent

Abstract

The invention relates to a preparation method of a profile control and water shutoff agent, and belongs to the technical field of profile control and water shutoff of oil fields. The preparation method of the plugging agent comprises the following steps: providing a mixture mainly composed of a modified inorganic reinforcing agent, a polymer monomer, a cross-linking agent and water, adjusting the pH value of the mixture to 5.5-7.0, and adding an initiator to carry out a cross-linking polymerization reaction; the modified inorganic reinforcing agent is obtained by modifying an inorganic reinforcing agent with a vinyl silane coupling agent; the inorganic reinforcing agent is one or two of silicon dioxide, oil well cement and bentonite; the polymer monomer is one or any combination of sodium allysulfonate, 2-acrylamido-2-methylpropanesulfonic acid, sodium p-styrenesulfonate and acrylamide. According to the preparation method, the surface of an inorganic reinforcing agent modified by a vinyl silane coupling agent is modified into carbon-carbon double bonds, and the carbon-carbon double bonds, a polymer monomer and a cross-linking agent are subjected to a cross-linking polymerization reaction under the action of an initiator, so that the organic-inorganic integrated three-dimensional net-shaped high-strength plugging agent is generated.

Description

Technical Field

[0001] The invention relates to a method for preparing a plugging control agent, and belongs to the technical field of oilfield profile control and water plugging. Background Art

[0002] At present, most of the domestic oilfield water drive development has entered the (very) high water content development period, (very) large pores and high permeability layer strips have been produced, and the contradictions between layers and layers have been further aggravated, which seriously restricts the effect of water drive development. Profile control and water plugging technology can change the direction of liquid flow by plugging the high water consumption layer section of the reservoir, thereby expanding the water drive swept volume and improving the recovery rate of water drive reservoirs. There are two main types of commonly used plugging agents, one is cross-linked polymer gel, and the other is polymer gel particles.

[0003] Cross-linked polymer gel plugging agents are mostly made of polyacrylamide polymers and cross-linking agents that react to form gel under conditions such as formation temperature and mineralization to form plugging agents. Cross-linked polymer gel plugging agents have a common defect: since the cross-linked polymer monomers are easily affected by shear, adsorption, degradation, dilution and other factors, there are problems such as difficulty in gelling or poor gel strength and stability, which seriously affect the plugging effect of the cross-linked polymer gel.

[0004] Another type of ground-polymerized gel particle plugging agent overcomes the problem that underground cross-linked polymer gel is difficult to gel or has poor gel strength. Because of its viscoelasticity, water absorption and expansion properties, it is a plugging agent widely used in oilfield profile control and water plugging technology. Most of the gel particle plugging agents commonly used in oil fields are gel particle plugging agents prepared on the ground by high molecular polymers such as polyacrylamide, or functional plugging agents prepared by molecular structure improvement and introduction of additives based on acrylamide as the basic monomer. For example, the Chinese patent with the authorization announcement number CN112390907B discloses a gel particle flooding agent, which is based on acrylamide monomers and adds a rare earth tracer containing carbon-carbon double bonds. The gel particle flooding agent is intended to determine the failure time of flooding and the distribution direction of large pores between flooding well groups, but the plugging strength is limited for high water consumption layers and dominant seepage channels in medium and high permeability reservoirs.

[0005] Among the gel particle plugging agents, some plugging agents add fibers or inorganic fillers such as inorganic nanoparticles, bentonite and other materials to increase the toughness or strength of the plugging agents. For example, the heat-resistant and salt-resistant high-toughness profile control agent disclosed in the Chinese patent application with application publication number CN114409847A is wrapped with basalt fibers, glass fibers and other toughening agents in the process of synthesizing polymers from acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, N,N,-dimethyloctadecylallylammonium chloride and diethylene glycol divinyl ether. The profile control agent has good heat and salt resistance. However, fibers, inorganic fillers such as inorganic nanoparticles, bentonite and other materials are basically physical fillings, and are simply coated with organic polymers, which are easy to precipitate. The plugging agent has an insignificant enhanced compressive resistance effect, is not resistant to subsequent injection water scouring, and the plugging measures have a short validity period. Summary of the invention

[0006] The purpose of the present invention is to provide a method for preparing a plugging agent which can significantly improve the strength of the plugging agent, so as to solve the problems that the existing plugging agents have low plugging strength, are not resistant to injection water scouring, and have a short effective period in plugging large pores, especially in high water consumption layers of medium and high permeability oil reservoirs.

[0007] In order to achieve the above objectives, the technical solution adopted by the preparation method of the plugging agent of the present invention is:

[0008] A preparation method of a plugging agent comprises the following steps: providing a mixture mainly composed of a modified inorganic reinforcing agent, a polymer monomer, a crosslinking agent and water, adjusting the pH of the mixture to 5.5-7.0, and then adding an initiator to carry out a crosslinking polymerization reaction at 30-50°C; the modified inorganic reinforcing agent is obtained by modifying an inorganic reinforcing agent with a vinyl silane coupling agent; the inorganic reinforcing agent is one or two of silicon dioxide, oil well cement and bentonite; the polymer monomer is one or any combination of sodium allyl sulfonate, 2-acrylamido-2-methylpropane sulfonic acid, sodium styrene sulfonate and acrylamide; and the mass ratio of the modified inorganic reinforcing agent to the polymer monomer is 10-30:13-32.

[0009] The preparation method of the plugging agent of the present invention utilizes the surface modification of the inorganic reinforcing agent modified by the vinyl silane coupling agent to contain carbon-carbon double bonds, and crosslinks and polymerizes with the polymer monomer and the crosslinking agent under the action of the initiator to generate an organic-inorganic integrated three-dimensional network high-strength plugging agent. The plugging agent not only has the water absorption and expansion properties of organic matter, and can deform and pass through the pore throat of the formation under certain pressure difference conditions, but also has the heat resistance and salt resistance and high-strength plugging properties of inorganic materials.

[0010] The preparation method of the plugging agent of the present invention has mild reaction conditions, can react at 30℃-50℃, is easy to operate, and can increase the strength of the plugging agent and its heat resistance and salt resistance by adjusting the addition ratio of the modified inorganic reinforcing agent. The heat resistance is 90℃ and the salt resistance is 25×10 4 mg / L.

[0011] Furthermore, the cross-linking polymerization reaction time is 1.5 to 2.5 hours, for example, 2 hours.

[0012] Further, the inorganic reinforcing agent is silica and oil well cement, and the mass ratio of silica to oil well cement is 8:6.8-7.2; or the inorganic reinforcing agent is oil well cement and bentonite, and the mass ratio of oil well cement to bentonite is 0.8-1.2:1. The oil well cement is preferably G-grade oil well oil water, for example, G-grade ultrafine oil well cement; further, 700-mesh G-grade ultrafine oil well cement can be used. The polymer monomer is a combination of sodium styrene sulfonate and acrylamide, and the mass ratio of sodium styrene sulfonate to acrylamide is 15:4-6, for example, 15:5; or the polymer monomer is a combination of sodium styrene sulfonate and sodium allyl sulfonate, and the mass ratio of sodium styrene sulfonate to sodium allyl sulfonate is 15:2.5-3.5, for example, 15:3. Furthermore, the modified inorganic reinforcing agent is prepared by a method comprising the following steps: the inorganic reinforcing agent is stirred and soaked in a vinyl silane coupling agent dispersion at 30-40° C. for 2-4 hours, and the solid-liquid separation is followed by drying. The vinyl silane coupling agent solution is formed by dispersing the vinyl silane coupling agent in an alcohol solvent; the volume ratio of the vinyl silane coupling agent to the alcohol solvent is 1:2-5. The mass ratio of the vinyl silane coupling agent to the inorganic reinforcing agent is 1:5-15.

[0013] Furthermore, the silane coupling agent is vinyltrialkoxysilane and / or vinyltrialkylsilane; the vinyltrialkoxysilane is vinyltrimethoxysilane and / or vinyltriethoxysilane; the vinyltrialkylsilane is vinyltrimethylsilane.

[0014] Furthermore, the mass ratio of the modified inorganic reinforcing agent to the polymerized monomer is 15-30:13-32.

[0015] Further, the crosslinking agent is one or two of N,N'-methylenebisacrylamide and N-hydroxymethylacrylamide. For example, the crosslinking agent is a combination of N,N'-methylenebisacrylamide and N-hydroxymethylacrylamide, and the mass ratio of N,N'-methylenebisacrylamide to N-hydroxymethylacrylamide is 0.05-0.15:0.03-0.07.

[0016] Furthermore, the mass ratio of the crosslinking agent to the polymer monomer is 0.07-0.18:13-32. For example, the mass ratio of the crosslinking agent to the polymer monomer is 0.12-0.18:18-20.

[0017] Furthermore, the initiator is a redox initiator, and the mass ratio of the initiator to the polymer monomer is 0.03-0.15:13-32. For example, the mass ratio of the initiator to the polymer monomer is 0.09-0.15:18-20.

[0018] Furthermore, the oxidant in the redox initiator is ammonium persulfate and / or potassium persulfate, and the reducing agent is sodium bisulfite. For example, the oxidant is ammonium persulfate, the reducing agent is sodium bisulfite, and the mass ratio of the oxidant to the reducing agent is 0.04-0.10:0.05.

[0019] The cross-linking polymerization reaction produces a plugging agent block. Furthermore, the method for preparing the plugging agent further comprises the following steps: granulating the plugging agent block produced by the cross-linking polymerization reaction.

[0020] Furthermore, the total weight of the polymer monomer, the crosslinking agent, the initiator and water is 100 parts; the weight of the polymer monomer is 13 to 32 parts, for example, 18 to 20 parts.

[0021] The plugging agent prepared by the preparation method of the plugging agent of the present invention not only has the high-strength pressure-bearing plugging performance of inorganic materials, but also has the water-absorbing and swelling performance of organic polymers, and can be deformed through the pore throat of the formation under a certain pressure difference condition, plugging the large pores of the formation, especially the high water consumption layer section of the medium-high permeability oil reservoir, and can be placed in a reasonable position of the formation as a high-strength plugging section, thereby improving the anti-scouring performance of the plugging system and extending the effective period of the plugging measures. The problem of low strength, poor injection scouring resistance and short effective period of conventional plugging agents is solved. DETAILED DESCRIPTION

[0022] The technical solution of the present invention is further described below in conjunction with specific implementation methods.

[0023] The oil well cement used in the examples is API standard G-grade ultrafine oil well cement (700 meshes), purchased from Puyang Hongda Chemical General Plant.

[0024] Example 1

[0025] The preparation method of the plugging agent of this embodiment comprises the following steps:

[0026] 1) placing 20 g of an inorganic reinforcing agent (including 10 g of silicon dioxide and 10 g of bentonite) in a mixing container with a stirring device, and then adding a modified treatment liquid (mixed with vinyl triethoxysilane and ethanol in a volume ratio of 1:3, wherein the mass of vinyl triethoxysilane is 4 g), stirring at 32° C. for 2 h to fully modify the silicon dioxide and bentonite, and then filtering and drying the solid to obtain a modified inorganic reinforcing agent;

[0027] 2) 20 g of the prepared modified inorganic reinforcing agent, 22 g of polymer monomer (including 12 g of sodium allyl sulfonate and 10 g of 2-acrylamido-2-methylpropane sulfonic acid), 0.11 g of a cross-linking agent (specifically N,N'-methylenebisacrylamide), and 57.74 g of pure water were added to a mixing container with a stirring device, the pH value was adjusted to 6.5 with a reaction regulator sodium carbonate, and a redox initiator (including 0.08 g of potassium persulfate and 0.07 g of sodium bisulfite) was added under stirring conditions, and the obtained mixture was subjected to cross-linking polymerization reaction at a temperature of 30° C. for 2 h to obtain a heat-resistant high-strength plugging agent block, and the obtained heat-resistant high-strength plugging agent block was granulated and sieved into heat-resistant high-strength plugging agents of different particle sizes.

[0028] Example 2

[0029] The preparation method of the plugging agent of this embodiment comprises the following steps:

[0030] 1) 5 g of silica and 5 g of oil well cement are placed in a mixing container with a stirring device, and then a modified treatment liquid (vinyl trimethoxysilane and ethanol are mixed in a volume ratio of 1:2, wherein the mass of vinyl trimethoxysilane is 2 g) is added, and stirred at 30° C. for 3 h to fully modify the silica and the oil well cement, and then filtered and dried to obtain a modified inorganic reinforcing agent;

[0031] 2) Add 10 g of modified inorganic reinforcing agent, 7 g of sodium styrene sulfonate, 8 g of 2-acrylamido-2-methylpropane sulfonic acid, 0.09 g of N-hydroxymethyl acrylamide and 74.86 g of pure water into a mixing container with a stirring device, adjust the pH value to 7.0 with a reaction regulator sodium carbonate, add 0.02 g of potassium persulfate and 0.03 g of sodium bisulfite under stirring conditions, and cross-link and polymerize the obtained mixture at a temperature of 35° C. for 2 h to obtain a heat-resistant high-strength plugging agent block, and granulate and sieve the obtained heat-resistant high-strength plugging agent blocks into heat-resistant high-strength plugging agents of different particle sizes.

[0032] Embodiments 3 to 7

[0033] The inorganic reinforcing agent and its mass, the composition of the modified treatment liquid and the stirring temperature used in step 1) of Examples 3-7, the polymer monomer and its mass, the mass of the modified inorganic reinforcing agent, the cross-linking agent and its mass, the pH value adjusted with the reaction regulator sodium carbonate, the initiator and its mass, the temperature of the cross-linked polymer reaction and the mass of water used in step 2) are shown in Table 1. The contents not mentioned are exactly the same as those in Example 1.

[0034] Table 1 Examples 3 to 7

[0035]

[0036]

[0037] Comparative Example 1

[0038] The plugging and regulating agent of this comparative example is a gel particle plugging and regulating agent prepared according to the preparation method of the gel particle plugging and regulating agent of Example 7 of the Chinese patent with authorization announcement number CN112390907B.

[0039] Comparative Example 2

[0040] The plugging control agent of this comparative example is a heat-resistant, salt-resistant, high-toughness granular profile control agent prepared according to the preparation method of the heat-resistant, salt-resistant, high-toughness profile control agent of Example 1 of the Chinese invention patent application with application publication number CN114409847A.

[0041] Experimental example

[0042] The strength, water absorption expansion multiple and elastic modulus after water absorption of the plugging agents prepared in Examples 1 to 7 and Comparative Examples 1 to 2 were tested respectively. The test results are shown in Table 2. The test method is as follows:

[0043] (1) Strength measurement

[0044] The heat-resistant high-strength plugging agent block is made into a size of 2cm×2cm×2cm, and is compressed at a speed of 0.5mm / min on a compression testing machine. The strength when it is compressed by 10mm is measured, which indicates the strength of the heat-resistant high-strength plugging agent block itself;

[0045] (2) Determination of water absorption expansion ratio

[0046] Weigh 2g to 3g of the sample of the granulated and screened plugging agent (accurate to 0.001g) and place it in a 100mL stoppered heat-resistant glass test tube. Add 25×10 4 mg / L (including Ca 2+ +Mg 2+=5000mg / L) standard brine 90mL, seal it and put it in an oven, heat it at 90℃, take it out every 24h, filter it with a Buchner funnel and weigh it to test its water absorption expansion multiple. Select the maximum mass (m max ) is the maximum expansion multiple.

[0047] R=m2 / m1

[0048] R——Expansion multiple of the sample after absorbing water;

[0049] m1——sample mass, in grams (g);

[0050] m2 – the mass of the sample after absorbing liquid, in grams (g).

[0051] (3) Determination of elastic modulus after water absorption

[0052] For the mineralization degree of 25×10 4 mg / L (including Ca 2+ +Mg 2+ =5000mg / L) standard brine for 24h, and use RS150 rheometer, select the rotor, and choose the oscillation shear measurement mode to measure its elastic modulus value under 0.136Hz and stress of (1.5-2.5)Pa, which is the elastic modulus of the plugging agent after water absorption and expansion.

[0053] Table 2 Test results

[0054]

[0055]

[0056] The expansion properties of the plugging agents prepared in Examples 1 to 7 and Comparative Examples 1 to 2 are shown in Table 3.

[0057] Table 3 Expansion performance data of the plugging agents prepared in Examples 1 to 7 and Comparative Examples 1 to 2

[0058]

[0059] It can be seen from Table 2 that compared with Comparative Examples 1 and 2, the heat-resistant high-strength plugging agent prepared by the present invention has a high 4 It has reasonable expansion performance under the condition of mg / L, and has high pressure bearing strength before and after water absorption. It can be used for high water consumption layers in medium and high permeability reservoirs and high-strength plugging of dominant seepage channels, and can withstand subsequent injection water erosion, and the effective period of profile control is extended.

Claims

1. A method for preparing a plugging agent, characterized in that: The following steps are involved: A mixture mainly consisting of a modified inorganic reinforcing agent, a polymer monomer, a crosslinking agent and water is provided, the pH value of the mixture is adjusted to 5.5-7.0, and then an initiator is added to carry out a crosslinking polymerization reaction at 30-50°C; the modified inorganic reinforcing agent is obtained by modifying an inorganic reinforcing agent with a vinyl silane coupling agent; the inorganic reinforcing agent is one or two of silicon dioxide, oil well cement and bentonite; the polymer monomer is one or any combination of sodium allyl sulfonate, 2-acrylamido-2-methylpropane sulfonic acid, sodium styrene sulfonate and acrylamide; and the mass ratio of the modified inorganic reinforcing agent to the polymer monomer is 10-30:13-32.

2. The method for preparing the plugging agent according to claim 1, characterized in that: The inorganic reinforcing agent is silicon dioxide and oil well cement, and the mass ratio of silicon dioxide to oil well cement is 8:6.8-7.2; or the inorganic reinforcing agent is oil well cement and bentonite, and the mass ratio of oil well cement to bentonite is 0.8-1.2:

1.

3. The method for preparing the plugging agent according to claim 1, characterized in that: The modified inorganic reinforcing agent is prepared by a method comprising the following steps: the inorganic reinforcing agent is stirred and soaked in a vinyl silane coupling agent dispersion at 30-40° C. for 2-4 hours, and then dried after solid-liquid separation.

4. The method for preparing the plugging agent according to claim 1, 2 or 3, characterized in that: The mass ratio of the vinyl silane coupling agent to the inorganic reinforcing agent is 1:5-15.

5. The method for preparing the plugging agent according to claim 1, 2 or 3, characterized in that: The silane coupling agent is vinyl trialkoxysilane and / or vinyl trialkylsilane; the vinyl trialkoxysilane is vinyl trimethoxysilane and / or vinyl triethoxysilane; the vinyl trialkylsilane is vinyl trimethylsilane.

6. The method for preparing the plugging agent according to claim 1, characterized in that: The cross-linking agent is one or both of N,N'-methylenebisacrylamide and N-hydroxymethylacrylamide.

7. The method for preparing the plugging agent according to claim 1 or 6, characterized in that: The mass ratio of the crosslinking agent to the polymer monomer is 0.07-0.18:13-32.

8. The method for preparing the plugging agent according to claim 1, 2 or 3, characterized in that: The initiator is a redox initiator, and the mass ratio of the initiator to the polymer monomer is 0.03-0.15:13-32.

9. The method for preparing the plugging agent according to claim 8, characterized in that: The oxidizing agent in the redox initiator is ammonium persulfate and / or potassium persulfate, and the reducing agent is sodium bisulfite.

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