Liquid rubber dilution-resistant support plugging W / O emulsion plugging agent as well as preparation method and application thereof

Abstract

The invention provides a liquid rubber dilution-resistant support plugging W / O emulsion plugging agent as well as a preparation method and application thereof, and belongs to the technical field of profile control and water plugging of high-temperature and high-salinity oil reservoirs. The liquid rubber dilution-resistant support plugging W / O emulsion plugging agent is prepared from the following raw materials in parts by mass: liquid rubber, an oily solvent, 30 to 45 parts of formation water, 1 to 3 parts of a calcium and magnesium ion complexing agent, 2 to 10 parts of a polymer type surfactant and 0.165 to 0.66 part of a high-temperature initiator, the total amount of the liquid rubber and the oily solvent is 55-70 parts. The emulsion plugging agent provided by the invention is used for profile control and water plugging of high-temperature and high-salt oil reservoirs so as to improve the water flooding sweep efficiency and further improve the oil reservoir recovery efficiency. The emulsion plugging agent has excellent water washing resistance, can resist the temperature of 150 DEG C and the salt of 22 * 10 < 4 > mg / L after being emulsified and gelatinized in a simulated high-temperature and high-salt oil reservoir environment, has good W / O emulsion stability at high temperature, and has controllable gelatinizing time.

Description

Technical Field

[0001] The invention relates to the technical field of profile control and water plugging in high-temperature and high-salinity oil reservoirs, and in particular to a liquid rubber dilution-resistant W / O emulsion plugging agent and a preparation method and application thereof. Background Art

[0002] As the oil field enters the high water content development period, due to the formation heterogeneity, the long-term scouring of the injected water to form large channels, etc., the dominant channel of the injected water is formed in the formation, resulting in the occurrence of cone, crossflow, and fingering, which seriously affects the water injection sweep coefficient and the economic benefits of oil field development. Water plugging and profile control technology is one of the main technical means to improve the effect of water injection development and achieve water control and oil stabilization. With the deepening of oil and gas field development, the water drive problem in oil fields is becoming more and more complicated. The plugging and regulating in the near-well area cannot fundamentally solve the problem of low water drive volume sweep coefficient. The research and development trend of plugging agents is gradually developing towards deep migration. It is required that the plugging agent can prolong the gelling time under high temperature and high mineralization conditions, and can be deeply migrated. The performance after gelling is stable for a long time, thereby improving the recovery rate of oil and gas fields.

[0003] However, the cross-linking reaction time of various conventional profile control and water plugging agents in high-temperature and high-salinity reservoirs is difficult to control, and the gelling time of conventional free radical polymerization reactions is too fast to meet the profile control and water plugging requirements of deep reservoirs. Cross-linked polymer gel is currently the most widely used water plugging and profile control system, but the use temperature of the reservoir is relatively narrow. The applicable temperature range of resin plugging agents is 60-100°C. The process flow of this type of plugging agent is complicated and the material cost is relatively high. The matrix of oil-based plugging agents is usually composed of oily substances (such as hydrocarbons, fatty acid esters, etc.), which are immiscible with water. Therefore, they can exist stably in the oil phase and be isolated from water after being injected into the reservoir to reduce water penetration. However, the cost of oil-based plugging agents is high, and the initial viscosity of the gelling liquid is high, which makes injection difficult. In order to control the viscosity and gelling time of the plugging agent, ensure the blocking of the high-permeability water flow channel in the high-temperature and high-salinity reservoir, control the invalid circulation, and improve the reservoir recovery rate has become a research hotspot. Among them, W / O emulsion polymer is formed by mixing and stirring the oil phase, water phase and emulsifier, and the outer phase is oil and the inner phase is water. It has a certain initial viscosity, which can ensure that it will not be washed away by formation water during injection. At the same time, the emulsion system reduces the cost of the oil-based system. However, the high-temperature and high-salt oil reservoir environment has extremely high requirements for the stability of the emulsion. Based on this, it is urgent to develop an emulsion plugging system with excellent properties such as high stability, controllable gelation time, temperature and salt resistance, low cost and water erosion resistance in high-temperature and high-salt oil reservoirs. Summary of the invention

[0004] In view of this, the present invention aims to provide a liquid rubber dilution-resistant W / O emulsion plugging agent and its preparation method and application. The liquid rubber dilution-resistant W / O emulsion plugging agent provided by the present invention is used for high-temperature and high-salinity oil reservoir profile control and water plugging to improve water drive sweep efficiency, thereby improving oil reservoir recovery and achieving the purpose of stabilizing oil production and increasing oil fields. The emulsion plugging agent has excellent water scouring resistance. After emulsification into gel in a simulated high-temperature and high-salinity oil reservoir environment, it can withstand temperatures of 150°C and salts of 22×10 4 mg / L, the W / O emulsion has good stability at high temperature, and the gelling time of the emulsion plugging agent is controllable. The raw materials of the emulsion water plugging agent are easy to obtain, the preparation process is simple and efficient, the cost is properly controlled, it can meet the construction requirements of the oil field site, and has good practicality and economy.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] One of the technical solutions of the present invention is a liquid rubber dilution-resistant plugging W / O emulsion plugging agent, which comprises, by weight, raw materials: liquid rubber, oily solvent, 30-45 parts of formation water, 1-3 parts of calcium and magnesium ion complexing agent, 1-10 parts of polymer surfactant and 0.165-0.66 parts of high-temperature initiator; the liquid rubber and the oily solvent account for 55-70 parts in total, wherein the liquid rubber accounts for 45%-55% of the total mass of the liquid rubber and the oily solvent.

[0007] The second technical solution of the present invention is a method for preparing the above-mentioned liquid rubber dilution-resistant W / O emulsion plugging agent, comprising the following steps:

[0008] Mixing the liquid rubber and the oily solvent uniformly to obtain an oil phase;

[0009] dissolving a calcium and magnesium ion complexing agent in formation water to obtain a water phase;

[0010] Adding a polymer surfactant to the oil phase, mixing evenly, adding the water phase under stirring, mixing evenly, to obtain a mixed solution;

[0011] The high temperature initiator is uniformly dispersed in the mixed solution to obtain the liquid rubber dilution-resistant plugging W / O emulsion plugging agent.

[0012] A third technical solution of the present invention is an application of the above-mentioned liquid rubber dilution-resistant W / O emulsion plugging agent in fixed-point water plugging in deep layers of high-temperature and high-salinity oil reservoirs.

[0013] A fourth technical solution of the present invention is a method for fixed-point water plugging in deep layers of a high-temperature and high-salinity oil reservoir, which comprises injecting the above-mentioned liquid rubber dilution-resistant plugging W / O emulsion plugging agent into the high-temperature and high-salinity oil reservoir.

[0014] The present invention discloses the following technical effects:

[0015] The present invention adds a calcium and magnesium ion complexing agent so that the calcium and magnesium ions contained in the water phase can be complexed with the added calcium and magnesium ion complexing agent to form nanoparticle precipitation, which plays a role similar to Pickering emulsification. The nanoparticles are adsorbed at the oil-water two-phase interface through electrostatic action, hydrogen bonding, etc. to form a mechanical barrier, which has the effect of stabilizing the emulsion. The synergistic effect of the two makes the liquid rubber dilution-resistant plugging emulsion system have excellent stability in the high-temperature and high-salt oil reservoir environment.

[0016] The liquid rubber dilution-resistant plugging emulsion system provided by the present invention has the advantages of good injectability, excellent water scouring resistance, good stability of the emulsion system in a high-temperature and high-salt environment, controllable gelation time, high gel mechanical strength and low cost, and has broad application prospects in profile control and water plugging in high-temperature and high-salt oil reservoirs. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 The morphology of the liquid rubber dilution-resistant plugging W / O emulsion plugging agent with different addition amounts of Arlacel P135 in Example 1 before (a) and after (b) gel reaction in a simulated reservoir environment;

[0019] Figure 2 This is the FTIR image of the emulsion gel obtained by the liquid rubber dilution-resistant plugging W / O emulsion plugging agent in Example 6 when simulating the reservoir environment;

[0020] Figure 3 The graphs are the rheological properties test graphs of the emulsion gel obtained by the liquid rubber dilution-resistant plugging W / O emulsion plugging agent in Example 6 in a simulated reservoir environment, wherein (a) is a strain sweep (0.1% to 1000%), and (b) is a frequency sweep (0.1 to 15 Hz);

[0021] Figure 4 The water dilution resistance test diagram of the liquid rubber dilution-resistant W / O emulsion plugging agent in Example 6, wherein (a) is a drop of liquid rubber dilution-resistant W / O emulsion plugging agent dripped into formation water, (b) is a glass bottle filled with part of formation water and part of liquid rubber dilution-resistant W / O emulsion plugging agent, and (c) is the liquid rubber dilution-resistant W / O emulsion plugging agent after gelling;

[0022] Figure 5The morphology of the emulsion gel formed by the liquid rubber dilution-resistant plugging W / O emulsion plugging agent in Examples 4, 5 and 6 in a simulated reservoir environment is shown before the plugging agent reacts (a), after the reaction (b) and at 1.0 wt% addition (c);

[0023] Figure 6 It is the Sydansk gel strength code method;

[0024] Figure 7 Schematic diagram of the cross-linking mechanism of liquid rubber dilution-resistant W / O emulsion plugging agent. DETAILED DESCRIPTION

[0025] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0026] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0027] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0028] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0029] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0030] The mass fractions described in the following embodiments may be grams, kilograms, tons or other mass units.

[0031] The first aspect of the present invention provides a liquid rubber dilution-resistant plugging W / O emulsion plugging agent, which comprises, by weight, liquid rubber, an oily solvent, 30-45 parts of formation water, 1-3 parts of a calcium and magnesium ion complexing agent, 1-10 parts of a polymer surfactant, and 0.165-0.66 parts of a high-temperature initiator; the liquid rubber and the oily solvent account for 55-70 parts in total, wherein the liquid rubber accounts for 45%-55% of the total weight of the liquid rubber and the oily solvent.

[0032] In the present invention, the liquid rubber is liquid polybutadiene; the oily solvent is kerosene and / or 3# white oil, preferably 3# white oil.

[0033] Formation water is also called oil layer water, which refers to the edge water and bottom water at the edge and bottom of the oil reservoir, interlayer water, and bound water in the same layer as crude oil. In the present invention, in order to simulate the composition of formation water, laboratory preparation was carried out. The content composition of simulated formation water is shown in Table 1.

[0034] Table 1 Content composition of simulated formation water

[0035]

[0036] In some embodiments of the present invention, the calcium and magnesium ion complexing agent is sodium bicarbonate, sodium oxalate, sodium citrate, sodium aluminate or sodium hydroxide.

[0037] In some embodiments of the present invention, the polymer surfactant is polyethylene glycol (30) dipolyhydroxystearate (Arlacel P135), polyether polyol or Span80, preferably Arlacel P135.

[0038] In some embodiments of the present invention, the high temperature initiator is tert-butyl hydroperoxide, cumene hydroperoxide, di-tert-butyl peroxide or tert-butyl perbenzoate, preferably tert-butyl perbenzoate.

[0039] The two large-volume long chains of the polymer surfactant used in the present invention form a three-dimensional space structure that is not easy to rotate at the emulsion interface, and are irreversibly adsorbed at the oil-water interface to form a strong and highly elastic interface film; the addition of a calcium and magnesium ion complexing agent can cause complexation with calcium and magnesium ions in formation water to generate solid particles that are adsorbed at the oil-water interface to form a strong physical barrier to maintain the stability of the emulsion. The synergistic effect of the polymer surfactant and the solid particles makes the liquid rubber W / O emulsion have excellent stability in high-temperature and high-salinity oil reservoirs, and can effectively block the water outlet area.

[0040] The second aspect of the present invention provides a method for preparing the above-mentioned liquid rubber dilution-resistant W / O emulsion plugging agent, comprising the following steps:

[0041] Mixing the liquid rubber and the oily solvent uniformly to obtain an oil phase;

[0042] dissolving a calcium and magnesium ion complexing agent in formation water to obtain a water phase;

[0043] Adding a polymer surfactant to the oil phase, mixing evenly, adding the water phase under stirring, mixing evenly, to obtain a mixed solution;

[0044] The high temperature initiator is uniformly dispersed in the mixed solution to obtain the liquid rubber dilution-resistant plugging W / O emulsion plugging agent.

[0045] The present invention does not impose any particular limitation on the manner of uniform mixing, dissolving and dispersing, and any technical means well known to those skilled in the art may be used, such as stirring.

[0046] A third aspect of the present invention provides an application of the above-mentioned liquid rubber dilution-resistant W / O emulsion plugging agent in fixed-point water plugging in deep layers of high-temperature and high-salinity oil reservoirs.

[0047] A fourth aspect of the present invention provides a method for deep-layer fixed-point water plugging in a high-temperature, high-salinity oil reservoir, wherein the above-mentioned liquid rubber dilution-resistant plugging W / O emulsion plugging agent is injected into the high-temperature, high-salinity oil reservoir.

[0048] After the liquid rubber dilution-resistant W / O emulsion plugging agent (i.e., plugging agent) is injected into a high-temperature and high-salt oil reservoir, the plugging agent gradually migrates to the deep part, becomes gelled in the high-temperature and high-pressure environment deep in the oil reservoir, and completes the profile control and water plugging of the deep oil reservoir.

[0049] The technical solutions described in the present invention, unless otherwise specified, are all conventional solutions in the art, and the reagents or raw materials used, unless otherwise specified, are purchased from commercial channels or have been disclosed.

[0050] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with the embodiments, but the content of the present invention is not limited to the following embodiments.

[0051] The formation water in the examples is laboratory simulated formation water, and the content composition of the simulated formation water is shown in Table 1.

[0052] Example 1

[0053] The preparation method of the liquid rubber dilution-resistant W / O emulsion plugging agent provided in this embodiment comprises the following steps:

[0054] (1) Weigh 30 parts of liquid polybutadiene and 30 parts of 3# white oil, stir them on a magnetic stirrer for 15 minutes to mix them evenly, and obtain an oil phase;

[0055] (2) Weigh 40 parts of formation water, then add 1.2 parts of NaOH to the formation water, and stir for 15 minutes to allow the NaOH to fully dissolve in the formation water to obtain an aqueous phase;

[0056] (3) Add Arlacel P135 (the amount of Arlacel P135 is 1.2 parts, 2.4 parts, 3.6 parts, 4.8 parts, and 6 parts, respectively) to the oil phase prepared in step (1), and stir for 15 minutes to fully mix it with the oil phase. Then, add the above-prepared water phase under stirring, and stir with a magnetic stirrer for 30 minutes to fully mix it to obtain a mixed solution;

[0057] (4) 0.6 parts of tert-butyl perbenzoate are dispersed in the mixed solution obtained in step (3) to obtain a liquid rubber dilution-resistant W / O emulsion plugging agent (hereinafter referred to as the plugging agent).

[0058] The performance of the plugging agent was tested by simulating the environment in which the plugging agent is actually applied to the reservoir. The plugging agent was placed in a high-temperature and high-pressure reactor and pressurized to 2.0 MPa with nitrogen to prevent the water phase from evaporating at high temperature. The agent was then reacted in a 150°C forced air drying oven at the simulated reservoir temperature for 8 hours. The emulsion gel formed before and after the reaction was as follows: Figure 1 (In the figure, 2wt% means that the amount of Arlacel P135 is 1.2 parts, and the mass ratio of Arlacel P135 to the oil phase is 2wt%, 4wt% means that the amount of Arlacel P135 is 2.4 parts, and the mass ratio of Arlacel P135 to the oil phase is 4wt%, 6wt% means that the amount of Arlacel P135 is 3.6 parts, and the mass ratio of Arlacel P135 to the oil phase is 6wt%, 8wt% means that the amount of Arlacel P135 is 4.8 parts, and the mass ratio of Arlacel P135 to the oil phase is 8wt%, and 10wt% means that the amount of Arlacel P135 is 6.0 parts, and the mass ratio of Arlacel P135 to the oil phase is 10wt%). It can be seen that the strength grade of the emulsion gel after gelation at a high temperature of 150°C is all grade I.

[0059] Example 2

[0060] The preparation method of the liquid rubber dilution-resistant W / O emulsion plugging agent provided in this embodiment comprises the following steps:

[0061] (1) Weigh 27 parts of liquid polybutadiene and 33 parts of 3# white oil, stir on a magnetic stirrer for 15 minutes to mix the two evenly, and obtain an oil phase;

[0062] (2) Weigh 40 parts of formation water, then add 1.2 parts of NaOH to the formation water, and stir for 15 minutes to allow the NaOH to fully dissolve in the formation water to obtain an aqueous phase;

[0063] (3) Add 3.6 parts of Arlacel P135 (i.e., Arlacel P135 accounts for 6% of the mass of the oil phase) to the oil phase prepared in step (1), and stir for 15 minutes to fully mix with the oil phase. Then, add the above-prepared water phase under stirring, and stir with a magnetic stirrer for 30 minutes to fully mix, to obtain a mixed solution;

[0064] (4) 0.405 parts of tert-butyl perbenzoate are dispersed in the mixed solution obtained in step (3) to obtain a liquid rubber dilution-resistant W / O emulsion plugging agent (hereinafter referred to as the plugging agent).

[0065] The performance of the plugging agent was tested by simulating the environment in which the plugging agent is actually applied to the reservoir. The plugging agent was placed in a high-temperature and high-pressure reactor and pressurized to 2.0 MPa with nitrogen to prevent the water phase from evaporating at high temperature. The agent was then reacted in a 150°C forced air drying oven at the simulated reservoir temperature for 8 hours. The strength grade of the emulsion gel formed after gelation at a high temperature of 150°C was all Grade I.

[0066] Example 3

[0067] The preparation method of the liquid rubber dilution-resistant W / O emulsion plugging agent provided in this embodiment comprises the following steps:

[0068] (1) Weigh 33 parts of liquid polybutadiene and 27 parts of 3# white oil, stir on a magnetic stirrer for 15 minutes to mix the two evenly, and obtain an oil phase;

[0069] (2) Weigh 40 parts of formation water, then add 1.2 parts of NaOH to the formation water, and stir for 15 minutes to allow the NaOH to fully dissolve in the formation water to obtain an aqueous phase;

[0070] (3) Add 3.6 parts of Arlacel P135 (i.e., Arlacel P135 accounts for 6% of the mass of the oil phase) to the oil phase prepared in step (1), and stir for 15 minutes to fully mix with the oil phase. Then, add the above-prepared water phase under stirring, and stir with a magnetic stirrer for 30 minutes to fully mix, to obtain a mixed solution;

[0071] (4) 0.495 parts of tert-butyl perbenzoate are dispersed in the mixed solution obtained in step (3) to obtain a liquid rubber dilution-resistant W / O emulsion plugging agent (hereinafter referred to as the plugging agent).

[0072] The performance of the plugging agent was tested by simulating the environment in which the plugging agent is actually applied to the reservoir. The plugging agent was placed in a high-temperature and high-pressure reactor and pressurized to 2.0 MPa with nitrogen to prevent the water phase from evaporating at high temperature. The agent was then reacted in a 150°C forced air drying oven at the simulated reservoir temperature for 8 hours. The strength grade of the emulsion gel formed after gelation at a high temperature of 150°C was all Grade I.

[0073] Example 4

[0074] The preparation method of the liquid rubber dilution-resistant W / O emulsion plugging agent provided in this embodiment comprises the following steps:

[0075] (1) Weigh 27.5 parts of liquid polybutadiene and 27.5 parts of 3# white oil, stir on a magnetic stirrer for 15 minutes to mix the two evenly, and obtain an oil phase;

[0076] (2) Weigh 45 parts of formation water, then add 1.35 parts of NaOH to the formation water, and stir for 15 minutes to allow the NaOH to fully dissolve in the formation water to obtain an aqueous phase;

[0077] (3) Add 3.3 parts of Arlacel P135 (i.e., Arlacel P135 accounts for 6% of the mass of the oil phase) to the oil phase prepared in step (1), and stir for 15 minutes to fully mix with the oil phase. Then, add the above-prepared water phase under stirring, and stir with a magnetic stirrer for 30 minutes to fully mix, to obtain a mixed solution;

[0078] (4) 0.1375 parts of tert-butyl peroxybenzoate are dispersed in the mixed solution obtained in step (3) to obtain a liquid rubber dilution-resistant W / O emulsion plugging agent (hereinafter referred to as the plugging agent). The amount of the high-temperature initiator used in this embodiment is lower than that of the comparative example of 0.165-0.66 parts.

[0079] The performance of the plugging agent was tested by simulating the environment in which the plugging agent is actually applied to the reservoir. The plugging agent was placed in a high-temperature and high-pressure reactor, and nitrogen was pressurized to 2.0 MPa to prevent the water phase from evaporating at high temperature. Then the agent was reacted in a 150°C forced air drying oven at the simulated reservoir temperature. After being placed at 150°C for 15 hours, no gelation occurred. This indicates that if the amount of high-temperature initiator is too small, the resulting emulsion plugging agent is difficult to react at high temperature.

[0080] Example 5

[0081] Same as Example 4, except that 0.275 parts of tert-butyl perbenzoate is added in step (4).

[0082] The performance of the plugging agent was tested by simulating the environment in which the plugging agent is actually applied in the reservoir. The plugging agent was placed in a high-temperature and high-pressure reactor and pressurized to 2.0 MPa with nitrogen to prevent the water phase from evaporating at high temperature. The agent was then reacted in a 150°C forced air drying oven at the simulated reservoir temperature for 13 hours. The strength grade of the emulsion gel formed after gelation at high temperature of 150°C was all Grade I.

[0083] Example 6

[0084] Same as Example 4, except that 0.4125 parts of tert-butyl perbenzoate are added in step (4).

[0085] The performance of the plugging agent was tested by simulating the environment in which the plugging agent is actually applied to the reservoir. The plugging agent was placed in a high-temperature and high-pressure reactor and pressurized to 2.0 MPa with nitrogen to prevent the water phase from evaporating at high temperature. The agent was then reacted in a 150°C forced air drying oven at the simulated reservoir temperature for 8 hours. The strength grade of the emulsion gel formed after gelation at a high temperature of 150°C was all Grade I.

[0086] The plugging agent obtained in this example was subjected to infrared characterization test ( Figure 2 ) and rheological properties tests ( Figure 3 ), and its water erosion resistance was evaluated. Figure 4 As shown. The rheological test results show that the elastic modulus (G′) of the formed emulsion gel is about 2000Pa, and the viscous modulus (G″) is about 260Pa, which shows that the plugging agent has excellent mechanical properties. This property enables the gel to effectively seal the cracks in the formation. In this way, it can improve the fluid conductivity efficiency during oil and gas production, thereby improving the recovery rate. In the evaluation of water dilution resistance, it can be found that after a drop of emulsion is dropped into the formation water, it can remain stable for a long time without demulsification. After pouring part of the formation water and part of the emulsion into the glass bottle, the emulsion remained uniform and there was no demulsification after gelation, indicating that the emulsion system has excellent water dilution resistance.

[0087] Depend on Figure 5 (In the figure, wt% is calculated from the mass ratio of tert-butyl perbenzoate and liquid polybutadiene, 0.5wt% represents Example 4, 1wt% represents Example 5, and 1.5wt% represents Example 6) It can be seen that the gelation time is different depending on the amount of high-temperature initiator used. The present invention can control the gelation time by controlling the amount of high-temperature initiator used.

[0088] Example 7

[0089] The same as Example 2, the only difference is that the polymer surfactant added to the oil phase is 3.6 parts of polyether polyol. The prepared liquid rubber dilution-resistant W / O emulsion plugging agent reacts at a high temperature of 150°C for 8 hours in a gelling experiment in a simulated reservoir environment. The emulsion gel formed after gelling shows partial demulsification, and the emulsion gel strength after gelling is H grade.

[0090] Example 8

[0091] The same as Example 2, the only difference is that the polymer surfactant added to the oil phase is 3.6 parts of Span 80. In the gelling experiment of the prepared liquid rubber dilution-resistant W / O emulsion plugging agent in the simulated reservoir environment, the emulsion gel formed after gelling showed partial demulsification phenomenon, and the emulsion gel strength after gelling was G grade.

[0092] It can be seen from Examples 2, 7 and 8 that the stability of Arlacel P135 emulsifier at high temperature is better than that of polyether polyol and Span80. Arlacel P135 has stronger thermal stability and anti-demulsification ability at high temperature and is more suitable for use in high-temperature and high-salinity oil reservoirs. All gel strengths in the present invention are evaluated by the Sydansk gel strength code method, such as Figure 6 The schematic diagram of the cross-linking mechanism of the liquid rubber dilution-resistant W / O emulsion plugging agent is shown in Figure 7 shown.

[0093] In summary, the preparation process of the liquid rubber dilution-resistant W / O emulsion plugging agent of the present invention is simpler, the cost is low, the gelling time is controllable under high temperature and high salt, it has excellent water dilution resistance and stability, and can effectively improve the water flooding sweep efficiency, thereby improving the oil reservoir recovery rate.

[0094] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A liquid rubber dilution-resistant W / O emulsion plugging agent, characterized in that: The raw materials include, by weight: liquid rubber, oily solvent, 30-45 parts of formation water, 1-3 parts of calcium and magnesium ion complexing agent, 1-10 parts of polymer surfactant and 0.165-0.66 parts of high-temperature initiator; the liquid rubber and oily solvent account for 55-70 parts in total, of which the liquid rubber accounts for 45%-55% of the total weight of the liquid rubber and the oily solvent.

2. The liquid rubber dilution-resistant W / O emulsion plugging agent according to claim 1, characterized in that: The liquid rubber is liquid polybutadiene; the oily solvent is kerosene and / or 3# white oil.

3. The liquid rubber dilution-resistant W / O emulsion plugging agent according to claim 1, characterized in that: The calcium and magnesium ion complexing agent is sodium bicarbonate, sodium oxalate, sodium citrate, sodium aluminate or sodium hydroxide.

4. The liquid rubber dilution-resistant W / O emulsion plugging agent according to claim 1, characterized in that: The polymer surfactant is polyethylene glycol (30) dipolyhydroxystearate, polyether polyol or Span80.

5. The liquid rubber dilution-resistant W / O emulsion plugging agent according to claim 1, characterized in that: The high temperature initiator is tert-butyl hydroperoxide, cumene hydroperoxide, di-tert-butyl peroxide or tert-butyl perbenzoate.

6. A method for preparing the liquid rubber dilution-resistant W / O emulsion plugging agent according to any one of claims 1 to 5, characterized in that: The following steps are involved: Mixing the liquid rubber and the oily solvent uniformly to obtain an oil phase; dissolving a calcium and magnesium ion complexing agent in formation water to obtain a water phase; Adding a polymer surfactant to the oil phase, mixing evenly, adding the water phase under stirring, mixing evenly, to obtain a mixed solution; The high temperature initiator is uniformly dispersed in the mixed solution to obtain the liquid rubber dilution-resistant plugging W / O emulsion plugging agent.

7. Use of the liquid rubber dilution-resistant W / O emulsion plugging agent according to any one of claims 1 to 5 in deep-layer fixed-point water plugging in high-temperature and high-salinity oil reservoirs.

8. A method for fixed-point water plugging in deep layers of high-temperature and high-salinity oil reservoirs, characterized in that: The liquid rubber dilution-resistant plugging W / O emulsion plugging agent according to any one of claims 1 to 5 is injected into a high-temperature and high-salt oil reservoir.

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