阅读说明：本技术 一种化学干预原位乳化体系 (Chemical intervention in-situ emulsification system ) 是由 杜代军 蒲万芬 邹滨阳 鹿嘉悦 刘锐 于 2021-07-15 设计创作，主要内容包括：本发明公开了一种化学干预原位乳化体系,以重量比计,该乳化体系由以下原料组成：0.1％～0.3％的CO-2响应性单体,0.1％～0.3％的表面活性剂,0.01％～0.1％的亲水纳米材料,余量为水,其中,表面活性剂为阴离子表面活性剂或阴-非离子表面活性剂,纳米材料为鳞片石墨粉、氧化石墨烯、亲水性二氧化硅、亲水性碳纳米管中的一种或者多种的混合物。本发明的化学干预乳化体系能够适用于稠油油藏和稀油油藏,同时将其粘度调节至适中的程度,使其粘度不至于过小,也不至于过大,能够用于非均质油藏。同时本发明在于原油形成乳液后,无需加入其它破乳剂,仅需通入N-2气体,即能够实现快速破乳脱水。(The invention discloses a chemical intervention in-situ emulsification system, which comprises the following raw materials in percentage by weight: 0.1 to 0.3 percent of CO 2 The polymer comprises a responsive monomer, 0.1-0.3% of surfactant, 0.01-0.1% of hydrophilic nano material and the balance of water, wherein the surfactant is anionic surfactant or anionic-nonionic surfactant, and the nano material is one or a mixture of more of crystalline flake graphite powder, graphene oxide, hydrophilic silicon dioxide and hydrophilic carbon nano tubes. The chemical intervention emulsification system can be suitable for heavy oil reservoirs and thin oil reservoirs, and is suitable for heavy oil reservoirs and thin oil reservoirsThe viscosity of the oil is adjusted to a moderate degree, so that the viscosity of the oil is not too small or too large, and the oil can be used for heterogeneous oil reservoirs. Meanwhile, after the crude oil forms the emulsion, other demulsifiers do not need to be added, and only N needs to be introduced 2 Gas, namely, the rapid demulsification and dehydration can be realized.)

1. A chemical intervention in-situ emulsification system is characterized by comprising the following raw materials in percentage by weight:

CO₂responsive monomer: 0.1 to 0.3 percent of,

surfactant (b): 0.1 to 0.3 percent of,

hydrophilic nano-materials: 0.01 to 0.1 percent of,

the balance of water;

mixing the above raw materials, introducing CO₂Make CO₂The response monomer is protonated to obtain the compound.

2. The emulsification system of claim 1, wherein the CO is present₂The responsive monomer is one of oleic acid amide propyl dimethyl tertiary amine, N, N-dimethyl cyclohexane-1, 4-diamine, 7- (oxygen-10-dimethylamino-decyl) -coumarin and N-dodecyl polyoxyethylene ether-N, N-dimethyl tertiary amine, wherein the polymerization degree of polyoxyethylene ether in the N-dodecyl polyoxyethylene ether-N, N-dimethyl tertiary amine is 7-20.

3. The emulsification system of claim 1, wherein the surfactant is an anionic surfactant or an anionic-nonionic surfactant.

4. The emulsifying system according to claim 3, wherein the anionic or anionic-nonionic surfactant is: one of sodium alkylphenol polyoxyethylene ether carboxylate, sodium alkyl alcohol polyoxyethylene ether carboxylate, sodium alkylphenol polyoxyethylene ether sulfonate, sodium alkyl alcohol polyoxyethylene ether sulfonate, sodium p-methyl benzene sulfonate, sodium petroleum sulfonate, sodium dodecyl sulfate or sodium styrene sulfonate.

5. The emulsification system of claim 4, wherein the alkyl chain length of the alkyl group of the sodium alkylphenol polyoxyethylene ether carboxylate, the sodium alkyl alcohol polyoxyethylene ether carboxylate, the sodium alkylphenol polyoxyethylene ether sulfonate, and the sodium alkyl alcohol polyoxyethylene ether sulfonate is 8 to 12, and the degree of polymerization of the polyoxyethylene ether is 7 to 20.

6. The emulsification system of claim 1, wherein the nanomaterial is: graphite powder, graphene oxide, silicon dioxide modified by a silane coupling agent KH550 or KH570, and carbon nanotubes modified by the silane coupling agent KH550 or KH 570.

7. The emulsification system of claim 1, wherein the water is tap water or oilfield injection water.

Technical Field

The invention relates to the technical field of oilfield chemistry, in particular to a chemical intervention in-situ emulsification system.

Background

At present, most oil fields enter a high water content stage after long-time water injection development, the oil field is more and more difficult to stabilize the yield, but most (60-70%) of crude oil is still present in a reservoir stratum, so the recovery rate needs to be improved by means of an enhanced oil recovery technology, and the chemical flooding in the enhanced oil recovery technology is most widely applied. At present, the chemical flooding mainly has the following three research directions: 1) the mobility ratio is improved by reducing the viscosity of the crude oil or increasing the viscosity of the displacement fluid, so that oil displacement methods such as polymer flooding, foam flooding and the like are formed; 2) the oil washing efficiency is improved based on the method for improving the wettability and the number of capillaries, and an oil displacement method such as surfactant flooding is formed; 3) two approaches are in between, such as three-component combination flooding.

Because the performance of the polymer is limited by temperature and mineralization degree, the chemical flooding based on the polymer and mainly controlled by fluidity has poor long-term stability under the condition of high-temperature and high-salinity oil reservoir, and the oil displacement effect is not ideal. Under the influence of reservoir heterogeneity, a chemical system based on foam and mainly based on fluidity control and a surfactant solution and mainly based on wettability improvement and capillary number increase are easy to generate cross flow along a dominant channel, and under the conditions of high temperature and high salt, the foam stability is poor and the effective action time is short. Chemical flooding, which is limited by the formation crude oil viscosity, mainly adopts mobility control and mainly adopts oil washing efficiency, is difficult to start residual oil of a heavy oil reservoir.

The method aims at the problems that the conventional chemical flooding is difficult to control the fluidity of a high-temperature and high-salinity reservoir, the channeling of a strong heterogeneous reservoir is serious, and the adaptability of a heavy oil reservoir is poor. Some researchers have proposed the use of emulsification to improve chemical flooding. The main mechanisms of the emulsification and oil displacement include emulsification carrying and emulsion profile control, in addition, no matter the emulsion is an external phase of oil or an external phase of water, the viscosity of the emulsion is higher than that of a water phase, the improvement of the fluidity ratio is facilitated, and the swept coefficient of emulsified liquid drops can be improved through a liquid resistance superposition effect generated by a high-permeability strip. Natural emulsifiers, such as gums, asphaltenes, and petroleum acids like surface active substances, oil solubility, are present in crude oil. Generally, in a state that crude oil can flow, the higher the viscosity of the crude oil is, the higher the content of a natural emulsifier is, the easier emulsification is, and the higher the viscosity of the formed emulsion is; the lower the viscosity of the crude oil, the less the natural emulsifier content in the crude oil, and the more difficult it is for the crude oil to form an emulsion. In addition, if the emulsion is W/O type, the viscosity of the emulsion is far greater than that of crude oil, which is not beneficial to the transportation of the crude oil on the ground, and the oil and water are required to be separated by a heat treatment or chemical method; if the emulsion is O/W type, the viscosity of the emulsion is obviously lower than that of crude oil, the flowing performance of the fluid is enhanced, but the fluidity control capability is weakened, and the contradiction between the development of high-low permeability layers is further aggravated.

After the crude oil is produced, the crude oil must be dehydrated, and methods such as gravity settling, heating settling, chemical dehydration, electric dehydration and electrochemical dehydration are generally adopted in the prior art. If gravity settling is adopted, the dehydration efficiency is lower, and meanwhile, the dehydration rate is also lower; if the other methods are adopted, larger energy consumption or addition of some medicaments are needed. Particularly, in the case of adding a chemical, the removal of water components is complicated, and the subsequent treatment is affected.

Aiming at the condition that an oil reservoir is either seriously emulsified or not emulsified, how to perform manual intervention on the water-drive oil reservoir controls the emulsification condition within a reasonable range, and emulsion is easy to break, so that the method is the key for realizing the ultimate recovery ratio improvement of the water-drive oil reservoir.

Disclosure of Invention

In view of the above technical problems, the present invention aims to provide a chemical in-situ intervention emulsification system, which can be applied to high viscosity crude oil and low viscosity crude oil simultaneously, and can form an emulsion with moderate viscosity for both the high viscosity crude oil and the low viscosity crude oil, thereby increasing the recovery ratio of the crude oil; simultaneously, the emulsion formed is pumped with N₂In the case of (2), dehydration can be performed at a higher rate and with higher efficiency.

The invention adopts the following technical scheme that:

a chemical intervention in-situ emulsification system comprises the following raw materials in percentage by weight:

CO₂responsive monomer: 0.1 to 0.3 percent of,

surfactant (b): 0.1 to 0.3 percent of,

hydrophilic nano-materials: 0.01 to 0.1 percent of,

the balance of water, wherein the water is tap water or oilfield injection water, the raw materials are mixed and stirred uniformly, and then CO is introduced₂Make CO₂The responsive monomer is completely protonated to obtain a wormlike micelle system, namely the in-situ emulsification intervention system.

In one embodiment of the present invention, the CO is₂The responsive monomer is one of oleic acid amide propyl dimethyl tertiary amine, N, N-dimethyl cyclohexane-1, 4-diamine, 7- (oxygen-10-dimethylamino-decyl) -coumarin and N-dodecyl polyoxyethylene ether-N, N-dimethyl tertiary amine, wherein the polymerization degree of polyoxyethylene ether in the N-dodecyl polyoxyethylene ether-N, N-dimethyl tertiary amine is 7-20.

One embodiment of the present invention is that the surfactant is an anionic surfactant or an anionic-nonionic surfactant, specifically a surfactant having an anionic group.

A further embodiment of the present invention is that the anionic surfactant or anionic-nonionic surfactant is: one of sodium alkylphenol polyoxyethylene ether carboxylate, sodium alkyl alcohol polyoxyethylene ether carboxylate, sodium alkylphenol polyoxyethylene ether sulfonate, sodium alkyl alcohol polyoxyethylene ether sulfonate, sodium p-methyl benzene sulfonate, sodium petroleum sulfonate, sodium dodecyl sulfate or sodium styrene sulfonate.

In a further embodiment of the present invention, in the sodium alkylphenol polyoxyethylene ether carboxylate, the sodium alkyl alcohol polyoxyethylene ether carboxylate, the sodium alkylphenol polyoxyethylene ether sulfonate, and the sodium alkyl alcohol polyoxyethylene ether sulfonate, the carbon chain length of the alkyl group is 8 to 12, and the degree of polymerization of the polyoxyethylene ether is 7 to 40.

One embodiment of the present invention is that the nanomaterial is: graphite powder, graphene oxide, silane coupling agent KH550 or KH570 modified silicon dioxide, and silane coupling agent KH550 or KH570 modified carbon nano-tubes, wherein the added nano-material has the function of improving the phase change point of the emulsion.

In the present invention, CO₂Responsive monomers with carbon monoxide in the presence of CO₂Then forms wormlike micelles with organic counter ions (namely anionic surfactants), has surface activity and can carry out emulsification reaction with crude oil. The thinner the crude oil is, the CO in the prepared system₂The higher the content of the responsive monomer, the more easily emulsification occurs to form W/O type emulsion, and the viscosity of the emulsion is obviously increased; the thicker the crude oil is, the higher the viscosity of the crude oil after self-emulsification is, the higher the content of organic counter ions in a preparation system is, a W/O emulsion is formed after the system and the crude oil are emulsified, and the viscosity of the emulsion is lower than the self-emulsification viscosity.

The invention has the beneficial effects that:

(1) the interfacial tension between the chemical intervention in-situ emulsification system and the crude oil can be reduced to 10^-1mN/m～10^-3mN/m, the oil washing efficiency of an injection system is improved, and meanwhile, the emulsification system has better salt tolerance, can be compounded with formation water, reduces the using amount of fresh water in an oil field, and can be more suitable for the formation environment;

(2) aiming at the serious emulsification condition (heavy oil reservoir) of water-drive reservoir injection development, the system can weaken the emulsification condition, has high phase-change point, weakens the development contradiction between high and low permeability layers during water injection development, and keeps the viscosity of the emulsion in a reasonable range;

(3) aiming at the situation that emulsification (thin oil reservoir) does not occur during water injection development of a water-drive reservoir, when the injected water easily flows along an advantageous channel, the system can promote the emulsification between the crude oil and the injected system to form W/O type emulsion, the phase change point is high, and the balanced displacement in the heterogeneous reservoir is finally realized;

(4) by injecting N into the produced fluid₂The mode of the method enhances the hydrophilicity of the system, reduces the emulsifying property of the system and forces the emulsion to be automatically broken.

Drawings

FIG. 1 is a graph showing the viscosity change of the emulsified system of example 1 after the injected water is emulsified with the thick oil;

FIG. 2 is a graph showing the viscosity change of the emulsified system of example 2 after the injected water is emulsified with the thin oil;

FIG. 3 is a graph of the effect of the emulsification system of example 1 on recovery factor;

FIG. 4 is a graph of the effect of the emulsification system of example 2 on recovery factor;

FIG. 5 shows the CO emulsion system of example 1₂And N₂Demulsification performance curve chart under the condition.

Detailed Description

The technical solutions of the present invention will be described in detail below in order to clearly understand the technical features, objects, and advantages of the present invention, but the present invention is not limited to the practical scope of the present invention.

In the following examples, the injection water is NaCl concentration 10X 10⁴mg/L simulated formation water;

in the following examples, all raw materials were chemically pure unless otherwise specified, and were commercially available.

Example 1

Chemical intervention composition of in situ emulsification system: 0.1% of oleamide propyl dimethyl tertiary amine, 0.3% of nonyl alcohol polyoxyethylene ether sodium sulfate (the polymerization degree of polyoxyethylene ether is 7), 0.05% of graphene oxide, and the balance of injected water (10 multiplied by 10)⁴mg/L NaCl), adding each component into the injected water, preparing a system with the total volume of 100mL, and introducing CO into the system at the speed of 300mL/min₂And (3) obtaining a worm-shaped micelle system after 30min, and preparing a chemical intervention emulsification system 1, wherein the system is used for adjusting the viscosity of the mixture of the thick oil and the clear water, so that the viscosity of the thick oil cannot be changed too much in the exploitation process, and the thick oil is easier to exploit.

Example 2

Chemical intervention the composition of the emulsification system: 0.3% of oleamide propyl dimethyl tertiary amine, 0.15% of sodium nonylphenol polyoxyethylene ether carboxylate (polyoxy)The polymerization degree of vinyl ether is 7), 0.05 percent of silane coupling agent KH550 modified silicon dioxide and the balance of injection water are added into the components, a system with the total volume of 100mL is prepared, and CO is introduced into the system at the speed of 300mL/min₂Obtaining a wormlike micelle system after 30min, and preparing a chemical intervention emulsification system 2. The system is used for adjusting the viscosity of a thin oil reservoir in water flooding, so that the viscosity of a mixture of thin oil and injected water is increased, and the exploitation is facilitated.

(II) Performance testing

This example relates to the testing of high viscosity crude (heavy) and low viscosity crude (thin) oils, both of which were dehydrated, and the specific viscosities of which are shown in table 1.

TABLE 1 crude oil viscometer

Temperature of	50℃(mPa·s)	90℃(mPa·s)
			Thin oil	80	9
Thickened oil	800	33

1. And (3) testing the emulsifying property: the chemical intervention emulsification system and the injected water which are configured in the embodiment 1 are taken and added into a glass vessel which can be sealed according to different proportions with crude oil, then the glass vessel is placed into a 90 ℃ oil bath kettle with mechanical stirring, after the temperature of the glass vessel rises to 90 ℃, the stirring is carried out for 1h at 500RPM, and then an Antopa high-temperature high-pressure rheometer is utilized to test the viscosity of the emulsion. The chemical intervention emulsification system compounded with thickened and thin oils is shown in table 2:

TABLE 2 compounding of chemically intervened emulsification systems, injected water and crude oil

The final test results are shown in fig. 1 and fig. 2, wherein fig. 1 is the viscosity change curve of the chemical intervention emulsification system and the injected water in the thick oil of the example 1, and fig. 2 is the viscosity change curve of the chemical intervention emulsification system and the injected water in the thin oil of the example 2.

As can be seen from fig. 1, as the water content increases, the viscosity of the emulsion formed by the injected water and the crude oil increases first and then decreases rapidly, and when the water content is 70%, the phase state of the emulsion is changed, and the viscosity of the emulsion is lower than that of the crude oil; after the chemical intervention emulsification system is added, the viscosity of the emulsion formed by the chemical intervention emulsification system and the crude oil is increased along with the increase of the water content, and the phase inversion does not occur when the water content is 80%, so that the intelligent control capability of the fluidity is shown.

As can be seen from fig. 2, the injected water does not emulsify with the thin oil. Along with the increase of the water content, the chemical intervention emulsification system and the crude oil form W/O type emulsion, the viscosity of the emulsion is increased, and the larger seepage resistance under the high water content is realized. Therefore, the chemical intervention emulsification system of the invention can realize balanced displacement.

Meanwhile, the interfacial tension of the compound system is measured in the embodiment. The interfacial tension of the chemical intervention emulsification system 1 and the thick oil is 2.1 multiplied by 10^-3mN/m, interfacial tension of chemical intervening emulsification system 2 and thin oil is 3.4X 10^-2mN/m. Showing good oil washing efficiency.

2. Testing of oil displacement performance

The three-layer heterogeneous rock core is used for researching the recovery ratio under water flooding and chemical intervention at the temperature of 90 ℃, the displacement speed is 0.5ml/min, and the experimental process is as follows: firstly, carrying out water drive, injecting a chemical intervention emulsification system when the water content is 98%, then continuing the water drive until the water content is 98%, and recording the recovery ratio in the displacement process, wherein the core data collected in the test is shown in table 3.

Table 3 core data

The final experimental results are shown in fig. 3 and 4, and as shown in fig. 3, when water flooding is carried out, the recovery ratio is 28.9% when the water content is 98% due to unfavorable fluidity ratio and core heterogeneity. After the chemical dry process, the water content is obviously reduced and slowly increased, which shows that the fluidity ratio in the displacement process is improved by chemical intervention, the sweep efficiency is increased, and the recovery ratio is finally increased by 29.1%.

As shown in fig. 4, when the water flooding was performed, the recovery rate was 25% when the water content was 98% due to the unfavorable fluidity ratio and the core heterogeneity. After the chemical dry process, the water content is obviously reduced and slowly increased, which shows that the fluidity ratio in the displacement process is improved by chemical intervention, the sweep efficiency is increased, and the recovery ratio is finally increased by 23%.

3. Demulsification performance test

Taking a chemical intervention emulsification system 1 and thickened oil, preparing the mixture into 100mL of emulsion with the water content of 70% by adopting a method for preparing the emulsion in an emulsification performance test, wherein 2 parts of the emulsion are prepared, and CO is introduced into one part of the emulsion at the speed of 300mL/min₂30min, introducing N into another part at the same speed₂And (3) 30 min. After the end, the free water amount under different standing times is recorded, the relation between the water-separating rate and the time is calculated, and the final result is shown in fig. 5.

As can be seen from FIG. 5, N is introduced₂The emulsion has faster water separating rate, and the final water separating rate is higher than that of the emulsion introduced with CO₂The main reason for the emulsion of (2) is that N is introduced₂Then, the protonation group in the system undergoes deprotonation reaction, the surface activity of the system is reduced, and the emulsifying performance is reduced. Therefore, the emulsion formed by the chemical intervention emulsification system can improve the emulsion breaking rate in an environment-friendly way andefficiency, and the current auxiliaries such as emulsifier, surfactant and the like used for oil recovery can be demulsified only by adding a demulsifier, and new chemical substances are brought into the system, so that the subsequent treatment process of the removed water is more complicated.

The present invention has been disclosed in the foregoing in terms of preferred embodiments, but it will be understood by those skilled in the art that these embodiments are merely illustrative of the present invention and should not be construed as limiting the scope of the present invention. Further modifications of the invention should also be considered within the scope of the invention without departing from its principles.