CN115029123B - Viscoelastic-active nano viscosity reducer and preparation method and application thereof - Google Patents
Viscoelastic-active nano viscosity reducer and preparation method and application thereof Download PDFInfo
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Abstract
The invention discloses a viscoelastic-active nano viscosity reducer and a preparation method and application thereof, and relates to the technical field of petroleum. According to the invention, firstly, a macromolecule group colloidal solution is synthesized by using an inverse emulsion method, then, a hydrothermal method is used for carrying out surface modification on a molybdenum sulfide nano sheet material, the prepared viscoelasticity-activity nano viscosity reducer has double effects of viscoelasticity and viscosity reduction, can increase the viscosity of a water phase, improve the water-oil fluidity ratio, simultaneously plays roles of oil finding, adsorption and permeation, penetrates into thick oil to scatter the aggregate structure of asphaltene and colloid, realizes the viscosity reduction effect of the thick oil from inside to outside, and the double effects of viscosity reduction of the water phase and the oil phase can obviously increase swept volume, improve a displacement profile and improve the recovery ratio of the thick oil in an oil reservoir. The viscoelastic-active nano viscosity reducer prepared by the invention has wide application range and obvious viscosity reducing effect, and is suitable for common heavy oil, extra heavy oil and super heavy oil reservoirs.
Description
Technical Field
The invention relates to the technical field of petroleum, in particular to a viscoelastic-active nano viscosity reducer and a preparation method and application thereof.
Background
With the large and continuous consumption of conventional petroleum resources, the urgency for developing and utilizing the heavy oil resources is increasingly prominent. Heavy oil, also known internationally as heavy crude oil or heavy oil, generally refers to a viscosity of greater than 50 mPa.s under geological conditions, or to a viscosity of greater than 100 mPa.s of degassed crude oil at reservoir temperature, having a density of greater than 0.92g/cm 3 The crude oil of (1). The heavy oil contains a large amount of heavy components such as asphaltene and colloid, wherein the asphaltene is a main factor influencing the viscosity of the heavy oil, has strong polarity, and can form a layered molecular aggregate under the action of intermolecular hydrogen bond, pi-pi interaction and chelation of aromatic lamellar heteroatoms and metal ions; aromatic carboxylic acid, ether, amine and phenolic compounds in the colloid enable the colloid to have stronger polarity, and association can be formed among colloid molecules and among colloid and asphaltene molecules through intermolecular force to be agglomerated into macromolecular aggregates, so that the viscosity of the thick oil is increased, the density is increased, the fluidity is deteriorated, the difficulty in mining and gathering is high, the resource utilization rate is poor, and the key for breaking through the barrier for limiting the development and utilization of the thick oil is realized by reducing the viscosity of the thick oil and improving the fluidity of the thick oil.
The heavy oil recovery technology can be divided into thermal recovery and cold recovery. The thermal recovery mainly utilizes the characteristic that the thickened oil has high viscosity but is sensitive to temperature, and the viscosity is reduced by increasing the temperature, so that the resistance is weakened to complete the recovery; cold recovery mainly utilizes the characteristics of heavy oil reservoirs, and adds appropriate chemical reagents, microorganisms and the like under the condition of not increasing the temperature, thereby achieving the purpose of reducing resistance.
The most common and effective thick oil exploitation technology at present is a chemical viscosity reduction exploitation technology, the purpose of exploitation is realized by adding chemical agents to reduce the viscosity of thick oil, and the technology can be divided into the following types according to different viscosity reduction mechanisms:
(1) Oil-soluble viscosity reduction exploitation: for the exploitation and the pipe transportation of low-water-content thick oil and offshore thick oil, the oil-soluble viscosity reducer containing functional groups with strong polarity, surface active functional groups or alkyl long chains is injected into the thick oil mainly depending on an oil-soluble viscosity reduction technology, aggregates of asphaltene and colloid in the thick oil are broken up through the penetration and dispersion effects by utilizing the capability of the viscosity reducer to form hydrogen bonds, so that new aggregates are formed, and the aggregates formed by the viscosity reducer through the hydrogen bonds are randomly piled up and have loose structures, so that the viscosity of the thick oil is reduced.
(2) Water-mixing emulsification viscosity reduction exploitation: the water-blended emulsification viscosity-reducing technology is the chemical viscosity-reducing technology with the strongest viscosity-reducing capability, the highest economic benefit, the widest application range, the simple process and the fast effect, and mainly injects active water containing an emulsifier into an oil layer to convert (W/O) thick oil in a water-in-oil state into oil-in-water (O/W) emulsion under the action of external force or spontaneously, thereby greatly reducing the viscosity of the thick oil and improving the fluidity. Important water-soluble viscosity reducers fall into the following two categories:
(1) surfactant type water-soluble thick oil viscosity reducer: the surfactant type water-soluble viscosity reducer is the most important water-soluble viscosity reducer for thick oil, can improve the surface activity of injected water, reduce the interfacial tension between oil and water, promote the dispersion and emulsification of thick oil, and is widely applied to viscosity reduction of thick oil.
(2) Polymer type water-soluble viscosity reducer for thick oil: the polymer type water-soluble viscosity reducer is an amphiphilic polymer containing a hydrophilic component and a hydrophobic component in terms of structure, can be collectively called as a high molecular surfactant, and the hydrophobically associating water-soluble polymer is one of the most important water-soluble thick oil viscosity reducers. The research suggests that the reduction of interfacial tension is the main cause of emulsification, and the stability of the formed thick oil emulsion is mainly related to the increase of steric repulsion caused by the adsorption of polymer chains on the oil-water interface.
However, the above techniques mainly have the following problems: (1) The oil-soluble viscosity reducer has higher price and larger dosage, but has low viscosity reduction rate and limited application range, and even can not meet the production requirement when being used for extra-thick oil and super-thick oil;
(2) The surfactant water-soluble viscosity reducer mainly relies on the reduction of interfacial tension and emulsification for viscosity reduction, the demulsification problem after viscosity reduction is difficult to solve, the viscosity of a surfactant solution is close to the viscosity of a water phase, the water-oil fluidity ratio is large, the water channeling phenomenon is easy to occur, and the recovery ratio of thickened oil is remarkably reduced;
(3) The polymer water-soluble viscosity reducer has poor capability of reducing interfacial tension and large molecular weight, is difficult to penetrate into the heavy oil to realize the viscosity reduction effect from inside to outside, and is mainly used for reducing the viscosity of common heavy oil reservoirs and is difficult to be applied to ultra-heavy oil reservoirs and extra-heavy oil reservoirs.
At present, the thickened oil viscosity reducer only concentrates on reducing the viscosity of thickened oil to improve the oil-water fluidity ratio, neglects the improvement effect of the increase of the viscosity of a displacement medium on the oil-water fluidity ratio, and has limited extraction degree.
Disclosure of Invention
The invention aims to provide a viscoelastic-active nano viscosity reducer, a preparation method and application thereof, which are used for solving the problems in the prior art, realizing the viscosity reduction effect of thick oil from inside to outside and improving the recovery ratio of a thick oil reservoir.
In order to achieve the purpose, the invention provides the following scheme:
the invention provides a preparation method of a viscoelastic-active nano viscosity reducer, which comprises the following steps:
A. preparing a macromolecular group colloid solution:
(1) Mixing the oil phase emulsifier with an alkane solvent, and carrying out deoxidization treatment to obtain a mixed system; the mass ratio of the oil-phase emulsifier to the alkane solvent is 0.5-1;
(2) Dissolving an acrylic acid monomer, a 2-acrylamide-2-methylpropanesulfonic acid monomer and an acrylamide monomer in water, and adjusting the pH value of the system to 8-12 to obtain a water phase;
(3) Adding a polybutene monomer (with the molecular weight of 56) into the mixed system obtained in the step (1), adjusting the temperature to be 80-100 ℃, adding an initiator, and then mixing and reacting with the water phase obtained in the step (2) to obtain the macromolecular group colloidal solution;
B. preparing modified nano molybdenum sulfide:
(4) Preparing molybdenum disulfide into molybdenum disulfide aqueous dispersion, and then adding (NH) 4 ) 2 ·MoO 4 And CH 4 N 2 O, then dispersing into dimethylbenzene, carrying out pressure reaction under inert atmosphere, cooling, washing and drying to obtain MoS 2 A nanomaterial;
(5) The MoS is treated 2 Nanomaterial and the sameMixing the macromolecular group colloidal solution, adding sodium chloride, and after the reaction is finished, washing, filtering, freezing and drying to obtain modified nano molybdenum sulfide;
C. preparing the viscoelastic-active nano viscosity reducer:
(6) Dissolving the modified nano molybdenum sulfide in water, adding OP-10, and mixing to obtain the viscoelastic-active nano viscosity reducer.
Further, the mass ratio of the acrylic acid monomer to the 2-acrylamide-2-methylpropanesulfonic acid monomer to the acrylamide monomer is 1.
Further, the mixing reaction time in the step (3) is 4-5h.
Further, the molybdenum disulfide is mixed with (NH) 4 ) 2 ·MoO 4 And CH 4 N 2 The mass ratio of O is 5-10: 1 to 3:0.5 to 1.
Further, the pressure reaction in the step (4) is carried out at the temperature of 200-220 ℃, the pressure of 10-15 MPa and the reaction time of 18-24 h.
Further, the MoS in the step (5) 2 The mass ratio of the nano material to the macromolecular group colloidal solution is 5-10: 95 to 90 percent.
Further, the concentration of the modified nano molybdenum sulfide dissolved in water in the step (6) is 0.005wt% -0.001 wt%, and the mass ratio of the modified nano molybdenum sulfide to OP-10 in the step (6) is 1:2.
further, according to the mass ratio of molybdenum disulfide to water of 3-5: 40-50 preparing the molybdenum disulfide aqueous dispersion.
The invention also provides the viscoelastic-active nano viscosity reducer prepared by the preparation method.
The invention also provides application of the viscoelastic-active nano viscosity reducer in viscosity reduction of thick oil.
The invention discloses the following technical effects:
the viscoelastic-active nano viscosity reducer is simple to prepare, has lower use concentration and use amount than conventional viscosity reducers, is simple in construction process and low in operation cost, and can obviously reduce the exploitation cost of thick oil;
firstly, synthesizing a macromolecular group colloidal solution by using an inverse emulsion method, and then modifying the surface of a molybdenum sulfide nano flaky material by using a hydrothermal method to enable the molybdenum sulfide nano flaky material to simultaneously have a hydrophilic group, a lipophilic group, a cationic group and an anionic group to form an amphiphilic-amphoteric nano modified material, wherein the nano molybdenum sulfide has flexibility and lubricity, plays an oil finding role, is adsorbed on an oil-water interface, has strong permeability and carries a grafting group to go deep into thick oil; the grafting group mainly depends on the anisotropy of polar groups and the destructive effect of nonpolar groups on macromolecular aggregates to realize the internal viscosity reduction of the thick oil, and the molybdenum sulfide adsorbed on the surface-surface after the oil-in-water emulsion is formed improves the strength of an interfacial film and prevents the thick oil from being stacked again;
the viscoelastic-active nano viscosity reducer has wide application range and obvious viscosity reducing effect, and is suitable for common heavy oil, extra heavy oil and super heavy oil reservoirs;
the viscoelasticity-activity nano viscosity reducer has double effects of viscoelasticity and viscosity reduction, can increase the viscosity of a water phase, improve the water-oil fluidity ratio, simultaneously play the roles of oil finding, adsorption and permeation, penetrate into the inside of thick oil to break up the aggregate structure of asphaltene and colloid, realize the viscosity reduction effect of the thick oil from inside to outside, obviously increase swept volume due to the double effects of water phase viscosity reduction and oil phase viscosity reduction, improve a displacement profile and improve the recovery ratio of a thick oil reservoir.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
FIG. 1 is a schematic diagram of the viscosity reduction mechanism of the viscoelastic-active nano viscosity reducer of the invention.
Detailed Description
Reference will now be made in detail to various exemplary embodiments of the invention, the detailed description should not be construed as limiting the invention but rather as a more detailed description of certain aspects, features and embodiments of the invention.
It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Further, for numerical ranges in this disclosure, it is understood that each intervening value, between the upper and lower limit of that range, is also specifically disclosed. Every smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in a stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference herein for the purpose of disclosing and describing the methods and/or materials associated with the documents. In case of conflict with any incorporated document, the present specification will control.
It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the present disclosure without departing from the scope or spirit of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification. The description and examples are intended to be illustrative only.
As used herein, the terms "comprising," "including," "having," "containing," and the like are open-ended terms that mean including, but not limited to.
The preparation process of the viscoelastic-active nano viscosity reducer comprises the following steps:
1. preparing a polymer group colloid solution: the inverse emulsion polymerization method is utilized to prepare the high molecular group colloidal solution, and the polymerization mechanism can be divided into 4 stages: dispersing stage, latex particle generating stage, latex particle growing stage and polymerization reaction finishing stage. The preparation process comprises the following steps:
taking 100-150 g of alkane solvent and 0.5-1 g of oil phase emulsifier, uniformly mixing, pouring into a reaction kettle, and introducing nitrogen for 1 hour to remove oxygen;
wherein the alkane solvent includes but is not limited to ISOPAR G isoparaffin solvent, 200# solvent naphtha, dearomatization D-series; oil phase emulsifiers include, but are not limited to, sodium alkyl sulfonates, sodium alkyl benzene sulfonates, sodium oleate, polyoxyethylene (120) lauryl ether, zinc stearate;
step two, weighing 50-60 g of water in a beaker, adding hydrophilic monomers such as Acrylic Acid (AA), 2-acrylamide-2-methylpropanesulfonic Acid (AMPS) and Acrylamide (AM) into the beaker according to different gram-weight ratios (1;
adding 2-3 g of hydrophobic monomer Polybutene (PB) (molecular weight 56) into a reaction kettle, putting the device into an adjustable temperature control electric heating jacket, adjusting the temperature to 80-100 ℃, putting a thermometer in the device to measure the temperature, adding an initiator (azodiisobutyronitrile, potassium persulfate or ammonium persulfate) into the reactor to perform inverse emulsion polymerization when the solution temperature is the same, adjusting the temperature of the electric heating jacket to the reaction temperature (80-100 ℃) while continuously stirring by using a stirrer, controlling the stirring time and the reaction time, adjusting the stirring speed to 200-400 r/min, slowly dropping the water phase into the oil phase to emulsify for 4-5 hours, and designing to form milky white colloidal solution to form high molecular groups with different monomer polymerization degrees. The macromolecular group structure is as follows:
wherein n is 1 ＝1～2、n 2 ＝2～3、n 3 ＝2～3、n 4 ＝3～5。
2. Preparing modified nano molybdenum sulfide:
preparing the molybdenum disulfide nano material by a hydrothermal method. Dispersing 5-10 g of molybdenum disulfide in 40-50 g of deionized water to obtain a mixture with the mass fraction of 10-25%A molybdenum sulfide dispersion. 1-3 g of ammonium tetramolybdate (NH) 4 ) 2 ·MoO 4 And 0.5 to 1g of Carbamide (CH) 4 N 2 O) was dissolved in 5 to 10g of the above molybdenum disulfide dispersion, and further dispersed in 40 to 50g of xylene. Putting the mixed solution into a high-pressure reaction kettle, introducing Ar gas into a high-pressure kettle to remove air, creating an inert gas atmosphere, and calcining for 18-24 h at 200-220 ℃ and 10-15 MPa. After the solution was cooled to room temperature, the MoS was washed several times with water and ethanol 2 And carrying out suction filtration on the mixture by using ultrapure water so as to remove unreacted reagents and other impurities. Using a freeze dryer (low temperature, negative pressure) to obtain unmodified solid MoS 2 A nano-material.
Unmodified solid MoS 2 The surface of the nano material is distributed with a plurality of active grafting sites, 5 to 10g of unmodified solid MoS 2 Dispersing the nano material in 95-90 g of the prepared macromolecular group colloidal solution with different monomer polymerization degrees, adding 1-3 mmol/L sodium chloride for graft modification, keeping the rotating speed at 150 r/min, keeping the temperature at 150-180 ℃, and reacting for 20-25 h under normal pressure. After cooling the solution to room temperature, the modified MoS was washed several times with water and ethanol 2 Nano material, pumping and filtering with ultrapure water to remove unreacted reagent and other impurities, and freeze drying to obtain MoS with different modification degrees 2 And (3) nano materials. The structure of the modified nano molybdenum sulfide is as follows:
wherein n is 1 ＝1～2、n 2 ＝2～3、n 3 ＝2～3、n 4 ＝3～5。
The nitrogen element of the polymer group can react with MoS 2 And the molybdenum element on the surface of the nanosheet is chemically grafted, so that the molybdenum element is grafted on the surface of the nanosheet to form the viscoelastic modified nano molybdenum sulfide.
3. Preparing a viscoelastic-active nano viscosity reducer:
mixing the prepared viscoelasticity modified nano molybdenum sulfide with water with different mineralization degrees (0-120000 mg/L) according to the proportion of 0.007wt% -0.015 wt%, and mixing the viscoelastic modified nano molybdenum sulfide: adding alkylphenol polyoxyethylene ether (OP-10) =1 to OP-10 in a mass ratio, placing the mixture into an ultrasonic stirrer for oscillation, taking out the mixture after ensuring that the viscoelastic modified nano molybdenum sulfide and the OP-10 are completely dissolved, and preparing the viscoelastic-active nano viscosity reducer, wherein the process is about 5-10 min.
Example 1
1. Preparing a macromolecular group colloid solution:
step one, taking 100g of alkane solvent and 0.5g of oil phase emulsifier, uniformly mixing, pouring into a reaction kettle, and introducing nitrogen for 1 hour to remove oxygen;
wherein, the alkane solvent is 200# solvent oil, and the oil phase emulsifier is sodium alkyl sulfonate;
step two, weighing 60g of water, hydrophilic monomers of Acrylic Acid (AA), 2-acrylamide-2-methylpropanesulfonic Acid (AMPS) and Acrylamide (AM) in a beaker, adding the mixture into the beaker according to different gram-weight ratios (1;
adding 2g of hydrophobic monomer Polybutene (PB) (molecular weight is 56) into a reaction kettle, putting the device into an adjustable temperature-controlled electric heating jacket, adjusting the temperature to 100 ℃, putting a thermometer in the device to measure the temperature, adding an initiator (azobisisobutyronitrile) into the reactor to perform inverse emulsion polymerization when the solution temperature is the same, adjusting the temperature of the electric heating jacket to the reaction temperature (80 ℃) while continuously stirring by using a stirrer, controlling the stirring time length and the reaction time length, adjusting the stirring rotation speed to 400r/min, slowly dropping the water phase into the oil phase to emulsify for 4.5 hours, and designing to form milky colloidal solution to form high molecular groups with different monomer polymerization degrees.
2. Preparing modified nano molybdenum sulfide:
dispersing 3g of molybdenum disulfide in 50g of deionized water to obtain a molybdenum disulfide dispersion, and adding 1g of ammonium tetramolybdate (NH) 4 ) 2 ·MoO 4 And 1g of Carboxamide (CH) 4 N 2 O) was dissolved in the above molybdenum disulfide dispersion, and further dispersed in 50g of xylene. Then the mixed solution is put into a high-pressure reaction kettle, and Ar gas is introduced into the high pressure reaction kettleThe mixture is calcined in a pot for 18 hours at the temperature of 200 ℃ and the pressure of 15MPa in order to remove air and create an inert gas atmosphere. After the solution was cooled to room temperature, the MoS was washed several times with water and ethanol 2 And carrying out suction filtration on the obtained product by using ultrapure water to remove unreacted reagents and other impurities, and obtaining unmodified solid MoS by using a freeze dryer (low temperature and negative pressure) 2 And (3) nano materials.
Unmodified solid MoS 2 The surface of the nano material is distributed with a plurality of active grafting sites, and 5g of unmodified solid MoS 2 Dispersing the nano material in 95g of macromolecular group colloidal solution with different monomer polymerization degrees, adding 1mmol/L sodium chloride for graft modification, keeping the rotating speed at 150 r/min, keeping the temperature at 180 ℃, and reacting for 20h under normal pressure. After cooling the solution to room temperature, the modified MoS was washed several times with water and ethanol 2 Nano material, pumping and filtering with ultrapure water to remove unreacted reagent and other impurities, and freeze drying to obtain MoS with different modification degrees 2 A nano-material.
3. Preparing a viscoelastic-active nano viscosity reducer:
mixing the prepared viscoelastic modified nano molybdenum sulfide with water with the mineralization degree of 120000mg/L according to the proportion of 0.01wt%, and mixing the components according to the weight ratio of the viscoelastic modified nano molybdenum sulfide: adding OP-10 into alkylphenol polyoxyethylene ether (OP-10) according to the mass ratio =1 of 3, placing into an ultrasonic stirrer for oscillation, taking out after ensuring that the viscoelastic modified nano molybdenum sulfide and OP-10 are completely dissolved, preparing the viscoelastic-active nano viscosity reducer, and treating for 5min in the process.
Example 2 Performance characterization of viscoelastic-active NanoDevicant
The viscoelastic-active nano viscosity reducer prepared in example 1 was subjected to the following performance characterization:
(1) Viscosity reduction mechanism of viscoelastic-active nano viscosity reducer
Hydrophobic monomer and hydrophilic monomer inverse emulsion polymerization are carried out to form high molecular groups with different polymerization degrees, and the high molecular groups are grafted on MoS by a chemical synthesis method 2 The surface of the nano sheet forms viscoelastic modified nano molybdenum sulfide. The viscoelasticity modified nano molybdenum sulfide has amphipathy, simultaneously contains hydrophilic groups and lipophilic groups, and has cations on the surfaceAnd an anion, which is an amphiphilic-amphoteric nanomaterial. Introducing sulfonate anions to strengthen the hydrophilic action and electrostatic repulsion force of anion groups so that the hydrophilicity is good; the hydrophilic group and the lipophilic group utilize the interaction between molecular chains, and the polar group exists in a side chain form, so that the rigidity of the molecular chains is improved, hydrogen bonds with water molecules are more easily formed, and the hydrophilic group and the lipophilic group are dissolved in water, and maintain good water solubility in hypersalinity saline water. Therefore, the structural design of the viscoelastic-active nano viscosity reducer can improve the temperature resistance and salt resistance of the viscosity reducer. Similarly, a benzene ring structure is introduced to break up a thick oil polar structure, a long side chain has strong space stretching capacity, molecular chains expand after being dissolved in water, the viscosity of a water phase is increased, and the thick oil enters the inside to block the stacking of flaky molecules; the introduction of the zwitterion amphiprotic groups further generates association with polar groups such as asphaltene and colloid in the heavy oil, promotes the decomposition of heavy oil components, and realizes the viscosity reduction of the heavy oil through dispersion and emulsification; the molybdenum sulfide nanosheet has a strong lubricating effect and a strong penetrating power, can carry a high molecular group to penetrate into thick oil with small resistance, and promotes deep viscosity reduction. Therefore, for MoS 2 The grafting modification on the surface of the nano material improves viscoelasticity, has better water phase thickening capability, reduces the viscosity of thick oil and enlarges swept volume, thereby improving the recovery ratio of the thick oil.
FIG. 1 is a schematic diagram of a viscosity reduction mechanism of the viscoelastic-active nano viscosity reducer.
(2) Interfacial tension: a rotary drop interfacial tension meter is selected to measure the interfacial tension between oil and water, the measuring temperature is 60 ℃, the rotating speed is 6000r/min, and the interfacial tension between the crude oil and the viscoelastic-active nano viscosity reducer solution with different polymerization degrees is measured, and the result is shown in Table 1.
TABLE 1 interfacial tension of visco-elastic-active nano viscosity reducer
The interfacial tension of the viscoelasticity-active nano viscosity reducer is 10 -1 mN/m order of magnitude, strong capability of reducing interfacial tension, and the reduction of interfacial tension is favorable for being adsorbed on an oil-water interface to form stable O/W emulsionLiquid to promote emulsification of the crude oil; meanwhile, the molybdenum sulfide nanosheets are adsorbed on an oil-water interface in a surface-to-surface form, the contact area is large, the space repulsion between oil drops is enhanced through the adsorption of the high molecular groups, and the stability of the emulsion is enhanced.
(3) The viscoelasticity-active nanometer viscosity reducer solution has the thickening performance: and (3) measuring the apparent viscosity of the viscoelastic-active nano viscosity reducer solution with different polymerization degrees by using a rheometer. The selected test temperature for rheological test is constant at 60 deg.C, and the CC26 Ti rotors are all in constant shear (CR) mode with shear rate of 7.1s -1 The shear frequency was 0.1Hz, and the shear stress was 1Pa.
TABLE 2 apparent viscosity of visco-elastic-active nano viscosity reducer
As can be seen from table 2, as the degree of polymerization of AMPS increases, the apparent viscosity of the visco-elastic-active nano viscosity reducer increases first and then decreases, and the visco-elastic-active nano viscosity reducer having a degree of polymerization of 1. Therefore, the viscoelasticity-activity nano viscosity reducer increases the viscosity of a water phase, improves the water-oil fluidity ratio in the oil displacement process and obviously inhibits water channeling.
(4) The viscosity reducing effect is as follows: (1) measuring the viscosity of the crude oil sample by using a Brookfield DV2T viscometer; (2) weighing 70g of crude oil and 30g of viscoelastic-active nano viscosity reducer, and mixing the crude oil and the viscoelastic-active nano viscosity reducer according to a volume ratio of 7; (3) and (3) stirring the mixture for 2min at the experiment temperature of 50 ℃ by using a mechanical stirrer at the rotating speed of 250r/min after mixing, quickly testing the viscosity of the oil-water mixture at the experiment temperature by using a viscometer after uniformly stirring, and calculating the viscosity reduction rate. The viscosity reduction rate was calculated as follows:
in the formula: f, shearing dynamic viscosity reduction rate; mu.s 0 -viscosity in mPa · s of crude oil sample at 50 ℃; mu-viscosity of oil-water mixture after 2min stirring in millipascal seconds (mP)a·s)。
(1) The viscosity of the Lukexin thick oil is 9500mPa & s, and the viscosity reducing effect of the viscoelastic-active nano viscosity reducer with different polymerization degrees on the Lukexin thick oil is shown in a table 3:
TABLE 3 viscosity reduction Rate of visco-elastic-active Nano viscosity reducer
From table 3, the viscosity reducing effect of the viscoelastic-active nano viscosity reducer is higher than 90%, wherein the viscosity reducing effect of the viscoelastic-active nano viscosity reducer with the polymerization degree of 1.
(2) The average viscosity of the thick oil of the du 813 block is 108880mPa · s, and the viscosity reducing effect of the viscoelastic-active nano viscosity reducer with different polymerization degrees on the thick oil of the du 813 block is shown in table 4:
TABLE 4 Deviscocity Rate of visco-elastic-active Nano viscosity reducer
As can be seen from Table 4, the viscosity reducing effect of the viscoelastic-active nano viscosity reducer is higher than 99%, which shows that the viscosity reducing effect of the viscoelastic-active nano viscosity reducer on the super-heavy oil is more excellent. Through viscosity reduction experiments of the viscoelastic-active nano viscosity reducer, the viscosity reduction effect on extra-heavy oil and super-heavy oil is obvious, and the viscosity reducer is more suitable for viscosity reduction of extra-heavy oil reservoirs.
(5) Oil displacement effect: an indoor oil displacement experiment is carried out to evaluate the oil displacement performance of the viscoelastic-active nano viscosity reducer, and the experimental steps are as follows: (1) and (3) filling quartz sand of 60-80 meshes and 80-100 meshes into a sand filling pipe, and calculating the pore volume, the porosity and the permeability. (2) Injecting the crude oil into a sand filling pipe at the speed of 0.20mL/min for saturated oil operation until only oil is discharged from an outlet end but water is not discharged, measuring the volume of the water discharged from the outlet end, namely the volume of the saturated oil, calculating the initial oil saturation degree, and aging for 72 hours. The initial oil saturation calculation formula is as follows:
in the formula: s. the o Initial oil saturation,%; v o The volume is the saturated oil volume of the sand filling pipe, mL; v w Saturated water volume for sand pack, mL.
(3) Injecting water into the sand filling pipe at the rate of 0.20mL/min to drive oil until the water content of the produced liquid is higher than 90%, and recording the volume and recovery ratio change of the produced liquid and the produced oil. The recovery ratio calculation formula is as follows:
in the formula: eta is recovery ratio,%; v Oil The volume of oil in the produced fluid, mL; v Mining Volume of produced fluid, mL.
(4) Injecting a viscoelastic-active nano viscosity reducer into the sand filling pipe at the rate of 0.20mL/min to drive oil until the water content of the produced fluid is higher than 90%, and recording the volume and recovery ratio changes of the produced fluid and the produced oil, wherein the results are shown in Table 5.
TABLE 5 oil displacement efficiency of viscoelastic-active nano viscosity reducer
The viscoelasticity-activity nano viscosity reducer with different polymerization degrees acts on the crude oil, so that the viscosity of the crude oil is greatly reduced; meanwhile, the viscosity of the subsequently injected viscoelastic-active nano viscosity reducer solution is higher than that of water, so that the water-oil mobility ratio is obviously reduced, the sweep coefficient is improved, the sweep range of the displacement fluid is increased, more crude oil is exploited, and the exploitation degree of the thick oil is greatly improved.
Therefore, through a viscous oil viscosity reduction experiment and a displacement experiment, the viscoelastic-active nano viscosity reducer reduces the viscosity of emulsified viscous oil by dispersing and emulsifying the viscous oil, improves the oil washing efficiency, improves the water phase viscosity, improves the water-oil fluidity ratio and improves the swept degree, and the viscous oil and the active nano viscosity reducer jointly act to improve the oil displacement efficiency, so that the recovery efficiency in the viscous oil exploitation process is improved.
The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.
Claims (3)
1. The preparation method of the viscoelastic-active nano viscosity reducer is characterized by comprising the following steps of:
A. preparing a polymer group colloid solution:
step one, taking 100g of alkane solvent and 0.5g of oil phase emulsifier, uniformly mixing to obtain a mixed system, and introducing nitrogen for 1 hour to remove oxygen;
the alkane solvent is 200# solvent oil, and the oil phase emulsifier is sodium alkyl sulfonate;
step two, adding hydrophilic monomers of acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid and acrylamide into 60g of water according to different gram mass ratios until the hydrophilic monomers are completely dissolved, adding a certain amount of sodium hydroxide powder to adjust the pH value to 8, and uniformly mixing to obtain a water phase;
the mass ratio of the hydrophilic monomers acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid and acrylamide is 1;
adding 2g of hydrophobic monomer polybutene with molecular weight of 56 into the mixed system in the first step, adjusting the temperature to 100 ℃, adding an initiator azobisisobutyronitrile to perform inverse emulsion polymerization, controlling the reaction temperature to be 80 ℃, stirring, controlling the stirring time and the reaction time, adjusting the stirring speed to 400r/min, slowly dropping into the water phase in the second step for emulsification for 4.5 hours, and designing to form a milky colloidal solution to form high molecular groups with different monomer polymerization degrees;
B. preparing modified nano molybdenum sulfide:
dispersing 3g of molybdenum disulfide in 50g of deionized water to obtain a molybdenum disulfide dispersion, and dispersing 1g of (NH) 4 ) 2 ·MoO 4 And 1gCH 4 N 2 O was dissolved in the molybdenum disulfide dispersion, further dispersed in 50g of xylene, and thenMixing the mixed solution with the high molecular group colloidal solution, and adding Ar 2 Calcining at 200 deg.C under 15MPa for 18h under atmosphere, cooling the solution to room temperature, washing MoS with water and ethanol 2 And carrying out suction filtration on the obtained product by using ultrapure water to remove unreacted reagents and other impurities, and carrying out freeze drying to obtain unmodified solid MoS 2 A nanomaterial;
5g of the unmodified solid MoS 2 Dispersing the nano material in 95g of macromolecular group colloidal solution with different monomer polymerization degrees, adding 1mmol/L sodium chloride for graft modification, keeping the rotation speed at 150 r/min and the temperature at 180 ℃, reacting for 20h under normal pressure, cooling the solution to room temperature, washing the modified MoS with water and ethanol 2 Filtering the nano material with ultrapure water to remove unreacted reagent and other impurities, and freeze-drying to obtain MoS with different modification degrees 2 A nanomaterial;
C. preparing the viscoelastic-active nano viscosity reducer:
mixing the modified nano molybdenum sulfide with water with the degree of mineralization of 120000mg/L according to the proportion of 0.01wt%, and mixing the modified nano molybdenum sulfide with the water according to the proportion of the modified nano molybdenum sulfide: and (2) adding OP-10 according to the mass ratio of OP-10 =1 and 3, ultrasonically oscillating to ensure that the modified nano molybdenum sulfide and OP-10 are completely dissolved, taking out to prepare the viscoelastic-active nano viscosity reducer, and treating for 5min in the process.
2. The viscoelastic-active nano viscosity reducer prepared by the preparation method of claim 1.
3. The use of the viscoelastic-active nano viscosity reducer of claim 2 in viscosity reduction of thick oil.
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