A reservoir reforming fluid and pressure-driven integrated production increasing method for tight oil reservoirs

Abstract

The present invention discloses a reservoir transformation fluid for tight oil reservoirs and a pressure-driven integrated production increase method, belonging to the technical field of oil and gas reservoir production increase. The method is for the purpose of pressure-driven integration, and the function of the fracturing fluid thickener is designed to prepare a pressure-driven integrated emulsion thickener with a special structure and special function; the product has entered the batch production stage, the raw materials are non-toxic and pollution-free, the price is moderate, the product performance is stable, and it has broad application prospects; in addition to integrating the functions of high-efficiency viscosity increase, low-viscosity drag reduction, high-viscosity elastic sand carrying, and low damage, the fracturing fluid also has an oil displacement function after gel breaking, which can well meet the construction requirements of tight oil reservoir pressure-driven integration; based on the research on tight oil reservoir reservoir transformation fluid, a tight oil reservoir pressure-driven integrated production increase method is proposed in a targeted manner, which simplifies the fracturing and oil displacement processes, shortens the operation time, saves construction costs, effectively improves the tight oil reservoir transformation effect, and increases the crude oil recovery rate.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas reservoir production increase, and in particular relates to a reservoir reforming fluid for tight oil reservoirs and a pressure-driven integrated production increase method. Background Art

[0002] Domestic tight oil reservoirs have huge reserves and good prospects for exploration and development. In particular, with the continuous deepening of unconventional reservoir transformation represented by tight oil and shale oil, large-scale volume transformation technology has become an effective technical means for the development of such tight oil reservoirs. However, due to the physical properties of reservoirs such as shale oil and tight oil, their production declines sharply in the early stage of development. Usually, the production drops to 10% of the initial level within the first two years of production. After the rapid decline, it is necessary to invest in repeated fracturing, oil displacement or water injection and drainage measures to partially restore production capacity. How to develop reservoirs with high efficiency and high recovery rate has been the research direction of technicians in this field, and it is also the most realistic problem facing the exploitation of unconventional tight oil resources.

[0003] At present, tight oil reservoirs are mostly divided into sections by horizontal wells, and sand fracturing is performed for each section, which can effectively increase the utilization volume of tight oil reservoirs. When the formation energy is gradually exhausted, some oil fields use single-well water injection or gas injection to replenish the formation energy to improve the recovery rate. However, due to the low permeability of the reservoir matrix, under the existing conditions, it is difficult to establish an effective injection and production well network through inter-well injection and production displacement oil production, and it is extremely difficult to improve the recovery rate. Therefore, combining fracturing construction with oil displacement at the same time is a high-efficiency option to solve the injection difficulties and construction costs - that is, integrated fracturing and oil displacement.

[0004] Research on integrated pressure-drive production-increasing measures has gradually become a hot topic in the transformation of tight oil and shale oil reservoirs. First, the damage of fracturing fluid residue and the large amount of fracturing fluid retained in the reservoir are facts that cannot be changed, which will lead to clogging damage of insoluble matter in the reservoir and water lock, emulsification damage, etc., reducing the effect of post-pressure increase. The research of low-damage and high-performance fracturing fluid is the key; secondly, when a large amount of fracturing fluid degelling fluid is retained in the formation, if the degelling fluid has good oil washing, oil displacement, and imbibition functions, when the degelling fluid enters the oil layer along relatively high permeability channels such as cracks or coarse pore throats, it will enter finer pore throats under the action of capillary force to replace crude oil, and at the same time change the wettability of reservoir rocks, reduce or eliminate the oil-water interfacial tension, thereby achieving pressure reduction and injection increase, stripping crude oil from the rock surface and increasing crude oil output. Therefore, the research on fracturing fluid with oil displacement function will become a highlight of tight oil development; finally, reasonable and effective fracturing and oil displacement on-site construction plans and processes are the guarantee for realizing pressure-drive integration.

[0005] Searching the patent reports in recent years, there are relatively few patents on integrated fracturing and oil displacement and on-site construction methods with the above-mentioned multiple functions. Patent CN110748331 A discloses a non-flowback integrated fracturing and oil displacement oil field production increase method, and patent CN110630238A discloses an integrated fracturing and oil displacement production increase method for oil fields. Both patents involve fracturing fluids with oil displacement functions, but their damage cannot be ignored and no on-site implementation method is proposed; Patent CN109025940B discloses a CO2-free fracturing fluid for tight oil reservoirs. 2 Integrated fracturing and oil recovery methods, especially those involving the use of CO 2 The on-site implementation process of fracturing oil recovery is carried out, but an efficient fracturing fluid system has not been truly proposed. Summary of the invention

[0006] The purpose of the present invention is to propose a low-damage and high-performance fracturing fluid system for the limited production increase effect and low recovery rate of existing unconventional tight oil and shale oil reservoirs, which can not only well meet the large-scale integrated sand fracturing construction and obtain good production increase effect, but also have excellent oil washing and oil displacement functions after the fracturing fluid breaks the gel, and can displace the crude oil in the reservoir matrix during the backflow process, significantly improving the crude oil recovery rate. Therefore, the present invention will focus on proposing a reservoir transformation fluid for tight oil reservoirs and a pressure-driven integrated production increase method to effectively improve the production increase effect and recovery rate of tight oil reservoirs.

[0007] The present invention is achieved through the following technical solutions:

[0008] A reservoir reforming fluid for tight oil reservoirs, based on a total weight fraction of 100%, mainly comprising:

[0009] 0.05%-1.2% pressure-driven integrated emulsion thickener, 0-0.1% gel breaker, the balance is water;

[0010] The pressure-driven integrated emulsion thickener is prepared from the following raw materials in a total mass fraction of 100 parts: 24-26 parts of main chain structure monomers, 3-5 parts of functional monomers, 1.5-2 parts of polymerizable surfactant monomers, 32-35 parts of biological solvents, 3-4 parts of emulsifiers, 0.05-0.1 parts of polymerization accelerators, 1-4 parts of pH value regulators, 0.03-0.1 parts of initiators, 6-10 parts of nano oil wash agents, and the balance is deionized water;

[0011] The debonding agent is ammonium persulfate.

[0012] Preferably, the main chain structure monomer is a mixture of agent A and agent B in a mass ratio of 3:1-3:2;

[0013] The agent A includes any one of acrylamide, methacrylamide, and N-methylacrylamide;

[0014] The agent B includes one of acrylic acid, sodium acrylate, potassium acrylate, methacrylic acid or sodium methacrylate.

[0015] Preferably, the functional monomer is composed of a salt-resistant monomer and an amphiphilic macromonomer, with a mass ratio of 5:1;

[0016] The salt-resistant monomer is any one of AMPS sodium salt, sodium styrene sulfonate, and N-vinyl pyrrolidone;

[0017] The amphiphilic macromonomer is one of citronellol maleic acid monoester carboxylic acid ammonium, methyl methacrylate-b-poly N,N-dimethylacrylamide, amphiphilic polyurethane acrylate, sodium hexadecyl allyl succinic acid diester sulfonate or 2-methylpropanesulfonic acid-2-acrylate hexadecyl ester.

[0018] Preferably, the polymerizable surfactant monomer is one of methacryloyloxyethyl dodecyldimethylammonium bromide, diethyl maleate didodecyldimethylammonium chloride, lauryl alcohol polyoxyethylene ether maleic acid trimethylammonium chloride, nonylphenol polyoxyethylene ether maleic acid ethyl trimethylammonium chloride, allyl ether sulfate, alkyl polyoxyalkylene ether sulfate, alkyl polyoxyalkylene ether phosphate or sulfonated fatty acid acrylate sodium salt.

[0019] Preferably, the biosolvent is one of coconut oil, palm oil, castor oil, isosorbide, glycerol derivatives, limonene or terpene compounds;

[0020] The emulsifier is one of coconut oil alkanolamide, fatty acid polyoxyethylene ester, glyceryl triisostearate, glycerol fatty acid ester, alginate, tetrapolyricinoleic acid ester, castor oil polyoxyethylene ether dioleate or citric acid fatty acid ester.

[0021] Preferably, the polymerization accelerator is one of diethylenetriaminepentaacetic acid (DTAP), ethylenediaminetetraacetic acid (EDTA), sodium citrate, sodium gluconate or sodium polyphosphate;

[0022] The pH value regulator is NaOH, liquid alkali or Na 2 CO 3 One of them.

[0023] Preferably, the initiator is one of 2,2'-azobisisobutylamidine dihydrochloride, azobisisopropylimidazoline hydrochloride, azobisisobutyronitrile or benzoyl peroxide.

[0024] Preferably, the preparation method of the nano oil washing agent is:

[0025] S1: using hexadecyl tertiary amine, epichlorohydrin and aminosulfonic acid as main raw materials to carry out ring-opening reaction, sulfonation reaction, distillation, vacuum filtration, washing and purification, and vacuum drying to obtain a high-efficiency surfactant for nano oil detergent; the high-efficiency surfactant is in powder form;

[0026] S2: Add deionized water to the reactor, set the heating temperature to 30-45°C, and then slowly add the high-efficiency surfactant under the action of an electric stirrer, mix and dissolve it completely to obtain a water phase;

[0027] S3: under the condition of a stirrer speed of 2500-3000 r / min, coconut oil, coconut oil alkanolamide and vinyl imidazole were added to the reactor in sequence, and after stirring and mixing evenly, the temperature of the reactor was set to 55-65° C., and stirring was continued for 30 minutes;

[0028] S4: Turn on the homogenizing shearing emulsifier equipped with the reactor, set the speed to 10000-12000r / min for homogenizing shearing, and the emulsion flows back to the reactor after shearing. The whole emulsion system is circulated for 1-1.5h to obtain a Pickering-like nanoemulsion with high effective content and high stability. After natural cooling, the material is discharged, which is the nano oil detergent.

[0029] Preferably, the main preparation process of the pressure-driven integrated emulsion thickener is as follows:

[0030] S1, adding the main chain structure monomer, functional monomer, polymerizable surfactant monomer, polymerization accelerator, and pH adjuster into a raw material tank controlled at a temperature below 25° C. and stirring to completely dissolve, thereby preparing a reaction water phase;

[0031] S2, controlling the temperature of the reactor within 25-30° C., adding the biosolvent and emulsifier into the reactor under nitrogen flow and stirring evenly, and slowly pumping the reaction water phase into the reactor under high-speed stirring conditions of 8000-8500 r / min to prepare a reaction emulsion phase;

[0032] S3, maintaining nitrogen flow and medium-speed stirring at 800-1000r / min, using a micro-injection pump to add the initiator solution to the reactor, the addition time is controlled at 45-60min, after the initiator is added, stop passing nitrogen, control the stirring speed at 500-600r / min, and allow the system to react for 2-3h; when the temperature in the reactor reaches the peak temperature 0.5h later, reduce the stirring speed to 300-400r / min, and according to the temperature in the reactor, pass hot water to the reactor jacket to increase the temperature of the reactor by 5-8°C, and keep warm for 1.5-2h;

[0033] S4, adding nano oil washing agent to the reaction kettle under continuous stirring and mixing evenly, thus obtaining a pressure-driven integrated emulsion thickener,

[0034] S5. Pump the emulsion thickener into the finished product storage tank, slowly stir and cool naturally to room temperature, and finally discharge and package.

[0035] An application of a reservoir reforming fluid for a tight oil reservoir in a pressure-drive integrated production enhancement method for a tight oil reservoir comprises the following steps:

[0036] S1. Preferentially select tight oil or shale oil wells, and optimize the formulation of reservoir transformation fluid suitable for target reservoir fracturing and oil displacement as claimed in claim 1 according to the reservoir conditions and physical property parameters of the target wells, and evaluate its corresponding performance;

[0037] S2. Divide the construction well into sections or layers, and conduct integrated design of fracturing and drive, mainly including fracturing scale design and construction parameter design, and use the target reservoir core to conduct the imbibition displacement oil displacement experiment of the reservoir transformation fluid of the present invention, and optimize the well shut-in time after the fracturing is completed, and the well shut-in time is controlled within 15-45 days;

[0038] S3, carry out integrated sand fracturing construction, do a good job in on-site quality control of the reservoir transformation fluid of the present invention, achieve large-scale sand addition, and ensure smooth construction;

[0039] S4. After the fracturing operation is completed, the well is shut down and the well is kept warm according to the designed time. When the well is opened, the sand control and rapid flowback is gradually changed to pressure control flowback to achieve oil recovery by flowback fluid.

[0040] Compared with the prior art, the present invention has at least the following technical effects:

[0041] The present invention provides a reservoir reforming fluid and a pressure-driven integrated production increasing method for tight oil reservoirs. The method has the following advantages:

[0042] (1) With the purpose of integrated pressure-drive, the function of the fracturing fluid thickener was designed. During the synthesis process, a variety of functional monomers and polymerizable surfactant monomers were introduced. At the same time, nano-detergents were compounded in the emulsion to prepare an integrated pressure-drive emulsion thickener with special structure and special functions.

[0043] (2) The integrated pressure-driven emulsion thickener has entered the mass production stage. It is synthesized using biological solvents and corresponding emulsifiers. The raw materials are non-toxic and pollution-free, the price is moderate, the production process is simple and easy to operate, the technical route is mature, the product performance is stable, and it has broad application prospects;

[0044] (3) In addition to integrating the functions of high-efficiency viscosity increase, low viscosity drag reduction, high-viscosity elastic sand carrying, and low damage, the reservoir transformation fluid used for tight oil reservoirs also has the function of oil displacement after the fracturing fluid breaks the gel, which can well meet the construction requirements of integrated pressure displacement of tight oil reservoirs;

[0045] Based on the research on tight oil reservoir transformation fluid, a tight oil reservoir pressure-drive integrated production increase method was proposed specifically, which simplified the fracturing and oil recovery processes, shortened the operation time, saved construction costs, and effectively improved the tight oil reservoir transformation effect and increased crude oil recovery. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is a diagram showing the pressure-driven integrated emulsion thickener and the prepared reservoir transformation fluid in Test Example 1;

[0047] Figure 2 The drag reduction curve of the reservoir reforming fluid used for tight oil reservoirs in Example 1 in Test Example 3;

[0048] Figure 3 This is the rheological test curve of the reservoir reforming fluid for tight oil reservoirs in Example 1 of Test Example 4;

[0049] Figure 4 The suspended sand state of the reservoir reforming fluid for tight oil reservoirs provided in Example 1 during on-site construction;

[0050] Figure 5 (a) is a schematic diagram of the wetting reversal performance of the reservoir reforming fluid for tight oil reservoirs before being treated with a degelling liquid in Example 1 of Experimental Example 7;

[0051] Figure 5 (b) is a schematic diagram of the wetting reversal performance of the reservoir reforming fluid for tight oil reservoirs after being treated with a degelling liquid in Example 1 of Experimental Example 7;

[0052] Figure 6 (a) is a schematic diagram of the oil washing effect of conventional fracturing fluid degelling fluid in Experimental Example 8;

[0053] Figure 6 (b) is a schematic diagram of the oil washing effect of the reservoir transformation fluid degelling liquid prepared in Example 1 at 0.4% in Experimental Example 8;

[0054] Figure 7 (a) is the oil displacement effect of 0.1% pressure-displacement integrated emulsion thickener breaker in Experimental Example 9;

[0055] Figure 7 (b) is the oil displacement effect of 0.4% pressure-displacement integrated emulsion thickener breaker in Experimental Example 9;

[0056] Figure 7 (c) is the oil displacement effect of 0.8% pressure-displacement integrated emulsion thickener breaker in Experimental Example 9;

[0057] Figure 8 Schematic diagram of optimization of reasonable shut-in time for pressure-drive integration in tight oil reservoirs in Experimental Example 10;

[0058] Fig. 9This is the fracturing construction curve of the reservoir transformation fluid used in the tight oil reservoir in the application experiment example. DETAILED DESCRIPTION

[0059] The embodiments of the present invention will be described in detail below in conjunction with examples. However, those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention. The specific conditions not specified in the examples are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used without indicating the manufacturer are all conventional products that can be purchased commercially.

[0060] Specific implementation:

[0061] Preparation method of nano oil detergent:

[0062] S1: using hexadecyl tertiary amine, epichlorohydrin and aminosulfonic acid as main raw materials, performing ring-opening reaction, sulfonation reaction, distillation, vacuum filtration, washing and purification, and vacuum drying to obtain a high-efficiency surfactant (powder) for nano oil detergent;

[0063] S2: Add deionized water to the reactor, set the heating temperature to 40°C, and then slowly add the high-efficiency surfactant (powder) under the action of an electric stirrer, mix and dissolve completely to obtain a water phase;

[0064] S3: adding coconut oil, coconut oil alkanolamide and vinyl imidazole to the reactor in sequence at a stirrer speed of 3000 r / min, stirring and mixing evenly, setting the reactor temperature to 55°C, and stirring continuously for 30 min;

[0065] S4: Turn on the homogenizing shearing emulsifier equipped with the reactor, set the speed to 12000r / min for homogenizing shearing, and the emulsion flows back to the reactor after shearing. The whole emulsion system is circulated for 1h to obtain a Pickering-like nanoemulsion with high effective content and high stability. After natural cooling, the material is discharged, which is the nano oil detergent.

[0066] Embodiment 1:

[0067] A pressure-driven integrated emulsion thickener and a preparation method thereof are prepared from 100 parts by weight of the following raw materials:

[0068] Main chain structure monomer-acrylamide 15 parts, sodium acrylate 10 parts, salt-resistant monomer-AMPS 2.5 parts, amphiphilic macromonomer-citronellol maleic acid monoester carboxylic acid ammonium 0.5 parts, polymerizable surfactant monomer-lauryl polyoxyethylene ether maleic acid trimethyl ammonium chloride 1.5 parts, biological solvent-coconut oil 32 parts, emulsifier-coconut oil acid alkanolamide 3 parts, polymerization accelerator-diethylenetriaminepentaacetic acid (DTAP) 0.08 parts, pH value regulator-liquid caustic soda 1 part, initiator-azobisisopropylimidazoline hydrochloride 0.05 parts, nano oil detergent 10 parts and the balance deionized water;

[0069] The main preparation process of the pressure-driven integrated emulsion thickener is as follows: the main chain structure monomer, functional monomer, polymerizable surfactant monomer, polymerization accelerator, and pH value regulator are added to a raw material tank with a temperature control range of less than 25° C. and stirred to completely dissolve to prepare a reaction water phase; the temperature of the reactor is controlled within 25° C., and under nitrogen flow conditions, the biological solvent and emulsifier are added to the reactor and stirred evenly, and the reaction water phase is slowly pumped into the reactor under a high-speed stirring condition of 8000 r / min to prepare a reaction emulsion phase; while maintaining nitrogen flow and medium-speed stirring at 1000 r / min, an initiator solution is added to the reactor using a micro-injection pump, The adding time is controlled within 60 minutes. After the initiator is added, the nitrogen is stopped, the stirring speed is controlled at 600 r / min, and the system is allowed to react continuously for 3 hours. When the temperature in the reactor reaches the temperature peak 0.5 hours later, the stirring speed is reduced to 300 r / min, and according to the temperature in the reactor, hot water is passed through the jacket of the reactor to increase the temperature of the reactor by 5°C, and the temperature is kept for 1.5 hours. Under continuous stirring, the nano-detergent is added to the reactor and mixed evenly to obtain a pressure-driven integrated emulsion thickener, numbered A1. The emulsion thickener is pumped into a finished product storage tank, slowly stirred and naturally cooled to room temperature, and finally discharged and packaged.

[0070] Embodiment 2:

[0071] A pressure-driven integrated emulsion thickener and a preparation method thereof are prepared from 100 parts by weight of the following raw materials:

[0072] Main chain structure monomer-acrylamide 18 parts, sodium methacrylate 8 parts, salt-resistant monomer-N-vinyl pyrrolidone 2.5 parts, amphiphilic macromonomer-hexadecyl allyl succinic acid diester sulfonate 0.5 parts, polymerizable surfactant monomer-diethyl maleate-based didodecyl dimethyl ammonium chloride 2 parts, biological solvent-limonene 35 parts, emulsifier-citric acid fatty acid ester 3.5 parts, polymerization accelerator-sodium polyphosphate 0.1 parts, pH value regulator-liquid alkali 2 parts, initiator-2,2'-azobisisobutylamidine dihydrochloride 0.08 parts, nano oil detergent 8 parts and the balance deionized water;

[0073] The main preparation process of the pressure-driven integrated emulsion thickener is as follows: the main chain structure monomer, functional monomer, polymerizable surfactant monomer, polymerization accelerator, and pH value regulator are added to a raw material tank with a temperature control range of less than 25° C. and stirred to completely dissolve to prepare a reaction water phase; the temperature of the reactor is controlled within 25° C., and under nitrogen flow conditions, the biological solvent and emulsifier are added to the reactor and stirred evenly, and the reaction water phase is slowly pumped into the reactor under a high-speed stirring condition of 8500r / min to prepare a reaction emulsion phase; while maintaining nitrogen flow and medium-speed stirring at 1000r / min, an initiator solution is added to the reactor using a micro-injection pump, The adding time is controlled at 60 minutes. After the initiator is added, the nitrogen is stopped, and the stirring speed is controlled at 600 r / min, so that the system continues to react for 2.5 hours. When the temperature in the reactor reaches the temperature peak 0.5 hours later, the stirring speed is reduced to 400 r / min, and according to the temperature in the reactor, hot water is passed through the jacket of the reactor to increase the temperature of the reactor by 8°C, and the temperature is kept for 2 hours. Under continuous stirring conditions, the nano-detergent is added to the reactor and mixed evenly to obtain a pressure-driven integrated emulsion thickener, No. A2. The emulsion thickener is pumped into a finished product storage tank, slowly stirred and naturally cooled to room temperature, and finally discharged and packaged.

[0074] Embodiment 3:

[0075] A pressure-driven integrated emulsion thickener and a preparation method thereof are prepared from 100 parts by weight of the following raw materials:

[0076] Main chain structure monomer-methacrylamide 19.5 parts, acrylic acid 6.5 parts, salt-resistant monomer-sodium styrene sulfonate 3 parts, amphiphilic macromonomer-amphiphilic polyurethane acrylate 0.6 parts, polymerizable surfactant monomer-alkyl polyoxyalkylene ether sulfate 2 parts, biological solvent-glycerol derivative 35 parts, emulsifier-glycerol triisostearate 4 parts, polymerization accelerator-ethylenediaminetetraacetic acid (EDTA) 0.1 parts, pH value regulator-NaOH 4 parts, initiator-benzoyl peroxide 0.1 parts, nano oil detergent 8 parts and the balance deionized water;

[0077] The main preparation process of the pressure-driven integrated emulsion thickener is as follows: the main chain structure monomer, functional monomer, polymerizable surfactant monomer, polymerization accelerator, and pH value regulator are added to a raw material tank with a temperature control range of less than 25°C and stirred to dissolve completely to prepare a reaction water phase; the temperature of the reactor is controlled within 30°C, and under nitrogen flow conditions, the biological solvent and emulsifier are added to the reactor and stirred evenly, and the reaction water phase is slowly pumped into the reactor under a high-speed stirring condition of 8500r / min to prepare a reaction emulsion phase; while maintaining nitrogen flow and medium-speed stirring at 1000r / min, a micro-injection pump is used to add an initiator solution to the reactor , the addition time is controlled at 45min. After the initiator is added, the nitrogen is stopped, the stirring speed is controlled at 500r / min, and the system is allowed to react for 3h. When the temperature in the reactor reaches the temperature peak 0.5h later, the stirring speed is reduced to 400r / min, and according to the temperature in the reactor, hot water is passed through the jacket of the reactor to increase the temperature of the reactor by 6°C, and the temperature is kept for 2h. Under continuous stirring, the nano-detergent is added to the reactor and mixed evenly to obtain a pressure-driven integrated emulsion thickener, No. A3. The emulsion thickener is pumped into the finished product storage tank, slowly stirred and naturally cooled to room temperature, and finally discharged and packaged.

[0078] Embodiment 4:

[0079] A pressure-driven integrated emulsion thickener and a preparation method thereof are prepared from 100 parts by weight of the following raw materials:

[0080] Main chain structure monomer-acrylamide 18 parts, acrylic acid sodium salt 6 parts, salt-resistant monomer-sodium styrene sulfonate 2.5 parts, amphiphilic macromonomer-2-methylpropanesulfonic acid-2-acrylate hexadecyl ester 0.5 parts, polymerizable surfactant monomer-sulfonated fatty acid acrylate sodium salt 1.8 parts, biological solvent-castor oil 34 parts, emulsifier-castor oil polyoxyethylene ether dioleate 3.5 parts, polymerization accelerator-sodium citrate 0.1 parts, pH value adjuster-Na 2 CO 3 4 parts, initiator-2,2'-azobisisobutylamidine dihydrochloride 0.05 parts, nano oil detergent 10 parts and the balance deionized water;

[0081] The main preparation process of the pressure-driven integrated emulsion thickener is as follows: the main chain structure monomer, functional monomer, polymerizable surfactant monomer, polymerization accelerator, and pH value regulator are added to a raw material tank with a temperature control range of less than 25° C. and stirred to completely dissolve to prepare a reaction water phase; the temperature of the reactor is controlled within 30° C., and under nitrogen flow conditions, the biological solvent and emulsifier are added to the reactor and stirred evenly, and the reaction water phase is slowly pumped into the reactor under a high-speed stirring condition of 8500 r / min to prepare a reaction emulsion phase; while maintaining nitrogen flow and medium-speed stirring at 1000 r / min, an initiator solution is added to the reactor using a micro-injection pump, The adding time is controlled at 60 minutes. After the initiator is added, the nitrogen is stopped, the stirring speed is controlled at 600 r / min, and the system is allowed to react continuously for 2.5 hours. When the temperature in the reactor reaches the temperature peak 0.5 hours later, the stirring speed is reduced to 400 r / min, and according to the temperature in the reactor, hot water is passed through the jacket of the reactor to increase the temperature of the reactor by 8°C, and the temperature is kept for 2 hours. Under continuous stirring, the nano oil detergent is added to the reactor and mixed evenly to obtain a pressure-driven integrated emulsion thickener, No. A4. The emulsion thickener is pumped into a finished product storage tank, slowly stirred and naturally cooled to room temperature, and finally discharged and packaged.

[0082] Test example:

[0083] In the above-mentioned Examples 1 to 4, four products A1, A2, A3 and A4 are obtained respectively, among which A1, A2 and A4 have been mass-produced by Sichuan Shenhe New Material Technology Co., Ltd. The following is an evaluation and comparison of the relevant performances of the products obtained in several examples and the prepared reservoir transformation fluids.

[0084] Test Example 1: Stability of pressure-driven integrated emulsion thickener

[0085] Four groups of samples, A1, A2, A3 and A4, were compared. The products were placed in 50 ml centrifuge tubes and centrifuged at 3000 r / min for 10 min to simulate the emulsion state after long-term standing. The volume of the upper clear liquid was tested, and the stratification and precipitation were observed. The test results are shown in Table 1.

[0086] Figure 1 The product of the integrated pressure-drive emulsion thickener A1 and the prepared fracturing fluid of Example 1 in Test Example 1 is shown in the left picture. The uniform, milky white viscous emulsion thickener is shown, and the prepared reservoir transformation fluid is shown in the right picture.

[0087] Table 1 Stability test results of pressure-driven integrated emulsion thickener

[0088]

[0089]

[0090] As can be seen from Table 1, the four products have moderate bulk viscosity and good fluidity. Except for product A3, the other products have no stratification, no precipitation, no micelles, the emulsion is still milky white, and has good stability.

[0091] Test Example 2: Dissolution performance of pressure-driven integrated emulsion thickener

[0092] Product A1 was selected and prepared with tap water to test the swelling properties of different dosages of pressure-driven integrated emulsion thickeners, including the normal drawing time of the solution (i.e., dissolution time), the apparent viscosity of the solution, and the state of the solution. The test results are shown in Table 2.

[0093] Table 2 Swelling properties of different dosages of pressure-driven integrated emulsion thickener in clean water

[0094]

[0095]

[0096] Test Example 3: Resistance reduction performance of reservoir reforming fluid for tight oil reservoirs

[0097] Product A1 was used to prepare different reservoir reconstruction fluids, including 0.05% emulsion thickener for low viscosity, 0.2% emulsion thickener, and 0.4% emulsion thickener for medium viscosity. The pressure drop of the reservoir reconstruction fluid through the pipeline at different flow rates was tested using an indoor flow loop friction test system (10 mm pipeline was selected for the pipeline), which is the friction resistance. Based on the displacement-pressure drop data, the drag reduction rate curve was fitted, as shown in Fig. Figure 2 , the resistance reduction rate of reservoir transformation fluid under specified displacement is obtained by fitting, and the results are shown in Table 3.

[0098] like Figure 2 As shown, it is the drag reduction rate curve of the product of Example 1. The results show that: with the increase of displacement, the drag reduction rate of the reservoir transformation fluid continues to increase and gradually tends to be stable. Finally, the drag reduction rates corresponding to the final curves are all over 70%.

[0099] Table 3 Fitting results of resistance reduction rate of reservoir transformation fluids of several formulations

[0100]

[0101] The experiment shows that within a certain range, the higher the displacement, the higher the resistance reduction rate of the reservoir transformation fluid. The fitting results show that at an extremely low dosage of 0.05% of the emulsion thickener, the resistance reduction rate of the reservoir transformation fluid can reach more than 70%. When the emulsion thickener dosage is 0.2%, the indoor fitting displacement is 3.5m 3 / h, the drag reduction rate of the fracturing fluid is close to 75%, which fully reflects the excellent drag reduction performance of the reservoir transformation fluid.

[0102] Test Example 4: Temperature and shear resistance of reservoir reforming fluid for tight oil reservoirs

[0103] In order to fully simulate the on-site online construction conditions, the rheometer test conditions were set in advance. An appropriate amount of water was taken from a beaker, and product A1 was added to the tap water in proportion. After stirring for 3 minutes, the mixture was poured into the rheometer test cylinder to conduct temperature and shear resistance tests on the reservoir transformation fluid.

[0104] Test equipment and test conditions:

[0105] RS6000 rheometer, rotor PZ38;

[0106] At specified temperature, 170s -1 Continuous shearing for 90 min under the same conditions.

[0107] The test formula and test data statistics are shown in Table 4.

[0108] Rheological test curves of reservoir reconstruction fluids with different formulations are shown in Figure 3 .

[0109] like Figure 3 The results show that with the extension of the test time, the viscosity of the reservoir transformation fluid under several formulations has a slow downward trend. When the temperature reaches the set value 30 minutes after the test, the viscosity of the reservoir transformation fluid basically remains in a relatively constant numerical range, which fully demonstrates the good temperature and shear resistance of the fracturing fluid.

[0110] Table 4 Test on temperature and shear resistance of reservoir transformation fluid

[0111] Recipe ingredients Test temperature, °C Initial viscosity, mPa·s Viscosity after shear, mPa·s 0.8% emulsion thickener 90 58.5 50.72 1.0% emulsion thickener 110 84.7 56.8 1.2% emulsion thickener 120 106.6 57.53

[0112] Experiments show that the reservoir reforming fluids at different temperatures -1 After 90 minutes of continuous shearing, the viscosity remained above 50 mPa·s, and this type of fracturing fluid has excellent sand-carrying performance when its apparent viscosity is above 25 m mPa·s. The experiment also shows that the reservoir transformation fluid has excellent temperature and shear resistance.

[0113] Test Example 5: Sand Suspension Performance of Reservoir Reform Fluid for Tight Oil Reservoirs

[0114] The A1 product in Example 1 was used for large-scale field application. The reservoir reforming fluid had good sand carrying performance and the sand adding construction was smooth. The suspended sand state of the reservoir reforming fluid used for tight oil reservoirs during field construction was shown in Figure 1. Figure 4 .

[0115] like Figure 4 The results showed that during the construction process, when 30 / 50 ceramsite proppant was added at a sand ratio of 26%, the mixed sand liquid sample was poured into a plastic bottle, and after standing for 5 minutes, the proppant had almost no sedimentation, indicating that the reservoir reconstruction fluid had excellent sand suspension performance.

[0116] Test Example 6: Low-damage performance of reservoir reforming fluid for tight oil reservoirs

[0117] Different formulations of tight oil reservoir reconstruction fluids were prepared using product A1, and different proportions of breakers were added and stirred evenly. After that, the mixture was placed in an oven, and the applicable temperature of the formulation was set. The breakers were broken for 2 hours. After cooling, the apparent viscosity, surface tension, and residue content of the breakers were measured, and the damage rate of the breakers to the core matrix permeability was tested. The test results are shown in Table 5.

[0118] Table 5 Statistics on the damage performance of tight oil reservoir reforming fluid degelling fluid

[0119]

[0120] The above table data show that the reservoir reforming fluid has low viscosity, extremely low residue content (even undetectable), and low surface tension, which can significantly reduce the damage to the reservoir matrix permeability. The tested damage rate is below 20%.

[0121] Test Example 7: Wetting reversal performance of reservoir reforming fluid and gel-breaking fluid for tight oil reservoirs

[0122] Shale oil, tight oil and other reservoirs are highly oil-wet. In order to improve the recovery rate of crude oil, changing the wettability of the core surface is one of the effective ways. Product A1 was used to prepare the reservoir transformation fluid and break the gel (0.4% pressure drive integrated thickener + 0.03% gel breaker), and the core surface contact angle test was carried out and compared with clean water. The experimental results are shown in Figure 5 .

[0123] like Figure 5 The results show that after treatment with the reservoir reforming fluid degelling fluid of Example 1 (A1), the rear contact angle of the core is significantly reduced, and the core surface is changed from oil-wet to water-wet, which is conducive to imbibition and thus promotes crude oil discharge. Figure 5 (a) is a schematic diagram before the gel-breaking liquid treatment; Figure 5 (b) is a schematic diagram after treatment with degelling liquid.

[0124] Test Example 8: Oil washing performance of reservoir reforming fluid and gel-breaking fluid for tight oil reservoirs

[0125] ① Product A1 was used to prepare reservoir transformation fluid and break gel (0.4% pressure-drive integrated emulsion thickener + 0.03% breaker), and conventional polyacrylamide emulsion thickener was used to prepare conventional fracturing fluid and break gel (0.4% conventional emulsion drag reducer + 0.03% breaker) as a control.

[0126] ② Mix quartz sand and simulated crude oil (crude oil: kerosene = 2:1) at a certain temperature to simulate the oil absorption state of rock. Take the mixture and place it in two test tubes respectively. Add the above-mentioned degelling liquid to the mixture, stir it evenly, and let it stand at the specified temperature for 1 hour to observe the oil absorption of the degelling liquid. The experimental phenomenon is shown in Figure 6 .

[0127] Figure 6 (a) is a schematic diagram of the oil washing effect of conventional fracturing fluid and gel breaking fluid; Figure 6 (b) is a schematic diagram of the oil washing effect of the reservoir transformation fluid degelling liquid prepared with 0.4% pressure-driven integrated emulsion thickener.

[0128] The results show that the oil washing effect of the reservoir reforming fluid degelling liquid of Example 1 (A1) for tight oil reservoirs is significantly better than that of the conventional fracturing fluid degelling liquid.

[0129] Test Example 9: Oil displacement performance of reservoir reforming fluid and gel-breaking fluid for tight oil reservoirs

[0130] Product A1 was used to prepare reservoir transformation fluids of different formulations for tight oil reservoirs: low viscosity: 0.1% pressure-driven integrated emulsion thickener + 0.03% breaker, medium viscosity: 0.4% pressure-driven integrated emulsion thickener + 0.03% breaker, high viscosity: 0.8% pressure-driven integrated emulsion thickener + 0.05% breaker, to prepare breaker fluid.

[0131] Use density 0.81g / cm 3 After the three groups of dense cores (permeability ≤ 1mD) were saturated with simulated crude oil, the three groups of cores and three groups of degelling liquid were placed in the infiltration bottle respectively. After 24 hours, the crude oil displaced by infiltration was observed. Figure 7 .

[0132] like Figure 7 The results show that Figure 7 (a) shows the oil displacement effect of 0.1% pressure-driven integrated emulsion thickener breaker; Figure 7 (b) shows the oil displacement effect of 0.4% pressure-driven integrated emulsion thickener breaker; Figure 7 (c) is the oil displacement effect of 0.8% pressure-driven integrated emulsion thickener breaker. It can be seen that with the increase in the amount of pressure-driven integrated emulsion thickener, more crude oil is displaced from the core, indicating that the reservoir transformation fluid breaker has a stronger ability to absorb and displace oil.

[0133] Test Example 10: Optimization of well soaking time for the production enhancement measure provided by the present invention

[0134] The target reservoir core was used to carry out the imbibition displacement oil displacement experiment of the reservoir transformation fluid of the present invention, and the relationship between the well-insertion time and the total amount of fluid entering the well was simulated and a curve of the relationship between the reasonable well-insertion time and the total amount of fluid entering the well was drawn (see Figure 8 ).

[0135] like Figure 8 The results show that the reasonable shut-in time for pressure-drive integration in tight oil reservoirs using the product of the present invention is 15-45 days.

[0136] Application Examples

[0137] The integrated pressure-drive emulsion thickener provided by the present invention is used in an example of integrated online fracturing construction of dense sandstone.

[0138] Since 2023, the tight oil reservoir reforming fluid provided by the present invention has been used to perform fracturing in three horizontal wells (40 sections) in the tight oil reservoir of the Qingyang block of Liaohe Oilfield. The reservoir temperature is 50-60°C, and the total liquid volume in a single well is 20,000-40,000m 3 , single stage liquid volume 1500~2500m 3 , single stage sand adding 160~260m 3 / min, the highest sand ratio was 31%, the liquid performance test was normal, the construction was smooth, and the well was kept shut down for 15 to 40 days after the construction was completed, generally achieving good production increase effects.

[0139] For example, in the XX-HXXX well, the vertical depth of the horizontal section is 1823 to 1846 meters. The total length of the horizontal section of the well is 1452 meters, which is divided into 18 sections for fracturing, and the average length of a single section is 80.7 meters. The construction uses tight oil reservoir transformation fluid for pressure-driven integrated production increase operations to promote the maximum transformation of the reservoir volume, while improving the oil washing and permeation and oil displacement capabilities of the fracturing fluid, and increasing the single well production and crude oil recovery rate. The low-viscosity + high-viscosity front-stage plug is used to create fractures, and the high-viscosity sand-carrying support is used to increase the complexity of the fractures. Low viscosity: 0.05%~0.1% pressure-driven integrated emulsion thickener + 0.01% breaker, medium viscosity: 0.4%~0.5% pressure-driven integrated emulsion thickener High viscosity + 0.03% breaker: 0.8%~1.0% pressure-driven integrated emulsion thickener + 0.05% breaker (adjust the amount of emulsion thickener in real time according to the fracturing construction situation)

[0140] The displacement of the 17th stage fracturing construction of the positive XX-HXXX well is 14 cubic meters, the general construction pressure is 18-45MPa, the maximum sand ratio is 24%, the designed liquid volume is 1829.2 cubic meters, the actual liquid volume is 1604.57 cubic meters, the designed sand addition is 173 cubic meters, the actual sand addition is 173.02 cubic meters, the pump stop pressure is 8MPa, and the construction curve of the embodiment (the 17th stage) is shown in Fig. 9 .

[0141] Based on the performance evaluation and field implementation cases of integrated pressure-drive emulsion thickener and reservoir transformation fluid, the present invention provides a reservoir transformation fluid and integrated pressure-drive production increase method for tight oil reservoirs. The low-damage reservoir transformation fluid with drag reduction, sand carrying and oil displacement functions is used for integrated pressure-drive production increase operations, which simplifies the fracturing and oil displacement processes, shortens the operation time, saves construction costs, effectively improves the transformation effect of tight oil reservoirs, and increases crude oil recovery. This technology has great advantages and application prospects in the integrated pressure-drive construction of unconventional oil reservoirs such as shale oil and tight oil.

[0142] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A reservoir reforming fluid for tight oil reservoirs, characterized in that: The total weight fraction is 100%, including: 0.05%-1.2% pressure-driven integrated emulsion thickener, 0-0.1% breaker, and the balance is water; The pressure-driven integrated emulsion thickener is prepared from the following raw materials in a total mass fraction of 100 parts: 24-26 parts of main chain structure monomers, 3-5 parts of functional monomers, 1.5-2 parts of polymerizable surfactant monomers, 32-35 parts of biological solvents, 3-4 parts of emulsifiers, 0.05-0.1 parts of polymerization accelerators, 1-4 parts of pH value regulators, 0.03-0.1 parts of initiators, 6-10 parts of nano oil wash agents, and the balance is deionized water; The breaker is ammonium persulfate; The main chain structure monomer is a mixture of agent A and agent B in a mass ratio of 3:1-3:2; The agent A includes any one of acrylamide and methacrylamide; The agent B comprises one of acrylic acid, sodium acrylate, potassium acrylate, methacrylic acid or sodium methacrylate; The functional monomers are composed of salt-resistant monomers and amphiphilic macromonomers, with a mass ratio of 5:1; The salt-resistant monomer is any one of AMPS sodium salt, sodium styrene sulfonate, and N-vinyl pyrrolidone; The amphiphilic macromonomer is one of citronellol maleic acid monoester carboxylic acid ammonium, methyl methacrylate-b-poly N,N-dimethylacrylamide, amphiphilic polyurethane acrylate, sodium hexadecyl allyl succinic acid diester sulfonate or hexadecyl 2-methylpropanesulfonic acid-2-acrylate; The polymerizable surfactant monomer is one of methacryloyloxyethyl dodecyl dimethyl ammonium bromide, diethyl maleate didodecyl dimethyl ammonium chloride, lauryl alcohol polyoxyethylene ether maleic acid trimethyl ammonium chloride, nonylphenol polyoxyethylene ether maleic acid ethyl trimethyl ammonium chloride, allyl ether sulfate, and sulfonated fatty acid acrylate sodium salt.

2. A reservoir reforming fluid for tight oil reservoirs according to claim 1, characterized in that: The biosolvent is one of coconut oil, palm oil, castor oil, limonene or terpene compounds; The emulsifier is one of coconut oil alkanolamide, fatty acid polyoxyethylene ester, glyceryl triisostearate, glycerol fatty acid ester, alginate, tetrapolyricinoleic acid ester, castor oil polyoxyethylene ether dioleate or citric acid fatty acid ester.

3. The reservoir reforming fluid for tight oil reservoirs according to claim 1, characterized in that: The polymerization accelerator is one of diethylenetriaminepentaacetic acid, ethylenediaminetetraacetic acid, sodium citrate, sodium gluconate or sodium polyphosphate; The pH regulator is one of NaOH, liquid alkali or Na2CO3.

4. The reservoir reforming fluid for tight oil reservoirs according to claim 1, characterized in that: The initiator is one of 2,2'-azobisisobutylamidine dihydrochloride, azobisisopropylimidazoline hydrochloride, azobisisobutyronitrile or benzoyl peroxide.

5. The reservoir reforming fluid for tight oil reservoirs according to claim 1, characterized in that: The preparation method of the nano oil washing agent is as follows: S1: using hexadecyl tertiary amine, epichlorohydrin and aminosulfonic acid as main raw materials to carry out ring-opening reaction, sulfonation reaction, distillation, vacuum filtration, washing and purification, and vacuum drying to obtain a surfactant for nano oil detergent; the surfactant is in powder form; S2: Add deionized water to the reactor, set the heating temperature to 30-45°C, and then slowly add the surfactant under the action of an electric stirrer, mix thoroughly and dissolve completely to obtain an aqueous phase; S3: under the condition of a stirrer speed of 2500-3000 r / min, coconut oil, coconut oil alkanolamide and vinyl imidazole were added to the reactor in sequence, and after stirring and mixing evenly, the temperature of the reactor was set to 55-65° C., and stirring was continued for 30 minutes; S4: Turn on the homogenizing shearing emulsifier equipped with the reactor, set the speed to 10000-12000r / min for homogenizing shearing, and the emulsion flows back to the reactor after shearing. The whole emulsion system is circulated for 1-1.5h to obtain a Pickering-like nanoemulsion, and the material is discharged after natural cooling, which is the nano oil detergent.

6. The reservoir reforming fluid for tight oil reservoirs according to claim 1, characterized in that: The main preparation process of the pressure-driven integrated emulsion thickener is as follows: S1. Add the main chain structure monomer, functional monomer, polymerizable surfactant monomer, polymerization accelerator, and pH adjuster into a raw material tank with a temperature controlled within 25° C. and stir to dissolve completely to prepare a reaction water phase; S2, controlling the temperature of the reactor within 25-30° C., adding the biosolvent and emulsifier into the reactor under nitrogen flow and stirring evenly, and slowly pumping the reaction water phase into the reactor under high-speed stirring conditions of 8000-8500 r / min to prepare a reaction emulsion phase; S3, maintaining nitrogen flow and medium-speed stirring at 800-1000r / min, using a micro-injection pump to add the initiator solution to the reactor, the addition time is controlled at 45-60min, after the initiator is added, stop passing nitrogen, control the stirring speed at 500-600r / min, and allow the system to react for 2-3h; when the temperature in the reactor reaches the peak temperature 0.5h later, reduce the stirring speed to 300-400r / min, and according to the temperature in the reactor, pass hot water to the reactor jacket to increase the temperature of the reactor by 5-8°C, and keep warm for 1.5-2h; S4, adding nano oil washing agent to the reaction kettle under continuous stirring and mixing evenly, thus obtaining a pressure-driven integrated emulsion thickener, S5. Pump the emulsion thickener into the finished product storage tank, slowly stir and cool naturally to room temperature, and finally discharge and package.

7. Use of the reservoir reforming fluid for tight oil reservoirs as claimed in claim 1 in a pressure-drive integrated production enhancement method for tight oil reservoirs, characterized in that: The steps include: S1. Select a tight oil or shale oil well, and optimize the formulation of the reservoir transformation fluid as claimed in claim 1 suitable for target reservoir fracturing and oil displacement according to the reservoir conditions and physical property parameters of the target well, and evaluate its corresponding performance; S2. Divide the construction well into sections or layers, and conduct integrated design of fracturing and drive, mainly including fracturing scale design and construction parameter design, and use the target reservoir core to conduct the reservoir transformation fluid permeation displacement oil displacement experiment, and optimize the well shut-in time after fracturing, which is controlled within 15-45 days; S3. Carry out integrated sand fracturing construction, do a good job in on-site quality control of the reservoir transformation fluid, achieve large-scale sand addition, and ensure smooth construction; S4. After the fracturing operation is completed, the well is shut down and the well is kept warm according to the designed time. When the well is opened, the sand control and rapid flowback is gradually changed to pressure control flowback to achieve oil recovery by flowback fluid.

Images