Activity-controllable displacement mining method for thickened oil

Abstract

The invention belongs to the technical field of thickened oil development, and particularly relates to a displacement exploitation method with controllable thickened oil activity. According to the displacement mining method with the controllable heavy oil activity, firstly, fracture development condition analysis is conducted on oil reservoir crude oil reserves, then different slugs are adopted for heavy oil mining according to the fracture development condition, and a water plugging agent, a composite viscosity reducer and a CO2 synergistic huff and puff mode and a CO2 response type alkyl amidine surfactant are adopted in the different slugs; the plugging agent can generate good water channeling plugging, viscosity reduction, gas channeling plugging and other effects, has good oil displacement capacity, can greatly improve the recovery efficiency, and is suitable for heavy oil recovery under harsh conditions.

Description

Technical Field

[0001] The invention belongs to the technical field of heavy oil development, and in particular relates to a heavy oil displacement production method with controllable activity. Background Art

[0002] With the increase in oil consumption, the decrease in ordinary light oil resources, and the increase in development difficulty, the development of heavy oil reservoirs has attracted more and more attention. Through more than ten years of technical research, heavy oil thermal recovery technology has achieved a leap from single steam throughput to steam drive, steam-assisted gravity drainage (SAGD) and air-fire drive development technology, maintaining a stable production of tens of millions of tons for 25 consecutive years. However, with the in-depth application of thermal recovery development, its high energy consumption defects in underground oil production and ground gathering and transportation have become increasingly prominent. On this basis, heavy oil cold recovery technology has become a research hotspot. Heavy oil has the characteristics of high acidity, high saturated hydrocarbon content, high non-hydrocarbon / asphaltene content, extremely poor fluidity, and extremely high difficulty in mining. The effective development of this type of deep ultra-heavy oil is of great significance to stabilizing the heavy oil production of PetroChina.

[0003] Various gas drive technologies and chemical drive technologies are important measures for heavy oil production. Invention patent CN102268983B proposes to use steam huff and puff and steam-assisted gravity drainage to optimize the location and operating parameters of wells, thereby improving the recovery rate of shallow oil reservoirs. However, this method is only applicable to shallow reservoirs with a depth of no more than 1,500 meters, and is not applicable to deep reservoirs above 2,800 meters; at the same time, steam injection will lead to problems such as heat loss, sand production, and casing damage in oil wells. Invention patent CN115368884B proposes to use a ternary chemical composite oil recovery system of anionic polyacrylamide + modified petroleum sulfonate surfactant + weak alkali to improve the efficiency of high-condensation crude oil production by reducing the interfacial tension and viscosity of high-condensation crude oil. However, this method is only applicable to crude oil with a wax content of 20-40%, and is not applicable to higher-condensation-point heavy oil with a wax content of more than 40%; at the same time, long-term use of a weak alkali system will also cause corrosion to the wellbore and pipeline. Invention patent CN104329066A proposes to use microorganisms and CO2 segmented plug composite huff-and-puff to reduce viscosity and interfacial tension, thereby improving the efficiency of heavy oil recovery. However, this method is only applicable to reservoirs with oil well temperature less than 100°C, crude oil viscosity less than 5000mPa.s, and formation mineralization less than 50000mg / L. It is not applicable to deep reservoirs with well-developed fractures, severe edge and bottom water coning, and prone to CO2 gas channeling, and reservoirs with temperatures greater than 100°C and crude oil viscosity greater than 5000mPa.s.

[0004] In this context, combined with the current status of CCUS-EOR technology in major domestic oil fields, the adoption of CO2 composite huff-and-puff technology is an effective and efficient heavy oil production measure. However, the viscosity difference between CO2 and heavy oil is large, which easily leads to fingering, resulting in unsatisfactory development results, specifically manifested as: low production and low energy coexist with crossflow, and uneven use of remaining oil; conventional plugging systems cannot adapt to the acidic environment of CO2; and single chemical flooding agents and traditional binary flooding systems have high water-oil flow ratios and limited expansion of swept volume, which cannot meet the requirements for efficient development of heavy oil reservoirs. Therefore, it is necessary to continue to explore new composite displacement technologies. Summary of the invention

[0005] In view of the above technical problems, the present invention provides a displacement mining method with controllable heavy oil activity. The displacement mining method provided by the present invention adopts a heavy oil composite mining technology with "water plugging + composite viscosity reduction huff and puff + gas channeling plugging" as the core. Through segmented plug injection and classified management mode, it has wide adaptability to different types of heavy oil, can carry out controllable mining of deep heavy oil reservoirs, achieve the effect of improving fluidity, can respond to CO2 acidic environment, expand the sweep coefficient of displacement phase, and improve the recovery rate of heavy oil reservoirs, which is suitable for heavy oil development.

[0006] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions: The present invention provides a displacement production method for heavy oil with controllable activity, which specifically comprises the following steps: Step 1: Analyze the fracture development of the oil layer structure; Step 2: Implement multiple plugs according to the development of fractures. If the porosity is greater than 20% and the permeability is greater than 100 mD, implement the following first plug, second plug and third plug; if the porosity is ≤20% or the permeability is ≤100 mD, implement the following second plug and third plug; The first plug is a plugging plug: a high-strength resin glue solution is used to plug the large pores, and the second plug is performed when the fluctuation value of the pressure rise in the pore is ≥30%; The second section plug is a composite viscosity reducer + CO2 injection main section plug: the composite viscosity reducer is injected at a rate of 5-7m 3 / h After the injection is completed, the 3 / h displacement injection of CO2 for composite huff and puff; the composite viscosity reducer contains 1%~2% graphene and 0.1%~0.2% macromolecular viscosity reducer, and the solvent is water; the macromolecular viscosity reducer is a mixture of alkyl glycoside viscosity reducer and low molecular weight polymer surfactant in a mass ratio of (5~3):1; the low molecular weight polymer surfactant is a copolymer of acrylamide and sodium acrylamide alkyl sulfonate or a copolymer of acrylamide and sodium allyl sulfonate, with a molecular weight of 5 to 8 million; the injection amount of the composite viscosity reducer is calculated according to the formula Q=oil well production×control time÷tubing length; The third plug is an active controllable alkyl amidine surfactant plug: a 0.1% to 0.3% wt aqueous solution of a CO2-responsive alkyl amidine surfactant is used at 6 to 8 m 3 / h displacement injection to perform foam plugging on the gas channel; the CO2 responsive alkyl amidine surfactant is injected immediately after the CO2 is injected into the second section plug; when there is no CO2 gas channeling, the injection amount of the CO2 responsive alkyl amidine surfactant is 1-1.2 times of the CO2 injection amount, and when there is CO2 gas channeling, the injection amount of the CO2 responsive alkyl amidine surfactant is 1.3-1.5 times of the CO2 injection amount.

[0007] In step 1, if the porosity is greater than 20% and the permeability is greater than 100mD, it means that large pores are developed, and the oil layer system with such fracture development is a layer system that is prone to water channeling; if the porosity is less than 20% or the permeability is less than 100mD, it means that no large pores are developed, and the oil layer system with such fracture development is a layer system without water channeling, the first plug can be omitted, and the second and third plugs can be implemented directly.

[0008] In the second plug, the control time refers to the effective action time of the viscosity reducer in the formation.

[0009] This displacement production method first conducts a reservoir dynamic analysis of the crude oil reserves of the oil layer to clarify the crude oil distribution and the oil layer structure. According to the development of fractures in the oil layer structure, different plugs are designed to produce heavy oil, so as to achieve controllable production activity. In view of the large difference in viscosity between CO2 and heavy oil, fingering is very likely to occur, resulting in low production, low energy and crossflow, uneven utilization of residual oil, the inability of conventional plugging systems to adapt to the CO2 acidic environment, and the inability of traditional oil recovery systems to meet the requirements for efficient development of heavy oil reservoirs. In the first section of the plug, the present invention uses high-strength resin glue to block the water channeling channel, which can avoid the loss of main section plug reagents caused by water channeling and improve the subsequent adjustment and displacement effect; in the second section of the plug, the present invention adopts a composite viscosity reducer + CO2 synergistic throughput mode to improve the viscosity reduction effect of heavy oil, wherein the composite viscosity reducer can improve the emulsification dispersibility and expand the swept volume; in the third section of the plug, the CO2 responsive alkyl amidine surfactant further reduces the interfacial tension, and at the same time foams and blocks the CO2 gas channeling channel, greatly improving the CO2 utilization rate, and can also be used as an oil recovery agent to further improve the heavy oil recovery efficiency.

[0010] This displacement production method uses a combination of multi-stage plugs, through the synergistic effect of "water plugging, viscosity reduction, stripping, and energy enhancement", and an active controllable production method that combines "plugging, adjustment, and drive" to greatly improve the recovery rate of heavy oil reservoirs.

[0011] For layers with severe CO2 gas channeling, the effect of plugging the gas channeling channel can be improved by increasing the amount of CO2-responsive alkyl amidine surfactant in the third plug (not exceeding 0.3% alkyl amidine surfactant). When the concentration of CO2-responsive alkyl amidine surfactant is greater than 0.3%wt, the plugging and oil recovery effects will not increase, and the cost will increase; when the concentration of alkyl amidine is less than 0.1%wt, the foaming volume will be insufficient and the plugging effect will be unsatisfactory.

[0012] Preferably, the high-strength resin glue in the first section plug adopts a resin glue whose main components are N, N-methylenebisacrylamide and acrylamide copolymer, N, N-methylenebisacrylamide and acrylic acid copolymer or phenolic resin. Such as the multi-resin glue (main components are N, N-methylenebisacrylamide and acrylamide copolymer) or high-strength resin glue (main components are N, N-methylenebisacrylamide and acrylic acid copolymer) of Ruifeng Company of Jidong Oilfield. The above high-strength resin glue will slowly gel with the change of underground temperature within 5 to 10 hours after being injected into the ground, and has high viscoelasticity and sealing strength after gelling, which can effectively block the water channeling channel.

[0013] Preferably, the solvent of the high-strength resin glue is water, and the concentration can be selected to be 0.8%~1.2%wt.

[0014] Preferably, the method of using high-strength resin glue to seal the macropores is: injecting an aqueous solution of the high-strength resin glue into the macropores.

[0015] Preferably, the injection amount of the high-strength resin glue is according to the formula Q=πR 2 HΦ is calculated, R is the treatment radius, Φ is the porosity of the water blocking layer, and H is the thickness of the water blocking layer. After 24 hours of injection, the second plugging can be carried out after the pressure rises significantly (fluctuation value ≥ 30%).

[0016] For example, when a 1% concentration of high-strength resin adhesive with N,N-methylenebisacrylamide and acrylic acid copolymer as the main components is used, it is heated at 8-10 m 3 / h displacement injection.

[0017] Preferably, the injection amount of CO2 in the second slug is calculated according to the type of the huff-and-puff well according to the following formula: For directional wells and vertical wells, the ellipsoid model is used and the calculation formula is as follows: Formula 1 For horizontal wells, the elliptical cylinder model is used and the calculation formula is as follows: Formula 2 In Formula 1 and Formula 2: ρ-CO2 density under formation conditions, kg / m 3 ; φ-porosity, %; Pv-empirical coefficient, 0.2~0.4; a, b-the long and short axis processing radius of the ellipsoid centered on the directional well trajectory, m; H- length of production section, m.

[0018] Preferably, the CO2-responsive alkyl amidine surfactant is N'-long-chain alkyl-N,N-diethylacetamidine or nano-modified CO2-responsive multi-chain alkyl amidine, and the structural formula of the nano-modified CO2-responsive multi-chain alkyl amidine is as follows:

[0019] Where R = C 14 H 28 .

[0020] The above-mentioned nano-modified CO2-responsive multi-chain alkyl amidine is obtained by electrostatic adsorption of the active adsorption center (tertiary carbon or tertiary nitrogen) of the multi-chain alkyl amidine and partially negatively charged nano-silicon dioxide (SiO2)-calcium carbonate (CaCO3). Among them, the multi-chain alkyl amidine has a specific absorption effect on CO2 and is a CO2-responsive multi-chain alkyl amidine. Compared with single-chain alkyl ethers, on the one hand, the multi-chain alkyl amidine is more sensitive to the stimulation of CO2, and on the other hand, the protonation of the multi-chain alkyl amidine combines with CO2 to form a multi-chain alkyl amidine bicarbonate, which has more long-chain lipophilic tail groups (R=C 14 H 28 ), thus having lower surface tension, better foaming effect, higher foaming volume and foam stability, and thus improving the recovery rate of heavy oil. By adsorbing some negatively charged nano-silica on the active adsorption center (tertiary carbon or tertiary nitrogen) of multi-chain alkyl amidine, combined with the cubic structure of nano-scale calcium carbonate, the dual effects of increasing strength and modification can be achieved, improving its temperature resistance and salt resistance, and further improving its stability. The nano-modified CO2-responsive multi-chain alkyl amidine combined with CO2 can achieve the purpose of high-strength plugging of oil layer cracks.

[0021] Preferably, the preparation method of the nano-modified CO2-responsive multi-chain alkyl amidine comprises the following steps: S1, N, N-dimethylacetamide dimethyl acetal and 1, 14-tetradecyl diamine are reacted in the presence of a catalyst to generate a multi-chain alkyl amidine through an amide acetal method; S2. Mix the nano-silica modified with nano-calcium carbonate with the multi-chain alkyl amidine, disperse them uniformly by ultrasonication, heat them to 60-70°C, and then keep them warm for 3-4 hours under stirring to obtain the nano-modified CO2-responsive multi-chain alkyl amidine.

[0022] The preparation method first uses polyamine as a raw material to generate a multi-chain alkyl amidine (systematically named 4,19-bis(14-aminotetradecyl)-2,3,20,21-tetramethyl-2,4,19,21-tetraazadocosane) through an amide acetal method. The reaction mechanism of this step is as follows:

[0023] Furthermore, the multi-chain alkyl amidine is modified by surface modification using nano-silica modified with nano-calcium carbonate, so that the multi-chain alkyl amidine is electrostatically adsorbed with Nano-SiO2-CaCO3, thereby forming a nano-modified CO2-responsive multi-chain alkyl amidine.

[0024] Preferably, the preparation method of the multi-chain alkyl amidine in S1 is: dissolving 1,14-tetradecyl diamine in methanol to obtain a 1,14-tetradecyl diamine solution; mixing the N,N-dimethylacetamide dimethyl acetal with the catalyst, and then dripping it into the 1,14-tetradecyl diamine solution at a rate of 23.5%~43.5% v / v per minute, and reacting at 80~90°C in an inert atmosphere for at least 4 hours after the dripping is completed; after the reaction is completed, methanol is removed from the reaction mixture, and the obtained liquid product is the multi-chain alkyl amidine. Wherein adding 23.6%~43.5% per minute means adding 23.6%~43.5% of the total volume of the mixture of N,N-dimethylacetamide dimethyl acetal and the catalyst per minute. Preferably, the molar ratio of the 1,14-tetradecyl diamine to the N,N-dimethylacetamide dimethyl acetal in S1 is 1:(0.46-0.68).

[0025] Preferably, the catalyst in S1 is selected from L-proline, p-toluenesulfonic acid or trifluoromethanesulfonic acid. Compared with conventional acidic catalysts, such as sulfuric acid, hydrochloric acid, aluminum oxide, etc., it has stronger activity, can greatly improve the reaction efficiency, reduce the generation of by-products, and ensure the yield of multi-chain alkyl amidine in the product.

[0026] Further preferably, the molar ratio of the N,N-dimethylacetamide dimethyl acetal to the catalyst in S1 is (1.5-2.5):1.

[0027] Optionally, the method for removing methanol from the reaction mixture can be to remove it at 40-60° C. by rotary evaporation or the like.

[0028] Preferably, 420-546 mL of the methanol is used to dissolve each mole of the 1,14-tetradecyl diamine.

[0029] Preferably, the preparation method of the nano-silicon dioxide modified by nano-calcium carbonate in S2 is: disperse 1-1.5 parts of calcium carbonate evenly in water, add 1.5-2 parts of nano-silicon dioxide, ultrasonically disperse, and then heat to 55-65°C, and keep the temperature under stirring for at least 20 hours to obtain a dispersion of the nano-silicon dioxide modified by nano-calcium carbonate.

[0030] More preferably, the rotation speed in the stirring state is 300-400 r / min.

[0031] Preferably, the mass ratio of the nano-silicon dioxide modified with nano-calcium carbonate to the polyalkyl amidine in the dispersion of the nano-silicon dioxide modified with nano-calcium carbonate in S2 is (1-2):(3-5).

[0032] Optionally, the ultrasonic dispersion time in S2 is 20 to 30 min.

[0033] Preferably, the stirring speed in the stirring state in S2 is 400-500 r / min.

[0034] The present invention also provides application of the displacement production method in heavy oil production in Dagang Oilfield.

[0035] The viscosity of the heavy oil and the state of the oil layer in Dagang Oilfield make it particularly suitable for heavy oil production using the above-mentioned displacement production method.

[0036] The beneficial effects of the present invention are: (1) The displacement production method provided by the present invention introduces reservoir dynamic analysis technology. By accurately predicting parameters such as the well network layer structure, remaining oil saturation, recoverable reserves, and production change trends over time, it can effectively identify the recoverable reserves and fracture development of the target reservoir, and design segmented plugs according to the fracture development to achieve controllable production activity.

[0037] (2) The displacement recovery method provided by the present invention adopts a mode of injecting different types of reagents in segmented plugs, utilizing the synergistic effect between different reagents to classify and manage deep heavy oil with medium-low permeability and medium-low porosity, thereby achieving targeted controllable activity of heavy oil recovery and greatly improving the efficiency of heavy oil recovery.

[0038] (3) The displacement mining method provided by the present invention introduces a high-strength resin glue. After being injected into the ground, the high-strength resin glue slowly gels with the change of underground temperature within 5-10 hours. After gelling, it has high viscoelasticity and plugging strength, which can effectively block water channeling channels. It is easier to degrade than thermosetting resin glue (conventional polymer gel plugging agent) used for cementing and is not easy to block formation pores.

[0039] (4) The displacement production method provided by the present invention adopts a composite viscosity reducer + CO2 huff-and-puff method. First, the electromagnetic response viscosity reduction of heavy oil is carried out by utilizing the staggered magnetic response principle of graphene. At the same time, the flake structure of graphene has an intercalation and cutting effect on the straight-linked alkanes in the heavy oil, which can reduce the length of the molecular chain of the straight-linked alkanes and further improve the viscosity reduction effect of the heavy oil. It can process high-freezing crude oil with a wax content of up to 50%; secondly, the macromolecular viscosity reducer can increase the swept volume of the heavy oil, further improving the viscosity reduction effect; finally, the contact between CO2 and the deep oil reservoir causes the crude oil to swell and reduce the viscosity again. The synergistic effect of the above three greatly improves the viscosity reduction effect of the heavy oil.

[0040] (5) The composite viscosity reducer of the present invention can adapt to the CO2 acidic environment, solving the problem that the conventional plugging system cannot adapt to the CO2 acidic environment.

[0041] (6) In the displacement production method provided by the present invention, a CO2-responsive alkyl amidine surfactant with controllable response activity to CO2 stimulation is introduced. By utilizing its characteristic of generating high-intensity foam, on the one hand, the CO2 gas channel can be blocked, and on the other hand, the crude oil mobility ratio can be improved through surface activity, thereby further improving the production efficiency and solving the problems that the traditional oil recovery system cannot meet the requirements for efficient development of heavy oil reservoirs due to the high water-oil mobility ratio and limited expansion of the swept volume.

[0042] (7) The displacement production method provided by the present invention is particularly suitable for the viscosity of the heavy oil and the state of the oil layer in the Dagang Oilfield, and can achieve efficient development of the heavy oil in the Dagang Oilfield. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work fall within the scope of protection of the present invention.

[0044] CO2 composite huff-and-puff technology is a high-efficiency heavy oil recovery measure, but the viscosity difference between CO2 and heavy oil is large, which easily leads to fingering, resulting in unsatisfactory development results, specifically manifested in: low production and low energy coexist with crossflow, and uneven utilization of remaining oil; conventional plugging systems cannot adapt to the acidic environment of CO2; and single chemical flooding agents and traditional binary flooding systems have high water-oil flow ratios and limited expansion of swept volume, which cannot meet the requirements for efficient development of heavy oil reservoirs.

[0045] To solve the above problems, the present invention has developed a composite displacement method of multi-stage plug combination, which can greatly improve the recovery rate of heavy oil reservoirs by combining "plugging, regulating and driving" through the synergistic effect of "water plugging, viscosity reduction, stripping and energy enhancement".

[0046] The method for displacement production of heavy oil with controllable activity provided by the embodiment of the present invention specifically comprises the following steps: Step 1: Analyze the fracture development of the oil layer structure; Step 2: Implement multiple plugs according to the development of fractures. If the porosity is greater than 20% and the permeability is greater than 100 mD, implement the following first plug, second plug and third plug; if the porosity is ≤20% or the permeability is ≤100 mD, implement the following second plug and third plug; The first plug is a plugging plug: a high-strength resin glue solution is used to plug the large pores, and the second plug is performed when the fluctuation value of the pressure rise in the pore is ≥30%; The second section plug is a composite viscosity reducer + CO2 injection main section plug: the composite viscosity reducer is injected at a rate of 5-7m 3 / h After the injection is completed, the 3 / h displacement injection of CO2 for composite huff and puff; the composite viscosity reducer contains 1%~2% graphene and 0.1%~0.2% macromolecular viscosity reducer, and the solvent is water; the macromolecular viscosity reducer is a mixture of alkyl glycoside viscosity reducer and low molecular weight polymer surfactant in a mass ratio of (5~3):1; the low molecular weight polymer surfactant is a copolymer of acrylamide and sodium acrylamide alkyl sulfonate or a copolymer of acrylamide and sodium allyl sulfonate, with a molecular weight of 5 to 8 million; the injection amount of the composite viscosity reducer is calculated according to the formula Q=oil well production×control time÷tubing length; The third plug is an active controllable alkyl amidine surfactant plug: a 0.1% to 0.3% wt aqueous solution of a CO2-responsive alkyl amidine surfactant is used at 6 to 8 m 3 / h displacement injection to perform foam plugging on the gas channel; the CO2 responsive alkyl amidine surfactant is injected immediately after the CO2 is injected into the second section plug; when there is no CO2 gas channeling, the injection amount of the CO2 responsive alkyl amidine surfactant is 1-1.2 times of the CO2 injection amount, and when there is CO2 gas channeling, the injection amount of the CO2 responsive alkyl amidine surfactant is 1.3-1.5 times of the CO2 injection amount.

[0047] The embodiment of the present invention also provides application of the displacement production method in heavy oil production in Dagang Oilfield.

[0048] The scheme of the present invention is described below through specific embodiments.

[0049] In the following embodiments, a crack having a porosity of less than 10% is considered low porosity, and a crack having a porosity of greater than 20% is considered high porosity.

[0050] The high-strength resin glue used in the following examples is a multi-component resin glue (the main components are N, N-methylenebisacrylamide and acrylamide copolymer) or a high-strength resin glue (the main components are N, N-methylenebisacrylamide and acrylic acid copolymer) purchased from Ruifeng Company of Jidong Oilfield. The low molecular weight polymer surfactant used in the following examples is provided by China Petroleum Exploration and Development Research Institute. The molecular weight of the low molecular weight polymer surfactant whose components are copolymers of acrylamide and sodium acrylamide alkyl sulfonate is 8 million, and the molecular weight of the low molecular weight polymer surfactant whose components are copolymers of acrylamide and sodium allyl sulfonate is 5 million.

[0051] The structural formula of the nano-modified CO2-responsive multi-chain alkyl amidine used in the following examples is as follows:

[0052] Where R = C 14 H 28 .

[0053] The formula 1 used in the following examples is: ; Formula 2 is:

[0054] In formula 1 and formula 2, ρ is the density of CO2 under formation conditions, kg / m 3 ; φ-porosity, %; Pv-empirical coefficient, 0.2~0.4; a, b-the long and short axis processing radius of the ellipsoid centered on the directional well trajectory, m; H- length of production section, m.

[0055] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0056] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0057] Example 1 This embodiment provides a displacement recovery method for heavy oil with controllable activity, and the specific steps are as follows: 1. Analysis of system composition and crack development By using reservoir dynamic analysis technology, it was identified that the remaining oil saturation in a block of Dagang Oilfield was high and there were no fractures and large pores. Physical and chemical analysis showed that the crude oil viscosity was 21335mPa.s at 50°C, the wax content was 45.5%, the permeability was 72mD, and the porosity was 6.1%. It was a low-porosity, low-permeability, high-wax heavy oil reservoir. There was no CO2 gas channeling in adjacent wells, and two-segment plug injection was adopted.

[0058] 2. Multi-stage plug displacement mining (1) The first plug is mainly composed of composite viscosity reducer + CO2 huff and puff. The composite viscosity reducer is a composite viscosity reducer system composed of 2% graphene + 0.1% macromolecular viscosity reducer (the solvent is water). 3 After the composite viscosity reducer is injected at a rate of 5m / h, 3 / h displacement injection of CO2 to carry out composite throughput. The macromolecular viscosity reducer in the composite viscosity reducer is prepared by alkyl glycoside viscosity reducer and low molecular weight polymer surfactant in a ratio of 3:1. The low molecular weight polymer surfactant is a copolymer of acrylamide and sodium acrylamide alkyl sulfonate. The injection target well is a vertical well, the oil well production is 3.2 tons / day, the control time is 30 days, the pipe string length is 15 meters, and according to the formula Q=oil well production×control time÷pipe string length, the amount of composite viscosity reducer added is calculated to be 6.4 tons; At a temperature of 53.4°C and a formation pressure of 14.03 MPa, the density of CO2 is 0.598 g / cm 3 , the major axis radius is 3m, the minor axis radius is 38m, the empirical constant is 0.4, and the CO2 consumption is calculated according to formula 1 to be 264 cubic meters.

[0059] (2) Second plug: Immediately after the CO2 injection, the CO2-responsive alkyl amidine surfactant was injected into the second plug. A 0.1%wt concentration of CO2-responsive alkyl amidine surfactant aqueous solution was used at 6 m 3 / h displacement to inject 300 cubic meters to displace residual oil.

[0060] The preparation method of the CO2-responsive alkyl amidine surfactant is as follows: ① Disperse 1.5 parts of nano-calcium carbonate in distilled water, stir evenly, add 1.5 parts of nano-silicon dioxide, and use ultrasonic vibration for 20 minutes to disperse the two evenly, then heat to 62°C, stir at 400 r / min, and keep warm for 25 hours to obtain a nano-silicon dioxide dispersion modified with nano-calcium carbonate.

[0061] ② Add 64.0g (0.28 mol) of 1,14-tetradecyl diamine to a 250 mL four-necked flask equipped with a stirrer, a constant pressure funnel, a nitrogen device, and a thermometer, and then add 130 mL of methanol and stir to dissolve it completely. Weigh 18.65g (0.14 mol) of N,N-dimethylacetamide dimethyl acetal in a 50 mL beaker, add 8.06 g (0.07 mol) of catalyst L-proline and stir evenly, then turn on the condenser, stir at a speed of 400-500 r / min, and slowly drop the solution in the beaker into the solution in the four-necked flask through the constant pressure funnel at a speed of 9 mL / min. After the dropwise addition is completed, nitrogen is introduced, and the reaction is heated at 87°C for 4.3 h under nitrogen protection. After the reaction is completed, the reaction mixture is rotary evaporated (40~60°C) to remove methanol to obtain a liquid product, namely CO2-responsive multi-chain alkyl amidine.

[0062] ③ Mix 2 parts of nano-calcium carbonate-modified nano-silica (the mass of nano-calcium carbonate-modified nano-silica in the dispersion) with 3 parts of CO2-responsive multi-chain alkyl amidine, oscillate with ultrasound for 20 min, heat to 60°C, stir at 400 r / min, and react for 3 h to obtain a CO2-responsive alkyl amidine surfactant.

[0063] Example 2 This embodiment provides a displacement recovery method for heavy oil with controllable activity, and the specific steps are as follows: 1. Analysis of crack development in system components Using reservoir dynamic analysis technology, it was identified that the remaining oil saturation in a block of Dagang Oilfield was high and large pores without fractures were developed; physical and chemical analysis showed that the crude oil viscosity was 19417 mPa.s at 50°C, the wax content was 42.1%, the permeability was 72mD, and the porosity was 10.5%. It was a low-porosity, low-permeability, high-wax heavy oil reservoir. There was CO2 gas channeling in adjacent wells, and two-segment plug injection was adopted.

[0064] 2. Multi-stage plug displacement mining (1) The first plug is a composite viscosity reducer + CO2 huff and puff plug. The composite viscosity reducer is a composite viscosity reducer system consisting of 1.8% graphene + 0.1% macromolecular viscosity reducer (the solvent is water). 3 After the composite viscosity reducer is injected at a rate of 5m / h, 3 / h displacement injection of CO2 to carry out composite throughput. Among them, the macromolecular viscosity reducer is prepared by alkyl glycoside viscosity reducer and low molecular weight polymer surfactant in a ratio of 4:1, and the low molecular weight polymer surfactant component is a copolymer of acrylamide and sodium acrylamide alkyl sulfonate; The injection target well is a horizontal well, the oil well production is 2.8 tons / day, the control time is 30 days, the pipe string length is 11 meters, according to the formula Q = oil well production × control time ÷ pipe string length, the amount of composite viscosity reducer added is calculated to be 7.6 tons; At a temperature of 55.77°C and an original formation pressure of 13.4 MPa, the CO2 density is 0.548 g / cm 3 , the major axis radius is 5m, the minor axis radius is 10m, the production section length is 115m, the empirical constant is 0.38, and the CO2 consumption is calculated according to Formula 2 to be 395 cubic meters.

[0065] (2) Step 2: Immediately after the CO2 injection, the CO2-responsive alkyl amidine surfactant was injected into the second plug, which served as an oil displacement agent and foam plugging agent. A 0.3%wt concentration of CO2-responsive alkyl amidine surfactant aqueous solution was used at 7m 3 550 cubic meters / h are injected to seal the gas channel with foam, and at the same time, it acts as an oil displacement agent to displace the remaining oil.

[0066] The preparation method of the CO2-responsive alkyl amidine surfactant is as follows: ① Disperse 1 part of nano-calcium carbonate in distilled water, stir evenly, add 1.5 parts of nano-silicon dioxide, and use ultrasonic vibration for 15 minutes to disperse the two evenly, then heat to 55°C, stir at 300 r / min, and keep warm for 20 hours to obtain a nano-silicon dioxide dispersion modified with nano-calcium carbonate.

[0067] ② Add 45.7g (0.2 mol) of 1,14-tetradecyl diamine to a 250 mL four-necked flask equipped with a stirrer, a constant pressure funnel, a nitrogen device, and a thermometer, and then add 100 mL of methanol and stir to dissolve it completely. Weigh 13.32 g (0.1 mol) of N,N-dimethylacetamide dimethyl acetal in a 50 mL beaker, add 5.76 g (0.05 mol) of catalyst L-proline and stir evenly, then turn on the condenser, stir at a speed of 400-500 r / min, and slowly add the solution in the beaker to the solution in the four-necked flask through the constant pressure funnel at a speed of 5 mL / min. After the addition is complete, nitrogen is introduced and heated at 80°C for 4 h under nitrogen protection. After the reaction is completed, the reaction mixture is rotary evaporated (40~60°C) to remove methanol to obtain a liquid product, namely CO2-responsive multi-chain alkyl amidine.

[0068] ③ Mix 1 part of nano-calcium carbonate-modified nano-silica (the mass of nano-calcium carbonate-modified nano-silica in the dispersion) with 3 parts of CO2-responsive multi-chain alkyl amidine, oscillate with ultrasound for 20 min, heat to 60°C, stir at 400 r / min, and react for 3 h to obtain a CO2-responsive alkyl amidine surfactant.

[0069] Example 3 This embodiment provides a displacement recovery method for heavy oil with controllable activity, and the specific steps are as follows: 1. Analysis of system composition and crack development Using reservoir dynamic analysis technology, it was identified that the remaining oil saturation in a block of Dagang Oilfield was high and there were developed fractures and large pores; physical and chemical analysis showed that the crude oil viscosity was 18527 mPa.s at 50°C, the wax content was 44.9%, the permeability was 116mD, and the porosity was 21.2%. It was a low-porosity, low-permeability, high-wax heavy oil reservoir. There was no CO2 gas crossover in adjacent wells, and a three-segment plug injection method was adopted.

[0070] 2. Multi-stage plug displacement mining (1) The first plug is a plugging plug, which uses a 1% high-strength resin glue (N, N-methylenebisacrylamide and acrylamide copolymer) aqueous solution to plug the large pores. 3 / h displacement injection, after injection, wait for 24 hours, observe the pressure rise obviously (fluctuation value ≥ 30%) before the second plugging can be carried out. Among them, the water plugging layer thickness is 3 meters, the treatment radius is 1 meter, the water plugging layer porosity is 21.5%, and the injection amount of high-strength resin glue solution is calculated to be 2 tons.

[0071] (2) The second plug is mainly composed of composite viscosity reducer + CO2 huff and puff. The composite viscosity reducer is a composite viscosity reducer system composed of 1.5% graphene + 0.1% macromolecular viscosity reducer (the solvent is water). 3 After the composite viscosity reducer is injected at a rate of 6m 3 / h displacement injection of CO2 to carry out composite throughput. Among them, the macromolecular viscosity reducer is prepared by alkyl glycoside viscosity reducer and low molecular weight polymer surfactant in a ratio of 5:1, and the low molecular weight polymer surfactant component is a copolymer of acrylamide and sodium acrylamide alkyl sulfonate; The injection target well is a horizontal well, the oil well production is 3.1 tons / day, the control time is 30 days, the pipe string length is 14 meters, and according to the formula Q=oil well production×control time÷pipe string length, the amount of composite viscosity reducer added is calculated to be 6.6 tons; At a temperature of 48.27°C and an original formation pressure of 11.6 MPa, the CO2 density is 0.435 g / cm 3, the major axis radius is 8m, the minor axis radius is 7.2m, the production section length is 130m, the empirical constant is 0.40, and the CO2 consumption is calculated according to Formula 2 to be 376 cubic meters.

[0072] (3) Immediately after the CO2 injection, the CO2-responsive alkyl amidine surfactant was injected into the third plug as an oil displacement agent (no CO2 gas channeling and no foam plugging). A 0.15%wt concentration of CO2-responsive alkyl amidine surfactant aqueous solution was used at 8 m 3 / h displacement of 430 cubic meters is injected to displace the remaining oil.

[0073] The preparation method of the CO2-responsive alkyl amidine surfactant is as follows: ① Disperse 1 part of nano-calcium carbonate in distilled water and stir evenly, add 2 parts of nano-silicon dioxide, and use ultrasonic vibration for 20 minutes to disperse the two evenly, then heat to 65°C, stir at 400 r / min, and keep warm for 24 hours to obtain a nano-silicon dioxide dispersion modified with nano-calcium carbonate.

[0074] ② Add 57.1 g (0.25 mol) of 1,14-tetradecyl diamine to a 250 mL four-necked flask equipped with a stirrer, a constant pressure funnel, a nitrogen device, and a thermometer, and then add 115 mL of methanol and stir to dissolve it completely. Weigh 16.65 g (0.125 mol) of N,N-dimethylacetamide dimethyl acetal in a 50 mL beaker, add 13.78 g (0.08 mol) of catalyst p-toluenesulfonic acid and stir evenly, then turn on the condenser, stir at a speed of 400-500 r / min, and slowly add the solution in the beaker to the solution in the four-necked flask through the constant pressure funnel at a speed of 7 mL / min. After the addition is complete, nitrogen is introduced and heated at 90°C for 5 h under nitrogen protection. After the reaction is completed, the reaction mixture is rotary evaporated (40~60°C) to remove methanol to obtain a liquid product, namely CO2-responsive multi-chain alkyl amidine.

[0075] ③ Mix 1 part of nano-calcium carbonate-modified nano-silica (the mass of nano-calcium carbonate-modified nano-silica in the dispersion) with 4 parts of CO2-responsive multi-chain alkyl amidine, oscillate with ultrasound for 30 min, heat to 70°C, stir at 500 r / min, and react for 4 h to obtain a CO2-responsive alkyl amidine surfactant.

[0076] Example 4 This embodiment provides a displacement recovery method for heavy oil with controllable activity, and the specific steps are as follows: 1. Analysis of system composition and crack development Using reservoir dynamic analysis technology, it was identified that the remaining oil saturation in a block of Dagang Oilfield was high and there were developed fractures and large pores; physical and chemical analysis showed that the crude oil viscosity was 23664 mPa.s at 50°C, the wax content was 47.8%, the permeability was 192mD, and the porosity was 25.1%. It was a medium-porosity, low-permeability, high-wax heavy oil reservoir. There was CO2 gas crossover in adjacent wells, and a three-segment plug injection method was adopted.

[0077] 2. Multi-stage plug displacement mining (1) The first plug is a plugging plug, which uses a 1%wt high-strength resin glue (N, N-methylenebisacrylamide and acrylamide copolymer) aqueous solution to plug the large pores. 3 / h displacement injection, after injection, wait for 24 hours, observe the pressure rise obviously (fluctuation value ≥ 30%) before the second plugging can be carried out. Among them, the water plugging layer thickness is 2.5 meters, the treatment radius is 1.2 meters, the water plugging layer porosity is 22.0%, and the injection amount of high-strength resin glue solution is calculated to be 2.5 tons.

[0078] (2) The second plug is mainly composed of composite viscosity reducer + CO2 huff and puff. The composite viscosity reducer is a composite viscosity reducer system composed of 1.5% graphene + 0.1% macromolecular viscosity reducer (the solvent is water). 3 After the composite viscosity reducer is injected at a rate of 6m 3 / h displacement injection of CO2 to carry out composite throughput. Among them, the macromolecular viscosity reducer is prepared by alkyl glycoside viscosity reducer and low molecular weight polymer surfactant in a ratio of 3:1, and the low molecular weight polymer surfactant component is a copolymer of acrylamide and sodium acrylamide alkyl sulfonate; The injection target well is a directional well, the oil well production is 2.5 tons / day, the control time is 30 days, the string length is 13 meters, according to the formula Q = oil well production × control time ÷ string length, the amount of composite viscosity reducer added is calculated to be 5.8 tons; At a temperature of 57.93°C and an original formation pressure of 13.35 MPa, the CO2 density is 0.492 g / cm 3 The major axis radius is 6.8m, the minor axis radius is 17.5m, the empirical constant is 0.40, and the CO2 consumption is calculated according to Formula 1 to be 259 cubic meters.

[0079] (3) Immediately after the CO2 injection, the CO2-responsive alkyl amidine surfactant was injected into the third plug. A 0.2%wt concentration of CO2-responsive alkyl amidine surfactant aqueous solution was used at 8 m 3 / h displacement of 400 cubic meters is injected to seal the gas channel with foam, and at the same time it acts as an oil displacement agent to displace the remaining oil.

[0080] The preparation method of the CO2-responsive alkyl amidine surfactant is as follows: ① Disperse 1.5 parts of nano-calcium carbonate in distilled water and stir evenly, add 2 parts of nano-silicon dioxide, and use ultrasonic vibration for 18 minutes to disperse the two evenly, then heat to 60°C, stir at 350 r / min, and keep warm for 22 hours to obtain a nano-silicon dioxide dispersion modified with nano-calcium carbonate.

[0081] ② Add 50.3 g (0.22 mol) of 1,14-tetradecyl diamine to a 250 mL four-necked flask equipped with a stirrer, a constant pressure funnel, a nitrogen device, and a thermometer, and then add 120 mL of methanol and stir to dissolve it completely. Weigh 19.98 g (0.15 mol) of N,N-dimethylacetamide dimethyl acetal in a 50 mL beaker, add 9.00 g (0.06 mol) of catalyst trifluoromethanesulfonic acid and stir evenly, then turn on the condenser, stir at a speed of 400-500 r / min, and slowly add the solution in the beaker to the solution in the four-necked flask through the constant pressure funnel at a speed of 8 mL / min. After the addition is complete, nitrogen is introduced and heated at 85°C for 4.5 h under nitrogen protection. After the reaction is completed, the reaction mixture is rotary evaporated (40~60°C) to remove methanol to obtain a liquid product, namely CO2-responsive multi-chain alkyl amidine.

[0082] ③ Mix 1 part of nano-calcium carbonate-modified nano-silica (the mass of nano-calcium carbonate-modified nano-silica in the dispersion) with 5 parts of CO2-responsive multi-chain alkyl amidine, oscillate with ultrasound for 25 min, heat to 65°C, stir at 450 r / min, and react for 3.5 h to obtain a CO2-responsive alkyl amidine surfactant.

[0083] Example 5 This embodiment provides a displacement recovery method for heavy oil with controllable activity, and the specific steps are as follows: 1. Analysis of system composition and crack development By using reservoir dynamic analysis technology, it was identified that the remaining oil saturation in a block of Dagang Oilfield was high and there were developed fractures and large pores. Physical and chemical analysis showed that the crude oil viscosity was 22631mPa.s at 50°C, the wax content was 30.5%, the permeability was 125mD, and the porosity was 22.6%. It was a high-porosity, medium-permeability, high-wax heavy oil reservoir. There was no CO2 gas channeling in adjacent wells, and a three-segment plug injection method was adopted.

[0084] 2. Multi-stage plug displacement mining (1) The first plug is a plugging plug, which uses a 1% high-strength resin glue (N, N-methylenebisacrylamide and acrylic acid copolymer) aqueous solution to plug the large pores. 3 / h displacement injection, after injection, wait for 24 hours, observe the pressure rise obviously (fluctuation value ≥ 30%) before the second plugging can be carried out. Among them, the water plugging layer thickness is 2.6 meters, the treatment radius is 1.5 meters, the water plugging layer porosity is 23%, and the injection amount of high-strength resin glue solution is calculated to be 4.2 tons.

[0085] (2) The second plug is mainly composed of composite viscosity reducer + CO2 huff and puff. The composite viscosity reducer is a composite viscosity reducer system composed of 1% graphene + 0.2% macromolecular viscosity reducer (the solvent is water). 3 After the composite viscosity reducer is injected at a rate of 6m 3 / h displacement injection of CO2 to carry out composite throughput. Among them, the macromolecular viscosity reducer is prepared by alkyl glycoside viscosity reducer and low molecular weight polymer surfactant in a ratio of 5:1, and the low molecular weight polymer surfactant component is a copolymer of acrylamide and sodium allyl sulfonate; The injection target well is a horizontal well, the oil well production is 2.7 tons / day, the control time is 28 days, the length of the pipe string is 12 meters, and according to the formula Q=oil well production×control time÷pipe string length, the amount of composite viscosity reducer added is calculated to be 6.3 tons; At a temperature of 49.35°C and an original formation pressure of 12.5 MPa, the CO2 density is 0.516 g / cm 3 The major axis radius is 6.1m, the minor axis radius is 17.9m, the production section length is 20m, the empirical constant is 0.4, and the CO2 consumption is calculated according to Formula 2 to be 320 cubic meters.

[0086] (3) Immediately after the CO2 injection, the CO2-responsive alkyl amidine surfactant was injected into the third plug as an oil displacement agent. A 0.3%wt concentration of CO2-responsive alkyl amidine surfactant aqueous solution was used at 7 m 3 / h displacement to inject 380 cubic meters to displace the remaining oil.

[0087] The preparation method of the CO2-responsive alkyl amidine surfactant is as follows: ① Disperse 1 part of nano-calcium carbonate in distilled water, stir evenly, add 1.5 parts of nano-silicon dioxide, and use ultrasonic vibration for 20 minutes to disperse the two evenly, then heat to 58°C, stir at 350 r / min, and keep warm for 23 hours to obtain a nano-silicon dioxide dispersion modified with nano-calcium carbonate.

[0088] ② Add 59.4g (0.26mol) of 1,14-tetradecyl diamine to a 250 mL four-necked flask equipped with a stirrer, a constant pressure funnel, a nitrogen device, and a thermometer, and then add 110 mL of methanol and stir to dissolve it completely. Weigh 15.98 g (0.12mol) of N,N-dimethylacetamide dimethyl acetal in a 50 mL beaker, add 10.33 g (0.06 mol) of catalyst p-toluenesulfonic acid and stir evenly, then turn on the condenser, stir at a speed of 400-500 r / min, and slowly drop the solution in the beaker into the solution in the four-necked flask through the constant pressure funnel at a speed of 10 mL / min. After the dropwise addition is completed, nitrogen is introduced, and the reaction is heated at 90°C for 4 h under nitrogen protection. After the reaction is completed, the reaction mixture is rotary evaporated (40~60°C) to remove methanol to obtain a liquid product, namely CO2-responsive multi-chain alkyl amidine.

[0089] ③ Mix 2 parts of nano-calcium carbonate-modified nano-silica (the mass of nano-calcium carbonate-modified nano-silica in the dispersion) with 4 parts of CO2-responsive multi-chain alkyl amidine, oscillate with ultrasound for 25 minutes, heat to 65°C, stir at 450 r / min, and react for 3 hours to obtain a CO2-responsive alkyl amidine surfactant.

[0090] Example 6 This embodiment provides a displacement recovery method for heavy oil with controllable activity, and the specific steps are as follows: 1. Analysis of system composition and crack development Using reservoir dynamic analysis technology, it was identified that the remaining oil saturation in a block of Dagang Oilfield was high and there were developed fractures and large pores; physical and chemical analysis showed that the crude oil viscosity was 19850 mPa.s at 50°C, the wax content was 27.6%, the permeability was 206mD, and the porosity was 23.7%. It was a high-porosity, medium-permeability, and high-wax heavy oil reservoir. There was CO2 gas crossover in adjacent wells, and a three-segment plug injection method was adopted.

[0091] 2. Multi-stage plug displacement mining (1) The first plug is a plugging plug, which uses a 1%wt high-strength resin glue (phenolic resin) aqueous solution to plug the large pores. 3 / h displacement injection, after injection, wait for 24 hours, observe the pressure rise obviously (fluctuation value ≥ 30%) before the second plugging can be carried out. Among them, the water plugging layer thickness is 2.3 meters, the treatment radius is 1.3 meters, the water plugging layer porosity is 22.2%, and the injection amount of high-strength resin glue solution is calculated to be 2.7 tons.

[0092] (2) The second plug is mainly composed of composite viscosity reducer + CO2 huff and puff. The composite viscosity reducer is a composite viscosity reducer system composed of 1% graphene + 0.2% macromolecular viscosity reducer (the solvent is water). 3After the composite viscosity reducer is injected at a rate of 6m 3 / h displacement injection of CO2 to carry out composite throughput. Among them, the macromolecular viscosity reducer is prepared by alkyl glycoside viscosity reducer and low molecular weight polymer surfactant in a ratio of 3:1, and the low molecular weight polymer surfactant component is a copolymer of acrylamide and sodium allyl sulfonate; The injection target well is a directional well, the oil well production is 3.1 tons / day, the control time is 20 days, the string length is 12 meters, according to the formula Q = oil well production × control time ÷ string length, the amount of composite viscosity reducer added is calculated to be 5.2 tons; At a temperature of 51.24°C and an original formation pressure of 13.53 MPa, the CO2 density is 0.492 g / cm 3 The major axis radius is 6.2m, the minor axis radius is 16.0m, the empirical constant is 0.4, and the CO2 consumption is calculated according to Formula 1 to be 310 cubic meters.

[0093] (3) Immediately after the CO2 injection, the CO2-responsive alkyl amidine surfactant (N'-long-chain alkyl-N,N-diethylacetamidine) was injected into the third plug. A 0.2%wt concentration of CO2-responsive alkyl amidine surfactant aqueous solution was used at 9 m 3 450 cubic meters / h are injected to seal the gas channel with foam and serve as an oil displacement agent to displace the remaining oil.

[0094] Comparative Example 1 This comparative example provides a displacement recovery method with controllable heavy oil activity, and its specific steps are basically the same as those in Example 3, except that the first segment plug is not implemented, and the remaining steps are the same as those in Example 3.

[0095] Comparative Example 2 This comparative example provides a method for displacement recovery of heavy oil with controllable activity, and its specific steps are basically the same as those of Example 4, except that the first plug is not implemented, and the third plug of the controllable activity alkyl amidine surfactant is not used.

[0096] Comparative Example 3 This comparative example provides a displacement recovery method with controllable heavy oil activity, and its specific steps are basically the same as those of Example 4, except that the composite oil displacement system of Example 1 in patent CN115368884B is used to replace the composite viscosity reducer of the second plug of Example 4.

[0097] Comparative Example 4 This comparative example provides a method for displacement production of heavy oil with controllable activity, and the specific steps are basically the same as those of Example 4, except that CO2 is not injected into the second plug.

[0098] Comparative Example 5 This comparative example provides a displacement production method with controllable heavy oil activity, and its specific steps are basically the same as those of Example 4, except that the composite viscosity reducer is not injected into the second plug.

[0099] Comparative Example 6 This comparative example provides a method for displacement production of heavy oil with controllable activity, and its specific steps are basically the same as those of Example 3, except that the high-strength resin glue is replaced with a low-molecular-weight polyphenol cross-linked polymer (conventional polymer gel plugging agent).

[0100] Comparative Example 7 This comparative example provides a method for displacement production of heavy oil with controllable activity, and the specific steps are basically the same as those of Example 3, except that graphene is removed from the composite viscosity reducer.

[0101] Comparative Example 8 This comparative example provides a method for displacement production of heavy oil with controllable activity, and its specific steps are basically the same as those of Example 3, except that the macromolecular viscosity reducer in the composite viscosity reducer is replaced with an oil-soluble polyacrylate (oil-soluble polymer viscosity reducer).

[0102] Comparative Example 9 This comparative example provides a method for displacement recovery of heavy oil with controllable activity, and its specific steps are basically the same as those of Example 3, except that the CO2-responsive alkyl amidine surfactant is replaced with a common oil recovery surfactant, petroleum sulfonate.

[0103] Test Example 1 The heavy oil viscosity reduction rate, plugging rate and oil displacement performance were evaluated for Examples 1 to 4 and Comparative Examples 1 to 8.

[0104] The viscosity reduction rate is evaluated in accordance with the standard Q / SHCG 65-2013 "Technical Requirements for Viscosity Reducers for Heavy Oil"; The plugging rate is evaluated according to the standard Q / BGBH 0013-2024 "Acrylamide BHWQ for oil recovery enhancement"; The oil displacement performance adopts the multifunctional oil displacement physical simulation experimental device produced by Jiangsu Huaan Scientific Research Instrument Co., Ltd. The slug design is: 1.5-2PV water drive slug + 0.5-0.8PV viscosity reducer slug + 1-1.3PV carbon dioxide slug + 1.5-2PV water drive slug.

[0105] The performance evaluation results are shown in Tables 1 to 3.

[0106] Table 1 Viscosity reduction test results

[0107] Table 2 Blockage rate test results

[0108] Table 3 Oil displacement performance test results

[0109] Note: Water drive recovery refers to the oil recovery rate when only water is injected.

[0110] It can be seen from the test results of Tables 1 to 3 above that the displacement production method of the present invention has good viscosity reduction effect, plugging performance and oil displacement capacity, can improve the recovery rate, and solves the problems of low production and low energy, crossflow, and uneven utilization of remaining oil in the CO2 composite huff and puff technology in the prior art. It can be promoted and applied in heavy oil reservoirs with harsh conditions across the country.

[0111] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for displacement production of heavy oil with controllable activity, characterized in that: The specific steps include: Step 1: Analyze the fracture development of the oil layer structure; Step 2: Implement multiple plugs according to the development of fractures. If the porosity is greater than 20% and the permeability is greater than 100 mD, implement the following first plug, second plug and third plug; if the porosity is ≤20% or the permeability is ≤100 mD, implement the following second plug and third plug; The first plug is a plugging plug: a high-strength resin glue solution is used to plug the large pores, and the second plug is performed when the fluctuation value of the pressure rise in the pore is ≥30%; The second section plug is a composite viscosity reducer + CO2 injection main section plug: the composite viscosity reducer is injected at a rate of 5-7m 3 / h After the injection is completed, the 3 / h displacement injection of CO2 for composite huff and puff; the composite viscosity reducer contains 1%~2% graphene and 0.1%~0.2% macromolecular viscosity reducer, and the solvent is water; the macromolecular viscosity reducer is a mixture of alkyl glycoside viscosity reducer and low molecular weight polymer surfactant in a mass ratio of (5~3):1; the low molecular weight polymer surfactant is a copolymer of acrylamide and sodium acrylamide alkyl sulfonate or a copolymer of acrylamide and sodium allyl sulfonate, with a molecular weight of 5 to 8 million; the injection amount of the composite viscosity reducer is calculated according to the formula Q=oil well production×control time÷tubing length; The third plug is an active controllable alkyl amidine surfactant plug: a 0.1% to 0.3% wt aqueous solution of a CO2-responsive alkyl amidine surfactant is used at 6 to 8 m 3 / h displacement injection to perform foam plugging on the gas channel; the CO2 responsive alkyl amidine surfactant is injected immediately after the CO2 is injected into the second section plug; when there is no CO2 gas channeling, the injection amount of the CO2 responsive alkyl amidine surfactant is 1-1.2 times of the CO2 injection amount, and when there is CO2 gas channeling, the injection amount of the CO2 responsive alkyl amidine surfactant is 1.3-1.5 times of the CO2 injection amount.

2. The displacement mining method according to claim 1, characterized in that: The high-strength resin glue in the first section plug adopts a resin glue whose main components are N,N-methylenebisacrylamide and acrylamide copolymer, N,N-methylenebisacrylamide and acrylic acid copolymer or phenolic resin; and / or The solvent of the high-strength resin glue is water, and the concentration is 0.8%~1.2%wt; and / or The injection amount of the high-strength resin glue is based on the formula Q=πR 2 HΦ is calculated, where R is the treatment radius, Φ is the porosity of the water blocking layer, and H is the thickness of the water blocking layer.

3. The displacement mining method according to claim 1, characterized in that: The injection amount of CO2 in the second plug is calculated according to the type of the huff and puff well using the following formula: For directional wells and vertical wells, the ellipsoid model is used and the calculation formula is as follows: Formula 1 For horizontal wells, the elliptical cylinder model is used and the calculation formula is as follows: Formula 2 In Formula 1 and Formula 2: ρ-CO2 density under formation conditions, kg / m 3 ; φ-porosity, %; Pv-empirical coefficient, 0.2~0.4; a, b-the long and short axis processing radius of the ellipsoid centered on the directional well trajectory, m; H- length of production section, m.

4. The displacement mining method according to claim 1, characterized in that: The CO2-responsive alkyl amidine surfactant is N'-long-chain alkyl-N, N-diethylacetamidine or nano-modified CO2-responsive multi-chain alkyl amidine. The structural formula of the nano-modified CO2-responsive multi-chain alkyl amidine is as follows: Where R = C 14 H 28 .

5. The displacement mining method according to claim 4, characterized in that: The preparation method of the nano-modified CO2-responsive multi-chain alkyl amidine comprises the following steps: S1, N, N-dimethylacetamide dimethyl acetal and 1, 14-tetradecyl diamine are reacted in the presence of a catalyst to generate a multi-chain alkyl amidine through an amide acetal method; S2. Mix the nano-silica modified with nano-calcium carbonate with the multi-chain alkyl amidine, disperse them uniformly by ultrasonication, heat them to 60-70°C, and then keep them warm for 3-4 hours under stirring to obtain the nano-modified CO2-responsive multi-chain alkyl amidine.

6. The displacement mining method according to claim 5, characterized in that: The preparation method of the multi-chain alkyl amidine in S1 is: dissolving 1,14-tetradecyl diamine in methanol to obtain a 1,14-tetradecyl diamine solution; mixing the N,N-dimethylacetamide dimethyl acetal with the catalyst, and then dripping it into the 1,14-tetradecyl diamine solution at a rate of 23.6% to 43.5% v / v per minute, and reacting at 80 to 90° C. in an inert atmosphere for at least 4 hours after the dripping is completed; after the reaction is completed, removing methanol from the reaction mixture, and the obtained liquid product is the multi-chain alkyl amidine; and / or The molar ratio of the 1,14-tetradecyl diamine to the N,N-dimethylacetamide dimethyl acetal in S1 is 1:(0.46-0.68); and / or The catalyst in S1 is selected from L-proline, p-toluenesulfonic acid or trifluoromethanesulfonic acid.

7. The displacement mining method according to claim 6, characterized in that: The molar ratio of the N,N-dimethylacetamide dimethyl acetal to the catalyst in S1 is (1.5-2.5):1; and / or Each mole of the 1,14-tetradecyl diamine is dissolved in 420-546 mL of the methanol.

8. The displacement mining method according to claim 5, characterized in that: The preparation method of the nano-silicon dioxide modified by nano-calcium carbonate described in S2 is: disperse 1-1.5 parts of calcium carbonate evenly in water, add 1.5-2 parts of nano-silicon dioxide, disperse by ultrasonic, then heat to 55-65°C, and keep the temperature under stirring for at least 20 hours to obtain the dispersion of the nano-silicon dioxide modified by nano-calcium carbonate.

9. The displacement mining method according to any one of claims 5 to 8, characterized in that: The mass ratio of the nano-silicon dioxide modified by nano-calcium carbonate in the dispersion of the nano-silicon dioxide modified by nano-calcium carbonate in S2 to the mass ratio of the polyalkyl amidine is (1-2):(3-5); and / or The ultrasonic dispersion time in S2 is 20 to 30 min; and / or The stirring speed in the stirring state described in S2 is 400~500 r / min.

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