Flue gas water-based three-phase foam system and profile control method

Abstract

The invention discloses a flue gas water-based three-phase foam system and a profile control method, the flue gas water-based three-phase foam system comprises dispersed-phase gas, suspended-phase solid particles and continuous-phase liquid, the liquid comprises the following components in percentage by weight: 0.5-2.0 wt% of a foaming agent, 0.05-0.5 wt% of a stabilizer, 0.05-0.2 wt% of a thickening agent, 0.1-0.8 wt% of a suspending agent, 0.3-1.0 wt% of inorganic salt and the balance of liquid preparation water; the gas comprises flue gas or mixed gas of one or at least two of nitrogen, natural gas, carbon dioxide, air and flue gas and the flue gas; the solid particles comprise one or a mixture of at least two of silicon dioxide particles, montmorillonite particles, bentonite particles, kaolin particles and fly ash particles, and the particle sizes of the solid particles are from nanometer to micrometer. According to the method, the flue gas discharged by the steam-injection boiler is captured and treated and then is injected into the stratum together with the water-based three-phase foam system and the steam segmented plug according to a certain proportion to assist in steam recovery of the thickened oil, so that the recovery rate of the thickened oil can be increased, the emission of greenhouse gases can be reduced, the capture, storage and utilization of CO2 can be realized, and the environmental protection situation requirements of carbon peak reaching and green development are met.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas exploitation, and specifically to a flue gas water-based three-phase foam system and a profile control method. Background Art

[0002] Steam stimulation is the main method for heavy oil thermal recovery in China at present. Most heavy oil fields have entered the late stage of multi-round steam stimulation development. The natural energy of the oil reservoir has obviously declined, the reservoir heterogeneity has been further aggravated, the reserves are unevenly utilized, the interference between wells is obvious, steam override and steam channeling phenomena occur, the oil production per cycle decreases, the water cut increases, the oil-gas ratio decreases, and the exploitation efficiency becomes poor. At the same time, during the steam injection thermal recovery process, a large amount of flue gas generated by the combustion of the steam injection boiler is discharged into the atmosphere, and the main components are N2, CO2, H2O, and a small amount of O2, etc. The national annual emission is expected to exceed 200×10 8 m 3 , and the environmental protection problem is prominent. How to realize the resource utilization and emission reduction of flue gas is a realistic problem to be solved urgently.

[0003] The foam profile control technology has been proved to be an effective means for water control and oil stabilization and improving the oilfield development effect. Foam has a selective plugging property of "plugging large pores but not small pores" and "plugging water but not oil", and the foam has little damage to the reservoir, and it is an excellent clean plugging agent. Therefore, using the foam profile control technology to control the steam override and steam channeling phenomena during steam stimulation is an effective technical idea. However, the foam fluid is a naturally thermodynamically unstable system, and it is prone to rupture especially under harsh reservoir conditions such as high temperature and high salinity, losing the plugging ability. In addition, the foam liquid film is relatively soft, and it is difficult to form a strong plugging for the dominant large channels. Aiming at the above existing problems, based on the purpose of realizing the resource utilization and emission reduction of flue gas, on the basis of fully optimizing the foaming agent suitable for flue gas foam profile control, by adding a certain proportion of solid particles to the flue gas foam to form a three-phase foam, the plugging and control effect of the foam system can be better strengthened.

[0004] Publication (Announcement) No.: CN115926770A, which discloses a high-temperature foaming agent for oilfields and its preparation method, belonging to the technical field of petrochemical engineering. The high-temperature foaming agent includes modified tea saponin, non-ionic surfactant, chelating agent, and low-carbon polyol. The modified tea saponin is prepared by reacting tea saponin aglycone with modified monosaccharide through a thiol-ene reaction; the high-temperature foaming agent of the present invention has excellent foaming and foam stabilizing properties, and has strong resistance to high salinity, and can meet the oilfield operation requirements in complex environments.

[0005] Publication (Announcement) Number: CN102703052B discloses a foam system formulation for profile control and oil displacement after polymer flooding in oilfields and a foam profile control and oil displacement method. The foam system formulation consists of the following components by weight percentage: surfactant 0.1 - 0.5 wt%, foam stabilizer 0.05 - 0.4 wt%, thickener 0.08 - 0.4 wt%, inorganic salt 0.05 - 1.2 wt%, and water as the remaining content. In the foam profile control and oil displacement method, the gas-liquid ratio of the foam system used is: at the injection pressure, the volume ratio of gas to liquid is 0.4:1 - 1:1. The foam system of this invention has both super foam performance and ultra-low interfacial tension. After polymer flooding, the foam profile control and displacement effect is obvious, the oil recovery rate can be increased by more than 20%, and the economic benefit is remarkable.

[0006] Publication (Announcement) Number: CN102011572B discloses a composite high-temperature profile control method for heavy oil wells. This method includes the steps: first injecting a solid high-temperature profile control agent into the heavy oil well to form a plugging substance to plug the main steam absorption channels; then injecting steam into the well while injecting a high-temperature foam profile control agent to plug the secondary steam absorption channels and the steam absorption channels in the far-well zone. Using the high-temperature profile control method for heavy oil wells of this invention is particularly beneficial for improving the steam injection efficiency and the degree of heavy oil utilization in the formation during steam injection for heavy oil recovery. According to the method of this invention, core simulation experiments and field tests were carried out, achieving the purpose of effectively plugging the main steam absorption channels and increasing the swept volume of high-temperature profile control.

[0007] The above-mentioned prior arts are all different from this invention. This invention is based on a process technology in which after the flue gas of the steam injection boiler is captured and treated, it is injected into the heavy oil well together with a certain proportion of profile control chemical agents and steam for thermal oil recovery.

[0008] In response to the technical development needs of carbon capture, utilization, and storage (CCUS), this invention captures and treats the flue gas discharged from the steam injection boiler, pressurizes it through a compressor, and injects it into the heavy oil well together with steam for thermal oil recovery. By using the CO2 and N2 mixed gas in the flue gas to form a flue gas water-based three-phase foam system, it can play roles such as profile control and water control in the heavy oil layer, expanding the steam swept range, enhancing energy and assisting in drainage. It can not only improve the heavy oil recovery rate but also reduce greenhouse gas emissions, realizing the capture, utilization, and storage of CO2, conforming to the environmental protection situation of carbon peak and green development, and having broad market application prospects.

[0009] In short, the technical solutions, the technical problems to be solved, and the beneficial effects of the above-mentioned disclosed technologies are all different from this invention. Regarding more technical features, the technical problems to be solved, and the beneficial effects of this invention, there is no technical inspiration in the above-mentioned disclosed technical documents. Summary of the Invention

[0010] In view of the above defects existing in the prior art, the object of the present invention is to provide a flue gas water-based three-phase foam system and a profile control method, so as to solve the problems of realizing efficient development by converting the development mode of high-round steam injection heavy oil wells, resource utilization of flue gas from steam injection boilers, and emission reduction, etc.

[0011] In order to achieve the above object, the present invention adopts the following technical solutions:

[0012] A flue gas water-based three-phase foam system includes a dispersed-phase gas, suspended-phase solid particles, and a continuous-phase liquid. The composition of the liquid by weight percentage includes: foaming agent: 0.5 - 2.0WT%, stabilizer: 0.05 - 0.5WT%, thickening agent: 0.05 - 0.2WT%, suspending agent: 0.1 - 0.8WT%, inorganic salt: 0.3 - 1.0WT%, and the balance is preparation water; the gas includes flue gas or one or at least two of nitrogen, natural gas, carbon dioxide, air, and a mixture of one or more of them and flue gas.

[0013] Further, the solid particles include one or at least two of silica particles, montmorillonite particles, bentonite particles, kaolin particles, and fly ash particles with particle sizes ranging from nanometers to micrometers.

[0014] Further, the foaming agent includes one or at least two of dialkyl quaternary ammonium salts, fluoroalkyl ether alcohol ammonium salts, dialkyl phthalamide polyoxyethylene ethers, α-olefin sulfonates, and sulfobetaine silicon surfactants, and any mixture thereof;

[0015] Specifically, the stabilizer includes one or at least two of ammonium stearate, dodecyldimethylamine oxide, and polyethylene glycol, and any mixture thereof;

[0016] Specifically, the thickening agent includes one or at least two of polyacrylamide, hydrolyzed polyacrylamide, fluoropolymer, hydrophobically associating polymer, and amphoteric branched polymer, or a mixture of one or at least two polymers with different molecular weights;

[0017] Specifically, the suspending agent includes one or at least two of dodecyldimethylbenzyl chloride, dodecylguanidine acetate, alkyl quaternary ammonium salts, and alkyl quaternary phosphonium salts, and any mixture thereof;

[0018] Specifically, the inorganic salt includes one or at least two of calcium chloride, sodium chloride, magnesium chloride, sodium sulfate, sodium bicarbonate, sodium carbonate, and potassium chloride, and any mixture thereof.

[0019] Further, by weight percentage in the liquid, the foaming agent includes 0.1 - 0.3WT% of dialkyl quaternary ammonium salt, 0.3 - 1.2WT% of α-olefin sulfonate, and 0.1 - 0.5WT% of sulfobetaine silicon surfactant;

[0020] Specifically, the stabilizer includes ammonium stearate at 0.05-0.5 WT% or dodecyldimethylamine oxide at 0.05-0.5 WT%;

[0021] Specifically, the thickening agent includes fluoropolymer at 0.02-0.08 WT% and hydrolyzed polyacrylamide at 0.03-0.12 WT%;

[0022] Specifically, the suspending agent includes benzalkonium chloride dodecyldimethyl at 0.3-0.8 WT% or alkyl quaternary ammonium salt at 0.1-0.4 WT%;

[0023] Specifically, the inorganic salts are calcium chloride at 0.05-0.1 WT% and sodium chloride at 0.25-0.9 WT%.

[0024] Furthermore, in terms of weight percentage in the system, the solid particles include silica nanoparticles at 0.1-0.4 WT% and bentonite microparticles at 0.05-0.3 WT%.

[0025] Furthermore, the liquid-making water is the clear water injected into the oilfield or the qualified treated oilfield sewage.

[0026] A profile control method for a flue gas water-based three-phase foam system includes the following steps:

[0027] S1. Select a suitable oil well;

[0028] S2. Parameter optimization;

[0029] A2.1. Steam consumption:

[0030] The cyclic steam injection volume for vertical and inclined wells: the steam injection volume per meter is 120 t / m to 200 t / m;

[0031] The cyclic steam injection volume for horizontal wells: the steam injection volume per meter is 10 t / m to 20 t / m;

[0032] A2.2. Flue gas consumption: The standard volume of flue gas consumption is 40000 Nm 3 ~80000 Nm 3 ;

[0033] The gas-steam ratio of the flue gas injection volume (standard volume, Nm 3 ) to the steam injection volume (water equivalent, t) is 30 Nm 3 / t to 50 Nm 3 / t;

[0034] A2.3. Foam system consumption: In the flue gas water-based three-phase foam system for implementing the pre-profile control slug, the gas injection volume (standard volume, Nm 3) The ratio of the liquid injection volume (water equivalent, t) is 80:1 to 150:1;

[0035] In the foam system implementing the steam accompanying profile control slug, the ratio of the gas injection volume (standard condition volume, Nm 3 ) to the liquid injection volume (water equivalent, t) is 2000:1 to 2500:1;

[0036] S3. Field injection. During injection, it is injected in the way of the annulus between the tubing and the casing or in the way of injecting from the tubing;

[0037] S4. Shut-in reaction.

[0038] Furthermore, in S1, the reservoir is screened according to the following conditions: the viscosity of the surface degassed crude oil at 50 °C < 100000 mPa·s, the reservoir burial depth < 2000 m, the effective thickness > 3 m, the permeability > 300 mD, and the ratio of the water body volume of the edge and bottom water to the oil layer volume < 100;

[0039] The oil wells are screened according to the following conditions: the peak production at the initial stage of thermal recovery production reaches more than 5 t / d, the water cut rises rapidly due to steam channeling or water channeling after multiple rounds of huff and puff, the steel grade and corrosion resistance of the oil well casing should meet the requirements of injecting flue gas, and there are no engineering problems such as casing damage, casing deformation, and sand burial.

[0040] Furthermore, in S2, the cyclic steam injection volume for vertical and inclined wells: for wells with an oil layer thickness greater than 10 m, the steam injection volume per meter is 120 t / m to 160 t / m; for wells with an oil layer thickness equal to 10 m, the steam injection volume per meter is 160 t / m; for thin layer wells with an oil layer thickness less than 10 m, the steam injection volume per meter ranges from 160 t / m to 200 t / m;

[0041] The cyclic steam injection volume for horizontal wells: for wells with a horizontal section length greater than 150 m, the steam injection volume per meter is 10 t / m to 15 t / m; for wells with a horizontal section length equal to 150 m, the steam injection volume per meter is 15 t / m; for wells with a horizontal section length less than 150 m, the steam injection volume per meter ranges from 15 t / m to 20 t / m.

[0042] Furthermore, in S3, first, after connecting the surface equipment and pipelines and passing the pressure test, then pump injection is carried out according to the pump injection procedure, and the dynamic construction parameters are monitored in real time to ensure the safe and smooth progress of the pump injection construction for each section;

[0043] The injection displacement for each slug is: the steam injection is 6 m 3 / h - 10 m 3 / h, the flue gas injection is 800 - 1200 Nm 3 / h, and the pre-profile control slug is 20 m 3 / h - 50 m 3 / h, with the steam flooding profile control slug being 0.5 m 3 / h - 1.0 m 3 / h;

[0044] During the on-site construction process, make appropriate adjustments according to the change of injection pressure. If the construction pressure is too high, reduce the construction displacement.

[0045] Furthermore, in S3;

[0046] A3.1. Inject the pre-injection profile control slug: For heavy oil wells with serious water or steam channeling in the early stage, implement the injection of flue gas water-based three-phase foam system to block the main water or steam channeling channels. Before injecting steam, first use hot water above 80 °C with a cleaning agent to backwash and treat the wellbore, and then squeeze in 40,000 Nm 3 ~80,000 Nm 3 of flue gas and 260 m 3 -1000 m 3 of the flue gas water-based three-phase foam system. Finally, squeeze into the formation a formation pretreatment agent which is one or at least two combinations of an oil-soluble viscosity reducer, a high-temperature clay stabilizer, and an anti-swelling and sand control agent;

[0047] A3.2. Inject the steam flooding profile control slug: While injecting steam from the heat-insulated tubing, inject 60,000 Nm 3 ~100,000 Nm 3 of flue gas and 25 m 3 -50 m 3 of a high-temperature resistant particle gel foam system to block the secondary water or steam channeling channels and the steam absorption channels in the far well zone, effectively improving the steam absorption profile of the oil reservoir section, increasing the steam heat sweep range, and realizing enhanced oil recovery by injecting steam with flue gas;

[0048] A3.3. Inject the pure steam displacement slug: Then inject high-temperature pure steam to increase the steam heat sweep range, and displace the flue gas near the well to a farther formation, reducing the gas influence on the lifting effect caused by the gas overflow near the well after opening the well for production.

[0049] Furthermore, in S4; Soak the well for 3 - 7 days to make the injected steam and flue gas foam profile control system fully play its role, and make the oil, gas, and water in the oil reservoir quickly reach a new distribution equilibrium state. After the pressure diffusion is stable, select the appropriate time to switch to pumping and open the well for production according to the pressure change.

[0050] The present invention has the following beneficial effects compared with the prior art:

[0051] After the flue gas discharged from the steam injection boiler is captured and processed, it is injected into the formation in a certain proportion together with the water-based three-phase foam system and steam slug, assisting steam to extract heavy oil. While plugging large channels of steam channeling or water channeling in the formation and adjusting the oil displacement profile, it can effectively improve the steam absorption profile of the oil reservoir section, inhibit the condensation of steam in the near-wellbore zone, increase the steam heat sweep range and form a gas cap for heat insulation at the top, thereby strengthening the heat transfer of steam to the deep formation and increasing the degree of remaining oil recovery.

[0052] At the same time, the co-injection of flue gas and steam has good heat insulation and heat preservation effects, which is beneficial to improving the steam dryness at the bottom of the well and enhancing the viscosity reduction effect of steam thermal recovery. Compared with the traditional single steam injection huff and puff thermal recovery method, it has significant technical advantages both in plugging channeling and water and in the huff and puff effect of thermal recovery. It can not only improve the heavy oil recovery rate, but also reduce greenhouse gas emissions, realize the capture, storage and utilization of CO2, meeting the environmental protection requirements of carbon peak and green development. Brief Description of the Drawings

[0053] Figure 1 is a schematic structural diagram of a three-dimensional physical model experiment device for a flue gas water-based three-phase foam system of the present invention;

[0054] Figure 2 is a schematic diagram of the on-site injection process of a flue gas water-based three-phase foam system and a profile control method of the present invention;

[0055] Figure 3 is a comparison curve of the production conditions of two cycles before and after foam profile control of a horizontal well in Example 6 of the present invention;

[0056] Figure 4 is a performance detection table of flue gas water-based three-phase foam systems with different ratios in Example 3 of the present invention;

[0057] In the figure: 1 - oil reservoir, 2 - injection oil well casing, 3 - annulus between casing and tubing, 4 - heat insulation pipe, 5 - steam injection boiler, 6 - flue gas treatment equipment, 7 - flue gas injection process, 8 - steam injection process, 9 - chemical liquid preparation tank, 10 - pump and liquid construction vehicle group, 11 - profile control chemical injection process. Detailed Embodiments

[0058] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0059] Example 1:

[0060] The invention provides a flue gas water-based three-phase foam system. The flue gas water-based three-phase foam system is a high-temperature resistant particulate gel foam system formed by dispersing gas in a liquid and suspending solid particles in the liquid, where the gas is the dispersed phase, the solid is the suspended phase, and the liquid is the continuous phase.

[0061] The liquid in the flue gas water-based three-phase foam system contains the following components by weight percentage: foaming agent: 0.5 - 2.0WT%, stabilizer: 0.05 - 0.5WT%, thickening agent: 0.05 - 0.2WT%, suspending agent: 0.1 - 0.8WT%, inorganic salt: 0.3 - 1.0WT%, and the balance is the liquid for preparing the solution.

[0062] Specifically, the foaming agent includes one or at least two of dialkyl quaternary ammonium salts, fluoroalkyl ether alcohol ammonium salts, dialkyl phthalamide polyoxyethylene ethers, α-olefin sulfonates, and sulfobetaine silicone surfactants; the foaming agent has high surface activity, good foaming and foam stabilizing properties, strong compounding synergistic effect, and at the same time has strong high-temperature resistance and salt tolerance, ensuring that the foam of the foam profile control system before gelation and the gel of the foam profile control system after gelation can be stable in the reservoir for a long time, enabling the foam profile control system to better play the role of in-depth profile control in the reservoir.

[0063] Preferably, by weight percentage in the liquid, the foaming agent includes 0.1 - 0.3WT% of dialkyl quaternary ammonium salt, 0.3 - 1.2WT% of α-olefin sulfonate, and 0.1 - 0.5WT% of sulfobetaine silicone surfactant.

[0064] The stabilizer can be selected from one or at least two of ammonium stearate, dodecyldimethylamine oxide, and polyethylene glycol; the addition of the stabilizer can improve the quality of the foam film, increase the viscoelasticity of the film, reduce the gas permeability of the foam, thereby enhancing the stability of the foam.

[0065] Preferably, by weight percentage in the liquid, the stabilizer includes 0.05 - 0.5WT% of ammonium stearate or 0.05 - 0.5WT% of dodecyldimethylamine oxide.

[0066] The thickening agent includes one or at least two of polyacrylamide, hydrolyzed polyacrylamide, fluoropolymer, hydrophobically associating polymer, and amphoteric branched polymer, or a mixture of one or at least two polymers with different molecular weights; the addition of the thickening agent can increase the viscosity of the foam liquid phase, form a viscoelastic film, and at the same time can increase the foam stability and enhance the plugging ability of the foam.

[0067] Preferably, by weight percentage in the liquid, the thickening agent includes 0.02 - 0.08WT% of fluoropolymer and 0.03 - 0.12WT% of hydrolyzed polyacrylamide.

[0068] The suspending agent includes one or any mixture of at least two of dodecyldimethylbenzyl chloride, dodecylguanidine acetate, alkyl quaternary ammonium salt, and alkyl phosphonium salt; the suspending agent can adsorb on the surface of solid particles, reduce the interaction between particles, ensure that the particle system is uniformly dispersed in the foam profile control system, and has a synergistic effect with the foaming agent, can form an ultra-low interfacial tension, and enhance the foaming performance and foam stability of the system.

[0069] Preferably, based on the weight percentage in the liquid, the suspending agent includes 0.3-0.8WT% of dodecyldimethylbenzyl chloride or 0.1-0.4WT% of alkyl quaternary ammonium salt.

[0070] The inorganic salt includes one or any mixture of at least two of calcium chloride, sodium chloride, magnesium chloride, sodium sulfate, sodium bicarbonate, sodium carbonate, and potassium chloride; adding inorganic salts to the foam profile control system can improve the compatibility and adaptability of the foam profile control system with reservoir fluids.

[0071] Preferably, the inorganic salt is 0.05-0.1WT% of calcium chloride and 0.25-0.9WT% of sodium chloride, based on the weight percentage in the system.

[0072] The prepared liquid water is the clear water injected into the oilfield or the qualified treated oilfield sewage.

[0073] Further, the solid particles in the flue gas water-based three-phase foam system may include one or at least two of silica particles, montmorillonite particles, bentonite particles, kaolin particles, and fly ash particles, with a mixture of particle sizes ranging from nanometers to micrometers. The solid particles can adsorb in the foam liquid film of the foam profile control system, increase the viscoelasticity of the liquid film, and make the foam of the foam profile control system more stable. In the underground reservoir, the solid particles can block the large pores in the reservoir and improve the profile control effect of the foam system.

[0074] Preferably, based on the weight percentage in the system, the solid particles include 0.1-0.4WT% of silica nanoparticles and 0.05-0.3WT% of bentonite microparticles.

[0075] Further, the gas in the flue gas water-based three-phase foam system includes flue gas or a mixture of one or at least two of nitrogen, natural gas, carbon dioxide, air, and flue gas and flue gas. Under the action of external force, a certain proportion of these low-solubility gases enter the liquid with a low surface tension and are isolated and dispersed in the liquid to form foam.

[0076] Preferably, the gas used is flue gas or any proportion of flue gas and nitrogen.

[0077] Furthermore, the profile control of the flue gas water-based three-phase foam system is to capture and process the flue gas discharged from the steam injection boiler, and then mix it with a certain proportion of profile control chemical agent solution, solid particles, etc. and inject it into the well to form a flue gas water-based three-phase foam system. Utilizing the characteristics that the flue gas foam is stable in water but unstable in oil and the mechanism that solid particles can block the large pores in the reservoir, while achieving the purpose of plugging the large pores of steam channeling or water channeling in the formation and adjusting the oil displacement profile, it can effectively improve the steam absorption profile in the oil layer section, inhibit the condensation of steam in the near-well zone, increase the steam heat sweep range and form a gas cap for heat insulation at the top, thereby strengthening the heat transfer of steam to the deep formation, increasing the degree of recovery of residual oil, and achieving the purpose of plugging channeling and controlling water and improving the oil displacement effect.

[0078] Example 2:

[0079] Based on Example 1, the specific implementation of the profile control method of the flue gas water-based three-phase foam system includes the following steps:

[0080] S1. Select oil wells and screen the oil reservoirs according to the following conditions: the viscosity of surface degassed crude oil at 50 °C < 100000 mPa·s, the burial depth of the oil reservoir < 2000 m, the effective thickness > 3 m, the permeability > 300 mD, and the ratio of the water body volume of the edge and bottom water to the oil layer volume < 100;

[0081] Screen the oil wells according to the following conditions: the peak production at the initial stage of thermal recovery production reaches more than 5 t / d, the water cut rises rapidly due to steam channeling or water channeling after multiple rounds of huff and puff, the steel grade and corrosion resistance of the oil well casing should meet the requirements of injecting flue gas, and there are no engineering problems such as casing damage, casing deformation, and sand burial;

[0082] S2. Parameter optimization: Based on the analysis of data such as the geological characteristics of the oil reservoir, the production history of the oil well, and the oil-water distribution status, determine the construction scale and pumping injection program of the profile control auxiliary steam injection process for heavy oil with the flue gas water-based three-phase foam system. The specific parameter optimization is as follows:

[0083] A2.1. Steam consumption:

[0084] The cyclic steam injection volume of vertical and inclined wells:

[0085] For wells with an oil layer thickness greater than 10 meters, the recommended steam injection volume per meter is 120 t / m - 160 t / m;

[0086] For thin-layer wells with an oil layer thickness less than 10 meters, the appropriate steam injection volume per meter ranges from 160 t / m to 200 t / m;

[0087] The cyclic steam injection volume of horizontal wells:

[0088] For wells with a horizontal section length greater than 150 meters, the recommended steam injection volume per meter is 10 t / m - 15 t / m;

[0089] For wells with a horizontal section length less than 150 meters, the appropriate steam injection volume per meter ranges from 15 t / m to 20 t / m.

[0090] A2.2, Flue gas dosage: The flue gas dosage for implementing the pre - profile - control slug is designed according to the water - invasion volume caused by edge - bottom water breakthrough, the volume of the reservoir to be treated, reservoir temperature and pressure, etc. Generally, the standard volume dosage of flue gas is designed to be between 40000 Nm 3 ~80000 Nm 3 ;

[0091] The flue gas dosage for the steam - accompanied profile - control slug is generally based on on - site statistics and numerical simulation results. Based on the viscosity of surface - degassed crude oil at 50 °C and combined with the reservoir thickness, the gas - to - steam ratio of the flue gas injection volume (standard condition volume, Nm 3 ) to the steam injection volume (water equivalent, t) is recommended to be 30 Nm 3 / t~50 Nm 3 / t.

[0092] A2.3, Foam system dosage: In the gas - water - based three - phase foam system for implementing the pre - profile - control slug, the ratio of the gas injection volume (standard condition volume, Nm 3 ) to the liquid injection volume (water equivalent, t) is 80:1~150:1;

[0093] In the foam system for implementing the steam - accompanied profile - control slug, the ratio of the gas injection volume (standard condition volume, Nm 3 ) to the liquid injection volume (water equivalent, t) is 2000:1~2500:1.

[0094] S3. Field injection: When injecting, the foam profile - control system is recommended to be injected through the annulus between the casing and the tubing, or it can also be injected through the tubing.

[0095] First, connect the surface equipment and pipelines and conduct a pressure test until qualified, and then carry out pumping according to the pumping procedure, monitor the dynamic construction parameters in real - time, and ensure the safe and smooth progress of each stage of pumping construction;

[0096] The optimized recommended injection displacement for each slug is as follows:

[0097] Steam injection is 6 m 3 / h - 10 m 3 / h, flue gas injection is 800 - 1200 Nm 3 / h, the pre - profile - control slug is 20 m 3 / h - 50 m 3 / h, the steam - accompanied profile - control slug is 0.5 m 3 / h - 1.0 m 3 / h;

[0098] During on-site construction, make appropriate adjustments according to the change of injection pressure. If the construction pressure is too high, consider reducing the construction displacement as appropriate.

[0099] A3.1. Injection of pre-injection profile control slug: For heavy oil wells with serious water channeling or steam channeling in the early stage, implement the injection of flue gas water-based three-phase foam system to block the main water channeling or steam channeling channels. Before injecting steam, first backwash the wellbore with hot water above 80 °C and a cleaning agent, and then squeeze in 40000 Nm 3 ~80000 Nm 3 of flue gas and 260 m 3 -1000 m 3 of flue gas water-based three-phase foam system, and finally squeeze into the formation a formation pretreatment agent which is one or at least two combinations of an oil-soluble viscosity reducer, a high-temperature clay stabilizer, and an anti-swelling and sand control agent;

[0100] A3.2. Injection of steam accompanying profile control slug: While injecting a certain amount of steam from the heat-insulated tubing, inject 60000 Nm 3 ~100000 Nm 3 of flue gas and 25 m 3 -50 m 3 of high-temperature resistant particle gel foam system, which can block secondary water channeling or steam channeling channels and block the steam absorption channels in the far well zone, effectively improve the steam absorption profile of the oil reservoir section, increase the steam heat sweep range, and realize enhanced oil recovery by injecting steam accompanied by flue gas;

[0101] A3.3. Injection of pure steam displacement slug: Then inject a certain amount of high-temperature pure steam to increase the steam heat sweep range, displace the flue gas near the well to a farther formation, and reduce the gas influence on the lifting effect caused by the overflow of near-well gas after opening the well for production;

[0102] S4. Soaking well reaction, it is recommended to soak the well for 3 to 7 days to make the injected steam and flue gas foam profile control system fully play its role, and make the oil, gas and water in the oil reservoir quickly reach a new distribution balance state. After the pressure diffusion is stable, select the appropriate time to switch to pumping and open the well for production according to the pressure change.

[0103] Example 3:

[0104] This example provides a performance detection experiment of flue gas water-based three-phase foam systems with different ratios to further describe the present invention. The specific ratios are shown in Figure 4 , it should be understood that the examples are only for the purpose of illustration and do not constitute any limitation to the present invention.

[0105] The performance detection experiment uses a high-temperature and high-pressure foam scanner to measure the foaming ability and foam stability of the foam system, and uses a simulated core tube and a steam displacement experimental device to measure the resistance factor.

[0106] The main test equipment and materials include: a high-temperature and high-pressure foam scanner, with a temperature resistance above 200 °C and a pressure resistance higher than the saturated water vapor pressure corresponding to the set temperature; a steam displacement experimental device, with a temperature resistance above 250 °C and a pressure resistance higher than 50 MPa; a simulated core tube, 25 mm x 500 mm; a high-pressure reciprocating pump: the flow control accuracy is 0.1 mL / min; flue gas, prepared from 85% nitrogen and 15% carbon dioxide, with an output pressure of 2.0 MPa to 10.0 MPa; a simulated core, quartz sand composed of 15% (20 - 40 mesh) + 50% (40 - 60 mesh) + 20% (60 - 100 mesh) + 15% (100 - 120 mesh); distilled water, meeting the requirements of grade three water specified in GB / T 6682.

[0107] Take 200.0 mL of the prepared foam system solution and place it in the sample container of the high-temperature and high-pressure foam scanner. Inject 80.0 mL into the sample chamber, set the temperature to 200 °C, fill with flue gas to 4 MPa, heat to the required temperature, and keep it constant for 30 min.

[0108] After the constant temperature is completed, adjust the gas flow controller to inject flue gas at a speed of 200 cm 3 / min. When the foam volume reaches 200 cm 3 , stop injecting flue gas, record the maximum volume and time of the foam as the initial value. Then record the time corresponding to when the foam volume drops to half of the initial volume, which is the half-life of the foam. Measure the foaming volume and half-life of the flue gas-water-based three-phase foam system with different ratios in turn, and record the measurement results in Table 1.

[0109] Connect the fabricated core tube to the vacuum saturation water process. Open the valve at the front end of the core tube, use a vacuum pump to evacuate the core tube (the vacuum degree reaches above -0.095 MPa), close the front-end valve and the vacuum pump, and observe through the pressure gauge at the front end of the core tube to ensure no air leakage. Then, weigh a certain amount of distilled water, open the valve at the rear end of the core tube for water saturation, and the saturation time is 12 h.

[0110] Place the saturated simulated core tube into the insulation sleeve of the steam displacement experimental device. The set temperature of the displacement experimental device is 250 °C, and keep it constant for 4.0 h. After the constant temperature, simply inject 250 °C zero-dryness hot water, and the displacement of the boiler water pump is 5.0 mL / min. Measure the pressure difference between the inlet and outlet of the core tube, and this pressure difference is the basic pressure difference P1.

[0111] Inject flue gas and high-temperature foam system solution along with hot water into the core barrel inlet. Take 200 g of the foam system solution sample with a concentration of 10%. Set the displacement. After mixing with zero-quality hot water, the concentration of the foam system solution reaches 2.5%. The set value of the flue gas displacement reaches a volume ratio of 1:1 to 2:1 with hot water under the test temperature and pressure conditions, and keep it constant for 0.5 h. Measure the pressure difference between the inlet and outlet of the core barrel. This pressure difference is the plugging pressure difference P2. The resistance factor is the ratio of the plugging pressure difference P2 to the basic pressure difference P1. Measure the resistance factors of the flue gas-water-based three-phase foam systems with different ratios in turn, and record the measurement results in Figure 4 the table.

[0112] The test data of the above examples show that the high-temperature foaming volume (200 °C) of the flue gas-water-based foam system formulations in all examples is greater than 200 mL, the foam half-life exceeds 20 min, and the resistance factor (250 °C) is greater than 30, all of which can meet the requirements of the general technical conditions for high-temperature foaming agents used in steam stimulation, indicating that the flue gas-water-based foam system has good foam performance and strong plugging and profile control capabilities.

[0113] Example 4:

[0114] This example provides a specific flue gas-water-based three-phase foam system and conducts experimental comparisons.

[0115] Use a temperature-resistant and pressure-resistant three-dimensional physical model to conduct performance evaluation experiments on the flue gas-water-based three-phase foam system. As Figure 1 shown, the length, width, and height of the three-dimensional physical model are 100×50×30 cm, the total volume of the three-dimensional physical model is 150 liters, the temperature resistance is 1000 °C, and the pressure resistance is 20 MPa; the number of temperature and pressure sensors is 1000. The supporting equipment includes a stirrer, an ISCO displacement pump, a high-temperature relative permeability measurement device (40 MPa), a steam generator, a rotational rheometer (300 °C, 40 MPa), a pressure piston container, a gas flowmeter, a vacuum pump, a backpressure pump, a backpressure valve, etc.

[0116] To effectively test the profile control effect of the three-phase foam system in heavy oil high-permeability formations, after mixing quartz sand in the proportion of 10% (20 - 40 mesh) + 20% (40 - 60 mesh) + 25% (60 - 80 mesh) + 25% (80 - 100 mesh) + 10% (100 - 120 mesh) + 10% (120 - 150 mesh) and heavy oil with a viscosity of 5000 mPa·s at 50 °C of surface degassed crude oil evenly, a horizontal well with a length of 50 cm is inserted at the middle position on the side of the model, which is on the same horizontal line as the model's rotating shaft. Filter screens with 120 meshes are placed on the top and bottom of the model. After placing the model, the top and bottom are filled with clay, and the middle part is filled with oil sand. The mixed heavy oil and quartz sand in the previous step are put into the model step by step. After filling each layer, it is tapped firmly with a rubber hammer before filling the next layer of sand. Record the total weight of the put-in oil sand mixture. The size and structure of the experimental model are shown in Figure 1 。

[0117] The configurations of other experimental materials are as follows:

[0118] Fuel gas flue gas (configured): 12% carbon dioxide, 3% oxygen, 600 PPM nitrogen oxides, nitrogen is the balance gas, and 40 liters of high-pressure gas are needed from a nitrogen gas cylinder (pressure 15 MPa);

[0119] Distilled water; used to generate high-quality steam;

[0120] Magnesium chloride and calcium chloride: used to configure formation water, 4000 - 8000 mg / L;

[0121] The liquid of the flue gas water-based three-phase foam system, in terms of weight percentage in the liquid: 0.5 WT% foaming agent, 0.05 WT% stabilizer, 0.05 WT% thickening agent, 0.3 WT% suspending agent, 0.3 WT% inorganic salt, and the balance is the liquid for preparing the solution;

[0122] Among them, in terms of weight percentage in the liquid, the foaming agent includes 0.1 WT% dialkyl quaternary ammonium salt, 0.3 WT% α-olefin sulfonate, and 0.1 WT% sulfobetaine silicon surfactant;

[0123] The stabilizer includes 0.05 WT% ammonium stearate;

[0124] The thickening agent includes 0.02 WT% fluoropolymer and 0.03 WT% hydrolyzed polyacrylamide;

[0125] The suspending agent includes 0.3 WT% dodecyldimethylbenzyl chloride;

[0126] The inorganic salt is 0.05 WT% calcium chloride and 0.25 WT% sodium chloride.

[0127] The solid particles of the flue gas water-based three-phase foam system, calculated by weight percentage in the system: 0.1WT% of silica nanoparticles and 0.05WT% of bentonite microparticles.

[0128] The gas of the flue gas water-based three-phase foam system: flue gas.

[0129] First, inject crude oil and formation water into the model to 5 MPa. If the pressure drop in the model does not exceed 0.5 MPa within 24 hours after closing the valve, it is considered qualified. Then start heating the model to the reservoir temperature of 60 °C. If the temperature fluctuation does not exceed ±3 °C, it is considered qualified.

[0130] Then, start the steam soak process for the injection well. Inject 180 mL of steam in the initial cycle (injection rate 12 mL / min), soak the well for 5 min, open the well to produce oil for 40 min. Manually measure the oil production and water production at the outlet, and record the changes in the temperature field and pressure field throughout the steam soak process. After the steam soak of the injection well ends, save the oil sample and conduct component analysis. Conduct the above steam soak process in sequence, and increase the injected steam volume by 8%-10% between cycles. After the end of the 8th steam soak cycle, transfer to the flue gas-assisted steam soak stage according to the oil production situation.

[0131] Before injecting steam, first inject 500 mL of flue gas and a pre-profile control slug of 15 mL of the flue gas water-based three-phase foam system, then inject 180 mL of steam while simultaneously injecting 200 mL of flue gas and 2 mL of the flue gas water-based three-phase foam system, and finally inject 40 mL of steam. Soak the well for 5 min, open the well to produce oil for 40 min. Manually measure the oil production and water production at the outlet, and record the changes in the temperature field and pressure field throughout the steam soak process. After the steam soak of the injection well ends, save the oil sample and conduct component analysis. Conduct the above steam soak process in sequence until the end of the 10th cycle, then take samples at different positions in the model to measure the oil content rate and four-component determination, and calculate the changes in the recovery rate of different steam soak cycles.

[0132] The experimental results show that after multiple rounds of steam injection through the horizontal well in the model, steam override and steam channeling phenomena occur, the periodic oil production decreases, the water cut increases, the oil-gas ratio decreases, and the production efficiency deteriorates. After starting to inject the flue gas water-based three-phase foam system in the 9th cycle, the steam channeling phenomenon is alleviated, the periodic oil production increases by 28%, the water cut decreases by 20 percentage points, the oil-gas ratio increases by 0.2, and the production efficiency improves. Therefore, the profile control method of the invention can achieve the purpose of plugging water or steam channeling channels, effectively improving the steam absorption profile of the oil reservoir section, increasing the steam heat sweep range, and at the same time, the enhanced oil displacement effect is also relatively obvious.

[0133] Example 5:

[0134] This example provides a specific flue gas water-based three-phase foam system:

[0135] The composition of the liquid by weight percentage includes: foaming agent: 1.5WT%, stabilizer: 0.25WT%, thickening agent: 0.15WT%, suspending agent: 0.5WT%, inorganic salt: 0.7WT%, and the balance is preparation water;

[0136] The gas includes one or at least two of nitrogen, natural gas, carbon dioxide, air, flue gas and a mixture of flue gas;

[0137] The solid particles are silica particles, montmorillonite particles, bentonite particles, kaolin particles, fly ash particles, with a particle size ranging from nanometers to micrometers.

[0138] More specifically, by weight percentage in the liquid, the foaming agent includes 0.1WT% of dialkyl quaternary ammonium salt, 0.1WT% of fluoroalkyl ether alcohol ammonium salt, 0.1WT% of dialkyl phthalamide polyoxyethylene ether, 0.3WT% of α-olefin sulfonate, and 0.1WT% of sulfobetaine silicon surfactant;

[0139] The stabilizer includes 0.05WT% of ammonium stearate, 0.05WT% of dodecyldimethylamine oxide, and 0.15WT% of polyethylene glycol;

[0140] The thickening agent includes 0.03WT% of polyacrylamide, 0.05WT% of hydrolyzed polyacrylamide, 0.03WT% of fluoropolymer, 0.02WT% of hydrophobically associating polymer, and 0.02WT% of amphoteric branched polymer;

[0141] The suspending agent includes 0.3WT% of dodecyldimethylbenzyl chloride, 0.05WT% of dodecylguanidine acetate, 0.1WT% of alkyl quaternary ammonium salt, and 0.05WT% of alkyl quaternary phosphonium salt;

[0142] The inorganic salt includes 0.05WT% of calcium chloride, 0.4WT% of sodium chloride, 0.05WT% of magnesium chloride, 0.05WT% of sodium sulfate, 0.05WT% of sodium bicarbonate, 0.05WT% of sodium carbonate, and 0.05WT% of potassium chloride;

[0143] By weight percentage in the system, the solid particles include 0.1WT% of silica particles, 0.05WT% of montmorillonite particles, 0.05WT% of bentonite particles, 0.05WT% of kaolin particles, and 0.05WT% of fly ash particles, with a particle size ranging from nanometers to micrometers.

[0144] The preparation water is the clear water injected into the oilfield or the qualified treated oilfield sewage.

[0145] Example 6:

[0146] This example provides a specific profile control method for a flue gas water-based three-phase foam system, using No. 4 in Example 3, that isFigure 4 The flue gas water-based three-phase foam system configured with No. 4 in the middle.

[0147] Taking a horizontal well in a certain block of an oilfield as an example, the certain block is a heavy oil reservoir with edge and bottom water. The viscosity of the surface degassed crude oil at 50 °C is 4500 mPa·s, the burial depth of the reservoir is 1080 m, the effective thickness is 5.8 m, the initial oil saturation is 0.7, the average porosity is 35%, the permeability is 1760 mD, the average shale content of the reservoir is 10.6%, the original reservoir pressure is 10.2 MPa, the pressure coefficient is 0.97, the original formation temperature is 52 °C, the measured geothermal gradient is 3.2 °C / 100 m, belonging to a normal temperature and pressure system, the volume ratio of the water body to the oil layer volume is 83, and it has strong edge and bottom water; the horizontal section length of the production interval of the oil well is 194.0 m, the water cut at the wellhead in the initial production stage is 32.0%, the peak production reaches 15.8 t / d, after multiple rounds of thermal recovery huff and puff, the water cut at the wellhead rises to 81.5%, the reservoir pressure drops to 6.3 MPa, and the formation temperature rises to 64 °C; the steel grade of the 7IN casing of the oil well is TP 110, and there are no engineering problems such as casing damage, casing deformation, and sand burial.

[0148] S1. The oil wells in the said block meet the well selection requirements of the oil reservoirs applicable to the process of the present invention.

[0149] S2. Parameter design: In this embodiment, based on the analysis of data such as the reservoir geological characteristics, oil well production history, and oil-water distribution status of the oil wells in a certain oilfield block, the construction scale and pumping program of the process plan for steam-assisted heavy oil recovery with boiler flue gas and chemical agents are determined. The specific construction parameter design is as follows:

[0150] A2.1. Steam consumption: According to the conditions such as the viscosity of the surface degassed crude oil at 50 °C < 5000 mPa·s, the oil layer thickness < 15 m, the huff and puff cycle is 8 cycles, and the horizontal well section length is 194.0 m in the well area of this horizontal well, referring to the recommended range of the recommended steam injection parameters for steam huff and puff wells, it is determined that the steam consumption in this cycle is 2200 t, that is, 11.34 t / m.

[0151] A2.2. Flue gas consumption: The flue gas consumption for implementing the pre-profile control slug is comprehensively calculated according to the water invasion volume generated by the edge and bottom water breakthrough, the volume of the reservoir to be treated, etc. The underground flue gas volume consumption is 996.7 m 3 , and then substituting the reservoir pressure of 6.3 MPa and the formation temperature of 64 °C into the formula (P1*V1) / T1 = (P2*V2) / T2, calculating and selecting the standard volume of flue gas consumption to be approximately 60000 Nm 3 ;

[0152] The flue gas consumption for implementing the steam-assisted profile control slug is based on the conditions such as the viscosity of the surface degassed crude oil at 50 °C < 5000 mPa·s and the oil layer thickness < 15 m in this well area. The gas-steam ratio of the recommended flue gas injection volume to the steam injection volume is 35 Nm3 / t; Determine that the standard volume of flue gas used is approximately 80,000 Nm 3 .

[0153] A2.3. Dosage of the flue gas water-based three-phase foam system: According to the dosage of flue gas for foam profile control implementation and the performance parameters of the foam system, calculate that the usage amount of the foam system corresponding to the 60,000 Nm of the pre-profile control slug is approximately 500 m 3 of the flue gas, that is, 120:1; Implement the associated steam profile control slug of 80,000 Nm 3 of the flue gas, and the usage amount of the corresponding foam system is approximately 40 m 3 of the flue gas, that is, 2000:1. 3

[0154] S3. Field injection: As shown in Figure 2 , inject in the way of the annulus between the tubing and the casing. It includes an oil layer 1 with an effective thickness of 5.8 m, an injection well with a 7-in oil layer casing 2. The casing 2 is used to isolate the formation to form a channel for oil and gas to reach the ground. Inside the casing 2, there is a 4.5-in steam injection heat insulation pipe 4 for injecting steam generated by a steam injection boiler 5. The annulus 3 between the casing 2 and the heat insulation pipe 4 is used to inject flue gas, formation pretreatment agents, foam systems, etc. The on-site injection construction includes the following steps:

[0155] First, use hot water above 80 °C and 5% cleaning agent, a total of 40 m 3 to backwash the wellbore. Then, in the way of injecting steam from the steam injection heat insulation pipe 4 and injecting flue gas from the annulus 3 between the tubing and the casing, after correctly connecting the ground equipment such as the steam injection boiler 5, the flue gas treatment equipment 6, the chemical liquid mixing tank 9, the pump liquid construction vehicle group 10, etc., and the pipe manifolds such as the flue gas injection process pipeline 7, the steam injection process pipeline 8, the chemical agent injection process pipeline 11, etc., close the wellhead gate and the casing gate, and test the pressure of the ground pipe manifolds to 30 MPa. If the pressure drop is less than 0.5 MPa within 30 minutes, it is qualified;

[0156] A3.1. Inject the pre-profile control slug. Use the pump liquid construction vehicle group 10 to inject the flue gas water-based three-phase foam system of 500 m 3 along the chemical agent injection process pipeline 11 from the annulus between the tubing and the casing, with a displacement of 10 m 3 / h; At the same time, open the casing gate, and use the flue gas treatment equipment 6 to inject flue gas of 60,000 Nm 3 along the flue gas injection process pipeline 7 in an associated manner, with an injection displacement of 900 Nm 3 / h; Open the wellhead gate, use the steam injection boiler 5 to inject 600 t of steam along the steam injection process pipeline 8 in an associated manner, with an injection displacement of 9 t / h, and finally squeeze an oil-soluble viscosity reducer into the formation;

[0157] ​A3.2. Steam-assisted profile control slug. Open the wellhead gate valve, and use a steam injection boiler 5 to inject 800 t of steam along the steam injection flow line 8 at an injection rate of 9 t / h. At the same time, open the casing gate valve, and use a flue gas treatment device 6 to inject 80,000 Nm 3 of flue gas along the flue gas injection flow line 7 at an injection rate of 900 Nm 3 / h. Use a pump truck group 10 to inject 40 m 3 of a flue gas water-based three-phase foam system into the annulus between the tubing and the casing along the chemical injection flow line 11 at a displacement of 0.5 m 3 / h.

[0158] A3.3. Inject pure steam for viscosity reduction. Continue to use the steam injection boiler 5 to inject 800 t of steam along the steam injection flow line 8 at an injection rate of 9 t / h;

[0159] It is required to limit the on-site construction pressure to 25 MPa. It is necessary to monitor the dynamic construction parameters in real time to ensure the safety of each stage of pumping construction. If the construction pressure is too high, it is necessary to consider reducing the construction displacement as appropriate.

[0160] S4. Optimize the soaking period for 3 days to enable the injected steam and flue gas to fully play their roles, and enable the oil, gas, and water in the oil reservoir to quickly reach a new distribution equilibrium state. After the pressure diffusion is stable, switch to pumping and open the well for production.

[0161] Effect after the measure: After steam injection in this horizontal well, it is normally switched to pumping and the well is opened. The peak daily oil production is up to 13.4 tons / day, an increase of 9.6 tons / day compared with the period before the measure; the average daily oil production in the cycle is 4.52 tons / day, and compared with before the measure, the average daily oil increase is 2.53 tons / day; the average water cut in the cycle is 66.5%, a decrease of 16.2% compared with the period before the measure; the effective production period in this cycle is 300 days, and the cumulative oil production in the cycle is 1357 tons, an increase of 760 tons compared with the period before the measure; the oil-steam ratio in the cycle is 0.9, an increase of 0.6 compared with the period before the measure; calculated according to the oil price of 50 US dollars / barrel and the production operation cost of 330 yuan / ton, the cycle benefit is 1.74 million yuan, and the input-output ratio is 1:2.7. For the specific production effect, see Figure 3 。

[0162] Example 7:

[0163] This example provides a specific method for profile control of a flue gas water-based three-phase foam system, using the flue gas water-based three-phase foam system configured with No. 7 in Example 3, that is, Figure 4 the flue gas water-based three-phase foam system configured with No. 7 in

[0164] Taking a vertical well in a certain block of an oilfield as an example, the viscosity of surface degassed crude oil at 50°C in a certain block is 12,500 mPa·s, the reservoir burial depth is 960 m, the effective thickness is 16.5 m, the initial oil saturation is 0.65, the average porosity is 31%, the permeability is 2,850 mD, the average shale content of the reservoir is 7.5%, the original reservoir pressure is 9.4 MPa, the pressure coefficient is 0.98, the original formation temperature is 49°C, the measured geothermal gradient is 3.4°C / 100 m, belonging to a normal temperature and pressure system, and the ratio of water volume to oil layer volume is 37; the perforated section length of the production interval of the oil well is 10.6 m / two layers, the wellhead water cut at the initial production stage is 28.0%, the peak production reaches 7.9 tons / day, and after multiple rounds of thermal recovery huff and puff, steam channeling occurs to varying degrees with 2 adjacent wells around, resulting in a deterioration of the well's periodic production effect, the daily oil level in the cycle drops to 1.2 t / d, and the oil-steam ratio in the cycle is only 0.35. It is urgent to take plugging and profile control process measures to reduce the impact of inter-well steam channeling on the development effect. For this reason, it is discussed and decided to adopt a process of using a flue gas water-based three-phase foam system for profile control to assist steam in exploiting heavy oil for this well.

[0165] S1. The oil wells in the said block meet the well selection requirements of the oil reservoirs applicable to the process of the present invention.

[0166] S2. Parameter design: Based on data such as the geological characteristics of the block reservoir, the production history of the oil well, and the oil-water distribution status, the specific parameters of the process of using a flue gas water-based three-phase foam system for profile control to assist steam in exploiting heavy oil are determined as follows:

[0167] A2.1. Steam consumption: According to the conditions that the viscosity of surface degassed crude oil at 50°C in this oil well area > 5,000 mPa·s, the oil layer thickness > 10 m, the huff and puff round is 9 cycles, the perforated section length is 10.6 m, etc., and referring to the recommended range of recommended steam injection parameters for steam huff and puff wells, the steam consumption in this cycle is determined to be 1,700 t, that is, the steam injection intensity is 160 t / m.

[0168] A2.2. Flue gas consumption: The flue gas consumption for implementing the pre-profile control slug is comprehensively selected according to the degree of inter-well steam channeling, the cumulative deficit volume of the oil well, etc. The standard volume of flue gas used is about 80,000 Nm 3 ;

[0169] The flue gas consumption for implementing the co-injected steam profile control slug is based on the conditions such as the crude oil viscosity and oil layer thickness in this well area. The gas-steam ratio of the recommended flue gas injection volume to the steam injection volume is 35 Nm 3 / t; The standard volume of flue gas used is determined to be about 60,000 Nm 3 .

[0170] A2.3. Consumption of flue gas water-based three-phase foam system: According to the flue gas consumption for implementing foam profile control and the performance parameters of the foam system, the usage amount of the foam system corresponding to 80,000 Nm 3 of flue gas for implementing the pre-profile control slug is calculated to be about 570 m3 , i.e., 140:1; implement the steam injection profile control slug of 60000 Nm 3 The usage amount of the foam system corresponding to the flue gas is about 30 m 3 , i.e., 2000:1.

[0171] S3. Field injection: Refer to Figure 2 As shown, it is injected in the way of the annulus between the tubing and the casing. It includes an oil reservoir 1 with an effective thickness of 5.8 m, an injection oil well with a 7-in casing 2. The casing 2 is used to isolate the formation to form a channel for oil and gas to reach the ground. Inside the casing 2, there is a 4.5-in steam injection heat insulation pipe 4 for injecting the steam generated by a steam injection boiler 5. The annulus 3 between the casing 2 and the heat insulation pipe 4 is used to inject flue gas, formation pretreatment agents, foam systems, etc. The on-site injection construction includes the following steps:

[0172] First, use hot water above 80 °C and 5% cleaning agent for a total of 35 m 3 to backwash the wellbore. Then, in the way of injecting steam from the steam injection heat insulation pipe 4 and injecting flue gas from the annulus 3 between the tubing and the casing, after correctly connecting the surface equipment such as the steam injection boiler 5, the flue gas treatment equipment 6, the chemical liquid preparation tank 9, the pump liquid construction vehicle group 10, etc., and the pipe manifolds such as the flue gas injection process pipeline 7, the steam injection process pipeline 8, the chemical agent inlet process pipeline 11, etc., close the wellhead gate and the casing gate, and test the pressure of the surface pipe manifold to 30 MPa. If the pressure drop is less than 0.5 MPa within 30 minutes, it is qualified;

[0173] A3.1. Inject the pre-injection profile control slug. Use the pump liquid construction vehicle group 10 to inject the flue gas water-based three-phase foam system of 570 m 3 along the chemical agent inlet process pipeline 11 from the annulus between the tubing and the casing, with a displacement of 12 m 3 / h; at the same time, open the casing gate, and use the flue gas treatment equipment 6 to accompany the injection of 80000 Nm of flue gas 3 along the flue gas injection process pipeline 7, with an injection displacement of 1000 Nm 3 / h; open the wellhead gate, and use the steam injection boiler 5 to accompany the injection of 400 t of steam along the steam injection process pipeline 8, with an injection displacement of 9 t / h; finally, squeeze the formation pretreatment agent composed of an oil-soluble viscosity reducer, a high-temperature clay stabilizer, and an anti-swelling and sand control agent into the formation.

[0174] A3.2. Inject the steam injection profile control slug. Open the wellhead gate, and use the steam injection boiler 5 to inject 800 t of steam along the steam injection process pipeline 8, with an injection displacement of 9 t / h; at the same time, open the casing gate, and use the flue gas treatment equipment 6 to accompany the injection of 60000 Nm of flue gas 3 along the flue gas injection process pipeline 7, with an injection displacement of 1000 Nm 3 / h; Use the pump liquid construction vehicle group 10 to inject the flue gas water-based three-phase foam system 30 m along the chemical injection process pipeline 11 from the annulus between the casing and the tubing 3 , with a displacement of 0.5 m 3 / h.

[0175] A3.3. Inject pure steam for displacement and viscosity reduction. Continue to use the steam injection boiler 5 to inject steam 500 t along the steam injection process pipeline 8, with an injection displacement of 9 t / h;

[0176] It is required that the on-site construction limit pressure is 25 MPa. It is necessary to monitor the dynamic construction parameters in real time to ensure the safety of each section of the pumping and injection construction. If the construction pressure is too high, it is necessary to consider reducing the construction displacement as appropriate.

[0177] S4. Optimize the soaking well for 7 days to make the injected steam and flue gas fully play their roles, and make the oil, gas and water in the oil reservoir quickly reach a new distribution balance state. After the pressure diffusion is stable, switch to pumping and open the well for production.

[0178] Effect after measures: After steam injection in this oil well, it is normally switched to pumping and opening the well. The highest daily oil production at the peak is 5.8 t / d, and the average daily oil production in a cycle is 2.7 t / d. Compared with before the measures, the average daily oil increase is 1.5 t / d; the average water cut in a cycle is 83.4%, which is 9.6% lower than that in the cycle before the measures; the effective production in this cycle is 380 days, and the cumulative oil production in a cycle is 1026 tons, which is 666 tons more than that in the cycle before the measures. The oil-steam ratio in a cycle is 0.6, which is 0.25 more than that in the cycle before the measures; calculated according to the oil price of 50 US dollars / barrel and the production operation cost of 330 yuan / ton, the economic benefit in a cycle is 1.41 million yuan, and the input-output ratio is 1:2.3.

[0179] In this application, all components that are not elaborated on themselves and the connection methods of each component in this application belong to the well-known technologies in the technical field. They can be directly applied and will not be elaborated further.

[0180] In the present invention, the term "plurality" refers to two or more, unless otherwise clearly defined. Terms such as "installation", "connection", "connection", "fixation" and other terms should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; "connection" can be a direct connection or an indirect connection through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0181] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "front", "rear", etc. is based on the orientation or positional relationship shown in the drawings. These are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or unit referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention.

[0182] In the description of this specification, the description of terms such as "one embodiment", "some embodiments", "specific embodiments", etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or instance. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0183] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A flue gas water-based three-phase foam system, comprising a dispersed-phase gas, suspended-phase solid particles, and a continuous-phase liquid, characterized in that ； The composition of the said liquid by weight percentage includes: foaming agent: 0.5 - 2.0WT%, stabilizer: 0.05 - 0.5WT%, thickening agent: 0.05 - 0.2WT%, suspending agent: 0.1 - 0.8WT%, inorganic salt: 0.3 - 1.0WT%, and the balance is make-up water; The said gas includes flue gas or one or at least two of nitrogen, natural gas, carbon dioxide, air, and a mixture of flue gas and a mixture of at least two of them.

2. The water-based three-phase foam system for flue gas according to claim 1, characterized in that, The said solid particles include one or at least two of silica particles, montmorillonite particles, bentonite particles, kaolin particles, fly ash particles with particle size ranging from nanometer to micrometer.

3. The water-based three-phase foam system for flue gas according to claim 1, characterized in that, The said foaming agent includes one or at least two of dialkyl quaternary ammonium salts, fluoroalkyl ether alcohol ammonium salts, dialkyl phthalamide polyoxyethylene ethers, α-olefin sulfonates, sulfobetaine silicon surfactants, and any mixture thereof; The said stabilizer includes one or at least two of ammonium stearate, dodecyldimethylamine oxide, polyethylene glycol, and any mixture thereof; The said thickening agent includes one or at least two of polyacrylamide, hydrolyzed polyacrylamide, fluoropolymer, hydrophobically associating polymer, amphoteric branched polymer, or a mixture of one or at least two polymers with different molecular weights; The said suspending agent includes one or at least two of dodecyldimethylbenzyl chloride, dodecylguanidine acetate, alkyl quaternary ammonium salts, alkyl quaternary phosphonium salts, and any mixture thereof; The said inorganic salt includes one or at least two of calcium chloride, sodium chloride, magnesium chloride, sodium sulfate, sodium bicarbonate, sodium carbonate, potassium chloride, and any mixture thereof.

4. The water-based three-phase foam system for flue gas according to claim 1, wherein By weight percentage in the liquid, the said foaming agent includes 0.1 - 0.3WT% of dialkyl quaternary ammonium salts, 0.3 - 1.2WT% of α-olefin sulfonates, and 0.1 - 0.5WT% of sulfobetaine silicon surfactants; The said stabilizer includes 0.05 - 0.5WT% of ammonium stearate or 0.05 - 0.5WT% of dodecyldimethylamine oxide; The said thickening agent includes 0.02 - 0.08WT% of fluoropolymer and 0.03 - 0.12WT% of hydrolyzed polyacrylamide; The said suspending agent includes 0.3 - 0.8WT% of dodecyldimethylbenzyl chloride or 0.1 - 0.4WT% of alkyl quaternary ammonium salts; The said inorganic salt is 0.05 - 0.1WT% of calcium chloride and 0.25 - 0.9WT% of sodium chloride.

5. The water-based three-phase foam system for flue gas according to claim 1, characterized in that By weight percentage in the system, the said solid particles include 0.1 - 0.4WT% of silica nanoparticles and 0.05 - 0.3WT% of bentonite microparticles.

6. A water-based three-phase foam system for flue gas according to any one of claims 1-5, characterized in that, The said make-up water is fresh water for oilfield injection or qualified treated oilfield sewage.

7. A profile control method for a flue gas water-based three-phase foam system, characterized in that, It includes the following steps: S1. Select a suitable oil well; S2. Parameter optimization; A2.

1. Steam consumption: The cyclic steam injection volume of vertical - inclined wells: the steam injection volume per meter is 120t / m - 200t / m; The cyclic steam injection volume of horizontal wells: the steam injection volume per meter is 10t / m - 20t / m; A2.

2. Flue gas dosage in the foam profile control system: The standard volume dosage of flue gas is 40,000 Nm 3 ~ 80,000 Nm 3 ; The flue gas injection volume for assisted thermal recovery (standard volume, Nm 3 ) and the gas-steam ratio of the steam injection volume (water equivalent, t) is 30 Nm 3 / t to 50 Nm 3 / t; A2.

3. Foam system dosage: In the flue gas water-based three-phase foam system for implementing the pre-treatment profile control slug, the ratio of the gas injection volume (standard condition volume, Nm 3 ) to the liquid injection volume (water equivalent, t) is 80:1 to 150:1; The ratio of the gas injection volume (standard volume, Nm 3 ) to the liquid injection volume (water equivalent, t) in the foam system for implementing the steam-assisted profile control slug is 2000:1 to 2500:1; S3. On - site injection: During injection, it is injected in the way of annulus between casing and tubing or in the way of injecting through insulated tubing; S4. Soaking well for reaction.

8. A profile control method for a flue gas water-based three-phase foam system according to claim 7, characterized in that In S1, screen the reservoir according to the following conditions: the viscosity of surface degassed crude oil at 50 °C < 100000 mPa·s, the reservoir burial depth < 2000 m, the effective thickness > 3 m, the permeability > 300 mD, and the ratio of the water body volume of the edge and bottom water to the oil layer volume < 100; Screen the oil wells according to the following conditions: the peak production at the initial stage of thermal recovery production reaches more than 5 t / d, the water cut rises rapidly due to steam channeling or water channeling after multiple rounds of huff and puff, the steel grade and corrosion resistance of the oil well casing should meet the requirements for injecting flue gas, and engineering problems such as no casing damage, casing deformation, and sand burial are satisfied.

9. A profile control method for a flue gas water-based three-phase foam system according to claim 7, characterized in that In S2, the cyclic steam injection volume of vertical and inclined wells: for wells with an oil layer thickness greater than 10 m, the steam injection volume per meter is 120 t / m to 160 t / m; for wells with an oil layer thickness equal to 10 m, the steam injection volume per meter is 160 t / m; for thin-layer wells with an oil layer thickness less than 10 m, the steam injection volume per meter ranges from 160 t / m to 200 t / m; The cyclic steam injection volume of horizontal wells: for wells with a horizontal section length greater than 150 m, the steam injection volume per meter is 10 t / m to 15 t / m; For wells with a horizontal section length equal to 150 m, the steam injection volume per meter is 15 t / m; for wells with a horizontal section length less than 150 m, the steam injection volume per meter ranges from 15 t / m to 20 t / m.

10. A profile control method for a flue gas water-based three-phase foam system according to claim 7, characterized in that, In S3, first, connect the surface equipment and pipelines and conduct a pressure test until qualified, and then carry out pump injection according to the pump injection procedure, and monitor the dynamic construction parameters in real time to ensure the safe and smooth progress of the pump injection construction for each section; The injection rate of each slug is as follows: the steam injection rate is 6 m 3 / h - 10 m 3 / h, the flue gas injection rate is 800 - 1200 Nm 3 / h, the pre - profile control slug is 20 m 3 / h - 50 m 3 / h, the steam - assisted profile control slug is 0.5 m 3 / h - 1.0 m 3 / h; During the on-site construction process, make appropriate adjustments according to the change of the injection pressure. If the construction pressure is too high, reduce the construction displacement.

11. A profile control method for a flue gas water-based three-phase foam system according to claim 10, characterized in that In S3; A3.

1. Injection pre-profile control slug: For heavy oil wells with serious water or steam channeling in the early stage, implement an injection of a flue gas-water-based three-phase foam system to plug the main water or steam channeling paths. Before injecting steam, first backwash the wellbore with hot water above 80°C and a cleaning agent, and then squeeze in 40,000 Nm 3 ~80,000 Nm 3 of flue gas and 260 m 3 -1000 m 3 of the flue gas-water-based three-phase foam system. Finally, squeeze into the formation a formation pretreatment agent that is one or a combination of at least two of an oil-soluble viscosity reducer, a high-temperature clay stabilizer, and an anti-swelling and sand control agent; A3.2, Steam-injected Profile Control Plug: While injecting steam through the heat-insulated tubing, inject 60,000 Nm 3 ~100,000 Nm 3 flue gas and 25 m 3 -50 m 3 high-temperature resistant particle gel foam system to plug the secondary water or steam channels and the steam intake channels in the far-well zone, effectively improving the steam intake profile of the reservoir interval, increasing the steam heat sweep area and realizing enhanced oil recovery by injecting steam with flue gas; A3.

3. Inject a pure steam displacement slug: Then inject high-temperature pure steam to increase the steam heat sweep range, and displace the flue gas near the well to a farther formation, reducing the gas influence on the lifting effect caused by the overflow of the gas near the well after opening the well for production.

12. A profile control method for a flue gas water-based three-phase foam system according to claim 7, characterized in that In S4; Soak the well for 3 to 7 days to enable the injected steam and the flue gas foam profile control system to fully play their roles, and enable the oil, gas, and water in the oil layer to quickly reach a new distribution equilibrium state. After the pressure diffusion is stable, select the appropriate time to switch to pumping and open the well for production according to the pressure change.

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