CN117552756A - Oil reservoir recovery ratio improving method based on microbubble oil displacement - Google Patents
Oil reservoir recovery ratio improving method based on microbubble oil displacement Download PDFInfo
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
- E21B43/166—Injecting a gaseous medium; Injecting a gaseous medium and a liquid medium
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
- E21B43/20—Displacing by water
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Abstract
The invention discloses an oil reservoir recovery ratio improving method based on microbubble oil displacement, which is applied to a water flooding development process of a low-permeability oil reservoir; the method comprises the following steps: adding micron-sized bubbles into the water injection water flow to obtain a microbubble water solution; injecting the micro-bubble water solution into an oil reservoir through a water injection well; in the migration process of the micro-bubble aqueous solution after entering the oil reservoir, the micron-sized bubbles in the micro-bubble aqueous solution are gathered to be large or sheared to be small, so that the liquid flow resistance of a first type permeation channel in the oil reservoir is increased, and the displacement pressure of the water flow in the micro-bubble aqueous solution in a second type permeation channel in the oil reservoir is increased; the micro-scale bubbles have good homogeneity and little damage to stratum; the micro-scale bubbles are utilized to effectively enlarge the water drive wave and volume of the oil reservoir through the effect of the gian effect, the viscosity increasing and the pressurizing, the cost is low, the recovery ratio of the low-permeability oil reservoir is further improved, and the purpose of improving the crude oil yield of the oil field is achieved.
Description
Technical Field
The invention belongs to the technical field of petroleum exploitation, and particularly relates to a reservoir recovery ratio improving method based on microbubble oil displacement.
Background
Low permeability reservoirs are typically buried relatively deeply and have air permeabilities ranging from 1 to 10 x 10 -3 μm 2 The method comprises the steps of carrying out a first treatment on the surface of the The non-uniformity of the low-permeability oil reservoir is strong, the pore throat radius is between 0.01 and 100 mu m, and part of the oil reservoir develops in micro-cracks; at present, in the water flooding development process of low-permeability oil reservoirs, the crude oil displacement efficiency is less than 30%, and the final recovery ratio of an oil field is below 30%; for example: the average final recovery rate of the water flooding of the tri-stack oil reservoir of a certain oil field is only 19.9%; therefore, for a low-permeability oil reservoir developed by adopting water flooding, more than 70% of crude oil stays in the reservoir due to the reasons of strong non-average property, microcrack development and the like, so that the yield of crude oil in the oil field is reduced, and the economic benefit is reduced.
At present, water flooding development is still one of the most effective and economical exploitation modes for oil field development; the foam has good plugging performance and the characteristic of selecting the oil-water and heterogeneous bottom layer, and becomes one of the main stable yield and yield increasing means of the old oil field; however, in the application process of foam flooding, the problems of poor foam stability, high injection pressure, defoaming when meeting oil, short effective period, emulsification of produced liquid, serious foaming agent adsorption and high construction cost exist, and the application and popularization of the foam flooding technology are seriously restricted.
In recent years, a micro-foam system prepared by a high-speed stirring shearing method by a learner has the particle size of 10-100 mu m, the liquid film thickness of 4-10 mu m, the foam liquid outlet time and half life of more than 24Hr, good dynamic stability and coalescence stability, and good application in drilling, oil extraction and water flooding; however, the micro-foam system generated by the chemical foaming agent and the stabilizer has the problems of poor foam homogeneity, large formation damage, high cost and the like in the using process.
Disclosure of Invention
Aiming at the technical problems in the prior art, the invention provides a reservoir recovery ratio improving method based on microbubble oil displacement, which aims to solve the technical problems of poor foam homogeneity, large stratum damage and high cost in the existing oil displacement process of a microbubble system.
In order to achieve the above purpose, the invention adopts the following technical scheme:
the invention provides an oil reservoir recovery ratio improving method based on microbubble oil displacement, which is applied to a water flooding development process of a low-permeability oil reservoir; the method comprises the following steps:
adding micron-sized bubbles into the water injection water flow to obtain a microbubble water solution;
injecting the micro-bubble water solution into an oil reservoir through a water injection well;
in the migration process of the micro-bubble aqueous solution after entering the oil reservoir, the micron-sized bubbles in the micro-bubble aqueous solution are gathered to be large or sheared to be small, so that the liquid flow resistance of a first type permeation channel in the oil reservoir is increased, and the displacement pressure of the water flow in the micro-bubble aqueous solution in a second type permeation channel in the oil reservoir is increased;
wherein the first type of permeation channel comprises permeation pores with water flow permeability of 3-125mD, permeation pore channels with water flow permeability of 40-600mD and permeation cracks with water flow permeability of 300-1500 mD; the second type of permeation channel comprises permeation pores with water flow permeability of less than 3mD, permeation pore channels with water flow permeability of less than 40mD and permeation cracks with water flow permeability of less than 300 mD.
Further, the bubble diameter of the micron-sized bubbles is matched with the pore throat size of the oil reservoir.
Further, the bubble diameter of the micron-sized bubbles is 1 μm to 100 μm.
Further, adding micron-sized bubbles into the water injection flow to obtain a microbubble aqueous solution, wherein the process is as follows:
the microbubble generating device is arranged on a high-pressure water injection pipeline of the water injection well; wherein, the microbubble generating device comprises a central exhaust pipe 1 and a plurality of micro pore plates 2; the central exhaust pipe 1 is concentrically arranged in the outer cylinder 4 of the high-pressure water injection pipeline; one end of the central exhaust pipe 1 is communicated with an air source, and the other end of the central exhaust pipe is closed; a plurality of exhaust ports are arranged on the central exhaust pipe 1 at intervals, and the micro pore plate 2 is arranged at the exhaust ports; a plurality of micron through holes are formed in the micron pore plate 2;
water injection water flow is introduced between the central exhaust pipe 1 and the outer cylinder 4, and high-pressure gas is introduced into the central exhaust pipe 1; when the high-pressure gas passes through the micro-pore plate 2 at the exhaust port, micro-scale bubbles are formed and enter the water injection water flow, and the micro-bubble water solution is obtained by mixing.
Further, the high-pressure gas is air or N 2 、CO 2 And one of natural gas.
Further, the pressure value of the high-pressure gas is larger than the pressure value of the water injection flow.
Further, the difference between the pressure value of the high-pressure gas and the pressure value of the water injection flow is 0.3-0.5Mpa.
Further, in the micro-bubble aqueous solution, the micro-scale bubbles are uniform disperse phases, and the water injection water flow is continuous phases.
Further, in the micro-bubble aqueous solution, the volume of the micro-scale bubbles accounts for 5% -30% of the volume of the water injection flow.
Further, the apparent viscosity of the aqueous solution of microbubbles increases as the bubble diameter of the microbubbles decreases.
Compared with the prior art, the invention has the beneficial effects that:
the invention provides an oil reservoir recovery ratio improving method based on microbubble oil displacement, which is characterized in that micron-sized bubbles are added into water injection water flow, so that the liquid flow resistance of a high-permeability channel in an oil reservoir is effectively increased by utilizing the characteristic that the aggregation length or the shearing of the micron-sized bubbles is reduced in the oil reservoir migration process, and the displacement pressure of the injected water flow in a low-permeability channel in the oil reservoir is improved; the homogeneity of micron-sized bubbles is good, and the damage to stratum is small; the micro-scale bubbles are utilized to effectively enlarge the water drive wave and volume of the oil reservoir through the effect of the gian effect, the viscosity increasing and the pressurizing, the cost is low, the recovery ratio of the low-permeability oil reservoir is further improved, and the purpose of improving the crude oil yield of the oil field is achieved.
Furthermore, the size of the bubble diameter of the micron-sized bubbles is matched with the pore-throat scale university of the oil reservoir, so that the micron-sized bubbles can be uniformly distributed in groups in water injection water flow, the floating speed of the micron-sized bubbles is effectively reduced, and the stability of the micron-sized bubbles is improved.
Furthermore, as the pore throat radius of the low-permeability oil reservoir is generally smaller than 100 mu m, the bubble diameter of the micron-sized bubbles is set to be 1 mu m-100 mu m, so that the micron-sized bubbles can enter the depth of the reservoir along with water injection flow; the micro-scale bubbles have the characteristics of small shearing, large aggregation and the like in migration, ensure the purpose of migration to the deep part of an oil reservoir and plugging the large pore throat, and effectively improve the displacement of the crude oil of the hypotonic reservoir through continuous migration and plugging, thereby achieving the purposes of expanding water flooding wave and volume and improving the recovery ratio of the crude oil.
Further, micro-scale bubbles with controllable concentration and bubble diameter are extruded into water injection water flow through a micro-bubble generating device to form a micro-bubble aqueous solution; after the microbubble aqueous solution is injected into the stratum, the water flooding wave and volume are enlarged by regulating and controlling the hypotonic reservoir so as to enlarge the water flooding efficiency and improve the crude oil yield and the final recovery ratio; the micro-bubble device is provided with a micro-pore plate on the central tube, when gas passes through the micro-through holes at high speed, micro-scale bubbles are formed by spraying, and the micro-bubbles enter water injection flow to form a water-gas dispersion system of a micro-bubble aqueous solution; the bubble diameter and concentration of the water-gas dispersion system of the microbubble aqueous solution by utilizing the microbubble generating device are related to high-pressure air flow speed, pore plate materials, a manufacturing method, water flow pressure, viscosity and the like, and the gas-liquid ratio can be regulated and controlled without being limited by temperature and pressure; the device has simple structure and convenient operation.
Further, the high-pressure gas adopts air and N 2 、CO 2 And one of natural gas, avoiding damage of micron-sized bubbles to the stratum; the method comprises the steps of selecting gases with different media to manufacture micron-sized bubbles, wherein the performance of the micron-sized bubbles is related to the property and source of a gas source; the use of different gas media to prepare microbubbles is different, the use of air considers the corrosion of oxygen to the pipe column, and N is used 2 N is to be considered 2 Or purchase transport N 2 Capital cost of (C) using CO 2 CO production is considered 2 Generated corrosion and CO 2 The natural gas is used to take into account the cost of natural gas production and the nature of high pressure gas evolution.
Further, the pressure value of the high-pressure gas is larger than the pressure value of the water injection flow, and the high-pressure gas is extruded into the water injection flow through a micro-pore plate in the micro-bubble generating device to generate water injection flow containing micro-scale bubbles; the pressure value of the high-pressure gas needs to overcome the shearing force of the special pore plate, is related to the pressure of water injection water flow and the micro pore plate and is determined by the pressure, bubble diameter, concentration and the like of microbubbles to be generated, so that the pressure value of the high-pressure gas is set to be 0.3-0.5Mpa higher than the pressure of the high-pressure water flow.
Further, the volume of the micron-sized bubbles accounts for 5% -30% of the volume of the water injection flow, and the concentration of the micron-sized bubbles in the water injection flow is determined according to the geological seepage condition of the oil reservoir; in general, the injection pressure is relatively low, and the concentration of the used micron-sized bubbles is high; the injection pressure is relatively low, and the concentration of the used micron-sized bubbles is higher; the volume fraction of the micron-sized bubbles is set, so that the micron-sized bubbles can enter the deep part of the oil reservoir to play a role and the hypertonic channel to be plugged in the oil displacement process of the water flow containing the micron-sized bubbles.
Drawings
FIG. 1 is a schematic diagram of a generating device of micron-sized bubbles in the invention;
FIG. 2 is a graph showing the effect of different gas-liquid ratios on flow resistance and apparent viscosity of aqueous microbubble solutions in accordance with the present invention;
FIG. 3 is a schematic diagram showing the effect of pressure difference between air and water on bubble diameter of micron-sized bubbles in the present invention; wherein, FIG. 3a is a micron-sized bubble chart with a gas-water pressure difference of 0.2MPa, FIG. 3b is a micron-sized bubble chart with a gas-water pressure difference of 0.5MPa, and FIG. 3c is a micron-sized bubble chart with a gas-water pressure difference of 0.8 MPa;
FIG. 4 is a graph showing the effect of pressure on bubble diameter of micron-sized bubbles in the present invention.
Wherein, 1 center blast pipe, 2 micron orifice plate, 3 gas connecting pipe, 4 urceolus, 5 inside connecting pipe, 6 inside filter, 7 inside check valve, 8 press the cap.
Detailed Description
In order to make the technical problems, technical schemes and beneficial effects solved by the invention more clear, the following specific embodiments are used for further describing the invention in detail. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
The invention provides an oil reservoir recovery ratio improving method based on microbubble oil displacement; the oil reservoir recovery ratio improving method is applied to the water flooding development process of the low-permeability oil reservoir; the oil reservoir recovery ratio improving method specifically comprises the following steps:
and step 1, adding micron-sized bubbles into water injection water flow to obtain a micro-bubble water solution.
Wherein, the preparation process of the micro-bubble water solution comprises the following steps:
the microbubble generating device is arranged on a high-pressure water injection pipeline of the water injection well; water injection water flow is introduced between the central exhaust pipe 1 and the outer cylinder 4, and high-pressure gas is introduced into the central exhaust pipe 1; when the high-pressure gas passes through the micro-pore plate 2 at the exhaust port, micro-scale bubbles are formed and enter the water injection water flow, and the micro-bubble water solution is obtained by mixing.
As shown in fig. 1, the microbubble generating device comprises a central exhaust pipe 1, a micro-pore plate 2, a gas connecting pipe 3, an internal connecting pipe 5, an internal filter 6, an internal one-way valve 7 and a pressure cap 8; the central exhaust pipe 1 is concentrically arranged in the outer cylinder 4 of the high-pressure water injection pipeline; one end of the central exhaust pipe 1 is communicated with an air source, and the other end of the central exhaust pipe is closed; a plurality of exhaust ports are arranged on the central exhaust pipe 1 at intervals, and the micro pore plate 2 is arranged at the exhaust ports; the micro pore plate 2 is provided with a plurality of micro through holes.
The top end of the outer cylinder 4 is provided with a mounting flange, and the mounting flange comprises an upper flange and a lower flange; the lower end of the lower flange is connected with the top end of the outer cylinder 4, and the upper end of the lower flange is fixedly connected with the upper flange; the centers of the upper flange and the lower flange are respectively provided with a center through hole; the inner connecting pipe 5 is arranged in the central hole of the upper flange, the upper end of the inner connecting pipe 5 is communicated with the lower end of the gas connecting pipe 3, and the upper end of the gas connecting pipe 3 is communicated with a gas source; the inner filter 6 is provided in the gas connection pipe 3 for filtering high-pressure gas.
The upper outer side and the outer side of the inner connecting pipe 5 are sleeved with a pressing cap 8, and the inner connecting pipe 5 and the upper flange are fixedly connected together by utilizing the pressing cap 8; an inner one-way valve 7 is arranged at the upper end of the central through hole of the upper flange, and the inner one-way valve 7 is arranged between the upper flange and the pressure cap 8; the upper end side wall of the outer barrel 4 is provided with a water inlet which is communicated with a water source through a pipeline, and water injection water flow can enter an annular space between the outer barrel 4 and the central exhaust pipe 1 through the water inlet and is mixed with micron-sized bubbles generated through the micron pore plate 2 to obtain a micro-bubble aqueous solution.
In the invention, micron-sized bubbles are formed by jet flow behind the micron-sized pore plate, the radius of the micron-sized bubbles is matched with the pore size of the low-permeability rock, the micro-bubble groups are uniformly distributed, and the gas-liquid ratio can be regulated and controlled; the microbubble generating device meets the environmental conditions of 150 ℃ and 70MPa, and is suitable for the oil reservoir conditions of high temperature and high pressure.
Step 2, injecting the micro-bubble aqueous solution into an oil reservoir through a water injection well;
and 3, in the migration process of the micro-bubble aqueous solution after entering the oil reservoir, the micro-scale bubbles in the micro-bubble aqueous solution are gathered or sheared to be small, so that the liquid flow resistance of a first type permeation channel in the oil reservoir is increased, and the displacement pressure of the water flow in the micro-bubble aqueous solution in a second type permeation channel in the oil reservoir is increased.
Wherein the first type of permeation channel comprises permeation pores with water flow permeability of 3-125mD, permeation pore channels with water flow permeability of 40-600mD and permeation cracks with water flow permeability of 300-1500 mD; the second type of permeation channel comprises permeation pores with water flow permeability of less than 3mD, permeation pore channels with water flow permeability of less than 40mD and permeation cracks with water flow permeability of less than 300 mD.
In the invention, the bubble diameter of the micron-sized bubbles is matched with the pore throat scale of the oil reservoir; preferably, the bubble diameter of the micron-sized bubbles is 1-100 μm; the high-pressure gas is air or N 2 、CO 2 And one of natural gas; the pressure value of the high-pressure gas is larger than the pressure value of the water injection flow; wherein the difference between the pressure value of the high-pressure gas and the pressure value of the water injection flow is 0.3-0.5Mpa.
In the invention, the micro-bubble aqueous solution is injected into an oil reservoir through a water injection well; in the micro-bubble aqueous solution, micron-sized bubbles are uniform disperse phases, and water injection water flow is continuous phases; in the micro-bubble aqueous solution, the volume of the micro-scale bubbles accounts for 5% -30% of the volume of the water injection flow; the apparent viscosity of the micro-bubble water solution is more than 2 times of that of water; the apparent viscosity of the aqueous solution of microbubbles increases as the bubble diameter of the microbubbles decreases.
According to the oil reservoir recovery ratio improving method based on microbubble oil displacement, in the migration process of the microbubble aqueous solution after entering the oil reservoir, micron-sized bubbles in the microbubble aqueous solution are subjected to aggregation length increase or shearing reduction so as to increase the liquid flow resistance of a high-permeability channel in the oil reservoir, and meanwhile, the displacement pressure of a low-permeability channel in the oil reservoir of water injection flow in the microbubble aqueous solution is improved.
According to the oil reservoir recovery ratio improving method based on microbubble oil displacement, in the water displacement development process of the low-permeability oil reservoir, as the water-flooding oil reservoir water-breakthrough channel is formed, the oil field gradually enters a medium-high water-containing period, the residual oil mainly exists in the area where the oil reservoir water displacement cannot be completely influenced, the oil field crude oil yield gradually decreases and finally recovery is less than 30%; according to the oil reservoir recovery ratio improving method based on microbubble oil displacement, micron-sized bubbles are added in the water displacement development process, after entering an oil reservoir along with high-pressure water injection flow, the driving pressure of an undulant oil displacement reservoir is improved, the water displacement wave and volume are enlarged, the water displacement efficiency is improved, the crude oil yield is improved, and the final recovery ratio of an oil field is improved by improving the water flow resistance in a water displacement channel.
Working principle:
according to the oil reservoir recovery ratio improving method based on microbubble oil displacement, micron-sized bubbles are added into water injection water flow to obtain a microbubble aqueous solution; in the migration process of the microbubble aqueous solution after entering the oil reservoir, micron-sized bubbles are large in aggregation length or small in shearing, and the micron-sized bubbles are subjected to the effects of a Jack effect, tackifying, pressurizing and the like in the oil reservoir so as to increase the liquid flow resistance of a high-permeability channel in the oil reservoir; meanwhile, the displacement pressure of the water injection flow in the low-permeability channel in the oil reservoir is increased, the water flooding wave and volume of the oil reservoir are enlarged, the crude oil yield is increased, and the recovery ratio is improved.
According to the oil reservoir recovery ratio improving method based on microbubble oil displacement, in the oil displacement process by utilizing the microbubble aqueous solution, the seepage resistance factor is effectively increased, the water flooding wave and the mention are enlarged, and the recovery ratio is improved; as shown in table 1 below, table 1 shows the results of the tests of the aqueous solutions of microbubbles to increase the drag factor and recovery of the porous core.
From table 1, it can be seen that the micro-bubble aqueous solution can effectively regulate and control the core flow rate ratio of the low-permeability reservoir, expand the references, and further improve the recovery ratio of crude oil.
TABLE 1 results of tests for increasing the drag factor and recovery of a porous core with aqueous microbubble solutions
| Permeability, mD | Factor of seepage resistance | The recovery ratio is improved by% |
| 0.57 | 4.89 | 8.42 |
| 5.3 | 3.74 | 10 |
| 40.5 | 1.92 | 16.83 |
In the invention, two hypotonic exposure heads with 10 times of permeability level difference are bonded and compacted to establish a two-layer hypotonic heterogeneous long core model which is longitudinally communicated; firstly, adopting water flooding to drive the core, wherein the water flooding extraction degree is as low as 35.5%; then using an ultralow IFT surfactant system to displace, and improving EOR by 1.5%; finally, the displacement was performed with a micro-bubble aqueous solution, and the EOR was increased by 17% cumulatively, as shown in table 2 below.
Table 2 results of the test for improving the extraction degree of fractured cores by microbubble flooding
According to the invention, the principle of generating microbubbles is researched through experiments, when gas passes through micropores on a microporous plate at high speed, the upper and lower partial areas of the micropores are in a turbulent state, and the gas passing through the micropores forms discrete micron-sized bubbles under the conditions of pressure difference, gas-water interfacial tension at the edges of the micropores and shearing action at the edges; in the high-pressure water injection process, the gas is injected into the micro holes of the micro hole plate at a high speed to form a high-pressure micro bubble system with the bubble diameter of 1-100 mu m, the high-pressure micro bubble system enters a reservoir, the resistance of a water flooding dominant channel is improved by adjusting the displacement pressure, the water flooding pressure of a hypotonic channel is increased, and the water flooding wave and efficiency are enlarged.
(1) Evaluation of enhanced recovery from heterogeneous reservoirs
A hypotonic dew head with 10 times of the difference of two permeability levels is formed; wherein the permeability of one block is 1.9mD, and the permeability of the other block is 22mD; bonding and compacting to establish a two-layer hypotonic heterogeneous long core model which is longitudinally communicated and utilizes water/N 2 The microbubble system improves the water flooding recovery rate by 36.50% to 50.62% of the microbubble flooding recovery rate; by means of water/CO 2 The microbubble system improves the water flooding recovery rate by 35.40% to 53.56% of the microbubble flooding recovery rate; through low-permeability heterogeneous long core displacement, the microbubble flooding system is verified to be capable of effectively improving the extraction degree after water flooding by more than 10% and expanding the swept volume by more than 20%; water/CO 2 The performance of the microbubble system is better than that of water/N 2 Properties of the microbubble system.
(2) Evaluation of enhanced recovery of porous reservoirs
Carrying out a water/microbubble displacement evaluation test by adopting a core with the permeability of 21.4mD, wherein the oil reservoir recovery ratio can reach 53.2% by using injected water, and the recovery ratio can be improved to 65.3% by using microbubble displacement; from the above, the microbubble flooding has a great improvement effect on improving the low-permeability recovery ratio; the test shows that: the process of improving the extraction degree by micro-bubble flooding is gentle, the action time is longer, and the effect is obvious.
Examples
The application of an aqueous solution of microbubbles to a layer of a certain oilfield length is taken as an example.
The method comprises the following steps that (1) a layer of rock oil deposit is formed in a certain oilfield, rock ore mainly comprises gray green powder, fine rock scraps, namely feldspar sandstone, filler mainly comprises chlorite and iron calcite, the average porosity is 12.69%, the permeability is 1.81mD, and the oil deposit belongs to a low-porosity and extremely-low-permeability reservoir; the original stratum pressure of the oil layer is 12.2MPa, the temperature is 54.73 ℃, and the viscosity of crude oil is 1.95 mPas; asphaltene content 2.96%; the mineralization degree of stratum water is 82g/l, the chloride ion content is 50481mg/l, the pH value is 5.9-6, belonging to CaCl 2 Water type.
Injecting micro-bubble water solution into 4 test wells in 11 months 2020, and developing the application of improving the recovery ratio; up to 202For 10 months 1 year, injecting gas 145.4 ×10 4 Nm 3 The completion rate is 11.7%, and the overall operation is stable; 4-mouth microbubble water solution test well group, daily oil production is improved to 26.6t from original 23.0t, and the water content is reduced to 60.1% from original 64.8%; the daily oil yield of the central well is improved to 1.45t from original 0.3, the water content is reduced to 76.8% from original 95.3, the cumulative oil is 2445t, and the input-output ratio is 1:1.13, obtaining a better preliminary effect; the stage decreasing rate is reduced from 6.57% to 21.06%, the water content increasing rate is reduced from 20.93% to-14.33%, and the dewatering and oil increasing effects are obvious.
In this example, from the relation curve of the water content rising rate and the geological reserve yield of the test well group, the water content rising is controlled after the micro-bubble aqueous solution test, especially the water content falling range is larger after the micro-bubble aqueous solution is injected, and the geological reserve yield of the 4-mouth micro-bubble aqueous solution test well group is improved by 0.23% compared with the water drive from the 11 th month of 2020 to the present, and the water drive can be expected to be improved by 5.75% in 25 years.
In the embodiment, 4 water injection wells of a microbubble oil displacement test are developed in one block of the oil field, 19 wells of the oil field are correspondingly participated in the effect evaluation well, the oil field is implemented for 18 months, the crude oil stage is decreased from 6.57% to 21.06%, and 3776.8t of oil is increased; the oil production rate of the central oil well driven by the 4-port injection micro-bubbles is increased from 0.3t/d to 1.45t/d, and the water content is reduced from 95.3% to 76.8%, so that a better primary effect is obtained.
As shown in fig. 2, fig. 2 shows a graph of the effect of different gas-liquid ratios on the flow resistance and apparent viscosity of the aqueous microbubble solution; as can be seen from the figure 2, for the homogeneous core, the micro-bubble aqueous solution can effectively regulate the flow ratio of the ultra-low permeability core and the low permeability core, expand the swept volume and improve the recovery ratio of crude oil, but the effects on the medium-high permeability core are not obvious.
As shown in fig. 3, fig. 3 shows a schematic diagram of the effect of the pressure difference between air and water on the bubble diameter of micron-sized bubbles; wherein, FIG. 3a is a micron-sized bubble chart with a gas-water pressure difference of 0.2MPa, FIG. 3b is a micron-sized bubble chart with a gas-water pressure difference of 0.5MPa, and FIG. 3c is a micron-sized bubble chart with a gas-water pressure difference of 0.8 MPa; as can be seen from fig. 3, the larger the pressure difference between the air and the water is, the larger the bubble diameter of the bubbles is, and the reasonable control of the pressure difference is the key of the bubble diameter control; under the same conditions, the bubble diameter generated by the pressure difference is 300 mu m at 0.2 MPa; the bubble diameter of 0.5MPa is 500 mu m; the bubble diameter of 0.8MPa is 1500 μm.
As shown in fig. 4, a schematic diagram of the bubble diameter effect of pressure on micron-sized bubbles is given in fig. 4; as can be seen from fig. 4, the bubble diameter is greatly reduced after pressurization; wherein N is 2 Microbubble flooding system: the surface 12MPa generates 300 μm bubbles, which migrate to the formation location to increase the 15MPa estimate, and the bubble diameter becomes 10 μm.
According to the oil reservoir recovery ratio improving method based on microbubble flooding, micron-sized bubbles are applied in the low-permeability oil reservoir water injection development process, the generated micron-sized bubbles are injected into an oil reservoir along with high-pressure water flow, the aggregation length or the shearing length is large or small in the oil reservoir migration process, the flow resistance of a hypertonic channel is increased, the displacement pressure of water flow in the hypotonic channel is improved, the water flooding wave and volume are enlarged, the water flooding efficiency is improved, the oil well yield is improved, and the oil field recovery ratio is improved; in the high-pressure water injection process, a pore plate method is adopted, high-pressure microbubbles with bubble diameters of 1-100 mu m are formed by gas high-speed injection pore plate micropores, and the gas-liquid ratio can be regulated and controlled; microbubbles are uniformly distributed in 5% -30% in high-pressure water injection, water is a continuous phase, microbubbles are a disperse phase, and the microbubbles enter a reservoir layer to effectively expand sweep efficiency of saturated parts of low-permeability and high-residual oil; the bubble diameter of the bubbles in the high-pressure microbubble aqueous solution is 1-100 mu m adjustable, the pore throat scale of the low-permeability reservoir is matched, the microbubble groups are uniformly distributed, the floating speed of the microbubbles is reduced, and the stability is improved; the viscosity increases with decreasing bubble diameter, and the gas may be air or N 2 、CO 2 And one of natural gas; wherein CO 2 The apparent viscosity of the micro-bubble aqueous solution can be improved by more than 2 times compared with water, and the micro-bubble aqueous solution is matched with CO 2 The comparison can be improved by more than 50 times; the high-pressure water injection pipeline of the water injection well is provided with a microbubble generating device, and the high-pressure gas is lifted by the microbubble generating device to generate microbubbles which are uniformly distributed in the high-pressure water; the microbubble generating device is composed of an inner structure and an outer structure, high-pressure gas in the central tube extrudes microbubbles through the core tube pore plate to enter high-pressure water between the inner tube and the outer tube, and enters the water injection well along with the high-pressure water flow, and the water flooding fluidity ratio is regulated and controlled in the process of entering a reservoir stratum to move, so that the expansion is realizedWater driving wave and volume; the gas type is matched with the reservoir, the reservoir needs to be pressurized by a gas booster pump, and the pressure is usually 0.3-0.5Mpa higher than the water injection pressure, and is related to the water injection pressure of the reservoir.
The above embodiment is only one of the implementation manners capable of implementing the technical solution of the present invention, and the scope of the claimed invention is not limited to the embodiment, but also includes any changes, substitutions and other implementation manners easily recognized by those skilled in the art within the technical scope of the present invention.
Claims (10)
1. The oil reservoir recovery ratio improving method based on microbubble oil displacement is characterized by being applied to a water flooding development process of a low-permeability oil reservoir; the method comprises the following steps:
adding micron-sized bubbles into the water injection water flow to obtain a microbubble water solution;
injecting the micro-bubble water solution into an oil reservoir through a water injection well;
in the migration process of the micro-bubble aqueous solution after entering the oil reservoir, the micron-sized bubbles in the micro-bubble aqueous solution are gathered to be large or sheared to be small, so that the liquid flow resistance of a first type permeation channel in the oil reservoir is increased, and the displacement pressure of the water flow in the micro-bubble aqueous solution in a second type permeation channel in the oil reservoir is increased;
wherein the first type of permeation channel comprises permeation pores with water flow permeability of 3-125mD, permeation pore channels with water flow permeability of 40-600mD and permeation cracks with water flow permeability of 300-1500 mD; the second type of permeation channel comprises permeation pores with water flow permeability of less than 3mD, permeation pore channels with water flow permeability of less than 40mD and permeation cracks with water flow permeability of less than 300 mD.
2. The method for improving oil reservoir recovery efficiency based on microbubble flooding of claim 1, wherein the bubble diameter of the micron-sized bubbles is matched with the pore-throat scale of the oil reservoir.
3. The method for improving oil recovery efficiency based on microbubble flooding of claim 1, wherein the micron-sized bubbles have a bubble diameter of 1-100 μm.
4. The oil reservoir recovery ratio improving method based on microbubble flooding of claim 1, wherein the process of adding micron-sized bubbles into water injection water flow to obtain a microbubble aqueous solution is as follows:
the microbubble generating device is arranged on a high-pressure water injection pipeline of the water injection well; wherein, the microbubble generating device comprises a central exhaust pipe 1 and a plurality of micro pore plates 2; the central exhaust pipe 1 is concentrically arranged in the outer cylinder 4 of the high-pressure water injection pipeline; one end of the central exhaust pipe 1 is communicated with an air source, and the other end of the central exhaust pipe is closed; a plurality of exhaust ports are arranged on the central exhaust pipe 1 at intervals, and the micro pore plate 2 is arranged at the exhaust ports; a plurality of micron through holes are formed in the micron pore plate 2;
water injection water flow is introduced between the central exhaust pipe 1 and the outer cylinder 4, and high-pressure gas is introduced into the central exhaust pipe 1; when the high-pressure gas passes through the micro-pore plate 2 at the exhaust port, micro-scale bubbles are formed and enter the water injection water flow, and the micro-bubble water solution is obtained by mixing.
5. The method for improving oil recovery efficiency based on microbubble flooding of claim 4, wherein the high-pressure gas is air or N 2 、CO 2 And one of natural gas.
6. The method of claim 4, wherein the high pressure gas has a pressure greater than the water injection stream.
7. The method for improving oil recovery efficiency based on microbubble flooding of claim 6, wherein the difference between the pressure value of the high-pressure gas and the pressure value of the water injection flow is 0.3-0.5Mpa.
8. The method for improving oil recovery efficiency based on microbubble flooding of claim 1, wherein the micron-sized bubbles in the microbubble aqueous solution are in a uniform dispersed phase, and the water injection water flow is in a continuous phase.
9. The method for improving oil recovery efficiency based on microbubble flooding of claim 1, wherein the volume of the micron-sized bubbles in the microbubble aqueous solution is 5% -30% of the volume of the water injection flow.
10. The method of claim 1, wherein the apparent viscosity of the aqueous solution of microbubbles increases as the bubble diameter of the microbubbles decreases.
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