CN115522901A - Experimental device and method for evaluating effect of improving recovery ratio by alternating huff and puff of nano emulsion - Google Patents
Experimental device and method for evaluating effect of improving recovery ratio by alternating huff and puff of nano emulsion Download PDFInfo
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- 239000007908 nanoemulsion Substances 0.000 title claims abstract description 81
- 238000011084 recovery Methods 0.000 title claims abstract description 46
- 238000000034 method Methods 0.000 title claims abstract description 30
- 230000000694 effects Effects 0.000 title claims abstract description 22
- 238000006073 displacement reaction Methods 0.000 claims description 102
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 70
- 239000008398 formation water Substances 0.000 claims description 62
- 239000011435 rock Substances 0.000 claims description 61
- 230000015572 biosynthetic process Effects 0.000 claims description 42
- 238000000926 separation method Methods 0.000 claims description 39
- 230000008569 process Effects 0.000 claims description 15
- 238000002347 injection Methods 0.000 claims description 14
- 239000007924 injection Substances 0.000 claims description 14
- 239000011148 porous material Substances 0.000 claims description 12
- 239000012530 fluid Substances 0.000 claims description 10
- 230000008859 change Effects 0.000 claims description 9
- 238000002474 experimental method Methods 0.000 claims description 9
- 239000007788 liquid Substances 0.000 claims description 9
- 238000001802 infusion Methods 0.000 claims description 7
- 239000012153 distilled water Substances 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 claims description 6
- 238000012544 monitoring process Methods 0.000 claims description 6
- 230000001502 supplementing effect Effects 0.000 claims description 6
- 229920006395 saturated elastomer Polymers 0.000 claims description 4
- 238000012935 Averaging Methods 0.000 claims description 3
- 230000001419 dependent effect Effects 0.000 claims description 3
- 238000009826 distribution Methods 0.000 claims description 3
- 238000001035 drying Methods 0.000 claims description 3
- 239000004530 micro-emulsion Substances 0.000 claims description 3
- 150000003839 salts Chemical class 0.000 claims description 3
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- 238000005406 washing Methods 0.000 claims description 3
- 238000005303 weighing Methods 0.000 claims description 3
- 238000009736 wetting Methods 0.000 claims description 3
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- 238000004088 simulation Methods 0.000 description 7
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- 230000009286 beneficial effect Effects 0.000 description 2
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- E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
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Abstract
The invention discloses an experimental device and method for evaluating the effect of improving the recovery efficiency by changing the huff and puff of a nano emulsion.
Description
Technical Field
The invention relates to the technical field of tight oil reservoir development, in particular to an experimental device and method for evaluating the effect of improving the recovery ratio by alternating huff and puff of nano emulsion.
Background
At present, low-permeability compact oil reservoirs become the key difficult field of oil-gas exploration and development in China, and the oil reservoirs have the outstanding characteristics of low porosity, poor permeability and difficulty in extracting oil attached to the wall surface of a pore channel. The water injection throughput effect is attenuated too fast along with the increase of the throughput rounds, and the throughput effect is very poor in the middle and later periods. In the process of injecting the nano emulsion for displacement, the nano emulsion can improve the effective radius of a pore channel and improve the integral permeability, but the displacement effect is not as good as the huff and puff effect because the nano emulsion has short retention time and does not contact with oil and water in the displacement process.
The problem that oil of the oil reservoir is attached to the wall surface of a pore passage and is difficult to draw can be solved by injecting the nano emulsion in a huff-and-puff mode, the huff-and-puff process enables the spread range of the nano emulsion to be increased, the nano emulsion is further in full contact with the oil, the wettability of oil and water in a stratum is changed, resistance in exploitation is reduced, and related indoor evaluation simulation device and method research have important significance.
Disclosure of Invention
The invention aims to simulate the effect of nanoemulsion rotation huff and puff on oil reservoir recovery ratio improvement under stratum conditions, and provides an experimental device and method for evaluating the effect of nanoemulsion rotation huff and puff on oil reservoir recovery ratio improvement.
In order to achieve the technical purpose, the invention provides an experimental device and method for evaluating the effect of improving the recovery efficiency by alternating huff and puff of nano emulsion. The device comprises a rock core holder, a confining pressure pump, a displacement pump, a differential pressure sensor, a formation water intermediate container, a nano emulsion intermediate container, a formation oil intermediate container, a three-way valve, a two-way valve, a four-way joint, an oil-water separation flowmeter, a beaker and a fluid infusion barrel;
the core holder is connected with the confining pump, the inlet end of the core holder is respectively connected with the formation water intermediate container, the nano emulsion intermediate container and the formation oil intermediate container through a four-way joint, the outlet end of the core holder is connected with the oil-water separation flowmeter and the beaker, and the formation water intermediate container, the nano emulsion intermediate container and the formation oil intermediate container are connected to the displacement pump through the four-way joint;
movable clapboards are arranged in the formation water intermediate container, the nano emulsion intermediate container and the formation oil intermediate container, and when a displacement pump pumps distilled water into a space on one side of the clapboard of the intermediate container, the clapboards can move to the other side of the intermediate container to transfer displacement pressure;
the displacement pump is connected with the pressure sensor through a high-strength pressure-resistant pipeline and is used for monitoring the pressure change of the displacement pump in real time in the experimental process; the displacement pump is connected with the fluid infusion barrel through a high-strength pressure-resistant pipeline, and distilled water for supplementing pressure transmitted in the displacement process of the displacement pump is filled in the fluid infusion barrel; the displacement pump is connected with the formation water intermediate container, the nano emulsion intermediate container and the formation oil intermediate container through high-strength pressure-resistant pipelines, and a two-way valve is arranged in the middle of each high-strength pressure-resistant pipeline;
the rock core holder is respectively connected with the formation water intermediate container, the nano emulsion intermediate container and the formation oil intermediate container through high-strength pressure-resistant pipelines; the core holder is connected with a confining pressure pump through a high-strength pressure-resistant pipeline and is used for providing confining pressure for fixing the core; the core holder is connected with a differential pressure sensor through a high-strength pressure-resistant pipeline and is used for monitoring the differential pressure at two ends of the core holder; the core holder is connected with the oil-water separation flowmeter and the beaker through a high-strength pressure-resistant pipeline, and a two-way valve is arranged in the middle of the high-strength pressure-resistant pipeline; the oil-water separation flowmeter and the beaker are used for measuring the volume of oil and water during an experiment;
correspondingly, the invention also provides a method for evaluating the effect of improving the recovery ratio by the rotation throughput of the nano emulsion, which comprises the following steps:
s1: washing oil and salt of the rock core according to the industry standard, drying for 24 hours in a constant temperature oven at 85 ℃, and recording the weight of the dried rock core as m Dry matter Measuring the length and diameter of the core, respectivelyMarking as L and D;
s2: putting the core into a beaker filled with formation water, putting the beaker into a vacuumizing device, setting the vacuumizing time to be 960 minutes and the pressure to be-0.1 MPa, completing the saturation of the formation water by the core after the vacuumizing is finished, and recording the weight of the core at the moment as m Wetting with water (ii) a Calculating the pore volume in the core
Where ρ is w Is the density of the formation water;
s3: fixing the rock core saturated with the formation water in the step S2 in a rock core holder, applying confining pressure to 3MPa, then opening a two-way valve of a formation oil intermediate container connected with a displacement pump, and ensuring that the two-way valve between the formation water intermediate container and the displacement pump and the two-way valve between a nano emulsion intermediate container and the displacement pump are closed at the moment; opening a two-way valve between the outlet end of the rock core holder and the oil-water separation flowmeter; starting a displacement pump to displace the formation oil in the formation oil intermediate container into the core holder; adjusting confining pressure, ensuring slow displacement of 0.01ml/min, closing a displacement pump to stop displacement until the water production rate is lower than 0.2%, opening a core holder to take out a core, weighing and recording the weight of the core at the moment as m Original (original) (ii) a According to
Calculating to obtain the original oil-containing volume V in the core simulating the oil-water distribution of the stratum state Total 0 Where ρ is o Is the density of the formation oil, p w Is the density of the formation water; recording the huff and puff turns n =0, and recording the huff and puff oil recovery E =0%;
s4: putting the rock core obtained in the step S3 into a rock core holder, closing a two-way valve of a formation oil intermediate container connected with a displacement pump, opening a two-way valve of a nano emulsion intermediate container connected with the displacement pump, and ensuring that the two-way valve between the formation oil intermediate container and the displacement pump is closed at the moment; closing a two-way valve between the outlet end of the core holder and the oil-water separation flowmeter; starting the displacement pump, setting the displacement speed of the displacement pump to be 0.01ml/min, injecting the nano emulsion at a constant speed of 0.01ml/min, and setting the confining pressure pump to be the tracing pumpTracking a pressure mode to ensure that the confining pressure of the rock core holder is always greater than the pressure of a rock core chamber; the injection volume reaches 0.5V pore Then, the displacement pump is closed, the two-way valve of the nano emulsion intermediate container connected with the displacement pump is closed, the nano emulsion is stopped from being continuously injected, and the mixture is kept stand for 1 day; opening a two-way valve between the outlet end of the core holder and the oil-water separation flowmeter after the standing is finished, waiting for the liquid outlet speed to be less than 0.01ml/min, closing the two-way valve between the outlet end of the core holder and the oil-water separation flowmeter, and recording the volume V of oil in the oil-water separation flowmeter 1 ；
S5: opening a two-way valve of the formation water intermediate container connected with the displacement pump, and ensuring that the two-way valve between the formation oil intermediate container and the displacement pump and the two-way valve between the nano emulsion intermediate container and the displacement pump are closed at the moment; closing a two-way valve between the outlet end of the core holder and the oil-water separation flowmeter; starting a displacement pump, setting the displacement speed of the displacement pump to be 0.01ml/min, injecting formation water at a constant speed of 0.01ml/min, and setting a confining pressure pump to be a pressure tracking mode so that the confining pressure of the rock core holder is always greater than the pressure of a rock core chamber; the injection volume reaches 0.5V pore When the stratum water is filled into the reservoir, the displacement pump is closed, the two-way valve of the reservoir in the stratum water, which is connected with the displacement pump, is closed, the stratum water is stopped from being continuously injected, and the reservoir is kept stand for 1 day; opening a two-way valve between the outlet end of the core holder and the oil-water separation flowmeter after standing is finished, waiting for the liquid outlet speed to be less than 0.01ml/min, closing the two-way valve between the outlet end of the core holder and the oil-water separation flowmeter, and recording the volume V of oil in the oil-water separation flowmeter 2 And calculating the percentage y = (V) of the oil produced in the huff-puff round to the total volume of the original oil in the core 1 +V 2 )/V Total 0 X is 100%; recording the huff and puff turns n = n +1, and recording the huff and puff oil recovery rate E = E + y;
s6: repeating the steps S4 and S5 until the oil production rate of the newly increased single huff and puff turn is lower than 0.05 percent, stopping the experiment and counting data to obtain the recovery ratio experiment data of the rotational huff and puff nano emulsion and the formation water;
s7: respectively repeating the steps S1 to S6 by adopting 10 rock cores, and averaging the experimental data of different rock cores to obtain the trend of the change of the recovery ratio of the stratum rock core during injection huff and puff; fitting according to experimental data to obtain an empirical formula of the change of the core recovery ratio of the region along with the huff and puff turns; the specific fit is as follows using an empirical formula:
wherein y is a dependent variable, and the meaning of y is recovery efficiency at different moments; x is an independent variable and means the number of times of the same volume handling; a, a, u, b and v are fitting parameters, the values of the fitting parameters are related to the basic properties of the rock core, and experimental data fitting adjustment is needed when the parameter values of different oil reservoir areas are different;
s8: and (4) independently adopting the formation water and the micro-nano emulsion to repeat the handling process without considering the alternate injection of the formation water and the micro-emulsion, and comparing the obtained experimental data.
According to the experimental device and method for evaluating the effect of improving the recovery efficiency by changing the huff and puff of the nano emulsion, the process of improving the recovery efficiency by injecting the nano emulsion into the core under the formation condition is simulated by building a physical simulation experiment, the effect of improving the recovery efficiency by injecting different fluids can be compared, the principle is reliable and applicable, the block nano emulsion huff and puff improvement recovery efficiency rule can be obtained through core data in a laboratory, the method has a guiding effect on the field formulation of huff and puff plans, and reference can be provided for efficient use of tight oil reservoirs.
Has the beneficial effects that:
compared with the prior art, the invention has the following beneficial effects:
the process of improving the recovery efficiency by injecting the nanoemulsion into the core under the stratum simulation condition through building a physical simulation experiment can be compared with the effect of improving the recovery efficiency by injecting different fluids, the principle is reliable and applicable, the block nanoemulsion can be obtained through the core data in a laboratory, the recovery efficiency can be improved by injecting the nanoemulsion, the field planning of the injection can be guided, and the reference can be provided for the efficient use of the tight oil reservoir.
Drawings
FIG. 1 is a schematic diagram of a simulation experiment apparatus for evaluating nanoemulsion rotation throughput enhanced recovery ratio;
FIG. 2 is a graph of recovery as a function of the number of shift throughputs for different shift throughput modes.
Shown in the figure: the device comprises a displacement pump (1), a pressure sensor (2), a three-way valve (3), a fluid infusion barrel (4), four-way connectors (5, 12), two-way valves (6, 7, 8, 17, 19), a formation oil intermediate container (9), a nano emulsion intermediate container (10), a formation water intermediate container (11), a rock core holder (13), a rock core (14), a confining pressure pump (15), a differential pressure sensor (16), an oil-water separation flowmeter (18) and a beaker (20).
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the invention.
Example (b):
as shown in fig. 1, the experimental device for evaluating the effect of improving the recovery efficiency by changing throughput of the nano emulsion provided by the invention comprises a core holder (13), a confining pressure pump (15), a displacement pump (1), a differential pressure sensor (16), a pressure sensor (2), a formation water intermediate container (11), a nano emulsion intermediate container (10), a formation oil intermediate container (9), a three-way valve (3), two-way valves (6, 7, 8, 17 and 19), four-way joints (5 and 12), an oil-water separation flowmeter (18), a beaker (20) and a fluid infusion barrel (4);
the core holder (13) is connected with a confining pressure pump (15), the inlet end of the core holder is respectively connected with a formation water intermediate container (11), a nano emulsion intermediate container (10) and a formation oil intermediate container (9) through a four-way joint (12), the outlet end of the core holder is connected with an oil-water separation flowmeter (18) and a beaker (20), and the formation water intermediate container (11), the nano emulsion intermediate container (10) and the formation oil intermediate container (9) are connected to a displacement pump (1) through a four-way joint (5);
movable clapboards are arranged in the formation water intermediate container (11), the nano emulsion intermediate container (10) and the formation oil intermediate container (9), and when the distilled water is pumped into a space on one side of the clapboard of the intermediate container by the displacement pump (1), the clapboards can move to the other side of the clapboard of the intermediate container to transfer displacement pressure;
the displacement pump (1) is connected with the pressure sensor (2) through a high-strength pressure-resistant pipeline and is used for monitoring the pressure change of the displacement pump in real time in the experimental process; the displacement pump (1) is connected with the liquid supplementing barrel (4) through a high-strength pressure-resistant pipeline, and distilled water for supplementing pressure transmitted in the displacement process of the displacement pump (1) is filled in the liquid supplementing barrel (4); the displacement pump (1) is connected with a formation water intermediate container (11), a nano emulsion intermediate container (10) and a formation oil intermediate container (9) through high-strength pressure-resistant pipelines, and two-way valves (6, 7 and 8) are arranged in the middle of the high-strength pressure-resistant pipelines;
the core holder (13) is respectively connected with the formation water intermediate container (11), the nano emulsion intermediate container (10) and the formation oil intermediate container (9) through high-strength pressure-resistant pipelines; the core holder (13) is connected with a confining pressure pump (15) through a high-strength pressure-resistant pipeline and is used for providing confining pressure for fixing the core; the core holder (13) is connected with a differential pressure sensor (16) through a high-strength pressure-resistant pipeline and is used for monitoring the differential pressure at two ends of the core holder; the core holder (13) is connected with an oil-water separation flowmeter (18) and a beaker (20) through a high-strength pressure-resistant pipeline, and a two-way valve (17) is arranged in the middle of the high-strength pressure-resistant pipeline; the oil-water separation flowmeter (18) and the beaker (20) are used for metering the volume of oil and water during the experiment;
correspondingly, the invention also provides a method for evaluating the effect of improving the recovery ratio by the rotation throughput of the nano emulsion, which comprises the following steps:
s1: washing oil and salt of the rock core according to the industry standard, drying for 24 hours in a constant temperature oven at 85 ℃, and recording the weight of the dried rock core as m Dry matter Measuring the length and the diameter of the rock core, and respectively recording as L and D;
s2: putting the core into a beaker filled with formation water, putting the beaker into a vacuumizing device, setting the vacuumizing time to be 960 minutes and the pressure to be-0.1 MPa, completing the saturation of the formation water by the core after the vacuumizing is finished, and recording the weight of the core at the moment as m Wetting with water (ii) a Calculating the pore volume in the core
Where ρ is w Is the density of the formation water;
s3: fixing the rock core saturated with the formation water in the step S2 in a rock core holder (13), applying confining pressure to 3MPa, then opening a two-way valve (6) of a formation oil intermediate container (9) connected with a displacement pump (1), and ensuring that a two-way valve (7) between the formation oil intermediate container (10) and the displacement pump (1) and a two-way valve (8) between a nano emulsion intermediate container (11) and the displacement pump (1) are closed at the moment; opening a two-way valve (17) between the outlet end of the core holder (13) and the oil-water separation flowmeter (18); starting a displacement pump (1) to displace the formation oil in the formation oil intermediate container (9) into a core holder (13); adjusting confining pressure, ensuring slow displacement of 0.01ml/min, closing the displacement pump (1) to stop displacement until the water production rate is lower than 0.2%, opening the rock core holder (13) to take out the rock core, weighing and recording the weight of the rock core at the moment as m Original (ii) a According to
Calculating to obtain the original oil-containing volume V in the core simulating the oil-water distribution of the stratum state Total 0 Where ρ is o Is the density of the formation oil, p w Is the density of the formation water; recording the huff and puff turns n =0, and recording the huff and puff oil recovery E =0%;
s4: putting the rock core obtained in the step S3 into a rock core holder (13), closing a two-way valve (6) of a formation oil intermediate container (9) connected with a displacement pump (1), opening a two-way valve (7) of a nano emulsion intermediate container (10) connected with the displacement pump (1), and ensuring that the two-way valve (8) between the formation water intermediate container (11) and the displacement pump (1) is closed at the moment; closing a two-way valve (17) between the outlet end of the core holder (13) and the oil-water separation flowmeter (18); starting a displacement pump (1), setting the displacement speed of the displacement pump (1) to be 0.01ml/min, injecting nano emulsion at a constant speed of 0.01ml/min, and setting a confining pressure pump (15) to be a pressure tracking mode, so that the confining pressure of a rock core holder (13) is always greater than the pressure of a rock core chamber; the injection volume reaches 0.5V pore When the nano-emulsion is injected into the water, the displacement pump (1) is closed, the two-way valve (7) of the nano-emulsion intermediate container (10) connected with the displacement pump (1) is closed, the nano-emulsion is stopped from being injected continuously, and the water is kept still for 1 day; after the standing is finished, a two-way valve (17) between the outlet end of the rock core holder (13) and an oil-water separation flowmeter (18) is opened, and the liquid outlet speed is waited to be lower than0.01ml/min, closing a two-way valve (17) between the outlet end of the rock core holder (13) and the oil-water separation flowmeter (18), and recording the volume V of oil in the oil-water separation flowmeter 1 ；
S5: opening a two-way valve (8) of a formation water intermediate container (11) connected with the displacement pump (1), and ensuring that a two-way valve (6) between the formation oil intermediate container (9) and the displacement pump (1) and a two-way valve (7) between the nano emulsion intermediate container (10) and the displacement pump (1) are closed at the moment; closing a two-way valve (17) between the outlet end of the core holder (13) and the oil-water separation flowmeter (18); starting a displacement pump (1), setting the displacement speed of the displacement pump (1) to be 0.01ml/min, injecting formation water at a constant speed of 0.01ml/min, and setting a confining pressure pump (15) to be a pressure tracking mode, so that the confining pressure of a rock core holder (13) is always greater than the pressure of a rock core chamber; the injection volume reaches 0.5V pore When the water is poured into the reservoir, the displacement pump (1) is closed, the two-way valve (8) of the reservoir (11) in the formation water, which is connected with the displacement pump (1), is closed, the formation water is stopped from being continuously poured into the reservoir, and the reservoir is kept still for 1 day; after the standing is finished, opening a two-way valve (17) between the outlet end of the core holder (13) and the oil-water separation flowmeter (18), waiting for the liquid outlet speed to be less than 0.01ml/min, closing the two-way valve (17) between the outlet end of the core holder (13) and the oil-water separation flowmeter (18), and recording the volume V of oil in the oil-water separation flowmeter 2 And calculating the percentage y = (V) of the oil produced in the huff-puff round to the total volume of the original oil in the core 1 +V 2 )/V Total 0 X 100%; recording the huff and puff turns n = n +1, and recording the huff and puff oil recovery rate E = E + y;
s6: repeating the steps S4 and S5 until the oil production rate of the newly increased single huff and puff turn is lower than 0.05 percent, stopping the experiment and counting data to obtain the recovery ratio experiment data of the rotational huff and puff nano emulsion and the formation water;
s7: respectively repeating the steps S1 to S6 by adopting 10 rock cores, and averaging the experimental data of different rock cores to obtain the trend of the change of the recovery ratio of the stratum rock core during injection huff and puff; fitting according to experimental data to obtain an empirical formula of the change of the core recovery ratio of the area along with the huff and puff turns; the specific fit is as follows using an empirical formula:
wherein y is a dependent variable, and the meaning of y is recovery efficiency at different moments; x is an independent variable and means the number of times of the same volume handling; a, a, u, b and v are fitting parameters, the values of the fitting parameters are related to the basic properties of the rock core, and experimental data fitting adjustment is needed when the parameter values of different oil reservoir areas are different;
s8: and (4) independently adopting the formation water and the micro-nano emulsion to repeat the handling process without considering the alternate injection of the formation water and the micro-emulsion, and comparing the obtained experimental data.
Example 1:
the 10 tight reservoir cores used in this example were from an oil field in Xinjiang, and the specific core parameters are shown in Table 1.
TABLE 1 rock core basic physical property parameter table
| Core number | L(cm) | D(cm) | m Dry matter (g) |
| 1 | 6.352 | 3.802 | 183.880 |
| 2 | 5.961 | 3.756 | 166.499 |
| 3 | 4.661 | 3.818 | 134.522 |
| 4 | 5.847 | 3.804 | 167.482 |
| 5 | 4.894 | 3.795 | 138.957 |
| 6 | 5.958 | 3.821 | 171.984 |
| 7 | 5.154 | 3.807 | 148.563 |
| 8 | 6.241 | 3.814 | 178.548 |
| 9 | 5.654 | 3.789 | 160.711 |
| 10 | 5.874 | 3.847 | 172.114 |
Fig. 2 shows the variation of the recovery ratio with the number of shift throughputs in different shift throughputs modes, and the results of fitting the experimental data are as follows:
injecting 0.5PV formation water +0.5PV formation water in each rotation throughput, and fitting an empirical formula of
Injecting 0.5PV nano emulsion and 0.5PV nano emulsion in each rotation throughput, and fitting an empirical formula of
Injecting 0.5PV nano emulsion and 0.5PV formation water in each rotation throughput, and fitting an empirical formula of
Comparing the recovery rates of the single-throughput nanoemulsion, the single-throughput formation water, the single-throughput nanoemulsion and the formation water, the highest recovery rate of the single-throughput nanoemulsion and the single-throughput formation water can be found.
According to the simulation experiment device and method for evaluating the huff and puff and improving the recovery efficiency of the micro-nano emulsion, the process of huff and puff and improving the recovery efficiency of the micro-nano emulsion injected into the rock core under the condition of simulating the formation by building a physical simulation experiment can be compared with the effect of improving the recovery efficiency of different injected fluids, the principle is reliable and applicable, the block micro-nano emulsion huff and puff and improve the recovery efficiency rule can be obtained through the rock core data of a laboratory, the method has a guiding effect on the on-site huff and puff plan making, and the method can provide reference for the efficient use of tight oil reservoirs.
Although the present invention has been described with reference to the above embodiments, it should be understood that the present invention is not limited to the above embodiments, and those skilled in the art can make various changes and modifications without departing from the scope of the present invention.
Claims (2)
1. An experimental device for evaluating the effect of improving the recovery efficiency by changing the huff and puff of the nano emulsion is characterized by comprising a rock core holder, a confining pressure pump, a displacement pump, a differential pressure sensor, a formation water intermediate container, a nano emulsion intermediate container, a formation oil intermediate container, a three-way valve, a two-way valve, a four-way joint, an oil-water separation flowmeter, a beaker and a liquid supplementing barrel;
the core holder is connected with the confining pump, the inlet end of the core holder is respectively connected with the formation water intermediate container, the nano emulsion intermediate container and the formation oil intermediate container through a four-way joint, the outlet end of the core holder is connected with the oil-water separation flowmeter and the beaker, and the formation water intermediate container, the nano emulsion intermediate container and the formation oil intermediate container are connected to the displacement pump through the four-way joint;
movable clapboards are arranged in the formation water intermediate container, the nano emulsion intermediate container and the formation oil intermediate container, and when a displacement pump pumps distilled water into a space on one side of the clapboard of the intermediate container, the clapboards can move to the other side of the intermediate container to transfer displacement pressure;
the displacement pump is connected with the pressure sensor through a high-strength pressure-resistant pipeline and is used for monitoring the pressure change of the displacement pump in real time in the experimental process; the displacement pump is connected with the fluid infusion barrel through a high-strength pressure-resistant pipeline, and distilled water for supplementing pressure transmitted in the displacement process of the displacement pump is filled in the fluid infusion barrel; the displacement pump is connected with the formation water intermediate container, the nano emulsion intermediate container and the formation oil intermediate container through high-strength pressure-resistant pipelines, and a two-way valve is arranged in the middle of each high-strength pressure-resistant pipeline;
the rock core holder is respectively connected with the formation water intermediate container, the nano emulsion intermediate container and the formation oil intermediate container through high-strength pressure-resistant pipelines; the core holder is connected with a confining pressure pump through a high-strength pressure-resistant pipeline and is used for providing confining pressure for fixing the core; the core holder is connected with a differential pressure sensor through a high-strength pressure-resistant pipeline and is used for monitoring the differential pressure at two ends of the core holder; the core holder is connected with the oil-water separation flowmeter and the beaker through a high-strength pressure-resistant pipeline, and a two-way valve is arranged in the middle of the high-strength pressure-resistant pipeline; a separate oil-water flow meter and beaker were used to meter the volume of oil and water during the experiment.
2. A method for evaluating the effect of improving the recovery ratio by the rotation throughput of nano emulsion is characterized by comprising the following steps:
s1: washing oil and salt of the core according to the industry standard, drying in a thermostat at 85 ℃ for 24 hours, and recording the weight of the dried core as m Dry food Measuring the length and the diameter of the rock core, and respectively recording as L and D;
s2: putting the core into a beaker filled with formation water, putting the beaker into a vacuumizing device, setting the vacuumizing time to 960 minutes and the pressure to-0.1 MPa, completing the saturated formation water of the core after the vacuumizing is finished, and recording the weight of the core at the moment as m Wetting with water (ii) a Calculating the pore volume in the core
Where ρ is w Is the density of the formation water;
s3: fixing the rock core saturated with the formation water in the step S2 in a rock core holder, applying confining pressure to 3MPa, then opening a two-way valve of a formation oil intermediate container connected with a displacement pump, and ensuring that the two-way valve between the formation water intermediate container and the displacement pump and the two-way valve between a nano emulsion intermediate container and the displacement pump are closed at the moment; opening a two-way valve between the outlet end of the rock core holder and the oil-water separation flowmeter; starting a displacement pump to displace the formation oil in the formation oil intermediate container into the core holder; adjusting confining pressure to ensure a buffer of 0.01ml/minRapidly displacing, closing a displacement pump to stop the displacement until the water production rate is lower than 0.2%, opening a rock core holder to take out a rock core, weighing and recording the weight of the rock core at the moment as m Original (ii) a According to
Calculating to obtain the original oil-containing volume V in the core simulating the oil-water distribution of the stratum state Total 0 Where ρ is o Is the density of the formation oil, p w Is the density of the formation water; recording the huff and puff turns n =0, and recording the huff and puff oil recovery E =0%;
s4: putting the rock core obtained in the step S3 into a rock core holder, closing a two-way valve of a formation oil intermediate container connected with a displacement pump, opening a two-way valve of a nano emulsion intermediate container connected with the displacement pump, and ensuring that the two-way valve between the formation oil intermediate container and the displacement pump is closed at the moment; closing a two-way valve between the outlet end of the core holder and the oil-water separation flowmeter; starting a displacement pump, setting the displacement speed of the displacement pump to be 0.01ml/min, injecting nano emulsion at a constant speed of 0.01ml/min, and setting a confining pressure pump to be a pressure tracking mode so that the confining pressure of the rock core holder is always greater than the pressure of a rock core chamber; the injection volume reaches 0.5V pore When the nano emulsion is injected into the nano emulsion tank, the displacement pump is closed, the two-way valve of the nano emulsion intermediate container connected with the displacement pump is closed, the nano emulsion is stopped from being injected continuously, and the nano emulsion tank is kept standing for 1 day; opening a two-way valve between the outlet end of the core holder and the oil-water separation flowmeter after standing is finished, waiting for the liquid outlet speed to be less than 0.01ml/min, closing the two-way valve between the outlet end of the core holder and the oil-water separation flowmeter, and recording the volume V of oil in the oil-water separation flowmeter 1 ；
S5: opening a two-way valve of the formation water intermediate container connected with the displacement pump, and ensuring that the two-way valve between the formation oil intermediate container and the displacement pump and the two-way valve between the nano emulsion intermediate container and the displacement pump are closed at the moment; closing a two-way valve between the outlet end of the core holder and the oil-water separation flowmeter; starting a displacement pump, setting the displacement speed of the displacement pump to be 0.01ml/min, injecting formation water at a constant speed of 0.01ml/min, and setting a confining pressure pump to be a pressure tracking mode so that the confining pressure of the rock core holder is always greater than the pressure of a rock core chamber; injection volumeReaches 0.5V pore When the water is in the water storage tank, the displacement pump is closed, the two-way valve of the formation water intermediate container connected with the displacement pump is closed, the formation water is stopped from being continuously injected, and the water is kept standing for 1 day; opening a two-way valve between the outlet end of the core holder and the oil-water separation flowmeter after standing is finished, waiting for the liquid outlet speed to be less than 0.01ml/min, closing the two-way valve between the outlet end of the core holder and the oil-water separation flowmeter, and recording the volume V of oil in the oil-water separation flowmeter 2 And calculating the percentage y = (V) of the oil produced in the huff-puff round to the total volume of the original oil in the core 1 +V 2 )/V Total 0 X 100%; recording the huff and puff turns n = n +1, and recording the huff and puff oil recovery rate E = E + y;
s6: repeating the steps S4 and S5 until the oil production rate of the new single huff and puff round is lower than 0.05%, stopping the experiment and counting data to obtain the recovery efficiency experiment data of the huff and puff nano emulsion and the formation water alternately;
s7: respectively repeating the steps S1 to S6 by adopting 10 rock cores, and averaging the experimental data of different rock cores to obtain the trend of the change of the recovery ratio of the stratum rock core during injection huff and puff; fitting according to experimental data to obtain an empirical formula of the change of the core recovery ratio of the region along with the huff and puff turns; the specific fitting uses an empirical formula as follows:
wherein y is a dependent variable, and the meaning of y is recovery efficiency at different moments; x is an independent variable and means the number of rounds of huffing and puff with the same volume; a, a, u, b and v are fitting parameters, values of the fitting parameters are related to basic properties of the rock core, and experimental data fitting adjustment is needed when different oil reservoir area parameter values are different;
s8: and (4) independently adopting the formation water and the micro-nano emulsion to repeat the handling process without considering the alternate injection of the formation water and the micro-emulsion, and comparing the obtained experimental data.
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| CN117433977B (en) * | 2023-12-08 | 2024-03-26 | 西南石油大学 | Supercritical CO 2 Device and method for detecting in-situ permeability of shale reaction |
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