CN114856511A - Nitrogen gas miscible flooding method - Google Patents
Nitrogen gas miscible flooding method Download PDFInfo
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- CN114856511A CN114856511A CN202110147672.5A CN202110147672A CN114856511A CN 114856511 A CN114856511 A CN 114856511A CN 202110147672 A CN202110147672 A CN 202110147672A CN 114856511 A CN114856511 A CN 114856511A
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- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 title claims abstract description 134
- 238000000034 method Methods 0.000 title claims abstract description 34
- 229910001873 dinitrogen Inorganic materials 0.000 title claims abstract description 12
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 64
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims abstract description 60
- 239000003921 oil Substances 0.000 claims abstract description 48
- 239000010779 crude oil Substances 0.000 claims abstract description 43
- 239000007789 gas Substances 0.000 claims abstract description 40
- 239000003345 natural gas Substances 0.000 claims abstract description 29
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen(.) Chemical compound [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 claims abstract description 20
- 230000015572 biosynthetic process Effects 0.000 claims description 24
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 22
- 238000010587 phase diagram Methods 0.000 claims description 13
- 238000002347 injection Methods 0.000 claims description 12
- 239000007924 injection Substances 0.000 claims description 12
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 11
- 239000001569 carbon dioxide Substances 0.000 claims description 11
- 239000012530 fluid Substances 0.000 claims description 11
- 238000006073 displacement reaction Methods 0.000 claims description 8
- 238000004364 calculation method Methods 0.000 claims description 6
- 238000002474 experimental method Methods 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 6
- OTMSDBZUPAUEDD-UHFFFAOYSA-N Ethane Chemical compound CC OTMSDBZUPAUEDD-UHFFFAOYSA-N 0.000 claims description 5
- 230000008569 process Effects 0.000 claims description 4
- 238000011084 recovery Methods 0.000 abstract description 8
- 238000011161 development Methods 0.000 abstract description 3
- 239000003129 oil well Substances 0.000 abstract description 2
- 238000005516 engineering process Methods 0.000 description 5
- 239000004215 Carbon black (E152) Substances 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 229930195733 hydrocarbon Natural products 0.000 description 3
- 150000002430 hydrocarbons Chemical class 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- MEKDPHXPVMKCON-UHFFFAOYSA-N ethane;methane Chemical compound C.CC MEKDPHXPVMKCON-UHFFFAOYSA-N 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 238000004088 simulation Methods 0.000 description 2
- 239000004094 surface-active agent Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- KPAMAAOTLJSEAR-UHFFFAOYSA-N [N].O=C=O Chemical compound [N].O=C=O KPAMAAOTLJSEAR-UHFFFAOYSA-N 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000006184 cosolvent Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000009533 lab test Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 230000008719 thickening Effects 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP 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
- E21B43/168—Injecting a gaseous medium
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
- C09K8/58—Compositions for enhanced recovery methods for obtaining hydrocarbons, i.e. for improving the mobility of the oil, e.g. displacing fluids
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
- C09K8/58—Compositions for enhanced recovery methods for obtaining hydrocarbons, i.e. for improving the mobility of the oil, e.g. displacing fluids
- C09K8/594—Compositions used in combination with injected gas, e.g. CO2 orcarbonated gas
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P90/00—Enabling technologies with a potential contribution to greenhouse gas [GHG] emissions mitigation
- Y02P90/70—Combining sequestration of CO2 and exploitation of hydrocarbons by injecting CO2 or carbonated water in oil wells
Abstract
The invention belongs to the technical field of oil and gas field development, and particularly relates to a nitrogen gas miscible flooding method which comprises the steps of injecting mixed gas containing nitrogen and natural gas into crude oil to realize miscible flooding; the content of nitrogen in the mixed gas is 20-39.2 vol%. The method solves the problems that the nitrogen content in the oil well is high, the quality of natural gas is seriously influenced, and the recovery treatment cost is high; and simultaneously, the problem that the crude oil is easy to thicken due to the existence of nitrogen in the crude oil is solved.
Description
Technical Field
The invention belongs to the technical field of oil and gas field development, and particularly relates to a nitrogen gas miscible-phase flooding method.
Background
Miscible flooding is that when one fluid displaces another fluid in a porous medium, because of diffusion and mass transfer effects between the two fluids, the two fluids can be mutually dissolved without an interface, so that the interface tension is completely eliminated, the capillary quasi-number becomes infinite, and simultaneously the capillary force in the porous medium is reduced to 0, so that the trapping of the capillary force on the fluid to be displaced is reduced, and the microcosmic displacement efficiency can reach 100% theoretically. The miscible flooding technology is introduced from abroad, particularly in the United states, and the crude oil yield of the technology for improving the recovery efficiency by utilizing the miscible flooding technology accounts for more than 90 percent of the world.
At present, carbon dioxide phase displacement is the most studied. Research shows that compared with water flooding, the carbon dioxide has lower injection pressure and stronger injection capability, so that the technology can improve the crude oil recovery ratio by 10-15% on the basis of the conventional technology, enables the recovery ratio of a low-permeability oil reservoir to reach more than 30%, and has wide application prospect. The method of adding liquefied gas and surfactant is mainly adopted to reduce the minimum miscible pressure of carbon dioxide in China.
For example, patent CN104610953A discloses a method for reducing the minimum miscible pressure of carbon dioxide and crude oil, which is to mix a carbon dioxide-philic surfactant with a cosolvent and supercritical carbon dioxide and inject the mixture into an oil reservoir to reduce the minimum miscible pressure.
The nitrogen injection not only can exert the effect and the advantage of common gas injection yield increase, but also has wide attention and research due to the advantages of wide sources, low price, wide applicable oil reservoir types, weak corrosivity to equipment and the like.
The miscible pressure of nitrogen is far higher than that of hydrocarbon gases such as carbon dioxide, rich gas and the like, if nitrogen miscible flooding is to be realized, the formation pressure is required to be high, or the contents of light hydrocarbon and intermediate hydrocarbon in formation oil are required to be high, and the nitrogen miscible flooding is difficult to mix under most oil reservoir conditions, so the nitrogen miscible flooding implementation range is narrow, and nitrogen injection is generally used for improving the crude oil recovery rate by utilizing the immiscible flooding mechanism.
But in the development process of the fracture-cavity type oil reservoir in the tower river oil field, along with the exploitation of the scale nitrogen injection, on one hand, the gas storage rate of part of wells is low; and with increasing output of injected nitrogen, 39% nitrogen in the content of natural gas is monitored on site, which seriously affects the quality of the natural gas, and has high recycling cost; on the other hand, the extraction of crude oil by nitrogen and the oxygen-containing of nitrogen thicken crude oil in the formation, which further causes many production problems. For example, the oxidation thickening of common thick oil increases by 20% when the nitrogen contains 3% oxygen.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention aims to provide a nitrogen gas miscible flooding method.
In order to achieve the above purpose, the present invention provides the following technical solutions:
a nitrogen gas miscible flooding method comprises the following steps: and injecting mixed gas containing nitrogen and natural gas into the crude oil to realize miscible flooding, wherein the content of the nitrogen in the mixed gas is 20-39.2% by volume.
Preferably, the crude oil is a common thick oil having a viscosity of 50 to 1000 mPas.
Further preferably, the viscosity of the ordinary thick oil is 50 to 500 mPas, and still more preferably 300-500 mPas.
Preferably, the gas composition of the mixed gas is: 2.3-6.2% of carbon dioxide, 32.5-82.5% of methane, 2.8-7.2% of ethane and 4.7-62% of nitrogen.
Further preferably, the gas composition of the mixed gas is: carbon dioxide 3.773%, methane 52.514%, ethane 4.601%, and nitrogen 39.112%.
Preferably, the pressure of the mixed gas and the crude oil for realizing miscible flooding is 40-54.5 MPa.
Preferably, the temperature of the crude oil sample is 130 ℃.
Preferably, the miscible temperature is 130 ℃.
Preferably, the specific steps of the phase mixing include:
step one, detecting gas components of nitrogen-containing natural gas, and determining that the content of nitrogen is less than 39.2%;
selecting common thick oil and an oil sample with the viscosity of less than 1000mPa & s at 50 ℃, and carrying out a miscible pressure experiment or calculation;
step three, if the miscible phase pressure is lower than the formation pressure, namely the miscible phase condition is met, performing gas injection miscible phase oil displacement operation;
and step four, if the mixed phase pressure is higher than the formation pressure, gradually reducing the nitrogen content until the mixed phase is obtained.
The invention relates to a method for calculating miscible phase pressure, which comprises a plurality of methods such as a laboratory test method or a theoretical calculation method, wherein the theoretical calculation method comprises an empirical formula method, a plate method, a multi-stage contact method, a numerical simulation method, a state method, a calculation method and a line analysis method.
Preferably, the miscible pressure determination comprises the steps of:
1) preparing experimental data including oil reservoir temperature, pressure and oil property parameters;
2) selecting a state equation PR/SRK and parameters in PVT phase state simulation software;
3) setting experimental data to be fitted, namely formation fluid PVT phase state experimental data, and fitting the data;
4) fitting experimental data, determining fluid state parameters, inputting different injected gases, simulating a multi-contact miscible flooding process, calculating a triangular phase diagram, and determining miscible pressure.
Compared with the prior art, the invention has the beneficial effects that:
(1) the invention provides a nitrogen gas miscible flooding method, which solves the problems that the nitrogen gas content in an oil well is high, the quality of natural gas is seriously influenced and the recovery treatment cost is high; and simultaneously, the problem that the crude oil is easy to thicken due to the existence of nitrogen in the crude oil is solved.
(2) The lowest miscible flooding pressure of nitrogen can be effectively reduced by using the miscible flooding method provided by the invention, and experimental results show that the pressure can be reduced by 20MPa (taking TK455 well as an example, 75MPa of unmiscible phase is adopted, and the miscible pressure is 54.25MPa when 20.734% of nitrogen-containing natural gas is less than the formation pressure of 55MPa, so that miscible phase can be realized); moreover, the viscosity of the oil sample after phase displacement can be reduced to 16.25-19.43% of the original thick oil, which is beneficial to improving the oil recovery rate.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention.
FIG. 1 is a pseudo-ternary phase diagram of crude oil injected with nitrogen for multiple times under TK227CH well at 75MPa
FIG. 2 is a pseudo-ternary phase diagram of TK227CH well crude oil prepared by injecting nitrogen-containing natural gas under 43.75MPa for multiple contact (containing 39.112% of nitrogen)
FIG. 3 is a pseudo-ternary phase diagram of crude oil injected with nitrogen for multiple times under 75MPa in TK455 well
FIG. 4 is a pseudo-ternary phase diagram of TK455 well crude oil injected with nitrogen-containing natural gas under 54.25MPa for multiple contacts (containing nitrogen 20.734%)
FIG. 5 is a pseudo-ternary phase diagram of crude oil under TH12177CH well 75MPa with nitrogen injection for multiple times
FIG. 6 is a pseudo-ternary phase diagram (4.767% nitrogen) of TH12177CH well crude oil obtained by injecting nitrogen-containing natural gas under 80 MPa.
Detailed Description
The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it will be understood that they are described herein for the purpose of illustration and explanation and not limitation.
A nitrogen gas miscible flooding method comprises the following steps: injecting mixed gas containing nitrogen and natural gas into crude oil to realize miscible flooding;
step one, detecting gas components of nitrogen-containing natural gas, and determining that the content of nitrogen is less than 39.2%;
selecting common thick oil and an oil sample with the viscosity of less than 500mPa & s at 50 ℃, and carrying out mixed phase pressure experiment simulation or calculation;
wherein the miscible pressure determination comprises the following steps:
1) preparing experimental data including reservoir temperature, pressure, oil property parameters (gas-oil ratio, viscosity, density);
2) selecting a state equation (PR/SRK) and parameters in PVT phase state simulation software;
3) setting experimental data to be fitted, namely formation fluid PVT phase state experimental data, and fitting the data;
4) fitting experimental data, determining fluid state parameters, inputting N 2 And injecting different gases such as natural gas, simulating a multi-contact miscible flooding process, calculating a triangular phase diagram, and determining miscible pressure.
Step three, if the miscible phase pressure is lower than the formation pressure, namely the miscible phase condition is met, gas injection miscible phase oil displacement is carried out to improve the recovery ratio;
and step four, if the mixed phase pressure is higher than the formation pressure, gradually reducing the nitrogen content until the mixed phase is obtained.
In order to investigate the influence of the nitrogen content in the mixed gas on the phase mixing effect, the following experimental settings were carried out:
table 1 table of injected gas components
| Serial number | Carbon dioxide | Nitrogen gas | Methane | Ethane (III) |
| 1 | 5.901 | 4.764 | 82.138 | 7.196 |
| 2 | 4.912 | 20.734 | 68.365 | 5.990 |
| 3 | 3.773 | 39.112 | 52.514 | 4.601 |
Example 1
Tahe oil field TK227CH well formation temperature 130 deg.C, original placeThe layer pressure is 55MPa, the viscosity of an oil sample is 420 mPa.s (50 ℃), the temperature of the oil sample is 130 ℃, and the gas-oil ratio of crude oil is 71(m 3 /m 3 ) And the nitrogen-natural gas miscible flooding experiment is carried out on the block formation crude oil at the original formation temperature according to the minimum miscible pressure test industry standard.
The results show that: the TK227CH well injected with nitrogen cannot realize miscible flooding, as shown in FIG. 1, the pseudo-ternary phase diagram is a crude oil injected with nitrogen for multiple times under 75MPa, and as can be seen from the diagram, miscible flooding cannot be realized even through multiple times of contact when nitrogen is injected only. However, when the nitrogen content in the mixed gas reaches 39.112% and the pressure reaches 43.75MPa, the gas-liquid lines are basically intersected, as shown in FIG. 2, the nitrogen-containing natural gas is injected into TK227CH well crude oil at 43.75MPa for multiple times to contact a pseudo-ternary phase diagram, namely the nitrogen content is less than 39.2%, and the nitrogen-containing natural gas injected into the well can realize multiple times of contact to realize mixed gas flooding phase flooding. Miscible flooding results are shown in table 2 below.
TABLE 2
| Injection pressure PV number | Oil displacement rate% |
| 0.1 | 6.43 |
| 0.2 | 16.27 |
| 0.5 | 45.26 |
| 1.0 | 70.67 |
TK277CH well miscible pressure statistics as shown in Table 3 below
Example 2
The formation temperature of a TK455 well of a Tahe oil field is 130 ℃, the original formation pressure is 55MPa, the viscosity of an oil sample is 455mPa & s (50 ℃), the temperature of the oil sample is 130 ℃, and the gas-oil ratio of crude oil is 42(m 3 /m 3 ) And the nitrogen-natural gas miscible flooding experiment is carried out on the block formation crude oil at the original formation temperature according to the minimum miscible pressure test industry standard.
The results show that: miscible flooding can not be realized when the pressure is 75MPa, as shown in figure 3, nitrogen is injected into crude oil under TK455 well at 75MPa for multiple times of contact to form a pseudo-ternary diagram, and as can be seen from figure 3, miscible flooding can not be realized by multiple times of contact only when nitrogen is injected. As shown in FIG. 4, nitrogen-containing natural gas was injected at 54.25MPa with multiple contacts in a pseudo-ternary phase diagram (containing 20.734% nitrogen). As can be seen from FIG. 4, miscible flooding is realized when the amount of nitrogen in the injected mixed gas is 20.734% under the condition of 54.25 MPa.
In the embodiment, the viscosity of crude oil is 88.4 mPas when the nitrogen-natural gas realizes miscible flooding, and the flooding efficiency is 60.23% (1 PV).
In this example, the composition of the natural gas-nitrogen mixed gas is:
nitrogen 20.734%, carbon dioxide 4.912%, methane 68.365%, ethane 5.99%.
TABLE 4 oil displacement rate for different injection pressures
TK455 well miscible pressure statistics are given in Table 5 below
Example 3
The formation temperature of a Tahe oil field TH12177CH well oil field is 130 ℃, the original formation pressure is 55MPa, the oil sample viscosity is 1917(70 ℃), the oil sample temperature is 130 ℃, and the crude oil gas-oil ratio is 20 (m) 3 /m 3 ) And the nitrogen-natural gas miscible flooding experiment is carried out on the block formation crude oil at the original formation temperature according to the minimum miscible pressure test industry standard.
The results show that: the crude oil of the well has high viscosity, and cannot realize miscible flooding. As shown in FIGS. 5 and 6, the phase flooding can not be realized by injecting nitrogen into crude oil at 75MPa and injecting nitrogen into crude oil at 80MPa, and then repeatedly contacting the nitrogen-containing natural gas with the pseudo-ternary phase diagram (containing 4.764% of nitrogen).
The minimum miscible pressure statistics before and after miscible flooding for the different wells described above are shown in table 6 below.
TABLE 6 table for calculating mixed phase pressure of different gas media
As shown in Table 6, the nitrogen injected into the crude oil of the three wells does not reach the miscible phase, and after certain nitrogen-containing natural gas is injected, the TK227CH and the TK455 wells can realize the miscible phase. The miscible phase pressure of the TK227CH well crude oil injected with 39.112% nitrogen-containing natural gas is 43.75 MPa; the miscible phase pressure of 20.734% nitrogen-containing natural gas injected by TK455 well crude oil is 54.25MPa, and the immiscible phase of nitrogen-containing natural gas injected by TH12177CH well crude oil is unmiscible. Along with the reduction of the nitrogen content, the miscible phase pressure is reduced, and the miscible phase capacity is increased, so that the common thickened oil can realize miscible phase by injecting 20-40% of nitrogen-containing natural gas.
Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art will understand that various changes, modifications and substitutions can be made without departing from the spirit and scope of the invention as defined by the appended claims. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A nitrogen gas miscible flooding method comprises the following steps: injecting mixed gas containing nitrogen and natural gas into crude oil to realize miscible flooding; the content of nitrogen in the mixed gas is 20-39.2 vol%.
2. The nitrogen gas miscible flooding method according to claim 1, wherein the crude oil is a common thick oil, and the viscosity thereof at 50 ℃ is 50 to 1000 mPa-s.
3. The nitrogen miscible-flooding method according to claim 2, wherein the viscosity of the common thick oil is 50 to 500 mPa-s at 50 ℃.
4. The nitrogen miscible-phase flooding method as set forth in claim 1, wherein the gas composition of the mixed gas is: 2.3-6.2% of carbon dioxide, 32.5-82.5% of methane, 2.8-7.2% of ethane and 4.7-62% of nitrogen.
5. The nitrogen miscible-phase flooding method of claim 4, wherein the gas composition of the mixed gas is: carbon dioxide 3.773%, methane 52.514%, ethane 4.601%, and nitrogen 39.112%.
6. The nitrogen miscible flooding method of claim 1, wherein the miscible flooding pressure of the mixed gas and the crude oil is 40-54.5 MPa.
7. The nitrogen miscible-phase flooding method of claim 1, wherein the temperature of the crude oil sample is 130 ℃.
8. The nitrogen miscible flooding method of claim 1, wherein the miscible temperature is 130 ℃.
9. The nitrogen miscible flooding method according to claim 1, wherein the miscible steps comprise:
step one, detecting gas components of nitrogen-containing natural gas, and determining that the content of nitrogen is less than 39.2%;
selecting common thick oil and an oil sample with the viscosity of less than 1000mPa & s at 50 ℃, and carrying out a miscible pressure experiment or calculation;
step three, if the miscible phase pressure is lower than the formation pressure, namely the miscible phase condition is met, performing gas injection miscible phase oil displacement operation;
and step four, if the mixed phase pressure is higher than the formation pressure, gradually reducing the nitrogen content until the mixed phase is obtained.
10. The nitrogen miscible-flooding method of claim 9, wherein the miscible-pressure determination comprises the steps of:
1) preparing experimental data including oil reservoir temperature, pressure and oil property parameters;
2) selecting a state equation PR/SRK and parameters in PVT phase state simulation software;
3) setting experimental data to be fitted, namely formation fluid PVT phase state experimental data, and fitting the data;
4) fitting experimental data, determining fluid state parameters, inputting different injected gases, simulating a multi-contact miscible flooding process, calculating a triangular phase diagram, and determining miscible pressure.
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| US3856086A (en) * | 1972-10-06 | 1974-12-24 | Texaco Inc | Miscible oil recovery process |
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