Method for determining daily nitrogen output of nitrogen injection reservoir producing well by using fluid components

Abstract

The invention belongs to the technical field of oilfield development, and relates to a method for determining the daily output of nitrogen in a nitrogen-injected oil reservoir producing well by using fluid components, which comprises the following steps: before nitrogen is injected into an oil reservoir, metering the daily output of crude oil and the daily output of dissolved gas of each producing well, and measuring the percentage of iC4 + nC4 components in the dissolved gas; according to the daily crude oil yield, the daily dissolved gas yield and the percentage of the iC4 + nC4 components in the dissolved gas of each producing well before nitrogen injection, calculating the yield of the iC4 + nC4 components in the dissolved gas corresponding to the unit crude oil yield of each producing well before nitrogen injection; after nitrogen is injected into the oil reservoir, the daily crude oil output of the oil producing well is metered regularly, and meanwhile, the percentage of iC4 + nC4 components and the percentage of nitrogen components in produced gas of the well are sampled and detected; and determining the daily output of the nitrogen component in the produced gas of the producing well by using a proportional method. At present, the application of oil field nitrogen injection development or potential tapping for improving the recovery efficiency is continuously expanded, and the method for determining the nitrogen yield of the nitrogen injection oil reservoir producing well through fluid components can reduce the metering operation link and the workload of operators.

Description

Technical Field

[0001] The present invention relates to the technical field of oilfield development, and particularly to a method for determining the daily nitrogen production of oil production wells in a nitrogen-injected reservoir by using fluid components. Background Art

[0002] During the process of developing a reservoir by injecting nitrogen, the nitrogen injected from the injection well drives the crude oil in the oil layer to flow towards the oil production well for production. When the nitrogen drive front reaches the oil production well, nitrogen will be produced from the oil production well. The daily nitrogen production of the oil production well in the nitrogen-injected reservoir is the basic measurement content of the nitrogen-injected reservoir development. This daily production and its changing trend are the basis for determining the production systems of the injection well and the oil production well, as well as the working system of the oil and gas treatment system. It is also an important basis for analyzing the sweep degree and oil displacement efficiency of nitrogen injection in the reservoir and evaluating the development effect.

[0003] Currently, for measuring the daily nitrogen production of oil production wells, first, a gas-liquid separation device is used to separate the gas-liquid mixture produced from the oil production well. A metering instrument is used to measure the daily production of the gas separated from each oil production well and the daily production of the crude oil. The separated gas is a mixture of nitrogen and the gas volatilized from the crude oil. A sample of the mixed gas is taken for component analysis to determine the percentage of nitrogen component in the mixed gas. The daily nitrogen production is calculated using the daily production of the mixed gas and the nitrogen content. Summary of the Invention

[0004] The purpose of the present invention is to overcome the problems of complex equipment and processes and low operation efficiency in the prior art, and provide a method for determining the daily nitrogen production of oil production wells in a nitrogen-injected reservoir by using fluid components.

[0005] To achieve the above-mentioned invention purpose, the technical solution adopted by the present invention is as follows:

[0006] Before injecting nitrogen into the reservoir, measure the daily crude oil production, daily dissolved gas production of each oil production well, and determine the percentage of iC4 + nC4 components in the dissolved gas;

[0007] According to the daily crude oil production, daily dissolved gas production, and the percentage of iC4 + nC4 components in the dissolved gas of each oil production well before injecting nitrogen into the reservoir, calculate the production of iC4 + nC4 components in the dissolved gas corresponding to the unit crude oil production of each oil production well before injecting nitrogen;

[0008] After injecting nitrogen into the reservoir, regularly measure the daily crude oil production of the oil production well, and at the same time, take samples to detect the percentage of iC4 + nC4 components and the percentage of nitrogen components in the gas produced from this well; use the proportional method to determine the daily production of nitrogen components in the gas produced from the oil production well.

[0009] In one embodiment, measuring the daily crude oil production, daily dissolved gas production of each oil production well, and determining the percentage of iC4 + nC4 components in the dissolved gas includes:

[0010] Before injecting nitrogen into the reservoir for development, measure the daily crude oil production of each production well and the daily production of separated dissolved gas in the nitrogen injection control area; measure the molar percentage of iC4 + nC4 components in the simultaneously produced dissolved gas sample.

[0011] In one embodiment, use mobile or other non-fixed oil and gas separation metering equipment to measure the daily crude oil production of each production well and the daily production of separated dissolved gas in the nitrogen injection control area.

[0012] In one embodiment, according to the daily crude oil production, the daily production of dissolved gas, and the percentage of iC4 + nC4 components in the dissolved gas of each production well before injecting nitrogen into the reservoir, calculate the production of iC4 + nC4 components in the dissolved gas corresponding to the unit crude oil production of each production well before injecting nitrogen, including:

[0013] Use formula (1) to calculate the production of iC4 + nC4 components in the dissolved gas corresponding to the unit crude oil production of each well before injecting nitrogen. The formula (1) is:

[0014] Xi = Qg * A / Qo (1)

[0015] In formula (1), Xi is the production of iC4 + nC4 components in the dissolved gas corresponding to the unit crude oil production of each well before injecting nitrogen (m³ / t); Qo is the daily crude oil production of each production well before injecting nitrogen (t / day); Qg is the daily production of dissolved gas before injecting nitrogen (m³ / day); A is the percentage of iC4 + nC4 components in the produced dissolved gas before injecting nitrogen (mole percentage).

[0016] In one embodiment, after injecting nitrogen into the reservoir, regularly measure the daily crude oil production of the production well, and at the same time, sample and detect the percentage of iC4 + nC4 components and the percentage of nitrogen components in the produced gas of this well, including:

[0017] After starting to inject nitrogen into the reservoir developed by nitrogen injection, regularly obtain produced gas samples from each production well;

[0018] Perform component determination on the taken gas samples to determine the molar percentage of iC4 + nC4 components and the molar percentage of nitrogen components therein. When taking the gas samples, measure the daily crude oil production of this production well at the same time.

[0019] In one embodiment, after starting to inject nitrogen into the reservoir developed by nitrogen injection, regularly obtain produced gas samples from each production well; the gas sampling position is the oil sample sampling port of the production tree of the production well.

[0020] In one embodiment, the gas sampling position is the oil sample sampling port of the production tree of the production well, and the separation pressure of the taken gas sample is controlled to be less than 0.1 MPa.

[0021] In one embodiment, use the proportional method to determine the daily production of nitrogen components in the produced gas of the production well, including:

[0022] Calculate the daily nitrogen production in the produced gas of the oil production well using formula (2), where formula (2) is:

[0023] Qn = Qoi * Xi * (Bi / Ai) (2)

[0024] In formula (2), Qn is the daily nitrogen production in the produced gas of the oil production well after nitrogen injection; Ai is the percentage content (mole percentage) of the iC4 + nC4 components in the produced gas of the oil production well after nitrogen injection; Bi is the percentage of the nitrogen component (mole percentage) after nitrogen injection; Qoi is the daily crude oil production (tons / day) after nitrogen injection; Xi is the production of the iC4 + nC4 components in the dissolved gas corresponding to the unit crude oil production of each well before nitrogen injection (cubic meters / ton).

[0025] In one embodiment, after determining the daily nitrogen component production in the produced gas of the oil production well by the proportional method, it further includes: determining the daily production of the produced gas of the oil production well by the proportional method.

[0026] In one embodiment, calculate the daily production of the produced gas of the oil production well through formula (3), where formula (3) is:

[0027] Qc = Qoi * Xi / Ai (3)

[0028] In formula (3), Qc is the daily production of the produced gas of the oil production well after nitrogen injection.

[0029] The advantages and beneficial effects of the present invention compared with the prior art are as follows:

[0030] In the reservoirs developed or exploited by nitrogen injection, the present invention has been applied to more than 40 oil production wells in the past three years, and the compliance between the determined gas production and nitrogen production of the oil production wells and the calibration of the oil and gas metering vehicle is over 90%. Currently, the application of nitrogen injection for enhanced oil recovery in oilfields is continuously expanding. The method of determining the nitrogen production of oil production wells in nitrogen-injected reservoirs using fluid components reduces the metering operation links and the workload of operators. This method has broad application prospects. Specific Embodiments

[0031] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer, the present invention will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0032] The present invention provides a method for determining the daily nitrogen production of oil production wells in nitrogen-injected reservoirs using fluid components, including:

[0033] Step S10, before injecting nitrogen into the reservoir, measure the daily crude oil production, daily dissolved gas production of each production well, and determine the percentage of iC4 + nC4 components in the dissolved gas;

[0034] Step S20, according to the daily crude oil production, daily dissolved gas production, and the percentage of iC4 + nC4 components in the dissolved gas of each production well before injecting nitrogen into the reservoir, calculate the production of iC4 + nC4 components in the dissolved gas corresponding to the unit crude oil production of each production well before nitrogen injection;

[0035] Step S30, after injecting nitrogen into the reservoir, regularly measure the daily crude oil production of the production well, and at the same time take samples to detect the percentage of iC4 + nC4 components and the percentage of nitrogen components in the produced gas of this well; use the proportional method to determine the daily production of nitrogen components in the produced gas of the production well.

[0036] When the bottom-hole flowing pressure during the production of the production well is controlled under the condition of being higher than the original saturation pressure of the formation crude oil, since the iC4 + nC4 components in the conventional crude oil dissolved gas are not affected by the nitrogen injection extraction effect, the amount of iC4 + nC4 components precipitated from the unit weight of produced crude oil remains unchanged. Before injecting nitrogen into the reservoir, measure the daily crude oil production and daily dissolved gas production of each production well, conduct component analysis on the produced dissolved gas, and determine the percentage of iC4 + nC4 components in the dissolved gas, so as to determine the relationship between the production of iC4 + nC4 components and the crude oil production; after injecting nitrogen into the reservoir, regularly measure the daily crude oil production of the production well, take samples of the produced gas for component analysis, determine the percentage of iC4 + nC4 components and the percentage of nitrogen components in the produced gas, and calculate the daily production of the produced gas of the production well and the daily production of nitrogen components therein by using the daily crude oil production of the production well, the percentage of iC4 + nC4 components in the produced gas, and the percentage of nitrogen components.

[0037] Using this method to determine the daily nitrogen production of the production well does not require the two steps of separating the gas-liquid mixture produced by the production well with a gas-liquid separation device and measuring the daily production of the gas separated from each production well with a measuring instrument; in the nitrogen injection development of the reservoir, the ground fixed equipment process can be simplified, and there is no need to build a gas-liquid separation and metering process for production wells, including but not limited to gas-liquid separators, pipelines and valve groups for controlling the gas-liquid mixture produced by each well to enter the gas-liquid separator respectively; the daily oil production can be measured by using the method of calculating the working conditions of the production equipment and the water cut analysis, and the daily nitrogen production can be regularly calibrated by using a mobile or other non-fixed oil and gas separation and metering equipment.

[0038] Furthermore, measuring the daily crude oil production, daily dissolved gas production of each production well, and determining the percentage of iC4 + nC4 components in the dissolved gas includes:

[0039] Before nitrogen injection for reservoir development, measure the daily crude oil production and the daily produced gas production of separated dissolved gas of each oil production well in the nitrogen injection control area; measure the molar percentage of iC4 + nC4 components in the produced dissolved gas sample.

[0040] Further, use mobile or other non-fixed oil and gas separation metering equipment to measure the daily crude oil production and the daily produced gas production of separated dissolved gas of each oil production well in the nitrogen injection control area. For example, use an oil and gas metering vehicle to measure the daily crude oil production and the daily produced gas production of separated dissolved gas of each oil production well in the nitrogen injection control area.

[0041] When measuring the daily crude oil production and the daily produced gas production of separated dissolved gas of each oil production well in the nitrogen injection control area, simultaneously sample the dissolved gas separated by the metering equipment and the dissolved gas at the crude oil sampling port of the Christmas tree. The separation pressure for sampling in both ways is controlled to be less than 0.1 MPa. For sampling the dissolved gas separated by the metering equipment, connect the gas sample bag to the separated gas sampling port of the equipment and sample in a sealed manner; for sampling the dissolved gas at the crude oil sampling port of the Christmas tree, use a sampling separator to connect to the crude oil sampling port of the oil production well Christmas tree, and connect the gas sample bag to the sampling port of the sampling separator and sample in a sealed manner. Measure the components of the gas samples taken in both ways respectively to determine the molar percentage of iC4 + nC4 components therein. The methods include but are not limited to chromatographic analysis. If the relative deviation of the percentage of each main component content of the two dissolved gas samples from the same well is less than 5%, the sampling test results can be used; the molar percentage of iC4 + nC4 components is selected as the test result of the gas sample taken from the crude oil sampling port of the Christmas tree.

[0042] Further, according to the daily crude oil production, the daily produced gas production, and the percentage of iC4 + nC4 components in the dissolved gas of each oil production well before nitrogen injection into the reservoir, calculate the production of iC4 + nC4 components in the dissolved gas corresponding to the unit crude oil production of each oil production well before nitrogen injection, including:

[0043] Use formula (1) to calculate the production of iC4 + nC4 components in the dissolved gas corresponding to the unit crude oil production of each well before nitrogen injection. The formula (1) is:

[0044] Xi = Qg * A / Qo (1)

[0045] In formula (1), Xi is the production of iC4 + nC4 components in the dissolved gas corresponding to the unit crude oil production of each well before nitrogen injection (m³ / t); Qo is the daily crude oil production of each oil production well before nitrogen injection (t / day); Qg is the daily produced gas production before nitrogen injection (m³ / day); A is the percentage of iC4 + nC4 components in the produced dissolved gas before nitrogen injection (mole percentage).

[0046] For each oil production well, before and after nitrogen injection into the reservoir, under the condition that the bottom-hole flowing pressure is controlled to be higher than the original saturation pressure of the formation crude oil during oil production, the proportional relationship Xi is a constant.

[0047] Furthermore, after nitrogen gas is injected into the reservoir, the daily crude oil production of the oil production well is regularly measured. Meanwhile, samples are taken to detect the percentages of iC4 + nC4 components and nitrogen components in the produced gas of this well, including:

[0048] After nitrogen gas injection into the reservoir for development starts, gas samples are regularly taken from each oil production well; the sampling location for the gas sample is the oil sample sampling port of the Christmas tree of the oil production well, and the separation pressure for taking the gas sample is controlled to be less than 0.1 MPa;

[0049] The sampling location for the gas sample is the oil sample sampling port of the Christmas tree of the oil production well. Closed sampling is carried out by connecting the sampling port through a sampling separation device to ensure the quality of the gas sample and avoid mixing with air;

[0050] Component determination is carried out on the taken gas sample to determine the molar percentage of iC4 + nC4 components and the molar percentage of nitrogen components therein. When taking the gas sample, the daily crude oil production of this oil production well is measured simultaneously.

[0051] When taking the gas sample, the daily crude oil production of this oil production well is measured simultaneously. The methods for measuring the daily crude oil production include but are not limited to methods such as measurement by a metering vehicle and calculation by a dynamometer card. The daily production of the oil-water mixture of this well is measured, the water content in the produced fluid is inspected, and the daily crude oil production of this well is calculated.

[0052] Furthermore, the daily production of nitrogen components in the produced gas of the oil production well is determined by the proportional method, including:

[0053] The daily production of nitrogen in the produced gas of this oil production well is calculated using formula (2), and the formula (2) is:

[0054] Qn = Qoi * Xi * (Bi / Ai) (2)

[0055] In formula (2), Qn is the daily production of nitrogen in the produced gas of this oil production well after nitrogen injection; Ai is the percentage (molar percentage) of iC4 + nC4 components in the produced gas of the oil production well after nitrogen injection; Bi is the percentage (molar percentage) of nitrogen components after nitrogen injection; Qoi is the daily crude oil production (tons / day) after nitrogen injection; Xi is the production of iC4 + nC4 components in the dissolved gas corresponding to the unit crude oil production of each well before nitrogen injection (cubic meters / ton).

[0056] Furthermore, after the daily production of nitrogen components in the produced gas of the oil production well is determined by the proportional method, it also includes:

[0057] The daily production of the produced gas of the oil production well is determined by the proportional method. The daily production of the produced gas of this oil production well is calculated using formula (3), and the formula (3) is:

[0058] Qc = Qoi * Xi / Ai (3)

[0059] In formula (3), Qc is the daily output of the produced gas from the oil production well after nitrogen injection.

[0060] Through an innovative method for determining the daily nitrogen output of an oil production well in a nitrogen-injected reservoir using fluid components, the two steps of separating the gas-liquid mixture produced by the oil production well using a gas-liquid separation device and measuring the daily output of the gas separated from each oil production well with a metering instrument are not required; during the oilfield production process, the metering operation links and related equipment are reduced, and the workload of the operators is reduced.

[0061] The present invention has been tested many times. Now, some test results are cited as a reference for further detailed description of the invention, and a detailed description will be given below in conjunction with specific embodiments.

[0062] Example 1

[0063] The method for determining the daily nitrogen output of an oil production well in a nitrogen-injected reservoir using fluid components adopts the following steps:

[0064] Step 1: Taking the XX-221 well as an example, before injecting nitrogen into the reservoir, measure the daily output of crude oil and dissolved gas of each oil production well, and determine the percentage of iC4 + nC4 components in the dissolved gas.

[0065] Before the reservoir is developed by nitrogen injection, on December 5, 2021, the oil and gas metering vehicle measured the daily output of crude oil of XX-221 to be 12.5 (tons), and the daily output of dissolved gas to be 101.3 (cubic meters).

[0066] Take samples of the dissolved gas separated by the metering vehicle. Connect the gas sample bag to the gas sampling port of the equipment for airtight sampling of 0.5 liters; take samples of the dissolved gas at the crude oil sampling port of the Christmas tree of the XX-221 well. Connect the sampling separator to the crude oil sampling port of the oil production well Christmas tree, and connect the gas sample bag to the sampling port of the sampling separator for airtight sampling of 0.5 liters.

[0067] Use a chromatographic analyzer to determine the component content of the gas samples taken in the two ways respectively, and determine the molar percentage of the iC4 + nC4 component content. The results are as follows in the table;

[0068] Component content table of two dissolved gas samples of XX-221 well on December 5, 2021 (molar percentage)

[0069]

[0070] The relative deviation of the content percentage of each main component in the two dissolved gas samples is less than 5%, and the sampling and detection results are available; the molar percentage of the iC4 + nC4 component content selects the detection result of 3.34% of the gas sample taken from the crude oil sampling port of the Christmas tree.

[0071] Step 2: Before injecting nitrogen into the reservoir, calculate the production of iC4 + nC4 components in the dissolved gas corresponding to the unit crude oil production of each oil production well based on the daily crude oil production, daily dissolved gas production, and the percentage of iC4 + nC4 components in the dissolved gas of each oil production well.

[0072] The daily crude oil production of each oil production well described in Step 1 is 12.5 (tons), the daily dissolved gas production is 101.3 (cubic meters), and the content of iC4 + nC4 components in the dissolved gas is 3.34 (mol%). Substitute these values into formula (1):

[0073] Xi = Qg * A / Qo

[0074] = 101.3 * 3.34% / 12.5

[0075] = 0.2707 (cubic meters per ton)

[0076] Step 3: After injecting nitrogen into the reservoir, regularly measure the daily crude oil production of the oil production well, and at the same time, take samples to detect the percentage of iC4 + nC4 components and the percentage of nitrogen components in the produced gas of this well.

[0077] Among them, on March 31, 2023, the component determination of the taken gas sample was carried out using a gas chromatograph, and the results are as follows in the table:

[0078] Component Content Table of the Produced Gas Sample of Well XX - 221 on March 31, 2023 (mol%)

[0079] Sampling point <![CDATA[O 2 > <![CDATA[N 2 > <![CDATA[CO 2 > <![CDATA[C 1 > <![CDATA[C 2 > <![CDATA[C 3 > <![CDATA[iC 4 > <![CDATA[nC 4 > <![CDATA[iC 5 > <![CDATA[nC 5 > <![CDATA[C 6 > <![CDATA[C 7 > <![CDATA[C 8 > <![CDATA[C 9 > <![CDATA[C 10 > iC4 + nC4 Christmas tree 0.008 64.31 0.035 24.76 3.364 3.662 0.691 1.503 0.804 0.486 0.313 0.064 0 0 0 2.194

[0080] Determine that the molar percentage of iC4 + nC4 components content is 2.194, and the molar percentage of nitrogen component content is 64.310. When taking the gas sample, the daily production of the oil - water mixture of Well XX - 221 was measured using the dynamometer card method, which is 14.1 tons. After checking that the water content in the produced fluid is 0, calculate that the daily crude oil production of this well is 14.1 tons.

[0081] Step 4: Use the proportional method to determine the daily production of nitrogen components in the produced gas of the oil production well.

[0082] The percentage of iC4 + nC4 components content in the component - analyzed gas sample is 2.194 (mol%), and the percentage of nitrogen component content is 64.310 (mol%). The simultaneously measured daily crude oil production of this well is 14.1 tons. The proportional relationship Xi of the production of iC4 + nC4 components per unit weight of crude oil produced from Well XX - 221 is 0.2707 (cubic meters per ton). Substitute these values into formula (2):

[0083] Qn = Qoi * Xi * (Bi / Ai)

[0084] = 14.1 * 0.2707 * (64.310% / 2.194%)

[0085] = 111.897 (m³ / day)

[0086] Step Five: Determine the daily gas production of the oil production well by the proportional method.

[0087] Substitute into formula (3):

[0088] Qc = Qoi * Xi / Ai

[0089] = 4.1 * 0.2707 / 2.194%

[0090] = 173.697 (m³ / day).

[0091] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. Method for determining daily nitrogen production of oil production wells in a nitrogen-injected reservoir using fluid components, characterized in that, it includes: Before injecting nitrogen into the reservoir, measure the daily crude oil production, daily dissolved gas production of each oil production well, and determine the percentage of iC4 + nC4 components in the dissolved gas; According to the daily crude oil production, daily dissolved gas production, and the percentage of iC4 + nC4 components in the dissolved gas of each oil production well before injecting nitrogen into the reservoir, calculate the production of iC4 + nC4 components in the dissolved gas corresponding to the unit crude oil production of each oil production well before injecting nitrogen; After injecting nitrogen into the reservoir, regularly measure the daily crude oil production of the oil production well, and at the same time take samples to detect the percentage of iC4 + nC4 components and the percentage of nitrogen components in the produced gas of this well; use the proportional method to determine the daily production of nitrogen components in the produced gas of the oil production well.

2. The method for determining the daily nitrogen production of an oil production well in a nitrogen-injected reservoir using fluid components according to claim 1, characterized in that, Measuring the daily crude oil production, daily dissolved gas production of each oil production well, and determining the percentage of iC4 + nC4 components in the dissolved gas includes: Before the reservoir is developed by injecting nitrogen, measure the daily crude oil production and the daily separated dissolved gas production of each oil production well in the nitrogen injection control area; determine the molar percentage of iC4 + nC4 components in the simultaneously produced dissolved gas sample.

3. The method for determining the daily nitrogen production of an oil production well in a nitrogen-injected reservoir using fluid components according to claim 2, characterized in that, Use mobile or other non-fixed oil and gas separation metering equipment to measure the daily crude oil production and the daily separated dissolved gas production of each oil production well in the nitrogen injection control area.

4. The method for determining the daily nitrogen production of an oil production well in a nitrogen-injected reservoir using fluid components according to claim 1, characterized in that, According to the daily crude oil production, daily dissolved gas production, and the percentage of iC4 + nC4 components in the dissolved gas of each oil production well before injecting nitrogen into the reservoir, calculating the production of iC4 + nC4 components in the dissolved gas corresponding to the unit crude oil production of each oil production well before injecting nitrogen includes: Use formula (1) to calculate the production of iC4 + nC4 components in the dissolved gas corresponding to the unit crude oil production of each well before injecting nitrogen, and the formula (1) is: Xi = Qg * A / Qo (1) In formula (1), Xi is the production of iC4 + nC4 components in the dissolved gas corresponding to the unit crude oil production of each well before injecting nitrogen (m³ / t); Qo is the daily crude oil production of each oil production well before injecting nitrogen (t / day); Qg is the daily dissolved gas production before injecting nitrogen (m³ / day); A is the percentage of iC4 + nC4 components in the produced dissolved gas before injecting nitrogen (mole percentage).

5. The method for determining the daily nitrogen production of an oil production well in a nitrogen-injected reservoir using fluid components according to claim 1, characterized in that, After injecting nitrogen into the reservoir, regularly measure the daily crude oil production of the oil production well, and at the same time take samples to detect the percentage of iC4 + nC4 components and the percentage of nitrogen components in the produced gas of this well, including: After the reservoir injected with nitrogen starts to inject nitrogen, each oil production well regularly obtains the produced gas sample; Perform component determination on the taken gas sample to determine the molar percentage of the iC4 + nC4 component and the molar percentage of the nitrogen component therein. When taking the gas sample, measure the daily crude oil production of this oil production well simultaneously.

6. The method for determining the daily nitrogen production of an oil production well in a nitrogen-injected reservoir by using fluid components according to claim 5, characterized in that, after the nitrogen injection starts in the reservoir developed by nitrogen injection, each oil production well regularly takes the produced gas sample; the gas sampling position is the oil sample sampling port of the Christmas tree of the oil production well.

7. The method for determining the daily nitrogen production of an oil production well in a nitrogen-injected reservoir by using fluid components according to claim 6, characterized in that, the gas sampling position is the oil sample sampling port of the Christmas tree of the oil production well, and the separation pressure of the taken gas sample is controlled to be less than 0.1 MPa.

8. The method for determining the daily nitrogen production of an oil production well in a nitrogen-injected reservoir by using fluid components according to claim 5, characterized in that, use the proportional method to determine the daily production of the nitrogen component in the produced gas of the oil production well, including: calculate the daily production of nitrogen in the produced gas of this oil production well by using formula (2), and the formula (2) is: Qn = Qoi * Xi * (Bi / Ai) (2) In formula (2), Qn is the daily production of nitrogen in the produced gas of this oil production well after nitrogen injection; Ai is the percentage content (molar percentage) of the iC4 + nC4 component in the produced gas of the oil production well after nitrogen injection; Bi is the percentage of the nitrogen component (molar percentage) after nitrogen injection; Qoi is the daily crude oil production (tons / day) after nitrogen injection; Xi is the production of the iC4 + nC4 component in the dissolved gas corresponding to the unit crude oil production of each well before nitrogen injection (cubic meters / ton).

9. The method for determining the daily nitrogen production of an oil production well in a nitrogen-injected reservoir by using fluid components according to claim 8, characterized in that, after using the proportional method to determine the daily production of the nitrogen component in the produced gas of the oil production well, it further includes: using the proportional method to determine the daily production of the produced gas of the oil production well.

10. The method for determining the daily nitrogen production of an oil production well in a nitrogen-injected reservoir by using fluid components according to claim 9, characterized in that, calculate the daily production of the produced gas of this oil production well by using formula (3), and the formula (3) is: Qc = Qoi * Xi / Ai (3) In formula (3), Qc is the daily production of the produced gas of the oil production well after nitrogen injection.

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