A method for identifying a late-stage gas filling proportion

Abstract

The present application belongs to the technical field of oil exploration, and relates to a method for identifying late-stage natural gas charging proportion. The method comprises the following steps: calculating a crude oil conversion rate; calculating a calculated value of a gas-oil ratio of a reservoir; establishing a corresponding relationship between the sum of the absolute concentrations of 3-methyl durene and 4-methyl durene and a measured value of the gas-oil ratio of the reservoir; taking the sum of the angle concentrations as a benchmark, adjusting the calculated value of the gas-oil ratio of the reservoir, so that the late-stage natural gas proportion is 0-99%, and obtaining a late-stage natural gas charging proportion identification chart; detecting the sum of the absolute concentrations of 3-methyl durene and 4-methyl durene in the crude oil to be evaluated; and based on the sum of the absolute concentrations and the measured value of the gas-oil ratio of the reservoir, according to the late-stage natural gas charging proportion identification chart, the identification of the late-stage natural gas charging proportion in the oil and gas reservoir to be evaluated is realized. The method is fast, intuitive and easy to operate, and improves the speed and accuracy of the identification of the late-stage natural gas charging proportion.

Description

Technical Field

[0001] This invention belongs to the field of petroleum exploration technology and relates to a method for identifying the late-stage natural gas charging ratio. Background Technology

[0002] With the development of the global petroleum industry, oil and gas exploration is gradually transitioning towards deep and ultra-deep reservoirs. Deep and ultra-deep reservoirs differ significantly from medium and shallow reservoirs. The phase structure of deep oil and gas has become a focus of attention for scholars both domestically and internationally. This issue not only affects oil and gas migration patterns and accumulation mechanisms but also relates to the direction of oil and gas exploration in deep reservoirs. Most deep and ultra-deep oil and gas reservoirs undergo two or more phases of oil and gas charging, with late-stage natural gas charging having a significant impact on the final accumulation state and production of the reservoir.

[0003] Typically, the proportion of natural gas charging can be analyzed based on modeling techniques such as hydrocarbon accumulation simulation. For example, Zhang Xiaoju, Deng Hucheng, Fu Meiyan, and others published "Distribution Characteristics and Semi-Quantitative Evaluation of Natural Gas in Low-Abundance Tight Sandstones—Taking the Upper Paleozoic in Dingbei Area of ​​the Ordos Basin as an Example" in Natural Gas Industry. Based on core, well logging, seismic, and production dynamic data, they clarified the distribution characteristics of natural gas, determined the natural gas charging mode by comprehensively considering the spatial combination relationship of source rocks, sand bodies, and fault distribution, and then determined the dominant charging path based on the charging point, charging power, and resistance. Finally, they conducted an evaluation of gas and water distribution under different charging paths. Han Xiaoqin, Fang Tao, Cao Jun, and others published "Simulation Experiment of Natural Gas Charging in Tight Sandstone Reservoirs of Shanxi Formation in Yan'an Gas Field, Ordos Basin and Variation Law of Gas-Bearing Properties" in *Natural Gas Geoscience*. They selected 12 sandstone samples from the Shanxi Formation in the Yan'an Gas Field of the Ordos Basin, classified them into three categories based on lithology, physical properties, and pore type, and conducted natural gas charging simulation experiments under different permeabilities, charging velocities, and charging pressure differentials. However, the above methods are typically applied to mature exploration blocks, providing a comprehensive and accurate understanding of the region's source, reservoir, caprock, spheroid, migration, and conservation ecosystems. Furthermore, the modeling process is complex, time-consuming, and economically costly, requiring experienced researchers. More importantly, the results are influenced by numerous factors and have low accuracy.

[0004] Therefore, how to provide a fast, easy-to-operate, and highly accurate method for identifying the proportion of late-stage natural gas charging is an urgent problem to be solved. Summary of the Invention

[0005] The purpose of this invention is to provide a method for identifying the proportion of late-stage natural gas charging. This method is fast, intuitive, and easy to operate, and can improve the speed and accuracy of identifying the proportion of late-stage natural gas charging.

[0006] The above-mentioned objective of this invention is achieved through the following technical solution:

[0007] The first aspect of this invention provides a method for identifying the proportion of late-stage natural gas charging, comprising the following steps:

[0008] Step S1: Calculate the crude oil conversion rate based on the absolute concentrations of 3-methyldiadamantane and 4-methyldiadamantane in the crude oil;

[0009] Step S2: Calculate the reservoir gas-oil ratio based on the crude oil conversion rate;

[0010] Step S3: Establish the correspondence between the sum of the absolute concentrations of 3-methyldiadamantane and 4-methyldiadamantane as the x-axis and the measured gas-oil ratio of the reservoir as the y-axis.

[0011] Step S4: Based on the sum of the absolute concentrations of 3-methyldiadamantane and 4-methyldiadamantane, adjust the calculated gas-oil ratio of the reservoir to make the late-stage natural gas ratio 0-99%, and obtain the late-stage natural gas charging ratio identification chart.

[0012] Step S5: Detect the sum of the absolute concentrations of 3-methyldiadamantane and 4-methyldiadamantane in the crude oil to be evaluated;

[0013] Step S6: Based on the sum of the absolute concentrations of 3-methyldiadamantane and 4-methyldiadamantane and the measured gas-oil ratio of the reservoir, the late-stage natural gas charging ratio of the reservoir to be evaluated is identified using the late-stage natural gas charging ratio identification chart.

[0014] In step S1, the absolute concentrations of 3-methyladiadamantane and 4-methyladiadamantane are the measured concentrations of 3-methyladiadamantane and 4-methyladiadamantane, respectively; the formula for calculating the crude oil conversion rate is: f(%)

[0015] =[1-C 基线 / (C 3-MD +C 4-MD )]×100, where f is the crude oil conversion rate, C 3-MD The measured concentration of 3-methyldiadamantane, C 4-MD The measured concentration of 4-methyldiadamantane; C 基线 The concentration is the baseline.

[0016] The baseline concentration was 20 ug / g.

[0017] In step S2, the formula for calculating the reservoir gas-oil ratio is: f = GOR / [GOR + (7.98 × 10⁻⁶) / 2] 5 [(crude oil density × average molecular weight of crude oil) × 100], where f is the crude oil conversion rate, in units of ft. 3 / bbl.

[0018] Preferably, step S4 specifically involves: using the sum of the absolute concentrations of 3-methyldiadamantane and 4-methyldiadamantane as a benchmark, adjusting the calculated gas-oil ratio of the reservoir so that the late-stage natural gas charging percentages are 0%, 20%, 40%, 60%, 80%, 90%, and 99%, respectively, to obtain a late-stage natural gas charging percentage identification chart.

[0019] The formula for calculating the natural gas injection ratio is: [(Measured value of reservoir gas-oil ratio - Calculated value of reservoir gas-oil ratio) / Measured value of reservoir gas-oil ratio] × 100.

[0020] Preferably, in step S5, gas chromatography-mass spectrometry is used to detect the sum of the absolute concentrations of 3-methyldiadamantane and 4-methyldiadamantane in the crude oil to be evaluated.

[0021] Preferably, the following processing steps are included before gas chromatography-mass spectrometry analysis and detection: weigh the crude oil sample, dilute it with dichloromethane, and add D... 16 - Monoadamantane was used as an internal standard.

[0022] Preferably, the following processing steps are included before gas chromatography-mass spectrometry analysis: Weigh 15-25 mg of crude oil sample, dilute with 0.15-0.25 mL of dichloromethane, and add 5-15 μg of D... 16 - Monoadamantane was used as an internal standard.

[0023] More preferably, the following processing steps are included before gas chromatography-mass spectrometry analysis and detection: Weigh 20 mg of crude oil sample, dilute with 0.2 mL of dichloromethane, and add 10 μg of D... 16 - Monoadamantane was used as an internal standard.

[0024] Preferably, the gas chromatography-mass spectrometry analysis conditions are as follows: the initial temperature is 50°C, the temperature is increased to 250°C at a rate of 3°C / min, then increased to 310°C at a rate of 20°C / min, and finally held at 310°C for 10 min.

[0025] Preferably, in step S5, the specific method for detecting the absolute concentrations of 3-methyladiadamantane and 4-methyladiadamantane in the crude oil to be evaluated is as follows: Manual integration is performed on the compound analysis software, ion chromatograms are extracted, ion 187 is input, 3-methyladiadamantane and 4-methyladiadamantane are identified and characterized, and the peak areas of 3-methyladiadamantane and 4-methyladiadamantane are calculated by manual integration. The absolute concentrations of 3-methyladiadamantane and 4-methyladiadamantane, as well as the sum of their absolute concentrations, are calculated based on the internal standard concentration.

[0026] The measured gas-oil ratio in an oil reservoir refers to the volume (in cubic meters) of natural gas carried out with each ton of crude oil produced during oil well production, when oil and gas are discharged simultaneously from the well.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] This invention provides a rapid, intuitive, and easy-to-operate method for identifying the proportion of late-stage natural gas charging in oil and gas reservoirs, which greatly improves the accuracy of identifying the proportion of late-stage natural gas and the genetic mechanism of oil and gas reservoirs. Attached Figure Description

[0029] Figure 1 The image shows the identification and characterization of 3-methyldiadamantane and 4-methyldiadamantane in crude oil samples from the Shunbei area in Example 1.

[0030] Figure 2 This is a distribution characteristic diagram of the sum of the absolute concentrations of 3-methyldiadamantane and 4-methyldiadamantane in the crude oil sample from the Shunbei area in Example 1, intersected with the measured values ​​of the reservoir gas-oil ratio.

[0031] Figure 3 A late-stage natural gas charge percentage identification chart constructed for Example 1;

[0032] Figure 4 For the 7 samples in Example 1 Figure 3 The identification results are shown in the late-stage natural gas injection ratio identification chart. Detailed Implementation

[0033] The following non-limiting embodiments are intended to enable those skilled in the art to gain a more comprehensive understanding of the present invention, but do not limit the invention in any way. The following description is merely an exemplary illustration of the scope of protection of the present invention, and those skilled in the art can make various changes and modifications to the invention based on the disclosed content, which should also fall within the scope of protection of the present invention.

[0034] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. In addition to the specific methods, apparatus, and materials used in the embodiments, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description of this invention, any prior art methods, apparatus, and materials similar to or equivalent to those described, apparatus, and materials in the embodiments of this invention may be used to implement the present invention.

[0035] The present invention will be further described below by way of specific embodiments. Unless otherwise specified, all chemical reagents used in the embodiments of the present invention are obtained through conventional commercial means.

[0036] Example 1

[0037] The late-stage natural gas charging ratio was determined for seven crude oil samples from the Shunbei area, including the following steps:

[0038] Step S1: Calculate the crude oil conversion rate based on the absolute concentrations of 3-methyladiadamantane and 4-methyladiadamantane in the crude oil; the absolute concentrations of 3-methyladiadamantane and 4-methyladiadamantane are the measured concentrations of 3-methyladiadamantane and 4-methyladiadamantane, respectively; the formula for calculating the crude oil conversion rate is: f(%) = [1-C 基线 / (C 3-MD +C 4-MD )]×100, where f is the crude oil conversion rate, C 3-MD The measured concentration of 3-methyldiadamantane, C 4-MD The measured concentration of 4-methyldiadamantane; C 基线 The concentration is the baseline.

[0039] In this embodiment, C1 3-MD It is 52.55 ug / g, C1 4-MD It is 26.59 ug / g, C 基线 It was 20 ug / g, and f1 was 74.72%;

[0040] C2 3-MD It is 32.93 ug / g, C2 4-MD It was 71.33 ug / g, C 基线 It is 20ug / g, and f2 is 80.82%;

[0041] C3 3-MD It is 13.72 ug / g, C3 4-MD It is 26.70 ug / g, C 基线 It was 20 ug / g, and f3 was 50.51%;

[0042] C4 3-MD It is 13.97 ug / g, C4 4-MD It is 36.76 ug / g, C 基线 It was 20 ug / g, and f4 was 60.58%;

[0043] C5 3-MD It is 4.42 ug / g, C5 4-MD It is 6.35 ug / g, C 基线 It is 20ug / g, and f5 is 0.00%;

[0044] C6 3-MD It is 39.35 ug / g, C6 4-MD It was 83.04 ug / g, C 基线 It was 20 ug / g, and f6 was 83.66%;

[0045] C7 3-MD It is 18.29 ug / g, C7 4-MD It is 36.81 ug / g, C 基线 It was 20ug / g, and f7 was 63.71%;

[0046] Step S2: Calculate the reservoir gas-oil ratio based on the series of oil and gas conversion rates obtained above. The formula for calculating the reservoir gas-oil ratio is: f = GOR / [GOR + (7.98 × 10⁻⁶) / 2] 5 [(f × crude oil density × average molecular weight of crude oil) × 100], where f is the crude oil conversion rate; GOR is the calculated gas-oil ratio of the reservoir, in units of...

[0047] ft 3 / bbl; In this embodiment, the oil density is based on the average density of crude oil from the Shunbei region, which is 0.78 g / cm³. 3 The average molecular weight of crude oil is 166.82 g / mol;

[0048] f = [1-C 基线 / (C 3-MD +C 4-MD Substituting 100 into the above formula, and converting the unit of f to m... 3 / m 3 The formula for calculating the gas-oil ratio of the reservoir is GOR = 664.11 × [(C 3-MD +C 4-MD )-20)] / 20, where C 3-MD The measured concentration of 3-methyldiadamantane, C 4-MD The measured concentration of 4-methyldiadamantane; GOR is the calculated gas-oil ratio of the reservoir, in m³. 3 / m 3 (When the conversion rate is 0.00%, the calculated GOR is 0m.) 3 / m 3 )

[0049] The calculated GOR value, GOR1 is 1964m. 3 / m 3 GOR2 is 2798m 3 / m 3 GOR3 is 678m 3 / m 3 GOR4 is 1021m 3 / m 3 GOR5 is 0m 3 / m 3 GOR6 is 3400m 3 / m 3 GOR7 is 1166m 3 / m3 .

[0050] Step S3: Using the sum of the absolute concentrations of 3-methyldiadamantane and 4-methyldiadamantane as the x-axis and the measured gas-oil ratio of the reservoir as the y-axis, establish the correspondence between the two. The distribution characteristics of crude oil samples from the Shunbei area in the intersection of the sum of the absolute concentrations of 3-methyldiadamantane and 4-methyldiadamantane and the measured gas-oil ratio of the reservoir are shown in the following figure. Figure 2 As shown;

[0051] Step S4: Using the sum of the absolute concentrations of 3-methyldiadamantane and 4-methyldiadamantane as a benchmark, adjust the calculated gas-oil ratio of the reservoir to achieve late-stage natural gas charging percentages of 0%, 20%, 40%, 60%, 80%, 90%, and 99%, respectively. The formula for calculating the natural gas charging percentage is: [(Measured gas-oil ratio of the reservoir - Calculated gas-oil ratio of the reservoir) / Measured gas-oil ratio of the reservoir] × 100; obtain the late-stage natural gas charging percentage identification chart; the results are as follows. Figure 3 As shown;

[0052] Step S5: Weigh 20 mg of each of the 7 selected crude oil samples, dilute with 0.2 mL of dichloromethane, and add 10 μg of D... 16 - Monoadamantane was used as an internal standard;

[0053] The processed sample was transferred into a sample vial and analyzed by gas chromatography-mass spectrometry.

[0054] Gas chromatography-mass spectrometry analysis conditions: initial temperature 50℃, increased to 250℃ at a rate of 3℃ / min, then increased to 310℃ at a rate of 20℃ / min, and finally held at 310℃ for 10 min.

[0055] Manual integration was performed on the compound analysis software (MSD ChemStation) to extract ion chromatograms. Ion 187 was input to identify and distinguish 3-methyldiadamantane and 4-methyldiadamantane. The results are as follows: Figure 1 As shown, the peak areas of 3-methyldiadamantane and 4-methyldiadamantane were calculated by manual integration, and the absolute concentrations of 3-methyldiadamantane and 4-methyldiadamantane were calculated based on the internal standard concentration.

[0056] The sum of the absolute concentrations of 3-methyldiadamantane and 4-methyldiadamantane in seven crude oil samples was calculated. In this example, the concentrations were as follows: Sample 1 from the Shunbei No. 4 fault zone was 79.14 ug / g; Sample 2 from the Shunbei No. 4 fault zone was 104.26 ug / g; Sample 3 from the Shunbei No. 4 fault zone was 40.41 ug / g; Sample 6 from the Shunbei No. 6 fault zone was 50.73 ug / g; Sample 7 from the Shunbei No. 7 fault zone was 10.77 ug / g; Sample 8 from the Shunbei No. 8 fault zone was 122.39 ug / g; and Sample 2 from the Shunbei No. 2 fault zone was 55.10 ug / g. The corresponding measured gas-oil ratios in the reservoir were 3427 m³ / g and 3427 m³ / g, respectively. 3 / m 3 3841m 3 / m 3 495.93m 3 / m 3 1738m 3 / m 3 96m 3 / m 3 6627m 3 / m 3 3022m 3 / m 3 .

[0057] Step S6: Combine the sum of the absolute concentrations of 3-methyldiadamantane and 4-methyldiadamantane in the 7 crude oil samples with the measured gas-oil ratio data from the reservoir, and then... Figure 3 The late-stage natural gas charging ratio was identified using a chart, and the proportion of late-stage natural gas charging in the Shunbei oil and gas reservoirs was determined. The results are as follows: Figure 4 As shown.

[0058] The results show that the method of the present invention can quickly identify the proportion of natural gas injected in the middle and late stages of oil and gas reservoirs, and the results are highly accurate and can be widely promoted.

[0059] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A method for determining the proportion of late-stage natural gas charging, characterized in that, Includes the following steps: Step S1: Calculate the crude oil conversion rate based on the absolute concentrations of 3-methyldiadamantane and 4-methyldiadamantane in the crude oil; Step S2: Calculate the reservoir gas-oil ratio based on the crude oil conversion rate; Step S3: Establish the correspondence between the sum of the absolute concentrations of 3-methyldiadamantane and 4-methyldiadamantane as the x-axis and the measured gas-oil ratio of the reservoir as the y-axis. Step S4: Based on the sum of the absolute concentrations of 3-methyldiadamantane and 4-methyldiadamantane, adjust the calculated gas-oil ratio of the reservoir to make the late-stage natural gas ratio 0-99%, and obtain the late-stage natural gas charging ratio identification chart. Step S5: Detect the sum of the absolute concentrations of 3-methyldiadamantane and 4-methyldiadamantane in the crude oil to be evaluated; Step S6: Based on the sum of the absolute concentrations of 3-methyldiadamantane and 4-methyldiadamantane and the measured gas-oil ratio of the reservoir, the late-stage natural gas charging ratio of the reservoir to be evaluated is identified using the late-stage natural gas charging ratio identification chart.

2. The method according to claim 1, characterized in that, In step S1, the formula for calculating the crude oil conversion rate is: f = [1-C 基线 / (C 3-MD +C 4-MD )]×100, where f is the crude oil conversion rate, C 3-MD The measured concentration of 3-methyldiadamantane, C 4-MD The measured concentration of 4-methyldiadamantane; C 基线 The concentration is the baseline.

3. The method according to claim 1, characterized in that, In step S2, the formula for calculating the reservoir gas-oil ratio is: f = GOR / [GOR + (7.98 × 10⁻⁶) / 2] 5 [(crude oil density × average molecular weight of crude oil) × 100], where f is the crude oil conversion rate, in units of ft. 3 / bbl.

4. The method according to claim 1, characterized in that, Step S4 specifically involves adjusting the calculated gas-oil ratio of the reservoir based on the sum of the absolute concentrations of 3-methyldiadamantane and 4-methyldiadamantane, so that the late-stage natural gas charging ratios are 0%, 20%, 40%, 60%, 80%, 90%, and 99%, respectively, to obtain the late-stage natural gas charging ratio identification chart.

5. The method according to claim 1, characterized in that, In step S5, gas chromatography-mass spectrometry is used to detect the sum of the absolute concentrations of 3-methyldiadamantane and 4-methyldiadamantane in the crude oil to be evaluated.

6. The method according to claim 5, characterized in that, The following pretreatment steps are included before gas chromatography-mass spectrometry analysis: Weigh the crude oil sample, dilute it with dichloromethane, and add D... 16 - Monoadamantane was used as an internal standard.

7. The method according to claim 6, characterized in that, Before gas chromatography-mass spectrometry (GC-MS) analysis, the following pretreatment steps are included: Weigh 15-25 mg of crude oil sample, dilute with 0.15-0.25 mL of dichloromethane, and add 5-15 μg of D... 16 - Monoadamantane was used as an internal standard.

8. The method according to claim 7, characterized in that, Before gas chromatography-mass spectrometry (GC-MS) analysis, the following pretreatment steps are included: Weigh 20 mg of crude oil sample, dilute with 0.2 mL of dichloromethane, and add 10 μg of D... 16 - Monoadamantane was used as an internal standard.

9. The method according to claim 8, characterized in that, Gas chromatography-mass spectrometry analysis conditions: initial temperature 50℃, increased to 250℃ at a rate of 3℃ / min, then increased to 310℃ at a rate of 20℃ / min, and finally held at 310℃ for 10 min.

10. The method according to claim 9, characterized in that, In step S5, the specific method for detecting the sum of the absolute concentrations of 3-methyladiadamantane and 4-methyladiadamantane in the crude oil to be evaluated is as follows: Manual integration is performed on the compound analysis software, ion chromatograms are extracted, ion 187 is input, 3-methyladiadamantane and 4-methyladiadamantane are identified and characterized, and the peak areas of 3-methyladiadamantane and 4-methyladiadamantane are calculated by manual integration. The absolute concentrations of 3-methyladiadamantane and 4-methyladiadamantane, as well as the sum of their absolute concentrations, are calculated based on the internal standard concentration.

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