A comprehensive evaluation method for gas source tracing

Abstract

The present invention discloses a comprehensive evaluation method for gas source tracing, comprising the following steps: S1: based on the inheritance effect of mantle-derived volatiles of rare gas isotopes, using 40 Ar / 36 Ar‑ 3 He / 4 He correlation diagram is used to judge whether there is deep foreign material intervention in natural gas; S2: after eliminating the mixing of mantle source, based on the parent material inheritance of hydrocarbon carbon and hydrogen isotopes and thermodynamic fractionation effect, the ln(C1 / C2)-ln(C2 / C3) correlation diagram, δ 13 The C1-δD1 correlation diagram comprehensively determines natural gas maturity, parent material type, and sedimentary environment. S3: Utilizing gas-gas correlation, reservoir asphalt-source rock correlation, reservoir formation event configuration, and rare gas chronology, a comprehensive geochemical tracing system is established that interconnects and mutually supports each other. This invention facilitates a more precise and comprehensive exploration of the patterns of gas reservoir formation and distribution across time and space, providing important theoretical foundations and technical support for the exploration and development of typical gas fields.

Description

Technical Field

[0001] The present invention relates to the field of gas source tracing synthesis, in particular to a gas source tracing comprehensive evaluation method. Background Art

[0002] The world's energy landscape is entering a new phase of development, transitioning from solid (wood and coal) and liquid (petroleum) to gas (natural gas), driven by low-carbon, diversified, and clean energy. In this era of addressing global climate change and vigorously developing low-carbon energy, natural gas has become an indispensable bridge in the transition to clean energy and will play an irreplaceable role. Therefore, there is an urgent need to increase natural gas exploration efforts, promote technological innovation and integration, strengthen basic research on complex gas reservoirs, and continuously tackle key technological challenges.

[0003] Extensive oil and gas exploration practice has demonstrated a close relationship between the distribution of discovered large and medium-sized gas fields and source rocks, with oil and gas accumulation primarily occurring near source rock kitchens, a phenomenon known as "source control." Therefore, uncovering the genesis of natural gas and clarifying its source conditions provide a crucial foundation for studying its accumulation mechanisms and reservoir dynamics. However, in recent years, oil and gas exploration has gradually expanded from conventional to unconventional, from shallow to deep, and from onshore to offshore, resulting in increasingly complex source conditions. Using only a single geochemical indicator often leads to multiple interpretations and one-sided results. Therefore, it is imperative to establish a comprehensive, interconnected and mutually reinforcing geochemical tracing system. This will facilitate a more precise and comprehensive exploration of the patterns of gas reservoir formation and distribution across time and space, thereby providing a crucial theoretical basis and technical support for the exploration and development of representative gas fields. Summary of the Invention

[0004] In order to solve the problems existing in the prior art, the present invention provides a comprehensive evaluation method for gas source tracing. The present invention urgently needs to establish a comprehensive geochemical tracing system that is interconnected and mutually reflected, which will help to explore the laws of gas reservoir formation and distribution more accurately and comprehensively in time and space, thereby providing important theoretical basis and technical support for the exploration and development of typical gas fields.

[0005] The technical solutions of the present invention are as follows:

[0006] A comprehensive evaluation method for gas source tracing includes the following steps:

[0007] S1: Based on the inheritance effect of mantle-derived volatiles from noble gas isotopes, using 40 Ar / 36 Ar- 3 He / 4 The He correlation diagram is used to determine whether the natural gas has the involvement of deep foreign materials;

[0008] S2: After removing the mixing of mantle sources, based on the parent material inheritance of hydrocarbon carbon and hydrogen isotopes and the thermodynamic fractionation effect, the ln(C1 / C2)-ln(C2 / C3) correlation diagram, δ 13 The C1-δD1 correlation diagram comprehensively judges the natural gas maturity, parent material type and depositional environment;

[0009] S3: Use natural gas stable isotope indicators to compare natural gas from various producing layers in the study area, identify their similarities and differences, and reveal potential source rocks for natural gas;

[0010] S4: If the result of S2 is crude oil cracking gas, based on the organic molecular inheritance effect of biomarker compounds, the reservoir asphalt-source rock ααα20R-C 27 、C 28 、C 29 In contrast, reservoir bitumen is used as a medium to indirectly reveal the potential source rocks of natural gas;

[0011] S5: Using the basin simulation software BasinMod 1D, we simulated the hydrocarbon generation and expulsion history of the potential source rocks mentioned above. Combining the structural characteristics and source-reservoir-caprock assemblage of the study area, we established the coupling relationship and spatiotemporal configuration of key natural gas reservoir-forming events from a geological macroscopic perspective, further confirming the above viewpoints.

[0012] S6: Based on the cumulative effect of the age of noble gas isotopes and the research results of S3 to S5, the age of the natural gas source rock is calculated;

[0013] S7: Compare the calculated results with the geological age of potential source rocks to quantitatively identify the natural gas source in the study area.

[0014] Preferably, the identification result of S2 is oil-type gas, which is calculated using the following formula:

[0015] T=5301gA-1323(Ma)

[0016] Where: T is the age of source rock formation, Ma; A is the oil-type gas 40 Ar / 36 Ar ratio.

[0017] Preferably, the identification result of S2 is coal-type gas, which is calculated using the following formula:

[0018] T=0.0574×B / (K×100)+190

[0019] Where: T is the stratigraphic age of the source rock, in Ma; B is the 40Ar / 36Ar ratio of the coal-type gas; K is the potassium content in the source rock, in %.

[0020] The beneficial effects of the comprehensive evaluation method of gas source tracing of the present invention are as follows:

[0021] The present invention helps to explore the laws of gas reservoir formation and distribution more accurately and comprehensively in time and space, thereby providing important theoretical basis and technical support for the exploration and development of typical gas fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 For the present invention 40 Ar / 36 Ar- 3 He / 4 And related illustrations.

[0023] Figure 2a This is the ln(C1 / C2)-ln(C2 / C3) correlation diagram of the present invention.

[0024] Figure 2b For the present invention 13 C1-δD1 correlation diagram.

[0025] Figure 3a is the natural gas δ 13 C2 comparison chart.

[0026] Figure 3b Source rock-reservoir asphalt ααα20R-C 27 、C 28 、C 29 Comparison picture.

[0027] Figure 3c Configure a relationship graph for reservoir formation events.

[0028] Figure 3d This is the age distribution map of natural gas source rocks. DETAILED DESCRIPTION

[0029] The specific embodiments of the present invention are described below to facilitate understanding of the present invention by those skilled in the art. However, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the appended claims, these changes are obvious, and all inventions and creations utilizing the concepts of the present invention are protected.

[0030] Step 1: Based on the inheritance effect of mantle-derived volatiles of noble gas isotopes, 40 Ar / 36 Ar- 3 He / 4 He related graphs are as follows Figure 1 As shown, Figure 1 middle 40 Ar / 36Ar represents the relative concentration of air argon and radioactive argon in the sample. 3 He / 4 He represents the relative concentration of the original nuclides formed during element synthesis in the sample and the decay products of the natural radioactive elements uranium and thorium on Earth. 40 Ar, 36 Ar, 3 He, 4 He values are obtained by noble gas isotope mass spectrometry to determine whether there is deep foreign matter involved in the natural gas.

[0031] Step 2: After removing the mixing of mantle-derived materials, based on the parent material inheritance of hydrocarbon carbon and hydrogen isotopes and the thermodynamic fractionation effect, the ln(C1 / C2)-ln(C2 / C3) correlation diagram is used as shown in the figure below. Figure 2a As shown, δ 13 The C1-δD1 correlation diagram is shown in the figure Figure 2b The figure shows a comprehensive judgment of natural gas maturity, parent material type and depositional environment; C1 is the methane content in natural gas, C2 is the ethane content in natural gas, and C3 is the propane content in natural gas, all of which are obtained by gas chromatography; δ 13 C1 is the carbon isotope of methane and δD1 is the hydrogen isotope of methane, both of which are obtained by mass spectrometry testing.

[0032] Step 3: Use the stable isotope index of natural gas to compare the natural gas in each production layer in the study area. Figure 3a As shown in the figure, the similarities and differences between them are identified to reveal the potential source rocks of natural gas; 13 C2 is a carbon isotope of ethane.

[0033] Step 4: If the result of the second step is crude oil cracking gas, the reservoir asphalt-source rock ααα20R-C 27 、C 28 、C 29 Comparison as shown Figure 3b As shown, Figure 3b Medium ααα20R-C 27 、C 28 、C 29 C 27 、C 28 、C 29 Regular steranes are obtained by saturated hydrocarbon chromatography mass spectrometry. Reservoir asphalt is used as a medium to indirectly reveal the potential source rocks of natural gas;

[0034] Step 5: Use basin simulation software (BasinMod 1D) to simulate the hydrocarbon generation and expulsion history of the above potential source rocks. Combined with the structural characteristics and source-reservoir-caprock combination of the study area, from a geological macroscopic perspective, establish the coupling relationship and spatiotemporal configuration of the key accumulation events of natural gas reservoirs (see Figure 1). Figure 3c The above viewpoints are further confirmed by the data shown in the figure. The burial history, generation and expulsion history are simulated by basin simulation software (BasinMod 1D), the structural characteristics and source-reservoir-caprock combination are obtained from literature research, and the formation and evolution of oil and gas reservoirs are the results of comprehensive evaluation.

[0035] Step 6: Based on the cumulative effect of the age of noble gas isotopes and the research results from steps 3 to 5, the age of the natural gas source rock is calculated as shown in the figure. Figure 3d As shown, the age of the gas source rock is calculated using the formula in step 6.

[0036] If the identification result in the second step is oil-type gas, use the following formula for calculation:

[0037] T=5301gA-1323(Ma)

[0038] Where: T is the age of source rock formation, Ma; A is the oil-type gas 40 Ar / 36 Ar ratio.

[0039] If the identification result in the second step is coal-type gas, use the following formula for calculation:

[0040] T=0.0574×B / (K×100)+190

[0041] Where: T-source rock formation age, Ma; B-coal-type gas 40 Ar / 36 Ar ratio; K-potassium content in source rock, %.

[0042] The calculated results are compared with the geological age of potential source rocks to finally determine the natural gas source in the study area from a quantitative perspective.

Claims

1. A comprehensive evaluation method for gas source tracing, characterized in that: The following steps are involved: S1: Based on the inheritance effect of mantle-derived volatiles from noble gas isotopes, using 40 Ar / 36 Ar- 3 He / 4 The He correlation diagram is used to determine whether the natural gas has the involvement of deep foreign materials; S2: After removing the mixing of mantle sources, based on the parent material inheritance of hydrocarbon carbon and hydrogen isotopes and the thermodynamic fractionation effect, the ln(C1 / C2)-ln(C2 / C3) correlation diagram, δ 13 The C1-δD1 correlation diagram comprehensively judges the natural gas maturity, parent material type and depositional environment; S3: Use natural gas stable isotope indicators to compare natural gas from various producing layers in the study area, identify their similarities and differences, and reveal potential source rocks for natural gas; S4: If the result of S2 is crude oil cracking gas, based on the organic molecular inheritance effect of biomarker compounds, the reservoir asphalt-source rock ααα20R-C 27 、C 28 、C 29 In contrast, reservoir bitumen is used as a medium to indirectly reveal the potential source rocks of natural gas; S5: Using the basin simulation software BasinMod 1D, we simulated the hydrocarbon generation and expulsion history of the potential source rocks mentioned above. Combining the structural characteristics and source-reservoir-caprock assemblage of the study area, we established the coupling relationship and spatiotemporal configuration of key natural gas reservoir-forming events from a geological macroscopic perspective, further confirming the above viewpoints. S6: Based on the cumulative effect of the age of noble gas isotopes and the research results of S3 to S5, the age of the natural gas source rock is calculated; S7: Compare the calculated results with the geological age of potential source rocks to quantitatively identify the natural gas source in the study area. The identification result of S2 is oil-type gas, which is calculated using the following formula: T=530lgA-1323(Ma) Where: T is the age of source rock formation, Ma; A is the oil-type gas 40 Ar / 36 Ar ratio; The identification result of S2 is coal-type gas, which is calculated using the following formula: T=0.0574×B / (K×100)+190 Where: T is the age of source rock formation, in Ma; B is the coal-type gas 40 Ar / 36 Ar ratio; K-potassium content in source rock, in %.

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