Method for quantitatively recovering organic matter degradation process of lacustrine facies hydrocarbon source rock and application

Abstract

The invention belongs to the field of petroleum and natural gas geology and exploration. The invention particularly relates to a method for quantitatively recovering the organic matter degradation process of lacustrine facies hydrocarbon source rock and application. The method comprises the following steps: S1, establishing a calculation formula for the current organic matter burial amount of the lacustrine facies hydrocarbon source rock; S2, establishing a calculation formula for the organic matter degradation amount of the lacustrine facies hydrocarbon source rock in the late diagenesis thermal degradation stage; s3, establishing an organic matter degradation amount calculation formula in the early diagenesis anaerobic degradation stage; s4, establishing an organic matter degradation amount calculation formula in the early diagenesis aerobic degradation stage; and S5, establishing a water column organic matter degradation amount calculation formula. According to the method, the degradation amount of each stage in the organic matter degradation process can be quantitatively recovered, and quantitative research on organic matter enrichment and hydrocarbon source rock development is facilitated; the method can meet quantitative research of lacustrine facies hydrocarbon source rock development, has a good application effect in a research area, can be popularized and applied to research of other lacustrine facies hydrocarbon source rocks, and can provide effective guidance for oil and gas geological exploration.

Description

Technical Field

[0001] The invention belongs to the field of petroleum and natural gas geology and exploration, and in particular relates to a method for quantitatively restoring the organic matter degradation process of lacustrine source rocks and its application. Background Art

[0002] The rich organic matter in source rocks is the material basis for the generation of oil and gas. The amount of organic matter has an important impact on the exploration potential of oil and natural gas. The degradation process of organic matter affects the abundance of organic matter in source rocks. After organic matter enters the sediment, source rocks are formed. As the burial depth gradually deepens and the temperature continues to rise, the organic matter gradually degrades during diagenesis. The degradation process of organic matter is one of the important factors affecting the abundance of organic matter in source rocks. Related research is of great significance to conventional and unconventional oil and gas exploration.

[0003] Previous researchers have conducted a large number of qualitative analyses on the degradation of organic matter in source rocks, such as paleo-salinity, paleo-redox conditions, paleo-climate, paleo-water depth, etc. The research mainly focused on the qualitative analysis of the effects of various factors on the degradation of organic matter, and lacked quantitative research.

[0004] How to quantitatively study organic matter enrichment and source rock development has become an urgent problem to be solved. Summary of the invention

[0005] In order to solve the above problems, the purpose of the present invention is to provide a method and application for quantitatively restoring the organic matter degradation process of lacustrine source rocks.

[0006] In order to achieve the above purpose, the embodiment of the present invention provides the following technical solutions:

[0007] According to a first aspect of an embodiment of the present invention, a method for quantitatively restoring the organic matter degradation process of lacustrine source rocks is provided, comprising the following steps:

[0008] S1. Establish a calculation formula for the current organic matter burial volume of lacustrine source rocks to quantify the current organic matter burial volume of source rocks:

[0009] S2. Establishing a calculation formula for the degradation amount of organic matter in the late diagenetic thermal degradation stage of lacustrine source rocks based on the current burial amount of organic matter in the source rocks;

[0010] S3. Establish a calculation formula for the degradation of organic matter in the early diagenetic anaerobic degradation stage;

[0011] S4. Establishing a calculation formula for the degradation amount of organic matter in the early diagenetic aerobic degradation stage according to the degradation amount of organic matter in the early diagenetic anaerobic degradation stage;

[0012] S5. Establish a calculation formula for the degradation of organic matter in the water column according to the degradation of organic matter in the late diagenetic thermal degradation stage, the loss of organic matter in the anaerobic degradation stage of the source rock, and the degradation of organic matter in the early diagenetic aerobic degradation stage.

[0013] Furthermore, the calculation formula for the current organic matter burial volume of the lacustrine source rock is:

[0014] F0=TOC×L×ρ

[0015] Among them, F0 is the current organic matter burial volume of lacustrine source rocks, in g / (m 2 ·yr); TOC is the organic carbon content, in %; L is the linear deposition rate, in m / yr, ρ is the density of mudstone, in g / m 3 .

[0016] Furthermore, the calculation formula for the organic matter degradation amount in the late diagenetic thermal degradation stage of the lacustrine source rock is:

[0017] F I =F0 / (10^(-0.32×R o ))

[0018] Among them, F I is the degradation amount of organic matter in the late diagenetic thermal degradation stage, in g / (m 2 ·yr); F0 is the current organic matter burial volume of lacustrine source rocks, in g / (m 2 ·yr); R o is the vitrinite reflectance of lacustrine source rock, in %.

[0019] Furthermore, the calculation formula for the organic matter degradation amount in the early diagenetic anaerobic degradation stage is:

[0020] F II =0.25×S×L×ρ

[0021] Among them, F II is the amount of organic matter lost during the anaerobic degradation of source rocks, in g / (m 2 ·yr); S is the reducing sulfur content in the source rock, unit %; L is the linear sedimentation rate, unit m / yr, ρ is the density of mudstone, in g / m 3 .

[0022] Furthermore, the calculation formula for the amount of organic matter degradation in the early diagenetic aerobic degradation stage is:

[0023] F III =(F0+F I +F II )×10^[3.2-LOG(ρ×L)]]-FII

[0024] Among them, F III is the degradation amount of organic matter in the early diagenetic aerobic degradation stage, g / (m 2 ·yr), L is the linear deposition rate, the unit is m / yr, ρ is the density of mudstone, in g / m 3 .

[0025] Furthermore, the calculation formula for the degradation amount of organic matter in the water column is:

[0026] F IV =(F0+F I +F II +F III ) / 0.4-F III

[0027] Among them, F IV is the amount of organic matter degradation in the water column.

[0028] Furthermore, the current organic matter burial volume of the lacustrine source rock is 0.2 to 2700 g / (m 2 ·yr).

[0029] According to a second aspect of an embodiment of the present invention, there is provided an application of any one of the above methods in a process of quantitatively restoring organic matter degradation in lacustrine source rocks.

[0030] Compared with the prior art, the advantages of the embodiments of the present invention are:

[0031] The embodiment of the present invention provides a method and application for quantitatively restoring the organic matter degradation process of lacustrine source rocks. By adopting the method of the present invention, the degradation amount of each stage in the organic matter degradation process can be quantitatively restored, which is beneficial to the quantitative study of organic matter enrichment and source rock development; and can meet the quantitative study of lacustrine source rock development, has a good application effect in the study area, can be promoted and applied to other lacustrine source rock studies, and can provide effective guidance for oil and gas geological exploration. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0033] Figure 1 Flow chart of the method of the present invention.

[0034] Figure 2 is the current organic matter burial volume of the lacustrine source rock in Well X in a typical embodiment of the present invention;

[0035] Figure 3 is the amount of organic matter degradation in the late diagenetic thermal degradation stage of the lacustrine source rock in Well X in a typical embodiment of the present invention;

[0036] Figure 4 is the amount of organic matter degradation in the anaerobic degradation stage of the early diagenesis of the lacustrine source rock in Well X in a typical embodiment of the present invention;

[0037] Figure 5 is the amount of organic matter degradation in the early diagenetic aerobic degradation stage of the lacustrine source rock in Well X in a typical embodiment of the present invention;

[0038] Figure 6 is the amount of organic matter degradation in the water column of the lacustrine source rock of Well X in a typical embodiment of the present invention;

[0039] Figure 7 The figure is a quantification of the organic matter degradation process of the lacustrine source rock in Well X in a typical embodiment of the present invention. DETAILED DESCRIPTION

[0040] In view of the deficiencies in the prior art, the inventor of this case has proposed the technical solution of the present invention after long-term research and extensive practice. The technical solution, its implementation process and principle will be further explained as follows.

[0041] The present invention is further described in detail below in conjunction with specific embodiments, and the examples provided are only for illustrating the present invention, rather than for limiting the scope of the present invention. The examples provided below can be used as a guide for further improvements by those of ordinary skill in the art, and do not constitute a limitation of the present invention in any way.

[0042] The experimental methods in the following examples, unless otherwise specified, are all conventional methods, and are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. The materials, reagents, etc. used in the following examples, unless otherwise specified, can all be obtained from commercial channels.

[0043] The embodiment of the present invention provides a method for quantitatively restoring the degradation process of organic matter in lacustrine source rocks. Taking the Lucaogou Formation in Well X of Jimusar Depression in Junggar Basin as an example, Figure 1 As shown, the following steps are included:

[0044] (1) Calculate the current organic matter burial volume of lacustrine source rocks in Well X: Using the organic carbon content, linear sedimentation rate and mudstone density data of Well X, the current organic matter burial volume is calculated using Formula 1:

[0045] F0=TOC×L×ρ Formula 1

[0046] Where F0 is the current organic matter burial volume of lacustrine source rocks, expressed in g / (m 2·yr); TOC is the organic carbon content, in %; L is the linear sedimentation rate, in m / yr; ρ is the mudstone density, in g / m 3 .

[0047] Calculate the current organic matter burial volume at each depth point of the lacustrine source rock in Well X, such as Figure 2 As shown in the figure, the results of the current organic matter burial amount of source rocks at different depths are shown. The current distribution range of organic matter burial amount is 0.5~15g / (m 2 ·yr), with an average value of about 5g / (m 2 ·yr).

[0048] (2) Calculate the degradation amount of organic matter in the late diagenetic thermal degradation stage of the lacustrine source rock in Well X: Based on the F0 and vitrinite reflectance calculated in Formula 1, the established calculation formula is:

[0049] F I =F0 / (10^(-0.32×R o )) Formula 2

[0050] F I is the degradation amount of organic matter in the late diagenetic thermal degradation stage, in g / (m 2 ·yr); F0 is the current organic matter burial volume of lacustrine source rocks, in g / (m 2 ·yr); R o is the vitrinite reflectance of lacustrine source rock, in %.

[0051] Calculate the degradation amount of organic matter at each depth point of the lacustrine source rock in Well X during the late diagenetic thermal degradation stage, such as Figure 3 As shown in the figure, the results of calculating the degradation amount of organic matter in the late diagenetic thermal degradation stage of source rocks at different depths are shown in the figure. The current distribution range of organic matter burial amount is 0.2~12g / (m 2 ·yr), with an average value of about 5g / (m 2 ·yr).

[0052] (3) Calculate the amount of organic matter degradation in the early diagenetic anaerobic degradation stage: Calculate based on formula 3:

[0053] F II =0.25×S×L×ρ Formula 3

[0054] In the formula, F II is the amount of organic matter lost during the anaerobic degradation of source rocks, in g / (m 2 ·yr); S is the reducing sulfur content in the source rock, unit: %; L is the linear sedimentation rate, unit: m / yr; ρ is the mudstone density, unit: g / m 3 .

[0055] Calculate the degradation amount of organic matter at each depth point of the lacustrine source rock in Well X during the late diagenetic thermal degradation stage, such as Figure 4 As shown in the figure, the results of the organic matter degradation in the early diagenetic anaerobic degradation stage of source rocks at different depths are shown. The current distribution range of organic matter burial is 1 to 120 g / (m 2 ·yr).

[0056] (4) Calculate the amount of organic matter degradation in the early diagenetic aerobic degradation stage: Based on the calculation in formula 4

[0057] F III =(F0+F I +F II )×10^[3.2-LOG(ρ×L)]-F II Formula 4

[0058] Where F III is the degradation amount of organic matter in the early diagenetic aerobic degradation stage, g / (m 2 ·yr), L is the linear sedimentation rate, in m / yr, and ρ is the mudstone density, in g / m 3 .

[0059] Calculate the degradation amount of organic matter at each depth point of the lacustrine source rock in Well X during the late diagenetic thermal degradation stage, such as Figure 5 As shown in the figure, the results of the calculation of the organic matter degradation amount in the early diagenetic aerobic degradation stage of source rocks at different depths are shown. The current distribution range of organic matter burial amount is 40~1600g / (m 2 ·yr).

[0060] (6) Calculation formula for the amount of organic matter degradation in the water column: Calculated based on formula 5

[0061] F IV =(F0+F I +F II +F III ) / 0.4-F III Formula 5

[0062] where F IV is the degradation amount of organic matter in the water column, in g / (m 2 ·yr).

[0063] Calculate the degradation amount of organic matter in the water column at each depth point of the lacustrine source rock in Well X, such as Figure 6 As shown in the figure, the results of the organic matter degradation in the water column of source rocks at different depths are shown. The distribution range of organic matter degradation in the water column is 70 to 2700 g / (m 2 ·yr).

[0064] In summary, the quantitative results of organic matter degradation in lacustrine source rocks are as follows: Figure 7As shown in the figure, the results of calculating the degradation amount of organic matter in source rocks at different stages are shown.

[0065] The embodiments described above are only for illustrating the preferred implementation of the present invention. It should be pointed out that, for ordinary technicians in this field, several improvements can be made without departing from the scope of protection of this patent, and these improvements should also be regarded as within the scope of protection of this patent.

Claims

1. A method for quantitatively restoring the degradation process of organic matter in lacustrine source rocks, characterized in that: The following steps are involved: S1. Establish a calculation formula for the current organic matter burial volume of lacustrine source rocks to quantify the current organic matter burial volume of source rocks: S2. Establishing a calculation formula for the degradation amount of organic matter in the late diagenetic thermal degradation stage of lacustrine source rocks based on the current burial amount of organic matter in the source rocks; S3. Establish a calculation formula for the degradation of organic matter in the early diagenetic anaerobic degradation stage; S4. Establishing a calculation formula for the degradation amount of organic matter in the early diagenetic aerobic degradation stage according to the degradation amount of organic matter in the early diagenetic anaerobic degradation stage; S5. Establish a calculation formula for the degradation of organic matter in the water column according to the degradation of organic matter in the late diagenetic thermal degradation stage, the loss of organic matter in the source rock anaerobic degradation stage, and the degradation of organic matter in the early diagenetic aerobic degradation stage.

2. The method for quantitatively restoring the degradation process of organic matter in lacustrine source rocks according to claim 1, characterized in that: The calculation formula for the current organic matter burial capacity of the lacustrine source rock is: F0=TOC×L×ρ Among them, F0 is the current organic matter burial volume of lacustrine source rocks, in g / (m 2 ·yr); TOC is the organic carbon content, in %; L is the linear sedimentation rate, in m / yr; ρ is the mudstone density, in g / m 3 .

3. The method for quantitatively restoring the degradation process of organic matter in lacustrine source rocks according to claim 1, characterized in that: The calculation formula for the degradation amount of organic matter in the late diagenetic thermal degradation stage of the lacustrine source rock is: F I =F0 / (10∧(-0.32×R o )) Among them, F I is the degradation amount of organic matter in the late diagenetic thermal degradation stage, in g / (m 2 ·yr); F0 is the current organic matter burial volume of lacustrine source rocks, in g / (m 2 ·yr); R o is the vitrinite reflectance of lacustrine source rock, in %.

4. The method for quantitatively restoring the degradation process of organic matter in lacustrine source rocks according to claim 1, characterized in that: The calculation formula for the organic matter degradation amount in the early diagenetic anaerobic degradation stage is: II =0.25×S×L×ρ Among them, F II is the amount of organic matter lost during the anaerobic degradation of source rocks, in g / (m 2 ·yr); S is the reducing sulfur content in the source rock, unit: %; L is the linear sedimentation rate, unit: m / yr; ρ is the mudstone density, unit: g / m 3 .

5. The method for quantitatively restoring the degradation process of organic matter in lacustrine source rocks according to claim 1, characterized in that: The calculation formula for the organic matter degradation amount in the early diagenetic aerobic degradation stage is: III =(F0+F I +F II )×10^[3.2-LOG(ρ×L)]-F II Among them, FⅢ is the degradation amount of organic matter in the early diagenetic aerobic degradation stage, g / (m 2 ·yr), L is the linear sedimentation rate, in m / yr, and ρ is the mudstone density, in g / m 3 .

6. The method for quantitatively restoring the degradation process of organic matter in lacustrine source rocks according to claim 1, characterized in that: The calculation formula for the degradation of organic matter in the water column is: F Iv =(F0+F I +F II +F III ) / 0.4-F III Among them, F IV is the amount of organic matter degradation in the water column.

7. The method for quantitatively restoring the degradation process of organic matter in lacustrine source rocks according to claim 1, characterized in that: The current organic matter burial volume of the lacustrine source rock is 0.2-2700 g / (m 2 ·yr).

8. Use of the method according to any one of claims 1 to 7 in the quantitative restoration of organic matter degradation in lacustrine source rocks.

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