Method and system for quickly determining hydrocarbon generation threshold depth of argillaceous source rock

Abstract

The application discloses a method and system for quickly determining a hydrocarbon generation threshold depth of argillaceous hydrocarbon source rock, and the method comprises the following steps: calculating total porosity of the argillaceous hydrocarbon source rock according to conventional logging data of an oil and gas exploration area; performing logarithmic scaling on the total porosity of the argillaceous hydrocarbon source rock to obtain a total porosity curve of the argillaceous hydrocarbon source rock; performing logarithmic scaling on the resistivity of the argillaceous hydrocarbon source rock to obtain a resistivity curve of the argillaceous hydrocarbon source rock; and determining the hydrocarbon generation threshold depth of the argillaceous hydrocarbon source rock according to the logarithmic scaling superposition result of the total porosity curve and the resistivity curve of the argillaceous hydrocarbon source rock. The method and system for determining the hydrocarbon generation threshold depth of the argillaceous hydrocarbon source rock can quickly determine the hydrocarbon generation threshold depth of the argillaceous hydrocarbon source rock in an exploration target area, so that the purpose of quickly determining the hydrocarbon generation threshold depth of the argillaceous hydrocarbon source rock at extremely low cost is achieved, and the efficiency of oil and gas exploration is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of oil and gas exploration, and particularly relates to a method and system for quickly determining the hydrocarbon generation threshold depth of argillaceous hydrocarbon source rock. BACKGROUND

[0002] The oil / gas generation threshold generally refers to the threshold depth at which kerogen begins to thermally degrade to form hydrocarbons during the diagenetic evolution. The kerogen before the hydrocarbon generation threshold not only does not contribute to hydrocarbon generation, but also enriches the "raw materials" for hydrocarbon generation and prepares conditions for subsequent thermal degradation. The soluble organic matter in the post-depositional rock at this stage is very active and is in a state of significant change, and provides important information about hydrocarbon generation.

[0003] Among the numerous geochemical methods for determining the oil generation threshold, there are two most authoritative methods: the first method is to determine the oil generation threshold according to the corresponding relationship between the oil generation threshold vitrinite reflectance value and the depth; and the second method is to determine the oil generation threshold according to the inflection point of the geochemical index (such as S1 / TOC, S1 / (S1+S2), chloroform bitumen "A" / TOC, total hydrocarbon / TOC) that measures the degree of transformation of insoluble organic matter into soluble organic matter with the change in burial depth. The first method is mainly based on the classic hydrocarbon generation model proposed by Tissot and Welte (1978), which believes that the rock enters the hydrocarbon generation threshold and begins to generate a large amount of hydrocarbons after Ro>0.5%, so the hydrocarbon generation threshold depth is often determined according to the depth corresponding to Ro=0.5%. This method is relatively simple to operate and requires less experimental analysis. However, in practical application, due to the differences in organic matter type, abundance and basin burial process of argillaceous hydrocarbon source rock in different oil and gas fields, the application of a single Ro value often cannot represent the situation of different oil and gas fields, resulting in errors. The second method is based on the theoretical basis of the critical condition of hydrocarbon expulsion, and takes the critical geological condition of argillaceous hydrocarbon source rock starting to expel oil and gas in free phase as the hydrocarbon generation / expulsion threshold. The evaluation results are more objective and accurate, and this method is the most intuitive and widely used method at present. However, this method requires selecting samples at different depths for multiple experimental tests, and has high requirements for sampling system. The actual operation is time-consuming.

[0004] Both of the above two methods for determining the hydrocarbon generation threshold depth of argillaceous hydrocarbon source rock are experimental analysis methods, and both require a certain amount or a large amount of geochemical analysis experimental data as the basis for determining the hydrocarbon generation threshold depth of argillaceous hydrocarbon source rock. The geochemical analysis experiment requires that the corresponding rock sample should have good representativeness, which is time-consuming, poor in timeliness, and high in time cost and economic cost, thereby affecting the progress of the originally high-cost risk exploration. Under such a technical background, there is an urgent need to develop a method that is high in timeliness and can quickly identify effective argillaceous hydrocarbon source rock and determine its hydrocarbon generation threshold depth. SUMMARY

[0005] In order to solve the above problems, the present application provides a method and system for quickly determining the hydrocarbon generation threshold depth of argillaceous hydrocarbon source rock, and quickly identifying effective argillaceous hydrocarbon source rock and determining its hydrocarbon generation threshold depth.

[0006] A method for quickly determining the hydrocarbon generation threshold depth of argillaceous hydrocarbon source rock comprises the following steps:

[0007] According to the conventional logging data of the oil and gas exploration area, the total porosity of the argillaceous hydrocarbon source rock is calculated.

[0008] The total porosity of the argillaceous hydrocarbon source rock is logarithmically scaled to obtain the total porosity curve of the argillaceous hydrocarbon source rock.

[0009] The resistivity of the argillaceous hydrocarbon source rock is logarithmically scaled to obtain the resistivity curve of the argillaceous hydrocarbon source rock.

[0010] According to the logarithmic scaling superposition result of the total porosity curve and the resistivity curve of the argillaceous hydrocarbon source rock, the hydrocarbon generation threshold depth of the argillaceous hydrocarbon source rock is determined.

[0011] Further, according to the conventional logging data of the oil and gas exploration area, the total porosity of the argillaceous hydrocarbon source rock comprises the following steps:

[0012] The argillaceous content in the argillaceous hydrocarbon source rock is calculated according to the natural gamma curve.

[0013] The mudstone section in the argillaceous hydrocarbon source rock is screened out according to the argillaceous content.

[0014] The total porosity of the mudstone section in the argillaceous hydrocarbon source rock is calculated by the method of neutron density crossplot.

[0015] Further, the total porosity of the argillaceous hydrocarbon source rock is logarithmically scaled to obtain the total porosity curve of the argillaceous hydrocarbon source rock, which specifically comprises the following steps:

[0016] In the drawing curve channel, the total porosity curve of the mudstone section in the argillaceous hydrocarbon source rock is logarithmically scaled, and the scaling value range is 100-1, unit: %, to obtain the total porosity curve of the argillaceous hydrocarbon source rock.

[0017] Further, the resistivity of the argillaceous hydrocarbon source rock is logarithmically scaled to obtain the resistivity curve of the argillaceous hydrocarbon source rock, which specifically comprises the following steps:

[0018] In the drawing curve channel, the resistivity curve of the mudstone section in the argillaceous hydrocarbon source rock is logarithmically scaled, and the scaling value range is 1-100, unit: Ω·m, to obtain the resistivity curve of the argillaceous hydrocarbon source rock.

[0019] Further, according to the logarithmic scaling superposition result of the total porosity curve and the resistivity curve of the argillaceous hydrocarbon source rock, the hydrocarbon generation threshold depth of the argillaceous hydrocarbon source rock is determined, which specifically comprises the following steps:

[0020] Put the total porosity curve and the resistivity curve of the argillaceous hydrocarbon source rock after the scale completion into the same logarithmic scale curve channel for superposition;

[0021] When the total porosity curve and the resistivity curve of the argillaceous hydrocarbon source rock with continuous thickness in the set range appear differences, and the total porosity curve of the lower mudstone section is no longer coincided with the resistivity curve, the vertical depth of the corresponding stratum at this place is the hydrocarbon generation threshold depth of the argillaceous hydrocarbon source rock.

[0022] Further, the argillaceous content V in the argillaceous hydrocarbon source rock is calculated according to the natural gamma GR curve sh Specifically as follows:

[0023] Ish=(GR-GR ｍｉｎ ) / (GR ｍａｘ -GR ｍｉｎ )

[0024] V sh =(2 ＧＣＵＲ×Ｉｓｈ -1) / (2 ＧＣＵＲ -1)

[0025] In the formula, V sh is the argillaceous content calculated by the natural gamma curve, a decimal number; Ish is the argillaceous index; GR ｍａｘ is the natural gamma logging value at the pure mudstone; GR ｍｉｎ is the natural gamma logging value at the pure sandstone; GR is the estimated natural gamma logging value of the well section; GCU is the empirical coefficient for calculating the argillaceous volume, generally taking 2 for old strata and 3.7 for tertiary strata.

[0026] Further, the mudstone section is selected in the argillaceous hydrocarbon source rock with the argillaceous content between 60% and 100%.

[0027] Further, the scale value of the resistivity is selected according to the following principle: the resistivity curves in the target layer section are all in the scale interval.

[0028] Further, the set range of the thickness is greater than 5 m.

[0029] The application further provides a system for quickly determining the hydrocarbon generation threshold depth of the argillaceous hydrocarbon source rock, comprising:

[0030] A porosity calculation module is used for calculating the total porosity of the argillaceous hydrocarbon source rock according to the conventional logging data of the oil and gas exploration area;

[0031] A first data processing module is used for logarithmic scaling of the total porosity of the argillaceous hydrocarbon source rock to obtain the total porosity curve of the argillaceous hydrocarbon source rock;

[0032] A second data processing module is used for logarithmic scaling of the resistivity of the argillaceous hydrocarbon source rock to obtain the resistivity curve of the argillaceous hydrocarbon source rock;

[0033] a data superimposition calculation module configured to determine the hydrocarbon generation threshold depth of the argillaceous hydrocarbon source rock according to the superimposition result of the total porosity curve and the resistivity curve of the argillaceous hydrocarbon source rock.

[0034] Further, the porosity calculation module is specifically configured to:

[0035] calculate the argillaceous content in the argillaceous hydrocarbon source rock according to the natural gamma curve;

[0036] screen the mudstone section in the argillaceous hydrocarbon source rock according to the argillaceous content;

[0037] calculate the total porosity of the mudstone section in the argillaceous hydrocarbon source rock by the method of neutron density crossplot.

[0038] Further, the first data processing module is specifically configured to:

[0039] logarithmically scale the total porosity curve of the mudstone section in the argillaceous hydrocarbon source rock in the drawing curve channel, and the scaling value range is 100-1, unit: %, to obtain the total porosity curve of the argillaceous hydrocarbon source rock.

[0040] Further, the second data processing module is specifically configured to:

[0041] logarithmically scale the resistivity curve of the mudstone section in the argillaceous hydrocarbon source rock in the drawing curve channel, and the scaling value range is 1-100, unit: Ω·m, to obtain the resistivity curve of the argillaceous hydrocarbon source rock.

[0042] Further, the data superimposition calculation module is specifically configured to:

[0043] superimpose the total porosity curve and the resistivity curve of the argillaceous hydrocarbon source rock after scaling in the same logarithmic scaling curve channel;

[0044] when the total porosity curve and the resistivity curve of the argillaceous hydrocarbon source rock with continuous thickness in the set range appear differences, and the total porosity curve and the resistivity curve of the lower mudstone section no longer coincide, the vertical depth of the corresponding formation at this position is the hydrocarbon generation threshold depth of the argillaceous hydrocarbon source rock.

[0045] The method and system for determining the hydrocarbon generation threshold depth of the argillaceous hydrocarbon source rock can quickly determine the hydrocarbon generation threshold depth of the argillaceous hydrocarbon source rock in the exploration target area, so as to achieve the purpose of quickly determining the hydrocarbon generation threshold depth of the argillaceous hydrocarbon source rock at extremely low cost, and improve the efficiency of oil and gas exploration.

[0046] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the present application. The objects and other advantages of the present application can be realized and attained by the structure particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF DRAWINGS

[0047] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0048] Figure 1 A flowchart of a method for quickly determining the hydrocarbon generation threshold depth of argillaceous source rock according to an embodiment of the present application is shown;

[0049] Figure 2 A first result map for quickly determining the hydrocarbon generation threshold depth of argillaceous source rock according to an embodiment of the present application is shown;

[0050] Figure 3 A second result map for quickly determining the hydrocarbon generation threshold depth of argillaceous source rock according to an embodiment of the present application is shown;

[0051] Figure 4 A third result map for quickly determining the hydrocarbon generation threshold depth of argillaceous source rock according to an embodiment of the present application is shown;

[0052] Figure 5 A system structure diagram for quickly determining the hydrocarbon generation threshold depth of argillaceous source rock according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0053] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without any creative effort fall within the protection scope of the present application.

[0054] In order to facilitate the understanding of the embodiments of the present application, the basic theory of determining the hydrocarbon generation threshold depth of argillaceous source rock in the embodiments of the present application will be briefly introduced.

[0055] When the argillaceous hydrocarbon source rock begins to generate hydrocarbon, its resistivity begins to increase because the conductive pore water is replaced by the non-conductive hydrocarbon. The porosity of the argillaceous hydrocarbon source rock begins to increase due to the pressure increase caused by hydrocarbon generation, which further leads to the increase of acoustic time difference. The generation of a large amount of low-speed and low-density organic matter also leads to the increase of acoustic time difference and the decrease of density. The comprehensive effect of the above changes in the physical properties of the argillaceous hydrocarbon source rock is the increase of total porosity and the increase of resistivity of the argillaceous hydrocarbon source rock. The immature argillaceous hydrocarbon source rock does not have the above characteristics and physical properties, and thus the hydrocarbon generation threshold depth of the argillaceous hydrocarbon source rock can be quickly determined by using this point.

[0056] For an oil and gas exploration block, especially in a less explored area, various types of geological data are limited, but there are usually conventional logging data of parameter wells or exploration wells. According to the conventional logging data and the rock physical model, the total porosity of the argillaceous hydrocarbon source rock is calculated by logging method, and then the total porosity and the resistivity curve in the conventional logging are reasonably scaled and superimposed, so that the hydrocarbon generation threshold depth of the argillaceous hydrocarbon source rock in the exploration target area can be quickly determined, thereby achieving the purpose of quickly determining the hydrocarbon generation threshold depth of the argillaceous hydrocarbon source rock at extremely low cost and improving the efficiency of oil and gas exploration.

[0057] Based on the characteristics and physical properties of the argillaceous hydrocarbon source rock, as shown in Figure 1 The embodiment of the present application provides a method for quickly determining the hydrocarbon generation threshold depth of the argillaceous hydrocarbon source rock, which comprises the following steps: calculating the total porosity of the argillaceous hydrocarbon source rock according to the conventional logging data of the oil and gas exploration area; logarithmically scaling the total porosity of the argillaceous hydrocarbon source rock to obtain the total porosity curve of the argillaceous hydrocarbon source rock; logarithmically scaling the resistivity of the argillaceous hydrocarbon source rock to obtain the resistivity curve of the argillaceous hydrocarbon source rock; and determining the hydrocarbon generation threshold depth of the argillaceous hydrocarbon source rock according to the scaling and superimposition result of the total porosity curve and the resistivity curve of the argillaceous hydrocarbon source rock.

[0058] It should be noted that the conventional logging data at least includes natural gamma (GR), caliper (CAL), acoustic time difference (AC), density (DEN), neutron (CNL), resistivity (RT) and depth scaling (DEPT).

[0059] Specifically, calculating the total porosity of the argillaceous hydrocarbon source rock according to the conventional logging data of the oil and gas exploration area comprises the following steps:

[0060] S101, calculating the argillaceous content V in the argillaceous hydrocarbon source rock according to the natural gamma GR curve sh The argillaceous content can also be calculated by the uranium-free gamma curve.

[0061] It should be noted that the high or low of the shale content of the rock will also affect the high or low of the measured GR value, the more the shale content, the more the content of the high radioactive mineral in the shale component, resulting in the formation GR rising. The organic matter kerogen in the shale hydrocarbon source rock layer is rich in radioactive elements such as uranium, thorium and potassium, which can also cause the formation GR value to rise. Generally, the shale hydrocarbon source rock layer rich in organic matter has a higher GR value than the shale hydrocarbon source rock layer (mudstone layer) poor in organic matter, and the GR curve shows a sharp rising trend in the shale hydrocarbon source rock layer rich in organic matter. The abnormally high GR value can identify the shale hydrocarbon source rock layer rich in organic matter.

[0062] According to the natural gamma GR curve, the shale content V in the shale hydrocarbon source rock is calculated sh Specifically as follows:

[0063] Ish = (GR - GR ｍｉｎ ) / (GR ｍａｘ - GR ｍｉｎ )

[0064] V sh = (2 ＧＣＵＲ×Ｉｓｈ - 1) / (2 ＧＣＵＲ - 1)

[0065] In the formula, V sh is the shale content calculated by the natural gamma curve, a decimal number; Ish is the shale index; GR ｍａｘ is the natural gamma logging value at the pure mudstone; GR ｍｉｎ is the natural gamma logging value at the pure sandstone; GR is the estimated natural gamma logging value of the well section; GCU is the empirical coefficient for calculating the shale volume, generally 2 for old formations and 3.7 for tertiary formations.

[0066] S102, the shale section in the shale hydrocarbon source rock is screened out according to the shale content V sh .

[0067] In this step, the shale section in the shale hydrocarbon source rock with the shale content V sh between 60% and 100% is selected as the mudstone section.

[0068] S103, the total porosity of the mudstone section in the shale hydrocarbon source rock is calculated by the method of neutron density crossplot, specifically as follows: determining the lithology skeleton value of the density logging; determining the lithology skeleton value of the density logging and the neutron logging by the crossplot skeleton parameter method; determining the rock density skeleton value according to the neutron and density skeleton values of the lithology, and determining the total porosity of the mudstone section in the shale hydrocarbon source rock according to the rock density and neutron skeleton values.

[0069] In this step, the total porosity is calculated by the method of neutron density crossplot, which can eliminate the influence of single factor. The key of this method is the selection of skeleton point. For conventional sandstone reservoir, the density skeleton value is generally selected as 2.65 g / cm 3 For the calculation of porosity of complex reservoir, the skeleton parameters of crossplot can be selected by the method of zero porosity line to determine the lithology skeleton value of density logging and neutron logging, and then the other skeleton parameters are selected by the method of crossplot skeleton parameters.

[0070] In one embodiment, the total porosity of the argillaceous hydrocarbon source rock is logarithmically scaled, specifically: in the drawing curve channel, the total porosity curve of the argillaceous hydrocarbon source rock in the mudstone section is logarithmically scaled, and the scaled value range is fixed as 100-1, unit: %, that is, the scaled range is 100-1%, to obtain the total porosity curve of the argillaceous hydrocarbon source rock.

[0071] In one embodiment, the resistivity of the argillaceous hydrocarbon source rock is logarithmically scaled, specifically: in the drawing curve channel, the resistivity curve of the argillaceous hydrocarbon source rock in the mudstone section is logarithmically scaled, and the scaled value range is generally 1-100, unit: Ω·m, that is, the scaled range is 1-100 Ω·m, to obtain the resistivity curve of the argillaceous hydrocarbon source rock.

[0072] It should be noted that, due to the different salinity of formation water in different regions, sometimes there can be a big difference, which greatly affects the resistivity of the argillaceous hydrocarbon source rock. Therefore, when scaling the resistivity of the argillaceous hydrocarbon source rock, the scaling should be performed according to the interval range of the actual distribution of the resistivity of the argillaceous hydrocarbon source rock in the target section, and the scaling value selection principle is: to ensure that the resistivity curve in the target section is within the scaled interval, except for the areas with large denudation thickness and fresh water intrusion, generally the logarithmic scaling form with the value range of 1-100 Ω·m can be adopted.

[0073] Specifically, according to the scaled superposition result of the total porosity curve and the resistivity curve of the argillaceous hydrocarbon source rock, the hydrocarbon generation threshold depth of the argillaceous hydrocarbon source rock includes the following steps:

[0074] S201: Superimpose the total porosity curve and the resistivity curve of the argillaceous hydrocarbon source rock after scaling in the same logarithmic scaling curve channel.

[0075] S202: When the total porosity curve and the resistivity curve of the argillaceous hydrocarbon source rock with a continuous thickness in the set range appear obvious difference (the total porosity curve is on the left and the resistivity curve is on the right), and the lower mudstone section rarely appears the coincidence of the total porosity and the resistivity curve again, the vertical depth of the corresponding formation at this point is the hydrocarbon generation threshold depth of the argillaceous hydrocarbon source rock.

[0076] In this step, the set range of thickness can be greater than 5m, when V shWhen the porosity scale line is more obvious than the resistivity scale line in more than 60-70% of the mudstone section, it indicates that the argillaceous hydrocarbon source rock starts to generate hydrocarbon, and the corresponding depth is the hydrocarbon generation threshold depth of the argillaceous hydrocarbon source rock.

[0077] The method for quickly determining the hydrocarbon generation threshold depth of the argillaceous hydrocarbon source rock is applied to the actual exploration to determine the hydrocarbon generation threshold depth, as shown in Figure 2 , and Figure 2 The middle curve shows that, from left to right, the first track is the depth track; the second track is the geological layering; the third track is the spontaneous potential and natural gamma; the fourth track is the compensated density and acoustic time difference curve; the fifth track is the lithology profile; the sixth track is the hydrocarbon generation threshold discrimination curve (total porosity and deep resistivity); the seventh track is the oil and gas indication curve (total water saturation); and the eighth track is the lithic analysis organic carbon and logging calculation organic carbon content curve.

[0078] As can be seen from Figure 2 , the hydrocarbon generation threshold depth of the well area is about 1700m, and the result of identifying and determining the hydrocarbon generation threshold depth of the argillaceous hydrocarbon source rock is in good consistency with the organic carbon content analysis and the thermal evolution simulation result, and the discrimination efficiency is significantly higher than that of the experimental analysis determination method.

[0079] As shown in Figure 3 , the hydrocarbon generation threshold depth determined by the method for quickly determining the hydrocarbon generation threshold depth of the argillaceous hydrocarbon source rock of the embodiment of the present application has good correspondence with the position of the development of the organic carbon content. In addition, when the neutron logging curve is lacking, the acoustic curve or the porosity and resistivity curve calculated by the acoustic curve in the figure can be used to replace the method to quickly determine the hydrocarbon generation threshold depth of the argillaceous hydrocarbon source rock.

[0080] Figure 3 The middle curve shows that, from left to right, the first track is the depth track; the second track is the geological layering; the third track is the lithology profile; the fourth track is the natural gamma curve; the fifth track is the acoustic time difference curve; the sixth track is the deep resistivity curve; the seventh track is the resistivity and acoustic time difference curve; and the eighth track is the lithic analysis organic carbon and logging calculation organic carbon content curve.

[0081] Figure 4 The middle curve shows that, from left to right, the first track is the argillaceous content and geological layering track; the second track is the depth track; the third track is the natural gamma; the fourth track is the acoustic time difference curve; the fifth track is the resistivity curve; and the sixth track is the lithic analysis organic carbon content.

[0082] As shown in Figure 4 , the hydrocarbon generation threshold depth of the argillaceous hydrocarbon source rock of the well is determined to be about 3400ft by the method for quickly determining the hydrocarbon generation threshold depth of the argillaceous hydrocarbon source rock of the embodiment of the present application, which is equivalent to the position of the development of the organic carbon content.

[0083] Based on the above method for quickly determining the hydrocarbon generation threshold depth of argillaceous hydrocarbon source rock, as shown in the figure, the embodiment of the present application also provides a system for quickly determining the hydrocarbon generation threshold depth of argillaceous hydrocarbon source rock, which comprises a porosity calculation module, a first data processing module, a second data processing module and a data superposition calculation module. Figure 5

[0084] The porosity calculation module is used to calculate the total porosity of the argillaceous hydrocarbon source rock according to the conventional logging data of the oil and gas exploration area; the first data processing module is used to logarithmically scale the total porosity of the argillaceous hydrocarbon source rock to obtain the total porosity curve of the argillaceous hydrocarbon source rock; the second data processing module is used to logarithmically scale the resistivity of the argillaceous hydrocarbon source rock to obtain the resistivity curve of the argillaceous hydrocarbon source rock; and the data superposition calculation module is used to determine the hydrocarbon generation threshold depth of the argillaceous hydrocarbon source rock according to the scaling superposition result of the total porosity curve and the resistivity curve of the argillaceous hydrocarbon source rock.

[0085] The method and system for quickly determining the hydrocarbon generation threshold depth of argillaceous hydrocarbon source rock according to the embodiment of the present application can quickly identify effective argillaceous hydrocarbon source rock and determine its hydrocarbon generation threshold depth, which is highly time-efficient, reduces exploration costs and improves the success rate of exploration.

[0086] Although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that the technical solutions recorded in the foregoing embodiments can still be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.​

Claims

1. A method for quickly determining the hydrocarbon-generating threshold depth of argillaceous source rock, characterized in that, The method comprises the following steps: According to the conventional logging data of the oil and gas exploration area, the total porosity of the argillaceous hydrocarbon source rock is calculated. The total porosity of the argillaceous hydrocarbon source rock is logarithmically scaled to obtain a total porosity curve of the argillaceous hydrocarbon source rock. The resistivity of the argillaceous hydrocarbon source rock is logarithmically scaled to obtain a resistivity curve of the argillaceous hydrocarbon source rock; the scaling value of the resistivity is selected according to the principle that the resistivity curves in the target layer section are all within the scaling interval. According to the logarithmic scaling superposition result of the total porosity curve and the resistivity curve of the argillaceous hydrocarbon source rock, the hydrocarbon generation threshold depth of the argillaceous hydrocarbon source rock is determined, comprising the following steps: the total porosity curve and the resistivity curve of the argillaceous hydrocarbon source rock after scaling are superimposed in the same logarithmic scaling curve channel; when the total porosity curve and the resistivity curve of the argillaceous hydrocarbon source rock with a continuous thickness in the set range are different, and the total porosity curve and the resistivity curve of the underlying mudstone section no longer coincide, the vertical depth of the stratum at this position is the hydrocarbon generation threshold depth of the argillaceous hydrocarbon source rock.

2. The method for quickly determining the hydrocarbon generation threshold depth of argillaceous source rock according to claim 1, characterized in that, According to the conventional logging data of the oil and gas exploration area, the total porosity of the argillaceous hydrocarbon source rock is calculated, comprising the following steps: The argillaceous content in the argillaceous hydrocarbon source rock is calculated according to the natural gamma ray curve. The mudstone section in the argillaceous hydrocarbon source rock is screened according to the argillaceous content. The total porosity of the mudstone section in the argillaceous hydrocarbon source rock is calculated by the method of neutron density crossplot.

3. The method for quickly determining the hydrocarbon generation threshold depth of argillaceous source rock according to claim 2, characterized in that, The total porosity of the argillaceous hydrocarbon source rock is logarithmically scaled to obtain a total porosity curve of the argillaceous hydrocarbon source rock, specifically as follows: In the drawing curve channel, the total porosity curve of the mudstone section in the argillaceous hydrocarbon source rock is logarithmically scaled, the scaling value range is 100-1, the unit is %, and the total porosity curve of the argillaceous hydrocarbon source rock is obtained.

4. The method for quickly determining the hydrocarbon generation threshold depth of argillaceous source rock according to claim 2, characterized in that, The resistivity of the argillaceous hydrocarbon source rock is logarithmically scaled to obtain a resistivity curve of the argillaceous hydrocarbon source rock, specifically as follows: In the drawing curve channel, the resistivity curve of the mudstone section in the argillaceous hydrocarbon source rock is logarithmically scaled, the scaling value range is 1-100, the unit is Ω·m, and the resistivity curve of the argillaceous hydrocarbon source rock is obtained.

5. The method for quickly determining the hydrocarbon generation threshold depth of argillaceous source rock according to claim 2, characterized in that, According to the natural gamma ray GR curve, the shale content V in the shale hydrocarbon source rock is calculated sh Specifically as follows: IsH = (GR - GR ｍｉｎ ) / (GR ｍａｘ - GR ｍｉｎ ) V sh ＝(２ ＧＣＵＲ×Ｉｓｈ －1) / (２ ＧＣＵＲ －1) where V sh Sh is the shale content calculated from the natural gamma curve, decimal; Is is the shale index; GR ｍａｘ GR is the natural gamma log value at pure shale; GR ｍｉｎ GR is the natural gamma log value at pure sandstone; GR is the estimated natural gamma log value of the well section; GCUR is the empirical coefficient for calculating the shale volume, 2 for old strata and 3.7 for Tertiary strata.

6. The method for quickly determining the hydrocarbon generation threshold depth of argillaceous source rock according to any one of claims 2-4, characterized in that, The argillaceous content in the argillaceous hydrocarbon source rock is calculated according to the natural gamma ray curve.

7. The method for quickly determining the hydrocarbon generation threshold depth of argillaceous source rock according to claim 1, characterized in that, The thickness set range is greater than 5 m.

8. A system for quickly determining the hydrocarbon generation threshold depth of argillaceous source rock, characterized in that, It comprises: A porosity calculation module is configured to calculate the total porosity of the argillaceous hydrocarbon source rock according to the conventional logging data of the oil and gas exploration area. A first data processing module is configured to logarithmically scale the total porosity of the argillaceous hydrocarbon source rock to obtain a total porosity curve of the argillaceous hydrocarbon source rock. A second data processing module is configured to logarithmically scale the resistivity of the argillaceous hydrocarbon source rock to obtain a resistivity curve of the argillaceous hydrocarbon source rock; the scaling value of the resistivity is selected according to the principle that the resistivity curves in the target layer section are all within the scaling interval. The data superimposition calculation module is used for determining the hydrocarbon generation threshold depth of the argillaceous hydrocarbon source rock according to the superimposition result of the total porosity curve and the resistivity curve of the argillaceous hydrocarbon source rock on a logarithmic scale, and comprises the following steps: placing the total porosity curve and the resistivity curve of the argillaceous hydrocarbon source rock after the scaling into the same logarithmic scale curve channel for superimposition; when the total porosity curve and the resistivity curve of the argillaceous hydrocarbon source rock with a continuous thickness in a set range appear differences, and the total porosity curve and the resistivity curve of the lower argillaceous section no longer coincide, the vertical depth of the corresponding stratum at this position is the hydrocarbon generation threshold depth of the argillaceous hydrocarbon source rock.

9. The system for quickly determining the hydrocarbon generation threshold depth of argillaceous source rock according to claim 8, characterized in that, The porosity calculation module is specifically used for: calculating the argillaceous content in the argillaceous hydrocarbon source rock according to the natural gamma curve; screening the argillaceous section in the argillaceous hydrocarbon source rock according to the argillaceous content; calculating the total porosity of the argillaceous section in the argillaceous hydrocarbon source rock by using the method of neutron density cross-plotting.

10. The system for quickly determining the hydrocarbon generation threshold depth of argillaceous source rock according to claim 9, characterized in that, The first data processing module is specifically used for: performing logarithmic scaling on the total porosity curve of the argillaceous section in the argillaceous hydrocarbon source rock in the drawing curve channel, the scaling value range is 100-1, and the unit is %, so as to obtain the total porosity curve of the argillaceous hydrocarbon source rock.

11. The system for quickly determining the hydrocarbon generation threshold depth of argillaceous source rock according to claim 9, characterized in that, The second data processing module is specifically used for: performing logarithmic scaling on the resistivity curve of the argillaceous section in the argillaceous hydrocarbon source rock in the drawing curve channel, the scaling value range is 1-100, and the unit is Ω·m, so as to obtain the resistivity curve of the argillaceous hydrocarbon source rock.

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