Method for discriminating hydrocarbon source rocks of coal series, terrestrial source marine facies and sea source marine facies based on molecular geochemical indexes and method for obtaining contribution ratios of three types of hydrocarbon source rocks to oil and gas

Abstract

The invention discloses a method for discriminating hydrocarbon source rocks of coal series, terrestrial source marine facies and sea source marine facies based on molecular geochemical indexes and a method for obtaining contribution ratios of the three types of hydrocarbon source rocks to oil and gas. The method for distinguishing the coal-series hydrocarbon source rocks, the terrestrial-source marine facies hydrocarbon source rocks and the sea-source marine facies hydrocarbon source rocks comprises the following steps: S1, testing pristane / plant ratios, dicadinane indexes and kerogen carbon isotope ratios delta 13C of coal-series hydrocarbon source rocks, terrestrial-source marine facies hydrocarbon source rocks and sea-source marine facies hydrocarbon source rocks, and obtaining molecular geochemical indexes for distinguishing the three types of hydrocarbon source rocks; and S2, testing the prime / plant ratio, the dicadinane index and the carbon isotope ratio of the to-be-tested sample, and determining the hydrocarbon source rock type of the to-be-tested sample. In addition, the contribution ratio of the three types of hydrocarbon source rocks to crude oil / condensate oil is obtained by constructing a contribution model of the end members of the three types of hydrocarbon source rocks to oil and gas. According to the method, the hydrocarbon source rock type and the oil and gas source can be quickly and reasonably judged, the contribution proportion of the three types of hydrocarbon source rocks can be calculated, and oil and gas exploration and development decision service is provided.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas exploration and development, and in particular to a method for distinguishing coal series, terrestrial marine, and marine marine source rocks based on molecular geochemical indicators, and a method for obtaining the contribution ratios of the three types of source rocks to oil and gas. Background Art

[0002] The oil and gas resources in the northern part of the South my country Sea are mainly derived from the Oligocene coal-bearing system, terrigenous marine and marine source rocks. Terrigenous marine source rocks refer to source rocks that are relatively developed in the delta mud-inner shallow sea, have dispersed sediments, and are mainly composed of organic matter from higher plants. Their organic matter abundance is low, and TOC usually does not exceed 1%. Coal-bearing source rocks are developed in the delta plain, and are coal-bearing source rocks with high organic matter abundance (TOC>6%, up to 80%). Marine source rocks are newly discovered and mainly developed in the bay environment where the delta is not developed. Marine algae contribute slightly more and there are a small amount of higher plant organic matter. The organic matter preservation conditions are better. Terrigenous marine source rocks are mainly gas-generating, and coal-bearing and terrigenous marine source rocks co-generate oil and gas.

[0003] Among the proven reserves of oil and gas discovered in the northern part of the South China Sea, taking the Qiongdongnan Basin as an example, coal-bearing source rocks account for about 20%, and marine source rocks account for about 75%. In the past two years, the exploration of the Yongle 10-6 structure on the southern slope of Baodao in the Qiongdongnan Basin has also discovered oil and gas from marine source rocks. At present, only organic geochemical methods can be used in China to distinguish between coal-bearing and marine source rocks (including terrestrial marine and marine marine source rocks). However, effective indicators that can effectively distinguish these three types of source rocks, namely coal-bearing, terrestrial marine and marine marine source rocks, and the corresponding oil and gas source comparison methods, as well as the calculation method of the contribution ratio of the three types of source rocks to crude oil / condensate have not yet been established. Therefore, it is still a technical problem that needs to be solved urgently to develop a method for identifying coal-measure, terrigenous marine and marine source rocks and oil and gas source comparison based on molecular geochemical indicators, to more accurately predict the distribution patterns of these three types of source rocks from the identification of coal-measure, terrigenous marine and marine source rocks and the oil and gas source comparison method, and to clarify the development patterns of coal-measure, terrigenous marine and marine source rocks and their contribution ratio to oil and gas. It can help the deployment and decision-making of the next step of oil and gas exploration. Summary of the invention

[0004] The purpose of the present invention is to provide a method for distinguishing coal-bearing, terrestrial marine, and marine marine source rocks based on molecular geochemical indicators, and a method for obtaining the contribution ratio of the three types of source rocks to oil and gas. The method is based on molecular geochemical indicators and can quickly and reasonably distinguish the type of source rocks, the source of oil and gas, and calculate the contribution ratio of the three types of source rocks, thus serving the decision-making of oil and gas exploration and development and having great promotion and application value.

[0005] In a first aspect, the present invention protects a method for distinguishing coal-bearing, terrestrial marine, and marine marine source rocks based on molecular geochemical indicators, characterized in that it comprises:

[0006] S1. Test the pristine / phyt ratio, bicadinane index and kerogen carbon isotope ratio δ of three different types of source rock samples, including coal-bearing, terrigenous marine and marine source rocks. 13 C, obtain molecular geochemical indicators for distinguishing coal-bearing, terrigenous-marine, and marine-marine source rocks;

[0007] S2. Testing the pristine / phyt ratio, bicadinane index and carbon isotope ratio of the sample to be tested, which are divided into the following two types: 1) When the sample to be tested is a source rock sample, the carbon isotope ratio is the kerogen carbon isotope ratio δ 13 C, according to the molecular geochemical index used to distinguish coal-bearing, terrestrial marine, marine marine source rocks, determine the source rock type of the source rock sample to be tested; 2) when the sample to be tested is a crude oil or condensate oil sample, the carbon isotope ratio is the whole oil carbon isotope ratio δ 13 C', determine the source rock type of the crude oil or condensate oil sample based on the molecular geochemical indicators used to distinguish coal-bearing, terrestrial marine, and marine marine source rocks.

[0008] In the above-mentioned method for distinguishing coal-measure, terrestrial marine, and marine source rocks based on molecular geochemical indicators, the molecular geochemical indicators used to distinguish coal-measure, terrestrial marine, and marine source rocks are as follows:

[0009] Coal-bearing source rocks: kerogen carbon isotope ratio δ 13 C<-27‰, mu / plant ratio>5, dijunipane index>6;

[0010] Terrigenous marine source rock: -26‰<kerogen carbon isotope ratio -27‰<δ 13 C<-25.5‰, 1.1<mu / plant ratio<5, dijunipane index<6;

[0011] Marine source rocks: kerogen carbon isotope ratio δ 13 C>-25.5‰, basal / plant ratio <1.1, dijunipane index <6.

[0012] In the above-mentioned method for distinguishing coal-bearing, terrestrial marine and marine marine source rocks based on molecular geochemical indicators, step S1 also includes: using the pristine / phytate ratio, bicadinane index and kerogen carbon isotope ratio δ of the three different types of source rock samples to determine the coal-bearing, terrestrial marine and marine source rocks. 13 C. Construct geochemical identification charts for coal-bearing, terrestrial marine, and marine marine source rocks;

[0013] Step S2 further includes any of the following: 1) when the sample to be tested is a source rock sample, the pristine / phytate ratio, the bicadinane index and the kerogen carbon isotope ratio δ of the source rock sample to be tested are calculated. 13 C is projected onto the plate to determine the source rock type of the source rock sample to be tested; 2) when the sample to be tested is a crude oil or condensate oil sample, the pristine / phytane ratio, the bicadinane index and the whole oil carbon isotope ratio δ 13 C' is projected onto the plate to determine the source rock type of the crude oil or condensate oil sample to be tested.

[0014] In the above-mentioned method for distinguishing coal-bearing, terrestrial marine, and marine marine source rocks based on molecular geochemical indicators, the source rock sample and the sample to be tested are from the Qiongdongnan Basin.

[0015] In the above-mentioned method for distinguishing coal-measure, terrigenous marine, and marine-derived marine source rocks based on molecular geochemical indicators, the three different types of source rock samples, including coal-measure, terrigenous marine, and marine-derived marine source rocks, are 78 terrigenous marine source rock samples, 12 marine-derived marine source rock samples, and 2 coal-measure source rock samples.

[0016] In a second aspect, the present invention protects a device for distinguishing coal series, terrestrial marine, and marine marine source rocks based on molecular geochemical indicators, comprising:

[0017] The molecular geochemical index acquisition module is configured to obtain the molecular geochemical index according to the input of the pristine / phyt ratio, the bicadinane index and the kerogen carbon isotope ratio δ of three different types of source rock samples. 13 C, obtain molecular geochemical indicators for distinguishing coal-bearing, terrigenous-marine, and marine-marine source rocks;

[0018] The source rock type discrimination module is configured to determine the source rock type of the sample to be tested according to the input pristine / phytane ratio, bicadinane index and carbon isotope ratio of the sample to be tested, as well as the molecular geochemical indicators used to distinguish coal series, terrestrial marine, and marine marine source rocks, which are divided into the following two types: 1) When the sample to be tested is a source rock sample, the carbon isotope ratio is the kerogen carbon isotope ratio δ 13 C; 2) When the sample to be tested is a crude oil or condensate oil sample, the carbon isotope ratio is the whole oil carbon isotope ratio δ 13 C'.

[0019] In a third aspect, the present invention protects a method for obtaining the contribution ratio of coal-bearing, terrestrial marine, and marine marine source rocks to oil and gas based on molecular geochemical indicators, comprising:

[0020] P1. Test the pristine / phyt ratio, bicadinane index and kerogen carbon isotope ratio δ of three different types of source rock samples, including coal-bearing, terrigenous marine and marine source rocks. 13 C;

[0021] P2, according to the number of samples of each type in the source rock samples and the total value of the pristine / phyt ratio, the total value of the bicadinane index and the kerogen carbon isotope ratio δ 13 C total value, respectively calculate the numerical center of gravity of the pristine / phyt ratio, the numerical center of gravity of the bicadinane index and the kerogen carbon isotope ratio δ of the coal series, terrigenous marine and marine source rock samples in the source rock samples 13 The numerical center of gravity of C is recorded as the coal-bearing source rock end member (Am', Bm', Cm'), the terrestrial marine source rock end member (Ap', Bp', Cp') and the marine marine source rock end member (Aq', Bq', Cq'), where:

[0022] Am', Bm' and Cm' are the numerical centroids of the pristine / phyt ratio, the numerical centroid of the bicadinane index and the kerogen carbon isotope ratio δ 13 The numerical center of gravity of C;

[0023] Ap', Bp' and Cp' are the numerical centroid of the pristine / phyt ratio, the numerical centroid of the bicadinane index and the kerogen carbon isotope ratio δ 13 The numerical center of gravity of C;

[0024] Aq', Bq' and Cq' are the numerical centroid of the pristine / phyt ratio, the numerical centroid of the bicadinane index and the kerogen carbon isotope ratio δ 13 The numerical center of gravity of C;

[0025] P3. Test the pristine / phytane ratio, bicadinane index and whole oil carbon isotope ratio δ of the crude oil or condensate sample to be tested 13 C', denoted as sample point (a1, b1, c1), calculates the contribution rates of coal-bearing, terrestrial-marine and marine-marine source rocks in the crude oil or condensate sample to be tested according to the distances from the crude oil or condensate sample point to the coal-bearing source rock end member, the terrestrial-marine source rock end member and the marine-marine source rock end member.

[0026] In the above method for obtaining the contribution ratio of coal-measure, terrestrial marine, and marine marine source rocks to oil and gas, the numerical centroids of the coal-measure source rock samples are all arithmetic means, which are calculated according to the following formulas:

[0027] Am'=(A1 +A2 +A3 + …Am) / m (1)

[0028] Bm'=(B1 +B2 +B3 + ...Bm) / m (2)

[0029] Cm'=(C1 +C2 +C3 + ...Cm) / m (3)

[0030] In formulas (1)-(3), Am' is the numerical centroid of the Pb / Ph ratio of coal-measure source rock samples, A1, A2, A3, ..., Am are the Pb / Ph ratios of each coal-measure source rock sample, Bm' is the numerical centroid of the bicadinane index of coal-measure source rock samples, B1, B2, B3, ..., Bm are the bicadinane index of each coal-measure source rock sample, and Cm' is the kerogen carbon isotope ratio δ 13 The numerical center of gravity of C, C1, C2, C3, ..., Cm are the kerogen carbon isotope ratios of each coal-bearing source rock sample, δ 13 C, m is the number of coal-measure source rock samples, pieces;

[0031] The numerical centroids of the terrigenous marine source rock samples are all arithmetic means, calculated according to the following formulas:

[0032] Ap'=(A1 +A2 +A3 + …Ap) / p (4)

[0033] Bp'=(B1 +B2 +B3 + ...Bp) / p (5)

[0034] Cp'=(C1 +C2 +C3 + ...Cp) / p (6)

[0035] In formulas (4)-(6), Ap' is the numerical center of gravity of the Pr / Ph ratio of the terrigenous marine source rock sample, A1, A2, A3, ..., Ap are the Pr / Ph ratios of each terrigenous marine source rock sample, Bp' is the numerical center of gravity of the bicadinane index of the terrigenous marine source rock sample, B1, B2, B3, ..., Bp are the bicadinane index of each terrigenous marine source rock sample, Cp' is the kerogen carbon isotope ratio δ 13 The numerical center of gravity of C, C1, C2, C3, ..., Cp are the kerogen carbon isotope ratios of the terrigenous and marine source rock samples, δ 13 C, p is the number of terrigenous marine source rock samples, pieces;

[0036] The numerical centroids of the marine source rock samples are all arithmetic means, which are calculated according to the following formulas:

[0037] Aq'=(A1 +A2 +A3 + ...Aq) / q (7)

[0038] Bq'=(B1 +B2 +B3 + ...Bq) / q (8)

[0039] Cq'=(C1 +C2 +C3 + ...Cq) / q (9)

[0040] In formulas (7)-(9), Aq' is the numerical center of gravity of the Pb / Ph ratio of the marine source rock sample, A1, A2, A3, ..., Aq are the Pb / Ph ratios of each marine source rock sample, Bq' is the numerical center of gravity of the bicadinane index of the marine source rock sample, B1, B2, B3, ..., Bq are the bicadinane index of each marine source rock sample, and Cq' is the kerogen carbon isotope ratio δ 13 The numerical center of gravity of C, C1, C2, C3, …, Cq are the kerogen carbon isotope ratios δ of the marine source rock samples of each source. 13 C, q is the number of marine source rock samples, pieces.

[0041] In the above method for obtaining the contribution ratio of coal-measure, terrestrial marine, and marine source rocks to oil and gas, the contribution ratios of coal-measure, terrestrial marine, and marine source rocks in the crude oil or condensate oil sample are calculated according to the following formulas:

[0042]

[0043] In formulas (10) and (11), Distance 1 is the distance from the sample point to the coal series end member, which is calculated according to the following formula:

[0044]

[0045] In formula (13), a1, b1, and c1 are the pristine / phytane ratio, bicadinane index, and carbon isotope ratio of the crude oil or condensate sample to be tested, respectively. 13 C', Am', Bm' and Cm' are the numerical centroids of the pristine / phyt ratio, the numerical centroid of the bicadinane index and the kerogen carbon isotope ratio δ 13 The numerical center of gravity of C;

[0046] In formulas (10) and (11), Distance 2 is the distance from the crude oil or condensate sample point to the terrestrial marine end member, which is calculated according to the following formula:

[0047]

[0048] In formula (14), a1, b1, and c1 are the pristine / phytane ratio, bicadinane index, and whole oil carbon isotope ratio δ of the crude oil or condensate sample to be tested, respectively. 13 C', Ap', Bp' and Cp' are the numerical centroids of the pristine / phyt ratio, the numerical centroid of the bicadinane index and the kerogen carbon isotope ratio δ13 The numerical center of gravity of C;

[0049] In formulas (10) and (11), Distance 3 is the distance from the crude oil or condensate sample point to the marine end member of the source sea, which is calculated according to the following formula:

[0050]

[0051] In formula (15), a1, b1, and c1 are the pristine / phytane ratio, bicadinane index, and whole oil carbon isotope ratio δ of the crude oil / condensate sample to be tested, respectively. 13 C', Aq', Bq' and Cq' are the numerical centroids of the pristine / phyt ratio, the numerical centroid of the bicadinane index and the kerogen carbon isotope ratio δ 13 The numerical center of gravity of C.

[0052] In a fourth aspect, the present invention provides a device for obtaining the contribution ratio of coal-bearing, terrestrial marine, and marine marine source rocks to oil and gas based on molecular geochemical indicators, comprising:

[0053] The numerical center of gravity acquisition module is configured to obtain the pristine / phyt ratio, bicadinane index and kerogen carbon isotope ratio δ of three different types of source rock samples including coal series, terrigenous marine and marine source rocks according to the input 13 C, to obtain the numerical center of gravity of the pristine / phyt ratio, the numerical center of gravity of the bicadinane index and the kerogen carbon isotope ratio δ of the coal-bearing, terrestrial marine and marine marine source rock samples in the source rock samples 13 The numerical center of gravity of C is recorded as the coal-bearing source rock end member (Am', Bm', Cm'), the terrestrial marine source rock end member (Ap', Bp', Cp') and the marine marine source rock end member (Aq', Bq', Cq'), where:

[0054] Am', Bm' and Cm' are the numerical centroids of the pristine / phyt ratio, the numerical centroid of the bicadinane index and the kerogen carbon isotope ratio δ 13 The numerical center of gravity of C;

[0055] Ap', Bp' and Cp' are the numerical centroid of the pristine / phyt ratio, the numerical centroid of the bicadinane index and the kerogen carbon isotope ratio δ 13 The numerical center of gravity of C;

[0056] Aq', Bq' and Cq' are the numerical centroid of the pristine / phyt ratio, the numerical centroid of the bicadinane index and the kerogen carbon isotope ratio δ 13 The numerical center of gravity of C;

[0057] The contribution ratio calculation module is configured to record the input crude oil / condensate sample's pristine / phytane ratio, bicadinane index and whole oil carbon isotope ratio δ 13 C' is the sample point (a1, b1, c1). According to the distance from the crude oil or condensate oil sample point to the coal-bearing source rock end member, the terrestrial marine source rock end member and the marine marine source rock end member, the contribution rate of coal-bearing, terrestrial marine and marine marine source rocks to oil and gas in the crude oil or condensate oil sample to be tested is calculated.

[0058] The present invention has the following beneficial effects:

[0059] The method of the present invention includes: 1. Determine the molecular geochemical indicators for classifying coal-measure, terrigenous marine, and marine-source source rocks; 2. Use the molecular geochemical indicator plates of the three types of source rocks to identify the source of oil and gas; 3. Use the three-unit mixed source model based on molecular geochemical indicators to calculate the contribution ratio of the three types of source rocks. The method of the present invention is a further development and improvement of the classification of coal-measure and marine source rocks in the northern South China Sea and the oil and gas source comparison method. It can easily and quickly determine the source rock types and oil and gas source analysis in the Qiongdongnan Basin and the northern South China Sea, clarify the types of coal-measure, terrigenous marine, and marine-source source rocks and their contribution ratios to oil and gas, and provide assistance for the deployment and decision-making of the next step of oil and gas exploration in the northern South China Sea. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 This is a flow chart for distinguishing coal-bearing, terrestrial marine, and marine marine source rocks in Example 1 of the present invention, and a flow chart for obtaining the contribution ratio of the three types of source rocks to oil and gas in Example 2.

[0061] Figure 2 Plates 2-1 and 2-2 are for identifying coal-bearing, terrestrial marine, and marine marine source rocks in Example 1 of the present invention.

[0062] Figure 3 This is an oil source analysis chart of crude oil / condensate samples in the Qiongdongnan Basin in Example 1 of the present invention.

[0063] Figure 4 This is a schematic diagram of the contribution ratio calculation of the three-end-member mixing model of the three types of source rocks in Example 2 of the present invention. DETAILED DESCRIPTION

[0064] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0065] The present invention aims to provide a method for distinguishing coal-bearing, terrestrial marine, and marine source rocks based on molecular geochemical indicators and a method for obtaining contribution ratios, in order to analyze and reveal the distribution patterns of coal-bearing, terrestrial marine, and marine source rocks, clarify the sources of oil and gas, and serve the decision-making of oil and gas exploration and development.

[0066] The present invention first provides a method for distinguishing coal-measure, terrigenous marine, and marine source rocks based on molecular geochemical indicators, comprising: S1, testing the pristine / phyt ratio, bicadinane index, and source rock kerogen carbon isotope ratio δ of three different types of source rock samples, including coal-measure, terrigenous marine, and marine source rocks. 13 C, to obtain molecular geochemical indicators for distinguishing coal series, terrigenous marine, and marine marine source rocks; S2, to test the pristine / phytane ratio, bicadinane index, and carbon isotope ratio of the sample to be tested, which are divided into the following two types: 1) When the sample to be tested is a source rock sample, the carbon isotope ratio is the kerogen carbon isotope ratio δ 13 C, according to the molecular geochemical index used to distinguish coal-bearing, terrestrial marine, marine marine source rocks, determine the source rock type of the source rock sample to be tested; 2) when the sample to be tested is a crude oil or condensate oil sample, the carbon isotope ratio is the whole oil carbon isotope ratio δ 13 C', according to the molecular geochemical index used to distinguish coal-bearing, terrestrial marine, marine marine source rocks, determine the source rock type of the crude oil or condensate sample. In the present invention, the sample types are divided into source rock samples and whole oil / condensate samples. When it is a whole oil / condensate sample, since there is no kerogen in the crude oil / condensate and the values ​​of the two are close, the whole oil carbon isotope ratio δ of the crude oil / condensate sample is tested. 13 C' and use this value to replace the kerogen carbon isotope ratio δ 13 C and kerogen carbon isotope ratios in molecular geochemical indicators δ 13 C is compared to determine the source rock type of the crude oil / condensate oil. The method of the present invention can not only identify the type of source rock samples, but also preliminarily identify which type of source rock the crude oil and condensate oil samples mainly come from. The method of the present invention can quickly and reasonably identify the type of source rock and the source of oil and gas, serve the decision-making of oil and gas exploration and development, and has great promotion and application value.

[0067] like Figure 1 As shown in the figure, one of the key technologies of the present invention is the selection of geochemical indicators for identifying coal-bearing, terrestrial marine, and marine source rocks. The inventors have screened out the pristine / phytate ratio, the bicadinane index, and the carbon isotope ratio of the source rock kerogen δ 13 C is a geochemical indicator for identifying three types of source rocks.

[0068] According to the present invention, kerogen is dispersed organic matter that is insoluble in alkali, non-oxidizing acid and non-polar organic solvent. Further, the carbon isotope ratio of the kerogen is δ 13 C is obtained by carbon isotope testing after the source rock sample is processed to obtain kerogen. The whole oil carbon isotope ratio δ 13 C is obtained by carbon isotope testing of crude oil samples. As an example, the kerogen carbon isotope ratio δ 13 C can be tested by the following steps: after removing carbonate minerals from the rock with hydrochloric acid and silicate minerals with hydrofluoric acid, washing to the center of gravity with distilled water, separating the heavy liquid by flotation and freeze-drying to obtain the sample; kerogen carbon isotope and whole oil carbon isotope analysis are completed using Vario Isotope Cube-Isprime 100 stable isotope mass spectrometer, and the kerogen carbon isotope ratio δ 13 C and whole oil carbon isotope ratio δ 13 C',‰.

[0069] In the above method, the pristane / phytane ratio and the bicadinane index of the source rock and crude oil / condensate are parameters for separating saturated hydrocarbons from organic matter, which can be specifically obtained by gas chromatography-mass spectrometry analysis of saturated hydrocarbons of the sample. The separation of saturated hydrocarbons and the pristane / phytane ratio and bicadinane index of saturated hydrocarbon gas chromatography-mass spectrometry analysis can be obtained by the following steps: the source rock is crushed to 200 meshes and subjected to Soxhlet extraction for 72 hours to obtain chloroform bitumen A; the extracted chloroform bitumen A and crude oil / condensate are separated by group component chromatography, asphaltene is precipitated by n-hexane, the soluble matter is passed through an alumina chromatography column activated at 400°C for 4 hours, and saturated hydrocarbons are eluted by n-hexane (the saturated hydrocarbon component is concentrated to 2 ml without drying); pristane and phytane in saturated hydrocarbons are detected by Agilent 7890B gas chromatography-mass spectrometry, and the detection standard refers to GB / T 18340.5-2010 "Organic geochemical analysis methods for geological samples: Part 5: Analysis of saturated hydrocarbons in rock extracts and crude oil-gas chromatography". The pristane / phytane ratio is the peak area ratio of pristane and phytane in gas chromatography. The bicadinane index can be obtained by the following steps: using an Agilent 7890B-Agilent 5977B chromatograph-mass spectrometer for detection, wherein bicadinane compounds W, T and C 30 The relative abundance of αβ-hopane compounds was determined by the peak area in the chromatogram of m / z 412, and the cadinane index was calculated as (W+T) / C 30 The kerogen / whole oil carbon isotope was determined using a Vario Isotope Cube-Isprime 100 stable isotope mass spectrometer, recording the kerogen carbon isotope ratio δ 13 C or whole oil carbon isotope ratio δ 13According to the present invention, further, the molecular geochemical indicators used to distinguish coal-bearing, terrestrial marine, and marine marine source rocks are as follows: Coal-bearing source rocks: kerogen carbon isotope ratio δ 13 C<-27‰, pristine / phyt ratio>5, bicadinane index>6; terrigenous marine source rocks: -26‰<kerogen carbon isotope ratio-27‰<δ 13 C<-25.5‰, 1.1<Pr / Ph<5, Bicadinane index<6; Marine source rock: kerogen carbon isotope ratio δ 13 C>-25.5‰, pristine / phyt ratio<1.1, and cadinane index<6. Among them, the molecular geochemical indicators used to distinguish coal-bearing, terrigenous marine, and marine-derived marine source rocks can be combined with the development law of source rocks, the source of organic matter, and the sedimentary environment analysis. In coal-bearing source rocks, higher plant organic matter dominated by C3 plants is relatively enriched (kerogen carbon isotope <-27‰), the sedimentary environment is highly oxidizing (high pristine / phyt ratio, >5), and the organic matter contains a high content of cadinane derived from resin deposited in situ (cadinane index>6); terrigenous marine source rocks are dominated by higher plant organic matter that has been transported far away, and marine algae with heavier carbon isotopes have less contribution (-26‰<kerogen carbon isotope<-27‰), The sedimentary environment is highly oxidizing (1.1<Pr / Ph<5), and the content of dicedinane derived from original deposited resin is moderate to low (dicedinane index <6); the marine source rocks are mainly composed of higher plants and marine algae organic matter, with a greater contribution from marine algae (kerogen carbon isotope>-25‰), and the sedimentary environment is highly reducing (low Pr / Ph<1.1), and the content of dicedinane derived from resin is moderate to low (dicedinane index <6).

[0070] like Figure 1 As shown, step S1 also includes: using the pristine / phyt ratio, bicadinane index and kerogen carbon isotope ratio δ of the three different types of source rock samples 13 C constructs geochemical identification plates 2-1 and 2-2 for coal series, terrestrial marine, and marine marine source rocks; in step S2, it also includes any of the following: 1) when the sample to be tested is a source rock sample, the pristine / phytate ratio, the bicadinane index, and the kerogen carbon isotope ratio δ of the source rock sample to be tested are calculated; 13 C is projected onto Plate 2-1 and Plate 2-2 to determine the source rock type of the source rock sample to be tested; 2) when the sample to be tested is a crude oil or condensate oil sample, the pristine / phytane ratio, the bicadinane index and the whole oil carbon isotope ratio δ 13 C' is projected onto the plate to determine the source rock type (crude oil / condensate source) of the crude oil or condensate sample to be tested.

[0071] like Figure 2As shown, in an optional embodiment of the present invention, the ratio of pristine to plant origin of the source rock sample is taken as the horizontal coordinate, and the bicadinane index (W+T) / C 30 αβ-hopane is used as the ordinate, and the boundary lines of Pr-Ph-V ratio = 1.1 and Pr-Ph-V ratio = 5 are made using office powerpoint or other mapping software. Three types of source rock areas are determined according to the data range, and Plate 2-1 is obtained. The carbon isotope ratio of the kerogen of the source rock sample δ 13 C is the ordinate, making the boundary line δ 13 C = -25.5‰ and δ 13 C = -27.0‰, three types of source rock areas are determined according to the data range, and Plate 2-2 is obtained. Finally, Plates 2-1 and 2-2 are obtained to distinguish coal-bearing, terrestrial marine, and marine marine source rocks; the pristine / phytate ratio, bicadinane index, and kerogen / whole oil carbon isotope ratio of the source rock or crude oil / condensate sample to be tested are projected onto Plates 2-1 and 2-2 ( Figure 2 ), according to the region to which the source rock and crude oil / condensate samples belong, the source rock type of the source rock sample to be tested can be determined, and the source of oil and gas can also be identified by using the molecular geochemical indicator plates of the three types of source rocks and crude oil / condensate.

[0072] According to the present invention, the three different types of source rock samples including coal-measure, terrestrial marine and marine marine source rocks are terrestrial marine, marine marine and coal-measure source rock samples of the sedimentary facies belts confirmed by drilling. In an optional embodiment of the present invention, the three different types of source rock samples including coal-measure, terrestrial marine and marine marine source rocks and the samples to be tested are from the Qiongdongnan Basin. The number of samples can be adjusted according to actual conditions, such as 78 terrestrial marine, 12 marine marine and 2 coal-measure source rock samples.

[0073] Secondly, the present invention also provides a device for distinguishing coal series, terrestrial marine, and marine marine source rocks based on molecular geochemical indicators, including: a molecular geochemical indicator acquisition module, configured to obtain the molecular geochemical indicator according to the input of the pristine / phytate ratio, the bicadinane index, and the kerogen carbon isotope ratio δ of three different types of source rock samples; 13 C, to obtain molecular geochemical indicators for distinguishing coal-bearing, terrestrial marine, and marine marine source rocks; the source rock type discrimination module is configured to identify the type of source rock according to the input pristine / phytate ratio, bicadinane index, and kerogen carbon isotope ratio δ 13 C, and the molecular geochemical index used to distinguish coal series, terrestrial marine, marine marine source rocks, and determine the source rock type of the sample to be tested, which is divided into the following two types: 1) When the sample to be tested is a source rock sample, the carbon isotope ratio is the kerogen carbon isotope ratio δ 13 C; 2) When the sample to be tested is a crude oil or condensate oil sample, the carbon isotope ratio is the whole oil carbon isotope ratio δ13 C'.

[0074] The present invention further provides a method for obtaining the contribution ratio of coal-measure, terrigenous marine and marine source rocks based on molecular geochemical indicators, comprising: P1, testing the pristine / phyt ratio, bicadinane index and kerogen carbon isotope ratio δ of three different types of source rock samples including coal-measure, terrigenous marine and marine source rocks. 13 P2, according to the number of each type of samples in the source rock samples and the total value of the pristine / phyt ratio, the total value of the bicadinane index and the total value of the kerogen carbon isotope ratio δ13C of each type of sample, respectively calculate the numerical center of gravity of the pristine / phyt ratio, the numerical center of gravity of the bicadinane index and the kerogen carbon isotope ratio δ13C of the coal-bearing, terrestrial marine and marine marine source rock samples in the source rock samples 13 The numerical centroids of C are recorded as coal-bearing source rock end members (Am', Bm', Cm'), terrestrial marine source rock end members (Ap', Bp', Cp') and marine marine source rock end members (Aq', Bq', Cq'), where Am', Bm' and Cm' are the numerical centroids of the pristine / phyt ratio of coal-bearing source rock samples, the numerical centroids of the bicadinane index and the kerogen carbon isotope ratio δ 13 C; Ap', Bp' and Cp' are the numerical center of gravity of the pristine / phyt ratio, the numerical center of gravity of the bicadinane index and the kerogen carbon isotope ratio δ 13 C; Aq', Bq' and Cq' are the numerical center of gravity of the pristine / phyt ratio, the numerical center of gravity of the bicadinane index and the kerogen carbon isotope ratio δ 13 C; P3, test the pristine / phytate ratio, bicadinane index and whole oil carbon isotope ratio δ of the crude oil / condensate sample to be tested 13 C', denoted as sample point (a1, b1, c1), calculates the contribution rates of coal-bearing, terrestrial-marine and marine-marine source rocks in the crude oil or condensate sample to be tested according to the distances from the crude oil or condensate sample point to the coal-bearing source rock end member, the terrestrial-marine source rock end member and the marine-marine source rock end member.

[0075] The method of the present invention can be used to calculate the contribution ratios of the three types of source rocks, further serving the decision-making of oil and gas exploration and development.

[0076] like Figure 1 As shown in the figure, similar to the above-mentioned method for distinguishing coal-bearing, terrestrial marine, and marine marine source rocks, the present invention also needs to select geochemical indicators for distinguishing the three types of source rocks when calculating the contribution ratios of the three types of source rocks. Both of them rely on the pristine / phytane ratio, the bicadinane index, and the carbon isotope ratio of the source rock kerogen, δ 13C, as a geochemical indicator for identifying three types of source rocks.

[0077] like Figure 1 As shown in Figure 2, in order to confirm the relevant geochemical indicators, it is necessary to first construct a three-end member mixing model based on molecular geochemical indicators, that is, according to the number of samples of each type in the source rock sample and the total value of the pristine / phyt ratio, the total value of the bicadinane index and the kerogen carbon isotope ratio δ 13 C total value, respectively calculate the numerical center of gravity of the pristine / phyt ratio, the numerical center of gravity of the bicadinane index and the kerogen carbon isotope ratio δ of the coal series, terrigenous marine and marine source rock samples in the source rock samples 13 In an optional embodiment of the present invention, the numerical centroids of the coal-bearing source rock samples are all arithmetic means, which are calculated according to the following formulas:

[0078] Am'=(A1 +A2 +A3 + …Am) / m (1)

[0079] Bm'=(B1 +B2 +B3 + ...Bm) / m (2)

[0080] Cm'=(C1 +C2 +C3 + ...Cm) / m (3)

[0081] In formulas (1)-(3), Am' is the numerical centroid of the Pb / Ph ratio of coal-measure source rock samples, A1, A2, A3, ..., Am are the Pb / Ph ratios of each coal-measure source rock sample, Bm' is the numerical centroid of the bicadinane index of coal-measure source rock samples, B1, B2, B3, ..., Bm are the bicadinane index of each coal-measure source rock sample, and Cm' is the kerogen carbon isotope ratio δ 13 The numerical center of gravity of C, C1, C2, C3, ..., Cm are the kerogen carbon isotope ratios of each coal-bearing source rock sample, δ 13 C, m is the number of coal-measure source rock samples, pieces;

[0082] The numerical centroids of the terrigenous marine source rock samples are all arithmetic means, calculated according to the following formulas:

[0083] Ap'=(A1 +A2 +A3 + …Ap) / p (4)

[0084] Bp'=(B1 +B2 +B3 + ...Bp) / p (5)

[0085] Cp'=(C1 +C2 +C3 + ...Cp) / p (6)

[0086] In formulas (4)-(6), Ap' is the numerical center of gravity of the Pr / Ph ratio of the terrigenous marine source rock sample, A1, A2, A3, ..., Ap are the Pr / Ph ratios of each terrigenous marine source rock sample, Bp' is the numerical center of gravity of the bicadinane index of the terrigenous marine source rock sample, B1, B2, B3, ..., Bp are the bicadinane index of each terrigenous marine source rock sample, Cp' is the kerogen carbon isotope ratio δ 13 The numerical center of gravity of C, C1, C2, C3, ..., Cp are the kerogen carbon isotope ratios of the terrigenous and marine source rock samples, δ 13 C, p is the number of terrigenous marine source rock samples, pieces;

[0087] The numerical centroids of the marine source rock samples are all arithmetic means, which are calculated according to the following formulas:

[0088] Aq'=(A1 +A2 +A3 + ...Aq) / q (7)

[0089] Bq'=(B1 +B2 +B3 + ...Bq) / q (8)

[0090] Cq'=(C1 +C2 +C3 + ...Cq) / q (9)

[0091] In formulas (7)-(9), Aq' is the numerical center of gravity of the Pb / Ph ratio of the marine source rock sample, A1, A2, A3, ..., Aq are the Pb / Ph ratios of each marine source rock sample, Bq' is the numerical center of gravity of the bicadinane index of the marine source rock sample, B1, B2, B3, ..., Bq are the bicadinane index of each marine source rock sample, and Cq' is the kerogen carbon isotope ratio δ 13 The numerical center of gravity of C, C1, C2, C3, …, Cq are the kerogen carbon isotope ratios δ of the marine source rock samples of each source. 13 C, q is the number of marine source rock samples, pieces.

[0092] The method for distinguishing coal-measure, terrestrial marine, and marine marine source rocks, the sample types include three different types of coal-measure, terrestrial marine, and marine marine source rocks, and the three different types of source rock samples including coal-measure, terrestrial marine, and marine marine source rocks are terrestrial marine, marine marine, and coal-measure source rock samples of the sedimentary facies belts that have been confirmed by drilling. In an optional embodiment of the present invention, the three different types of source rock samples including coal-measure, terrestrial marine, and marine marine source rocks and the samples to be tested are from the Qiongdongnan Basin. The number of samples can be adjusted according to actual conditions. The more the number of three types of source rocks, the higher the accuracy of the discrimination method. Taking the Qiongdongnan Basin as an example, it includes 78 terrestrial marine, 12 marine marine, and 2 coal-measure source rock samples.

[0093] In the above method, it is further preferred that the contribution rates of coal-bearing, terrestrial marine, and marine marine source rocks in the crude oil or condensate oil sample to be tested are calculated according to the following formulas:

[0094]

[0095] In formulas (10) and (11), Distance 1 is the distance from the sample point to the coal series end member, which is calculated according to the following formula:

[0096]

[0097] In formula (13), a1, b1, and c1 are the pristine / phytane ratio, bicadinane index, and whole oil carbon isotope ratio δ of the crude oil or condensate sample to be tested. 13 C', Am', Bm' and Cm' are the numerical centroids of the pristine / phyt ratio, the numerical centroid of the bicadinane index and the kerogen carbon isotope ratio δ 13 The numerical center of gravity of C;

[0098] In formulas (10) and (11), Distance 2 is the distance from the sample point to the terrigenous marine end member, which is calculated according to the following formula:

[0099]

[0100] In formula (14), a1, b1, and c1 are the pristine / phytane ratio, bicadinane index, and whole oil carbon isotope ratio δ of the crude oil or condensate sample to be tested. 13 C', Ap', Bp' and Cp' are the numerical centroids of the pristine / phyt ratio, the numerical centroid of the bicadinane index and the kerogen carbon isotope ratio δ 13 The numerical center of gravity of C;

[0101] In formulas (10) and (11), Distance 3 is the distance from the crude oil or condensate sample point to the marine end member of the source sea, which is calculated according to the following formula:

[0102]

[0103] In formula (15), a1, b1, and c1 are the pristine / phytane ratio, bicadinane index, and carbon isotope ratio of the crude oil or condensate sample to be tested, δ 13 C', Aq', Bq' and Cq' are the numerical centroids of the pristine / phyt ratio, the numerical centroid of the bicadinane index and the kerogen carbon isotope ratio δ 13 The numerical center of gravity of C.

[0104] According to the present invention, the contribution of the three end members to the crude oil or condensate oil sample point (a1, b1, c1) is the contribution rate of the inverse of the distance from the sample point to the three end members. The smaller the spatial distance between the crude oil or condensate oil sample point and a certain type of source rock end member, the greater the contribution of this end member to the sample point.

[0105] The present invention also provides a device for obtaining the contribution ratio of coal-measure, terrigenous marine and marine source rocks based on molecular geochemical indicators, comprising: a numerical center of gravity acquisition module, configured to obtain the contribution ratio of coal-measure, terrigenous marine and marine source rocks according to the input of three different types of source rock samples including coal-measure, terrigenous marine and marine source rocks, the pristine / phytane ratio, the bicadinane index and the kerogen carbon isotope ratio δ 13 C, to obtain the numerical center of gravity of the pristine / phyt ratio, the numerical center of gravity of the bicadinane index and the kerogen carbon isotope ratio δ of the coal-bearing, terrestrial marine and marine marine source rock samples in the source rock samples 13 The numerical centroids of C are recorded as coal-bearing source rock end members (Am', Bm', Cm'), terrestrial marine source rock end members (Ap', Bp', Cp') and marine marine source rock end members (Aq', Bq', Cq'), where Am', Bm' and Cm' are the numerical centroids of the pristine / phyt ratio of coal-bearing source rock samples, the numerical centroids of the bicadinane index and the kerogen carbon isotope ratio δ 13 C; Ap', Bp' and Cp' are the numerical center of gravity of the pristine / phyt ratio, the numerical center of gravity of the bicadinane index and the kerogen carbon isotope ratio δ 13 C; Aq', Bq' and Cq' are the numerical center of gravity of the pristine / phyt ratio, the numerical center of gravity of the bicadinane index and the kerogen carbon isotope ratio δ 13 C; the contribution ratio calculation module is configured to record the input crude oil or condensate sample to be tested, the pristine / phytane ratio, the bicadinane index and the whole oil isotope ratio δ 13 C' is the sample point (a1, b1, c1). According to the distance from the crude oil or condensate oil sample point to the coal-bearing source rock end member, the terrestrial marine source rock end member and the marine marine source rock end member, the contribution rate of the coal-bearing, terrestrial marine and marine marine source rocks in the crude oil or condensate oil sample to be tested is calculated.

[0106] 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.

[0107] The methods used in the following examples, unless otherwise specified, are all conventional methods, carried out according to the techniques or conditions described in the literature in the art or according to the product instructions. The materials, reagents, etc. used in the following examples, unless otherwise specified, can all be obtained from commercial sources.

[0108] Example 1: Identification of coal-bearing, terrestrial marine and marine source rocks based on molecular geochemistry

[0109] Step S1, testing the pristine / phyt ratio, bicadinane index and kerogen carbon isotope ratio δ of three different types of source rock samples including coal series, terrigenous marine and marine source rocks 13 C. Obtaining molecular geochemical indicators for distinguishing coal-bearing, terrestrial marine, and marine marine source rocks. The specific steps are as follows:

[0110] S1.1: Through a large amount of saturated hydrocarbon chromatography and chromatography-mass spectrometry data of coal-bearing, terrestrial marine, and marine marine source rocks, the geochemical indicators for distinguishing these three types of source rocks are determined.

[0111] Taking the Qiongdongnan Basin as an example, based on the measured saturated hydrocarbon pristine / phyt ratios, bicadinane index and kerogen carbon isotope ratios δ1 of 78 terrigenous marine, 12 marine marine and 2 coal-bearing source rock samples in the sedimentary facies belt confirmed by drilling, the results show that the saturated hydrocarbon pristine / phyt ratios, bicadinane index and kerogen carbon isotope ratios δ1 of kerogen are 96.8%, 97.3% and 96.7% respectively. 13 C, establish molecular geochemical indicators for distinguishing coal-bearing, terrestrial marine, and marine source rocks (Table 1). The pristane / phytane ratio is the peak area ratio of pristane and phytane in gas chromatography. The bicadinane index can be obtained by the following steps: using an Agilent 7890B-Agilent 5977B chromatograph-mass spectrometer for detection, wherein bicadinane compounds W, T and C 30 The relative abundance of αβ-hopane compounds was determined by the peak area in the chromatogram of m / z 412, and the cadinane index was calculated as (W+T) / C 30 αβhopane. The kerogen isotope is completed using a Vario Isotope Cube-Isprime 100 stable isotope mass spectrometer, recording the kerogen carbon isotope or whole oil carbon isotope ratio, ‰.

[0112] Table 1 Molecular geochemical indicators for distinguishing coal-bearing, terrigenous marine, and marine source rocks

[0113] Molecular geochemical parameters Coal-bearing source rocks Terrigenous marine source rock Marine source rocks grandma / value ratio >5 1.1～5 <1.1 Bicadinane Index >6 <6 <6 Kerogen carbon isotopes <-27‰ -27‰～-25.5‰ >-25.5‰

[0114] The bicadinane index (W+T) / C is taken as the horizontal axis, with the ratio of Pb / T of source rock samples as the horizontal axis. 30αβ-hopane is used as the ordinate, and the boundary lines of Pr-Ph = 1.1 and Pr-Ph = 5 are made using mapping software. Three types of source rock areas are determined based on the data range, and Plate 2-1 is obtained. The carbon isotope ratio of kerogen in source rock samples δ 13 C is the ordinate, making the boundary line δ 13 C = -25.5‰ and δ 13 C = -27.0‰. Three types of source rock areas are determined based on the data range, and Plate 2-2 is obtained.

[0115] Step S2, testing the pristine / phytane ratio, bicadinane index and kerogen carbon isotope of the sample to be tested, and determining the source rock type of the sample to be tested according to the molecular geochemical indicators used to distinguish coal-bearing, terrestrial marine and marine marine source rocks, and specifically using the molecular geochemical indicator plates of the three types of source rocks to identify the source of oil and gas, the steps are as follows:

[0116] S2.1: Select typical crude oil / condensate samples in the Qiongdongnan Basin: crude oil E13-1, crude oil E13-2, crude oil A10-6, condensate D21-1 and condensate C36-2; test the pristine / phytane ratio, bicadinane index and whole oil carbon isotope ratio δ of crude oil or condensate samples 13 C', the sampling point where the crude oil / condensate sample is obtained;

[0117] S2.2: The typical crude oil / condensate samples of the Qiongdongnan Basin are respectively projected onto the Pr / Ph ratio, Bicadinane Index Plate 2-1, and Whole Oil / Kerogen Carbon Isotope Plate 2-2 ( Figure 2 ), it is preliminarily determined that the crude oils of E13-1 and E13-2 are mainly derived from coal-bearing source rocks, the crude oil of A10-6 is mainly derived from marine source rocks, and the condensate oils of D21-1 and C36-2 are mainly derived from terrestrial marine source rocks. Figure 3 .

[0118] Example 2: Obtaining the contribution ratio P1 of coal-measure, terrigenous marine, and marine source rocks based on molecular geochemical indicators; Testing the pristine / phyt ratio, bicadinane index, and kerogen carbon isotope ratio δ of three different types of source rock samples, including coal-measure, terrigenous marine, and marine source rocks 13 C, the specific steps are as follows: the source rock samples are the same as in Example 1. Taking the Qiongdongnan Basin as an example, based on the saturated hydrocarbon pristine / phyt ratio, bicadinane index and kerogen carbon isotope number δ of 78 terrigenous marine source rocks, 12 marine marine source rocks and 2 coal-bearing source rock samples, the 13 C.

[0119] P2. Calculate the numerical center of gravity of coal-bearing source rock samples according to the following formula:

[0120] Am'=(A1 +A2 +A3 + …Am) / m (1)

[0121] Bm'=(B1 +B2 +B3 + ...Bm) / m (2)

[0122] Cm'=(C1 +C2 +C3 + ...Cm) / m (3)

[0123] In formulas (1)-(3), Am' is the numerical centroid of the Pb / Ph ratio of coal-measure source rock samples, A1, A2, A3, ..., Am are the Pb / Ph ratios of each coal-measure source rock sample, Bm' is the numerical centroid of the bicadinane index of coal-measure source rock samples, B1, B2, B3, ..., Bm are the bicadinane index of each coal-measure source rock sample, and Cm' is the kerogen carbon isotope ratio δ 13 The numerical center of gravity of C, C1, C2, C3, ..., Cm are the kerogen carbon isotope ratios of each coal-bearing source rock sample, δ 13 C, m is the number of coal-measure source rock samples, pieces;

[0124] The numerical centroids of the terrigenous marine source rock samples were calculated according to the following formula:

[0125] Ap'=(A1 +A2 +A3 + …Ap) / p (4)

[0126] Bp'=(B1 +B2 +B3 + ...Bp) / p (5)

[0127] Cp'=(C1 +C2 +C3 + ...Cp) / p (6)

[0128] In formulas (4)-(6), Ap' is the numerical center of gravity of the Pr / Ph ratio of the terrigenous marine source rock sample, A1, A2, A3, ..., Ap are the Pr / Ph ratios of each terrigenous marine source rock sample, Bp' is the numerical center of gravity of the bicadinane index of the terrigenous marine source rock sample, B1, B2, B3, ..., Bp are the bicadinane index of each terrigenous marine source rock sample, Cp' is the kerogen carbon isotope ratio δ 13 The numerical center of gravity of C, C1, C2, C3, ..., Cp are the kerogen carbon isotope ratios of the terrigenous and marine source rock samples, δ 13 C, p is the number of terrigenous marine source rock samples, pieces;

[0129] The numerical centroids of marine source rock samples were calculated according to the following formula:

[0130] Aq'=(A1 +A2 +A3 + ...Aq) / q (7)

[0131] Bq'=(B1 +B2 +B3 + ...Bq) / q (8)

[0132] Cq'=(C1 +C2 +C3 + ...Cq) / q (9)

[0133] In formulas (7)-(9), Aq' is the numerical center of gravity of the Pb / Ph ratio of the marine source rock sample, A1, A2, A3, ..., Aq are the Pb / Ph ratios of each marine source rock sample, Bq' is the numerical center of gravity of the bicadinane index of the marine source rock sample, B1, B2, B3, ..., Bq are the bicadinane index of each marine source rock sample, and Cq' is the kerogen carbon isotope ratio δ 13 The numerical center of gravity of C, C1, C2, C3, …, Cq are the kerogen carbon isotope ratios δ of the marine source rock samples of each source. 13 C, q is the number of marine source rock samples, pieces.

[0134] From this, it is calculated that the coal-bearing source rock end members in the three end members are (Am', Bm', Cm'), the terrestrial marine source rock end members are (Ap', Bp', Cp'), and the marine marine source rock end members are (Aq', Bq', Cq'). The results are as follows: the centroid coordinates of the pristine / phytane ratio, bicadinane index, and kerogen carbon isotope value of the coal-bearing source end member are (8.0, 13.8, -28‰), the corresponding coordinates of the terrestrial marine end member are (2.45, 0.65, -26.5‰), and the corresponding coordinates of the marine marine source end member are (0.86, 0.64, -24.6‰).

[0135] P3. As in Example 1, typical crude oil or condensate samples were selected from the Qiongdongnan Basin: crude oil E13-1, E13-2, A10-6, B29-1 condensate D21-1, condensate C36-2 (corresponding to Table 2), and the pristine / phytane ratio, bicadinane index and whole oil isotope ratio δ of each crude oil / condensate sample to be tested were tested respectively. 13 C', denoted as sample point (a1, b1, c1);

[0136] like Figure 4 As shown in the figure, the contribution rates of coal-bearing, terrestrial marine, and marine marine source rocks in the crude oil or condensate oil sample to be tested are calculated according to the following formulas:

[0137]

[0138] In formulas (10) and (11), Distance 1 is the distance from the sample point to the coal series end member, which is calculated according to the following formula:

[0139]

[0140] In formula (13), a1, b1, and c1 are the pristine / phytane ratio, bicadinane index, and carbon isotope ratio of the whole oil in the crude oil or condensate sample to be tested, respectively. 13 C', Am', Bm' and Cm' are the numerical centroids of the pristine / phyt ratio, the numerical centroid of the bicadinane index and the kerogen carbon isotope ratio δ 13 The numerical center of gravity of C;

[0141] In formulas (10) and (11), Distance 2 is the distance from the crude oil or condensate sample point to the terrestrial marine end member, which is calculated according to the following formula:

[0142]

[0143] In formula (14), a1, b1, and c1 are the pristine / phytane ratio, bicadinane index, and carbon isotope ratio of the whole oil in the crude oil or condensate sample to be tested, respectively. 13 C', Ap', Bp' and Cp' are the numerical centroids of the pristine / phyt ratio, the numerical centroid of the bicadinane index and the kerogen carbon isotope ratio δ 13 The numerical center of gravity of C;

[0144] In formulas (10) and (11), Distance 3 is the distance from the sample point to the marine end member of the source sea, which is calculated according to the following formula:

[0145]

[0146] In formula (15), a1, b1, and c1 are the pristine / phytane ratio, bicadinane index, and whole oil isotope ratio δ in the crude oil or condensate sample to be tested, respectively. 13 'C, Aq', Bq' and Cq' are the numerical centroid of the pristine / phyt ratio, the numerical centroid of the bicadinane index and the kerogen carbon isotope ratio δ 13 The numerical center of gravity of C.

[0147] The pristine / phyt ratio, bicadinane index and whole oil carbon isotope of 6 crude oil or condensate samples in the Qiongdongnan Basin are shown in Table 1. Among them, previous studies have shown that crude oil samples E13-1 and E13-2 are crude oils mainly derived from coal-bearing source rocks in the Ya 13-1 structure in the Qiongdongnan Basin.

[0148] Table 2 Pr / Ph ratio, bicadinane index and whole oil carbon isotope of six crude oil or condensate samples from Qiongdongnan Basin

[0149] Crude oil / condensate samples grandma / plant ratio Bicadinane Index Total oil carbon isotope (‰) E13-1 9.70 13.1 -26.8 E13-2 9.11 10.8 -27.0 A10-6 0.72 0.25 -24.9 B29-1 7.5 2.52 -26.7 C36-2 3.67 0.67 -27.3 D21-1 4.1 5.6 -25.7

[0150] Therefore, the calculation results of the contribution rates of coal-measure, terrestrial marine, and marine marine source rock end members in typical crude oil / condensate samples in the Qiongdongnan Basin are shown in Table 3:

[0151] Table 3 Calculation results of the contribution ratios of coal-bearing, terrestrial marine, and marine marine source rocks in typical crude oil / condensate samples in the Qiongdongnan Basin

[0152]

[0153] Those skilled in the art should understand that the discussion of the above embodiments is merely illustrative and is not intended to imply that the scope of the present invention (including the claims) is limited to these examples. Under the concept of the present invention, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the present invention as described above.

[0154] The present invention is intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for distinguishing coal-bearing, terrestrial marine, and marine marine source rocks based on molecular geochemical indicators, characterized in that: include: S1. Test the pristine / phyt ratio, bicadinane index and kerogen carbon isotope ratio δ of three different types of source rock samples, including coal-bearing, terrigenous marine and marine source rocks. 13 C, obtain molecular geochemical indicators for distinguishing coal-bearing, terrigenous-marine, and marine-marine source rocks; S2. Testing the pristine / phyt ratio, bicadinane index and carbon isotope ratio of the sample to be tested, which are divided into the following two types: 1) When the sample to be tested is a source rock sample, the carbon isotope ratio is the kerogen carbon isotope ratio δ 13 C, according to the molecular geochemical index used to distinguish coal-bearing, terrestrial marine, marine marine source rocks, determine the type of source rock sample to be tested; 2) when the sample to be tested is a crude oil or condensate oil sample, the carbon isotope ratio is the whole oil carbon isotope ratio δ 13 C', determine the type of source rock from which the crude oil or condensate oil sample originates based on the molecular geochemical indicators used to distinguish coal-bearing, terrestrial marine, and marine marine source rocks.

2. The method for distinguishing coal-bearing, terrestrial marine, and marine marine source rocks based on molecular geochemical indicators according to claim 1, characterized in that: The molecular geochemical indicators used to distinguish coal-bearing, terrestrial marine, and marine marine source rocks are as follows: Coal-bearing source rocks: kerogen carbon isotope ratio δ 13 C<-27‰, mu / plant ratio>5, dijunipane index>6; Terrigenous marine source rock: -26‰<kerogen carbon isotope ratio -27‰<δ 13 C<-25.5‰, 1.1<mu / plant ratio<5, dijunipane index<6; Marine source rocks: kerogen carbon isotope ratio δ 13 C>-25.5‰, basal / plant ratio <1.1, dijunipane index <6.

3. The method for distinguishing coal-bearing, terrestrial marine, and marine marine source rocks based on molecular geochemical indicators according to any one of claims 1 to 2, characterized in that: Step S1 also includes: using the pristine / phyt ratio, bicadinane index and kerogen carbon isotope ratio δ of the three different types of source rock samples to obtain the 13 C. Construct geochemical identification charts for coal-bearing, terrestrial marine, and marine marine source rocks; Step S2 further includes any of the following: 1) when the sample to be tested is a source rock sample, the pristine / phytate ratio, the bicadinane index and the kerogen carbon isotope ratio δ of the source rock sample to be tested are calculated. 13 C is projected onto the plate to determine the source rock type of the source rock sample to be tested; 2) when the sample to be tested is a crude oil or condensate oil sample, the pristine / phytane ratio, the bicadinane index and the whole oil carbon isotope ratio δ 13 C' is projected onto the plate to determine the source rock type from which the crude oil or condensate oil sample to be tested originates.

4. The method for distinguishing coal-bearing, terrestrial marine, and marine marine source rocks based on molecular geochemical indicators according to any one of claims 1 to 3, characterized in that: The source rock samples and the samples to be tested are from the Qiongdongnan Basin.

5. The method for distinguishing coal-bearing, terrestrial marine, and marine marine source rocks based on molecular geochemical indicators according to any one of claims 1 to 4, characterized in that: The three different types of source rock samples, including coal-bearing, terrestrial marine and marine marine source rocks, are 78 terrestrial marine source rock samples, 12 marine marine source rock samples and 2 coal-bearing source rock samples.

6. A device for distinguishing coal-bearing, terrestrial marine, and marine marine source rocks based on molecular geochemical indicators, characterized in that: include: The molecular geochemical index acquisition module is configured to obtain the molecular geochemical index according to the input of the pristine / phyt ratio, the bicadinane index and the kerogen carbon isotope ratio δ of three different types of source rock samples. 13 C, obtain molecular geochemical indicators for distinguishing coal-bearing, terrigenous-marine, and marine-marine source rocks; The source rock type discrimination module is configured to determine the source rock type of the sample to be tested according to the input pristine / phytane ratio, bicadinane index and carbon isotope ratio of the sample to be tested, as well as the molecular geochemical indicators used to distinguish coal series, terrestrial marine, and marine marine source rocks, which are divided into the following two types: 1) When the sample to be tested is a source rock sample, the carbon isotope ratio is the kerogen carbon isotope ratio δ 13 C; 2) When the sample to be tested is a crude oil or condensate oil sample, the carbon isotope ratio is the whole oil carbon isotope ratio δ 13 C'.

7. A method for obtaining the contribution ratio of coal-bearing, terrestrial marine, and marine marine source rocks to oil and gas based on molecular geochemical indicators, characterized in that: include: P1. Test the pristine / phyt ratio, bicadinane index and kerogen carbon isotope ratio δ of three different types of source rock samples, including coal-bearing, terrigenous marine and marine source rocks. 13 C; P2, according to the number of samples of each type in the source rock samples and the total value of the pristine / phyt ratio, the total value of the bicadinane index and the kerogen carbon isotope ratio δ 13 C total value, respectively calculate the numerical center of gravity of the pristine / phyt ratio, the numerical center of gravity of the bicadinane index and the kerogen carbon isotope ratio δ of the coal series, terrigenous marine and marine source rock samples in the source rock samples 13 The numerical center of gravity of C is recorded as the coal-bearing source rock end member (Am', Bm', Cm'), the terrestrial marine source rock end member (Ap', Bp', Cp') and the marine marine source rock end member (Aq', Bq', Cq'), where: Am', Bm' and Cm' are the numerical centroids of the pristine / phyt ratio, the numerical centroid of the bicadinane index and the kerogen carbon isotope ratio δ 13 The numerical center of gravity of C; Ap', Bp' and Cp' are the numerical centroids of the pristine / phyt ratio, the numerical centroid of the bicadinane index and the kerogen carbon isotope ratio δ 13 The numerical center of gravity of C; Aq', Bq' and Cq' are the numerical centroid of the pristine / phyt ratio, the numerical centroid of the bicadinane index and the kerogen carbon isotope ratio δ 13 The numerical center of gravity of C; P3. Test the pristine / phytane ratio, bicadinane index and whole oil carbon isotope ratio δ of the crude oil or condensate sample to be tested 13 C', denoted as sample point (a1, b1, c1), calculates the contribution rates of coal-bearing, terrestrial-marine and marine-marine source rocks in the crude oil or condensate sample to be tested according to the distances from the crude oil or condensate sample point to the coal-bearing source rock end member, the terrestrial-marine source rock end member and the marine-marine source rock end member.

8. The method for obtaining the contribution ratio of coal-bearing, terrestrial marine, and marine marine source rocks to oil and gas according to claim 7, characterized in that: The numerical centroids of the coal-bearing source rock samples are all arithmetic means, calculated according to the following formulas: Am'=(A1 +A2 +A3 + …Am) / m (1) Bm'=(B1 +B2 +B3 + ...Bm) / m (2) Cm'=(C1 +C2 +C3 + ...Cm) / m (3) In formulas (1)-(3), Am' is the numerical centroid of the Pb / Ph ratio of coal-measure source rock samples, A1, A2, A3, ..., Am are the Pb / Ph ratios of each coal-measure source rock sample, Bm' is the numerical centroid of the bicadinane index of coal-measure source rock samples, B1, B2, B3, ..., Bm are the bicadinane index of each coal-measure source rock sample, and Cm' is the kerogen carbon isotope ratio δ 13 The numerical center of gravity of C, C1, C2, C3, ..., Cm are the kerogen carbon isotope ratios of each coal-bearing source rock sample, δ 13 C, m is the number of coal-measure source rock samples, pieces; The numerical centroids of the terrigenous marine source rock samples are all arithmetic means, calculated according to the following formulas: Ap'=(A1 +A2 +A3 + …Ap) / p (4) Bp'=(B1 +B2 +B3 + ...Bp) / p (5) Cp'=(C1 +C2 +C3 + ...Cp) / p (6) In formulas (4)-(6), Ap' is the numerical center of gravity of the Pr / Ph ratio of the terrigenous marine source rock sample, A1, A2, A3, ..., Ap are the Pr / Ph ratios of each terrigenous marine source rock sample, Bp' is the numerical center of gravity of the bicadinane index of the terrigenous marine source rock sample, B1, B2, B3, ..., Bp are the bicadinane index of each terrigenous marine source rock sample, Cp' is the kerogen carbon isotope ratio δ 13 The numerical center of gravity of C, C1, C2, C3, ..., Cp are the kerogen carbon isotope ratios of the terrigenous and marine source rock samples, δ 13 C, p is the number of terrigenous marine source rock samples, pieces; The numerical centroids of the marine source rock samples are all arithmetic means, which are calculated according to the following formulas: Aq'=(A1 +A2 +A3 + ...Aq) / q (7) Bq'=(B1 +B2 +B3 + ...Bq) / q (8) Cq'=(C1 +C2 +C3 + ...Cq) / q (9) In formulas (7)-(9), Aq' is the numerical center of gravity of the Pb / Ph ratio of the marine source rock sample, A1, A2, A3, ..., Aq are the Pb / Ph ratios of each marine source rock sample, Bq' is the numerical center of gravity of the bicadinane index of the marine source rock sample, B1, B2, B3, ..., Bq are the bicadinane index of each marine source rock sample, and Cq' is the kerogen carbon isotope ratio δ 13 The numerical center of gravity of C, C1, C2, C3, …, Cq are the kerogen carbon isotope ratios δ of each marine source rock sample. 13 C, q is the number of marine source rock samples, pieces.

9. The method for obtaining the contribution ratio of coal-measure, terrestrial marine, and marine marine source rocks to oil and gas according to any one of claims 7 to 8, characterized in that: The contribution rates of coal-bearing, terrestrial marine, and marine marine source rocks in the crude oil or condensate sample to be tested are calculated according to the following formulas: In formulas (10) and (11), Distance 1 is the distance from the sample point to the coal series end member, which is calculated according to the following formula: In formula (13), a1, b1, and c1 are the pristine / phytane ratio, bicadinane index, and carbon isotope ratio of the crude oil or condensate sample to be tested, respectively. 13 C', Am', Bm' and Cm' are the numerical centroids of the pristine / phyt ratio, the numerical centroid of the bicadinane index and the kerogen carbon isotope ratio δ 13 The numerical center of gravity of C; In formulas (10) and (11), Distance 2 is the distance from the sample point to the terrigenous marine end member, which is calculated according to the following formula: In formula (14), a1, b1, and c1 are the pristine / phytane ratio, bicadinane index, and whole oil carbon isotope ratio δ of the crude oil or condensate sample to be tested, respectively. 13 C', Ap', Bp' and Cp' are the numerical centroids of the pristine / phyt ratio, the numerical centroid of the bicadinane index and the kerogen carbon isotope ratio δ 13 The numerical center of gravity of C; In formulas (10) and (11), Distance 3 is the distance from the crude oil or condensate sample point to the marine end member of the source sea, which is calculated according to the following formula: In formula (15), a1, b1, and c1 are the pristine / phytane ratio, bicadinane index, and whole oil carbon isotope ratio δ of the crude oil / condensate sample to be tested, respectively. 13 C', Aq', Bq' and Cq' are the numerical centroids of the pristine / phyt ratio, the numerical centroid of the bicadinane index and the kerogen carbon isotope ratio δ 13 The numerical center of gravity of C.

10. A device for obtaining the contribution ratio of coal-bearing, terrestrial marine, and marine marine source rocks to oil and gas based on molecular geochemical indicators, characterized in that: include: The numerical center of gravity acquisition module is configured to obtain the pristine / phyt ratio, bicadinane index and kerogen carbon isotope ratio δ of three different types of source rock samples including coal series, terrigenous marine and marine source rocks according to the input 13 C, to obtain the numerical center of gravity of the pristine / phyt ratio, the numerical center of gravity of the bicadinane index and the kerogen carbon isotope ratio δ of the coal-bearing, terrestrial marine and marine marine source rock samples in the source rock samples 13 The numerical center of gravity of C is recorded as the coal-bearing source rock end member (Am', Bm', Cm'), the terrestrial marine source rock end member (Ap', Bp', Cp') and the marine marine source rock end member (Aq', Bq', Cq'), where: Am', Bm' and Cm' are the numerical centroids of the pristine / phyt ratio, the numerical centroid of the bicadinane index and the kerogen carbon isotope ratio δ 13 The numerical center of gravity of C; Ap', Bp' and Cp' are the numerical centroids of the pristine / phyt ratio, the numerical centroid of the bicadinane index and the kerogen carbon isotope ratio δ 13 The numerical center of gravity of C; Aq', Bq' and Cq' are the numerical centroid of the pristine / phyt ratio, the numerical centroid of the bicadinane index and the kerogen carbon isotope ratio δ 13 The numerical center of gravity of C; The contribution ratio calculation module is configured to record the input crude oil or condensate sample's pristine / phytane ratio, bicadinane index and whole oil carbon isotope ratio δ 13 C' is the sample point (a1, b1, c1). According to the distance from the crude oil or condensate oil sample point to the coal-bearing source rock end member, the terrestrial marine source rock end member and the marine marine source rock end member, the contribution rate of coal-bearing, terrestrial marine and marine marine source rocks to oil and gas in the crude oil or condensate oil sample to be tested is calculated.

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