Method for restoring original organic geochemical parameters of high-over mature hydrocarbon source rock based on fr-ir model

Abstract

The application discloses a method for restoring original organic geochemical parameters of high-overmature hydrocarbon source rock based on a FR-IR model, S1: collecting a large amount of marine and terrestrial basin from immature to overmature I, II1 and II2 type hydrocarbon source rock organic geochemical data; S2: establishing a HI and Tamx trend chart; S3: establishing a TOC threshold value and hydrogen index assignment; S4: selecting a large number of I, II1 and II2 type hydrocarbon source rock samples; S5: performing thermal simulation experiment, TOC and pyrolysis experiment on the samples, and performing hydrocarbon source rock evaluation; S6: establishing a FR restoration model; S7: establishing an IR restoration model; S8: collecting a large amount of world typical marine and terrestrial I, II1 and II2 type high-overmature hydrocarbon source rock organic geochemical data, and respectively performing restoration by applying the FR and IR models. The application proposes a high-precision FR-IR restoration model with universality, which can accurately restore original organic matter abundance and original hydrocarbon generation potential of high-overmature hydrocarbon source rock.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of unconventional oil and gas exploration and development, and particularly relates to a method for restoring original organic geochemical parameters of high-over mature hydrocarbon source rock based on a FR-IR model. BACKGROUND

[0002] At present, the hydrocarbon source rock of shale gas and deep gas under exploration and development is basically in the high-over mature stage, and most scholars pay more attention to the pore type, reservoir characteristics and pore throat structure of deep hydrocarbon source rock, and only use the measured TOC, rock pyrolysis or organic maceral data to carry out general analysis on the evaluation of hydrocarbon source rock. However, due to the influence of a large amount of hydrocarbon generation and expulsion of high-over mature hydrocarbon source rock, the composition and chemical properties of organic matter have changed, resulting in that the actual test of organic matter abundance and hydrocarbon generation and expulsion potential is far lower than the original organic matter abundance and hydrocarbon generation and expulsion potential. Only according to the measured organic geochemical data to analyze the high-over mature hydrocarbon source rock will lead to the unreliability of the evaluation of hydrocarbon source rock and the assessment of oil and gas potential resources. Therefore, it is very important to carry out the restoration of the original organic matter abundance and hydrocarbon generation and expulsion potential of deep high-over mature hydrocarbon source rock for the determination of the hydrocarbon generation potential of deep high-over mature hydrocarbon source rock and the assessment of resource potential.

[0003] At present, there are some relatively mature methods for the restoration of original organic matter abundance and hydrocarbon generation and expulsion potential, such as thermal simulation method, mass conservation method and chemical kinetics model. Although the chemical kinetics method can quantitatively describe the chemical reaction process, it ignores the description of the complex expulsion process, and the determination of parameters is prone to error, resulting in large restoration error, which may not be suitable for the study of deep high-over mature hydrocarbon source rock. Thermal simulation mainly takes immature-low mature hydrocarbon source rock as the research object, and can intuitively reflect the conversion of hydrocarbon generation amount of hydrocarbon source rock from immature to over mature stage, and reveal the characteristics of hydrocarbon generation and expulsion and the characteristics of organic matter thermal evolution. Since the calculation model and experience chart based on thermal simulation for the restoration of organic matter have not been established at present, the original organic matter abundance and hydrocarbon generation potential of deep high-over mature hydrocarbon source rock cannot be directly restored according to the existing research. The mass conservation method relies on the data of thermal simulation and TOC of hydrocarbon source rock at different maturity to establish a hydrocarbon generation and expulsion model, which can objectively and quantitatively determine the hydrocarbon generation and expulsion potential of hydrocarbon source rock. However, it is difficult to obtain immature-low mature hydrocarbon source rock samples corresponding to deep hydrocarbon source rock under the same geological conditions in the same basin by using the mass conservation method, and it is difficult to establish a hydrocarbon generation and expulsion model to restore the original organic matter abundance and hydrocarbon generation potential of deep high-over mature hydrocarbon source rock with high precision, and it is difficult to objectively assess the resource potential of oil and gas bearing basin. In addition, in the process of hydrocarbon generation potential restoration of hydrocarbon source rock, the initial hydrogen index is often assigned too high, especially for those samples with low organic matter abundance, resulting in a large difference between the restored data and the actual situation.

[0004] Therefore, a high-precision and universal method is needed to restore the original organic matter abundance and hydrocarbon generation potential of high-over mature hydrocarbon source rocks, so as to realize objective and accurate assessment of resource potential of oil and gas bearing basins. SUMMARY

[0005] The present application aims at the above-mentioned problems existing in the prior art, and provides a method for restoring original organic geochemical parameters of high-over mature hydrocarbon source rocks based on a FR-IR model.

[0006] The object of the present application can be achieved by the following technical solutions.

[0007] The method for restoring original organic geochemical parameters of high-over mature hydrocarbon source rocks based on a FR-IR model comprises the following steps:

[0008] S1: collecting a large amount of organic geochemical data of immature-over mature hydrocarbon source rocks of types I, II1 and II2 with different maturities;

[0009] S2: establishing a trend chart of HI and Tamx to prove whether the hydrocarbon generation potential characteristics of marine and terrestrial hydrocarbon source rocks of the same organic matter type are similar;

[0010] S3: establishing TOC threshold value and hydrogen index assignment;

[0011] S4: selecting a large number of hydrocarbon source rock samples of types I, II1 and II2;

[0012] S5: performing thermal simulation experiment, TOC and pyrolysis experiment on the samples;

[0013] S6: establishing a FR restoration model;

[0014] S7: establishing an IR restoration model;

[0015] S8: collecting a large amount of organic geochemical data of typical marine and terrestrial hydrocarbon source rocks of types I, II1 and II2 with high-over maturity in the world, and respectively performing restoration by applying the FR and IR models;

[0016] S9: comparing the restoration results of the FR and IR models, and comprehensively restoring by the FR and IR models;

[0017] S10: evaluating the restored marine and terrestrial high-over mature hydrocarbon source rocks.

[0018] Further, in S1, the collection of a large amount of organic geochemical data of immature-over mature hydrocarbon source rocks of types I, II1 and II2 with different maturities comprises HI, TOC, Tmax and Ro.

[0019] Further, in S2, a trend chart is established by collecting HI and Tmax of immature-mature source rocks. Further, in S3, according to the collected data of immature-low mature source rocks, a HI-TOC trend chart is established, and a TOC threshold value and hydrogen index assignment are established.

[0020] Further, in S4, the selected samples are mainly dark mudstone and oil shale samples of immature organic matter of types I, II1 and II2 in different basins.

[0021] Further, in S5, the specific steps of the thermal simulation experiment, TOC and pyrolysis experiment are as follows:

[0022] S51: The dark mudstone and oil shale samples (about 50 grams per sample) are heated according to the standard of China Petroleum and Chemical Standard SH / T0508-92;

[0023] S52: A full-automatic heating device and a thermocouple feedback system are used to ensure the accuracy of each heating temperature;

[0024] S53: When the heating temperature reaches 520°C, the constant temperature is maintained for 4 hours to ensure that the complete hydrocarbons in the sample are discharged;

[0025] S54: The dark mudstone and oil shale samples before and after heating are respectively taken and ground into powder by a pulverizer;

[0026] S55: Hydrochloric acid is added to remove inorganic mineral carbon, and distilled water is used for cleaning;

[0027] S56: The total organic carbon (TOC) content of the unheated and heated samples is measured using a LECO CS-230 instrument; S57: The rock pyrolysis of the unheated and heated samples is performed using a Rock-Eval 6 instrument according to the standard procedure, and about 50 mg of sample is used;

[0028] S58: Each powder sample is heated in a helium environment at a programmed rate of 300-550 degrees Celsius to obtain S1, S2 and Tmax;

[0029] S58: Each powder sample is heated in a helium environment at a programmed rate of 300-550 degrees Celsius to obtain S1, S2 and Tmax;

[0030] Further, in S6, the specific steps for establishing the FR restoration model are as follows:

[0031] S61: According to the TOC data before and after heating, the conversion rate of TOC is determined;

[0032] S62: According to the conversion rate of TOC and the establishment of the TOC threshold value and hydrogen index assignment, the FR restoration model is established.

[0033] Further, in S61, the conversion rate of TOC is calculated as follows:

[0034]

[0035] wherein δ is the hydrocarbon generation conversion rate, %; H TOC is the amount of organic carbon (TOC) after thermal simulation, wt. %; is the amount of organic carbon (TOC) before thermal simulation, wt. %; TOC o is the amount of original organic carbon (TOC) recovered, wt. %; TOC is the amount of present organic carbon (TOC), wt. %;

[0036] Further, in S7, the specific steps for establishing the IR model are as follows:

[0037] S71: According to the collected data of low-mature to over-mature marine and terrestrial basin type I, II1, II2 hydrocarbon source rocks, a residual hydrocarbon generation potential index GPIr and Ro data trend chart is established;

[0038] S72: A residual hydrocarbon generation potential index GPIr and Ro relationship function is established;

[0039] S73: A recovery coefficient k formula is established;

[0040] S74: An original organic carbon (TOC o ) formula is established;

[0041] S75: A hydrocarbon expulsion potential (qe) formula is established;

[0042] S76: An original pyrolysis hydrocarbon S2 o

[0043] S77: A residual TOC and Ro constraint template is established, and the TOC threshold value is determined

[0044] S78: An IR model is established

[0045] Further, in S71, the formula of the residual hydrocarbon generation potential index GPIr is as follows:

[0046]

[0047] wherein TOC r is the amount of present residual organic carbon (TOC), wt. %; S1 is the amount of free hydrocarbon; S2 is the amount of kerogen hydrocarbon

[0048] Further, in S73, the formula of the recovery coefficient k is as follows:

[0049]

[0050] wherein GPIo GPIr is the residual hydrocarbon generation potential index.

[0051] Further, in S74, the original organic carbon (TOC o ) is calculated by the following formula:

[0052] TOC o = TOC r × k

[0053] In the formula, TOC r is the present residual organic carbon (TOC) amount, wt.%; and k is the recovery coefficient.

[0054] Further, in S75, the hydrocarbon expulsion potential (qe) is calculated by the following formula respectively:

[0055] qe = GPI o -GPI r

[0056] In the formula, GPI o is the original hydrocarbon generation potential index; and GPIr is the residual hydrocarbon generation potential index.

[0057] Further, in S76, the original pyrolysis hydrocarbon S2 o is calculated by the following formula:

[0058]

[0059] In the formula, HI o is the original hydrogen index; and TOCo is the original TOC.

[0060] Further, in S9, the recovery results of the FR and IR models are compared, mainly according to the correlation and coincidence degree, and the recovery results of the FR and IR are averaged to realize comprehensive recovery.

[0061] Compared with the prior art, the method has the following advantages:

[0062] The present application, through a large number of immature-mature hydrocarbon source rock HI and Tmax statistics, finds that the hydrocarbon generation potential characteristics of marine and terrestrial hydrocarbon source rocks of the same organic matter type have similarities. Based on the relationship between immature-low mature hydrocarbon source rock TOC and HI, the original HI is corrected, the limits of the original TOC of different organic matter type hydrocarbon source rocks are determined, and the shortcomings of the mass conservation method (inversion method) and the thermal simulation method (forward method) are made up. A high-precision, universal FR-IR model is established through the collected immature-mature hydrocarbon source rock organic geochemical data and thermal simulation experiments, so as to establish a method for restoring the original organic matter abundance and hydrocarbon generation potential of marine and terrestrial basins. BRIEF DESCRIPTION OF DRAWINGS

[0063] Figure 1 Schematic diagram of the process of restoring the original organic geochemical parameters of highly-overmature source rocks based on the FR-IR model in the present invention;

[0064] Figure 2 Schematic diagram of the trends of HI and Tamx of type I, III1, and II2 organic source rocks in marine and continental basins in the present invention;

[0065] Figure 3 This is a scatter plot diagram of TOC values ​​and HI values ​​of type I, III1, and II2 organic source rocks in marine and continental basins in the present invention;

[0066] Figure 4 This is a schematic diagram of the discrimination of type I, III1, and II2 organic source rocks before and after the thermal simulation experiment in the present invention;

[0067] Figure 5 Schematic diagram of the TOC conversion rate of type I, III1, and II2 organic source rocks after thermal simulation experiments and the TOC comparison before and after complete hydrocarbon generation in the present invention;

[0068] Figure 6 Schematic diagram of the relationship between GPIr and Ro of type I, III1, and II2 source rocks in marine and continental basins in the present invention;

[0069] Figure 7 This is a schematic diagram of the TOC threshold constraint model of the IR model in the present invention.

[0070] Figure 8 Schematic diagram of the relationship between the original S2 or original total organic carbon (TOC) restored by the IR model and the FR model in the present invention.

[0071] Figure 9 This is a schematic diagram of the relationship between the original S2 and the original TOC restored by the comprehensive FR-IR model in the present invention.

[0072] Figure 10 This is a schematic diagram of the hydrocarbon expulsion simulation model for Type I, III1, and II2 source rocks in marine and continental basins in the present invention. DETAILED DESCRIPTION

[0073] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solutions of the present invention, but the present invention is not limited to these embodiments.

[0074] like Figure 1 As shown, the present invention provides a method for recovering the original organic geochemical parameters of high-overmature source rocks based on the FR-IR model, comprising the following steps:

[0075] S1: Collect a large number of organic geochemical data of I, II1, II2 type immature-mature source rocks of different maturities to determine the similarity of the hydrocarbon generation potential characteristics of marine and terrestrial source rocks of the same organic matter type;

[0076] S2: Establish a trend chart of HI and Tamx to prove whether the hydrocarbon generation potential characteristics of marine and terrestrial source rocks of the same organic matter type have similarity;

[0077] S3: Establish TOC threshold and hydrogen index assignment;

[0078] S4: Select a large number of I, II1 and II2 type source rock samples;

[0079] S5: Perform thermal simulation experiment, TOC and pyrolysis experiment on the sample;

[0080] S6: Establish an IR model;

[0081] S7: Establish a FR recovery model;

[0082] S8: Collect a large number of organic geochemical data of typical marine and terrestrial I, II1, II2 type high-mature source rocks in the world, and apply FR and IR models for recovery;

[0083] S9: Compare the recovery results of FR and IR models, and comprehensively recover FR and IR models;

[0084] S10: Evaluate the recovered marine and terrestrial high-mature source rocks

[0085] The present application, through a large number of immature-mature source rock HI and Tmax statistics, finds that the hydrocarbon generation potential characteristics of marine and terrestrial source rocks of the same organic matter type have similarity. Based on the relationship between TOC and HI of immature-low mature source rocks, the original HI is corrected, the limit of the original TOC of different organic matter type source rocks is determined, and the shortcomings of the mass conservation method (inversion method) and the thermal simulation method (forward method) are made up. Through the collected organic geochemical data and thermal simulation experiment of immature-mature source rocks, a high-precision and universal FR-IR model is established, thereby a method for recovering the original organic matter abundance and hydrocarbon generation potential of marine and terrestrial high-mature source rocks is established.

[0086] Example 1:

[0087] S1: Collect a large number of organic geochemical data of I, II1, II2 type immature-mature source rocks of different maturities;

[0088] S2: Establish a trend chart of HI and Tamx to prove whether the hydrocarbon generation potential characteristics of marine and terrestrial source rocks of the same organic matter type have similarity;

[0089] Based on these data, the HI-Tmax trend line ( Figure 2 During the thermal evolution process, the HI of different organic matter types shows a certain change pattern ( Figure 2 According to the data collected by the system, the HI of type I organic matter in the immature to low-mature stages is greater than 600 mg HC / g TOC on average ( Figure 2 a), the HI decreases rapidly in the mature stage (the slope is about 14.11). The initial HI of type II1 organic matter is between 300 and 600 mg HC / g TOC ( Figure 2 b), the slope of HI change in the mature stage is about 9.90. The average organic matter of type II2 immature-low-mature soil is between 100 and 300 mg HC / g TOC ( Figure 2 c) In the mature stage, the HI slope is very small, only 5.33. However, in the highly mature to overmature stage, the HI of all organic matter types in source rocks is stable and low, with little difference between the organic matter types. This indicates that marine and terrestrial source rocks of the same organic matter type and similar organic matter abundance within highly mature to overmature source rocks exhibit similar evolutionary patterns, effectively resolving the problem that thermal simulation methods (forward modeling) and mass conservation methods (inversion methods) cannot accurately recover the original organic matter abundance and original hydrocarbon generation potential of deep highly mature to overmature source rocks.

[0090] S3: Establish TOC threshold and hydrogen index assignment;

[0091] After determining the organic matter type, the simple original HI assignment is also arbitrary, resulting in biased recovery results. We collected a large amount of immature-low-mature source rock data and formed a HI-TOC trend diagram for source rocks of different organic matter types ( Figure 3 ). The HI-TOC of immature to low-mature source rocks shows a very obvious regularity. When the TOC of source rocks containing type I, II1 and II2 organic matter is at 3.5%, 3.0% and 2.0%, there are obvious thresholds. On the left side of the threshold, the HI and TOC of source rocks with different organic matter types all show a significant positive correlation, but the slope of the trend line gradually decreases from I, II1 to II2. On the right side of the threshold, there is basically no correlation between HI and TOC, and HI fluctuates only on one main axis. The main axes of HI fluctuation of type I, II1 and II2 organic matter are 670 mg / g, 500 mg / g and 200 mg / g, respectively. Considering that the recovery of the hydrogen index of highly mature to overmature source rocks is not only crucial for the evaluation of the original hydrocarbon generation potential of source rocks, but also has an important impact on the mathematical models established by forward and inversion methods, we established the assignment function of the original hydrogen index of source rocks with different organic matter types under different organic matter abundance conditions based on the HI-TOC trend analysis:

[0092]

[0093]

[0094] where HI o is the original hydrogen index, TOC o is the original TOC

[0095] Accurate obtaining of HIo of different types of organic matter and different abundances of hydrocarbon source rocks will provide the most critical parameters for the recovery of the original organic matter abundance and hydrocarbon potential of high-mature to over-mature hydrocarbon source rocks. Moreover, marine and terrestrial hydrocarbon source rocks of the same type of organic matter have similar hydrocarbon generation characteristics Figure 2 ), which also provides an opportunity to establish a universally practical method for recovering hydrocarbon source rocks.

[0096] S4: Select a large number of I, II1 and II2 type hydrocarbon source rock samples;

[0097] The selected samples are mainly I, II1, and II2 type immature organic-rich dark mudstone and oil shale samples in different basins

[0098] S5: Perform thermal simulation experiments, TOC and pyrolysis experiments on the samples;

[0099] S51: Heat the dark mudstone and oil shale samples (about 50 grams per sample) according to the Chinese Petroleum and Chemical Standard SH / T0508-92 standard;

[0100] S52: Use a full-automatic heating device and a thermocouple feedback system to ensure the accuracy of each heating temperature;

[0101] S53: When the heating temperature reaches 520℃, maintain a constant temperature for 4 hours to ensure that the complete hydrocarbons in the sample are discharged;

[0102] S54: Respectively, take the unheated and heated dark mudstone and oil shale samples and grind them into powder with a pulverizer;

[0103] S55: Add hydrochloric acid to remove inorganic mineral carbon and wash with distilled water;

[0104] S56: Use LECO CS-230 instrument to measure the total organic carbon (TOC) content of the unheated and heated samples; S57: Use Rock-Eval 6 instrument to perform rock pyrolysis on the unheated and heated samples according to the standard procedure, with about 50mg of sample;

[0105] S58: Heat each powder sample in a helium environment at a program rate of 300-550℃ to obtain S1, S2 and Tmax;

[0106] S58: Heat each powder sample in a helium environment at a program rate of 300-550℃ to obtain S1, S2 and Tmax;

[0107] S59: Evaluation of the source rock before and after heating.

[0108] Before thermal simulation, the source rock was mainly type I, II1 and II2 kerogen, which had not entered the oil window. Figure 4 a) Among the pyrolysis parameters, the S1 value was 0.59-3.49 mg / g (average 1.51 mg / g), the S2 value of the source rock was 8.62-355.73 mg / g (average 99.34 mg / g), the S1+S2 value was 9.34-358.35 mg / g (average 99.34 mg / g), and the HI value was 200-976 mg / g TOC (average 520.39 HC / g TOC). The cross plot of HI and TOC showed that the source rock before thermal simulation had very high organic matter content and basically had good oil and gas generation capacity. Type I organic matter source rock had strong oil generation characteristics, type II1 organic matter had good oil generation characteristics, and type II2 organic matter had moderate oil generation characteristics. Figure 4 b) The source rock was mainly of good to excellent type. Figure 4 c, d) See Table 1.

[0109] Table 1 TOC and pyrolysis data of the source rock before thermal simulation

[0110]

[0111] After thermal simulation, the hydrocarbon generation characteristics of the source rock were similar to type IV-VIII kerogen, and the sample points were distributed in the dry gas zone. Figure 4 a) After heating, the S1 value of the sample was 0.09-1.91 mg / g (average 0.74 mg / g), the S2 value was 0.3-4.23 mg / g (average 1.36 mg / g), and the S1+S2 (Potential Yield) value was 0.68-4.88 mg / g (average 2.10 mg / g). The HI of the mudstone with different types of organic matter after heating was not much different, being 2-83 HC / g TOC (average 20.54 HC / g TOC). The experiment showed that when the source rock with different types of organic matter reached the high mature-overmature stage, although it had a certain organic matter content, the hydrocarbon generation potential was very low, and it was mainly fair-poor source rock. Figure 4 b, c, d) Therefore, the restoration of the original organic matter abundance and the hydrocarbon generation and expulsion potential of the high-overmature source rock with different types of organic matter is of great significance for the estimation of the hydrocarbon generation amount of the source rock. See Table 2.

[0112] Table 2 TOC and pyrolysis data of the source rock after thermal simulation (high mature to overmature)

[0113]

[0114]

[0115] S6: Establishing the IR model;

[0116] S61: According to the TOC data before and after heating, the conversion rate of TOC is determined;

[0117] In this paper, the original and residual organic matter abundances of different types of organic matter in source rocks were compared through thermal simulation experiments. The original TOC of type I organic matter without heating was between 3.5 and 46.5wt.%, and the residual TOC after heating was between 1.60 and 21.25wt.%. The original TOC of type II1 organic matter was between 2.2 and 43.2wt.%, and the residual TOC was between 1.26 and 23.76wt.%. The original TOC of type II2 organic matter was between 4.3 and 57.7wt.%, and the residual TOC was between 3.05 and 38.2wt.% Figure 5 b);

[0118] The formula for the conversion rate of TOC is:

[0119]

[0120] In the formula, δ is the hydrocarbon conversion rate, %; H TOC is the amount of organic carbon (TOC) after thermal simulation, wt.%; is the amount of organic carbon (TOC) before thermal simulation, wt.%; TOC o is the amount of recovered original organic carbon (TOC), wt.%; TOC is the amount of present-day organic carbon (TOC), wt.%;

[0121] According to the comparison of TOC before and after heating, the conversion rate of type I organic matter was between 49.8 and 60.0%, with an average of 54.7%, which was the highest; the conversion rate of type II1 organic matter was between 37.0 and 50.2%, with an average of 43.5%, which was the second highest; the conversion rate of type II2 organic matter was relatively low, between 21.9 and 38.6%, with an average of only 30.3% Figure 5 a). Since the overall hydrocarbon generation capacity of type III is poor, it is not analyzed in this paper.

[0122] S62: According to the conversion rate of TOC and the establishment of TOC threshold value and hydrogen index assignment, the FR recovery model is established.

[0123] The recovery of original TOC through the TOC conversion rate of different types of organic matter in source rocks has good indicative significance. By using the assignment function of original hydrogen index under different organic matter abundances of different types of organic matter in source rocks, the mathematical model for recovering the original hydrocarbon generation potential of source rocks is obtained:

[0124] Type I organic matter:

[0125]

[0126]

[0127] Type II1 organic matter:

[0128]

[0129]

[0130] Type II2 organic matter:

[0131]

[0132]

[0133] In the table: TOCo is original organic carbon; TOC is residual organic carbon; S2 is original pyrolytic hydrocarbon.

[0134] S7: Establishing a FR recovery model

[0135] S71: According to the collected data of marine and terrestrial basin low-mature to mature Type I, II1, II2 hydrocarbon source rocks, a residual hydrocarbon-generating potential index GPIr and Ro data trend chart is established;

[0136] The formula of the residual hydrocarbon-generating potential index GPIr is:

[0137]

[0138] In the formula, TOC r is the present residual organic carbon (TOC) amount, wt.%; S1 is the amount of free hydrocarbon; S2 is the amount of kerogen hydrocarbon

[0139] S72: Establishing a relationship function between the residual hydrocarbon-generating potential index GPIr and Ro;

[0140] According to the relationship characteristics of marine and terrestrial hydrocarbon source rock hydrocarbon-generating potential index and Ro, Figure 6 the hydrocarbon source rock hydrocarbon-generating threshold of Type I, II1, II2 organic matter is 0.5% Ro, and the hydrocarbon expulsion threshold is 0.6% Ro. Before the hydrocarbon source rock expels hydrocarbon, the original hydrocarbon-generating potential index (GPIo) is approximately equal to HI o ( Figure 6 ). Therefore, the hydrocarbon source rock hydrocarbon-generating potential index (GPI o ) of Type I, II1, II2 organic matter refers to the assignment function of the original hydrogen index under the condition of different organic matter abundance of different organic matter types of hydrocarbon source rock. When the hydrocarbon expulsion threshold is reached, the residual hydrocarbon-generating potential index (GPIr) in the hydrocarbon source rock will decrease. Therefore, according to the relationship function between the residual hydrocarbon-generating potential index (GPIr) and Ro, the residual hydrocarbon-generating potential index (GPIr) of the hydrocarbon source rock can be calculated.Figure 6 Establishing the equation to establish the relationship function of GPIr and Ro;

[0141] Type I organic matter:

[0142]

[0143] R 2 = 0.79

[0144] Type II1 organic matter:

[0145]

[0146] R 2 = 0.76

[0147] Type II2 organic matter:

[0148]

[0149] R 2 = 0.74

[0150] S73: Establishing the formula of recovery coefficient k;

[0151] Formula of recovery coefficient k:

[0152]

[0153] In the formula, GPI o is the original hydrocarbon generation potential index; GPIr is the residual hydrocarbon generation potential index.

[0154] According to the established relationship function of GPIr and Ro and the assignment function of original hydrogen index under different organic matter abundance conditions, the formula of recovery coefficient k is established:

[0155] Type I organic matter:

[0156]

[0157] Type II1 organic matter:

[0158]

[0159] Type II2 organic matter:

[0160]

[0161] In the formula, a, b, and c are respectively the constraint conditions of different types of organic matter.

[0162] S74: Establishing the formula of original organic carbon (TOC o );

[0163] Original organic carbon (TOCo ) formula is:

[0164] TOC o = TOC r x k

[0165] where TOC r is the present residual organic carbon (TOC) amount, wt.%; k is the recovery factor.

[0166] The original organic carbon (TOC o ) is established according to the recovery factor k formula:

[0167] Type I organic matter:

[0168]

[0169] Type II1 organic matter:

[0170]

[0171] Type II2 organic matter:

[0172]

[0173] where a, b, c are constraint conditions for different types of organic matter, respectively.

[0174] S75: Establish the hydrocarbon expulsion potential (qe) formula;

[0175] The hydrocarbon expulsion potential (qe) formula is:

[0176] qe = GPI o - GPI r

[0177] where GPI o is the original hydrocarbon generation potential index; GPIr is the residual hydrocarbon generation potential index.

[0178] The hydrocarbon expulsion potential (qe) is established according to the relationship function of GPIr and Ro and the assignment function of the original hydrogen index under different organic matter abundance conditions:

[0179] Type I organic matter:

[0180]

[0181] where a, b, c are constraint conditions for different types of organic matter, respectively.

[0182] Type II1 organic matter:

[0183]

[0184] Type II2 organic matter:

[0185]

[0186] S76: Establishing the original pyrolysis hydrocarbon S2 o

[0187] Original pyrolysis hydrocarbon S2 o The formula is:

[0188]

[0189] Where HI o is the original hydrogen index; TOCo is the original TOC.

[0190] According to the original organic carbon (TOC o ) and the original hydrogen index assignment function under different organic matter abundance conditions to establish the original pyrolysis hydrocarbon S2 o :

[0191] Type I organic matter:

[0192]

[0193] Type II1 organic matter:

[0194]

[0195]

[0196] Where a, b, and c are the constraints for different organic matter types.

[0197] S76: Establish a constraint template for residual TOC and Ro, and clarify the TOC threshold;

[0198] According to the above formula, the constraints of the inversion method in restoring TOCo, hydrocarbon expulsion intensity, and original S2 are different from those of the FR model. The IR model cannot directly restore the original TOC, and the constraints in the formula need to be limited by residual TOC. Therefore, we establish the original organic carbon (TOC o ) formula and established the inversion method for residual TOC and Ro constraint templates for different organic matter types ( Figure 7 According to the constraint template of residual TOC and Ro, the residual TOC and Ro curves in the high-overmature range are basically flat. Therefore, the constraint conditions of the high-overmature source rock are fixed values, among which the constraint conditions of type I organic matter a = 1.56 wt.%, the constraint conditions of type II1 organic matter b = 2.10 wt.%, and the constraint conditions of type II2 organic matter c = 1.67 wt.%. When the residual TOC is in the red area (TOC r>1.56wt.%, 2.10wt.%, 1.67wt.%), Type I, Type II1 and Type II2 original hydrogen index can be directly assigned to 670mg HC / g TOC, 500mg HC / g TOC, 200mg HC / g TOC respectively; when residual TOC is in yellow region (TOC r ≤1.56wt.%, 2.10wt.%, 1.67wt.%), Type I, Type II1 and Type II2 original hydrogen index need to be obtained by assignment function of original hydrogen index under different organic matter abundance conditions. This template can be generally applied to Type I, Type II1 and Type II2 source rocks of different maturity in marine and terrestrial basins.

[0199] S77: Establishing IR model;

[0200] According to the known values of constraints a, b, c, substitute into original organic carbon (TOC o ), original pyrolysis hydrocarbon (S2 o ), hydrocarbon expulsion potential (qe), recovery coefficient k, a complete IR model can be established.

[0201] S8: Collecting a large amount of organic geochemical data of typical marine and terrestrial Type I, Type II1 and Type II2 high-over mature source rocks in the world, and applying FR and IR models to restore;

[0202] In order to prove the accuracy of the forward and inverse models, we collected the organic geochemical data of high-over mature source rocks in Sichuan Basin, Songliao Basin, Bohaiwan Basin, Junggar Basin, Pearl River Mouth Basin, Lower Indus Basin, Delaware Basin and Al-Jawf Basin, and restored the organic matter abundance and hydrocarbon generation potential thereof. Among them, the residual TOC is between 0.36 and 9.31wt%, and the S2 is between 0.01 and 6.91mg HC / g rock. The forward recovery results show that the restored TOCo is between 0.51 and 13.30wt%, with an average of 4.24wt%, and the S2o is between 0.26 and 57.69mg HC / g rock, with an average of 15.54mg HC / g rock. According to the inverse recovery results, the restored TOCo is between 0.37 and 11.88wt%, with an average of 3.66wt%, and the S2o is between 0.14 and 60.66mg HC / g rock, with an average of 13.78mg HC / g rock. See Table 3:

[0203] Table 3 IR model and FR model restored original TOC and S2 data

[0204]

[0205]

[0206] S9: Compare the recovery results of FR and IR models, and integrate FR and IR models for recovery;

[0207] The TOCo and S2o recovered by IR and FR models have good correlation, with correlation coefficients of 0.95 and 0.96, respectively. Figure 8 The coincidence rates of TOCo and S2o recovered by forward modeling and inverse modeling are also relatively high, with averages of 77.3% and 67.0%, respectively, and the overall coincidence rate is as high as 72.2% on average. Therefore, we take the average of the results of forward modeling and inverse modeling as the final recovery result of the source rock.

[0208] S10: Evaluate the recovered marine and terrestrial high-over mature source rocks.

[0209] According to the recovery results of the integrated FR-IR model, type I source rock is mainly good- excellent source rock, Figure 9 type II1 source rock is mainly very good- excellent, Figure 9 and type II2 source rock is mainly poor- very good. Figure 9 According to the hydrocarbon expulsion intensity, with the gradual increase of maturity, the hydrocarbon expulsion intensity of high-over mature source rock increases rapidly and gradually reaches equilibrium, and the final hydrocarbon expulsion efficiency can reach 99%. Figure 10 Through comparison, type I organic matter source rock has the strongest hydrocarbon expulsion capacity (avg. 381.16 mg HC / g TOC), with a maximum hydrocarbon expulsion intensity of 669.27 mg HC / g TOC; type II1 organic matter source rock has the second strongest hydrocarbon expulsion capacity (avg. 294.36 mg HC / g TOC), with a maximum hydrocarbon expulsion intensity of 497.84 mg HC / g TOC; and type II2 organic matter source rock has the weakest hydrocarbon expulsion capacity (avg. 112.66 mg HC / g TOC), with a maximum hydrocarbon expulsion intensity of only 184.20 mg HC / g TOC. Figure 10 )

Claims

1. A method for restoring original organic geochemical parameters of high-overmature source rocks based on FR-IR model, characterized in that, The method comprises the following steps: S1: collecting a large amount of organic geochemical data of immature-mature hydrocarbon source rocks of types I, II1 and II2 with different maturities, including TOC, Ro, S2, S1, HI and Tmax; S2: establishing a trend chart of HI and Tmax to prove whether the hydrocarbon generation potential characteristics of marine and terrestrial hydrocarbon source rocks of the same organic matter type are similar; S3: establishing a TOC threshold value and hydrogen index assignment function of different organic matter types according to the collected data; S4: selecting immature hydrocarbon source rock samples of types I, II1 and II2 in different basins; S5: performing thermal simulation experiment, TOC and pyrolysis experiment on the samples, and evaluating the hydrocarbon source rocks; S6: determining the conversion rate of TOC according to the TOC data before and after heating, and establishing a FR recovery model according to the conversion rate of TOC and the TOC threshold value and hydrogen index assignment function; S7: Establishing the IR restoration model, specifically, according to the collected data of low-mature to over-mature marine and terrestrial basin type I, II1, II2 hydrocarbon source rock, establishing the residual hydrocarbon generation potential index GPIr and Ro data trend chart, the residual hydrocarbon generation potential index GPI r The formula is: wherein TOC is the amount of total organic carbon, wt.%; S1 is the amount of free hydrocarbons; S2 is the amount of kerogen hydrocarbons; and S3 is the amount of residual hydrocarbons. r is the amount of total organic carbon, wt.%; S1 is the amount of free hydrocarbons; S2 is the amount of kerogen hydrocarbons; and S3 is the amount of residual hydro establishing a relationship function of residual hydrocarbon generation potential index GPIr and Ro; and establishing a recovery coefficient k formula: wherein GPI o is the original hydrocarbon generation potential index; GPI r is the residual hydrocarbon generation potential index; Establishment of raw organic carbon TOC o Formula: TOC o = TOC r x k where TOC is the amount of total organic carbon, wt.%; k is the recovery factor; and r is the amount of residual organic carbon, TOC, wt.%; k is the recovery factor; and establishing a hydrocarbon expulsion potential qe formula: qe = GPI o - GPI r wherein GPI o is the original hydrocarbon generation potential index; GPI r is the residual hydrocarbon generation potential index; Establishment of the original pyrolysis hydrocarbon S2 o : wherein HI o is the original hydrogen index; TOC o original TOC; The constraint template of residual TOC and Ro is established, and the TOC threshold is determined; according to the TOC threshold, the complete IR model is established by substituting into the original organic carbon TOC o , original pyrolysis hydrocarbon S2 o , hydrocarbon expulsion potential qe, and recovery coefficient k S8: collecting a large amount of organic geochemical data of high-mature hydrocarbon source rocks of types I, II1 and II2 in typical marine and terrestrial basins in the world, and applying the FR and IR models for recovery respectively; S9: comparing the recovery results of the FR and IR models, and comprehensively recovering the FR and IR models; S10: evaluating the recovered marine and terrestrial high-mature hydrocarbon source rocks.

2. The method for restoring original organic geochemical parameters of high-overmature source rocks based on FR-IR model according to claim 1, characterized in that, In S2, a trend chart of HI and Tmax of immature-mature hydrocarbon source rocks is established.

3. The method for restoring original organic geochemical parameters of high-overmature source rocks based on FR-IR model according to claim 1, characterized in that, In S3, a HI-TOC trend chart is established according to the collected data of immature-mature hydrocarbon source rocks, and a TOC threshold value and hydrogen index assignment are established.

4. The method for restoring original organic geochemical parameters of high-overmature source rocks based on FR-IR model according to claim 1, characterized in that, In S4, the selected samples are immature organic matter dark mudstone and oil shale samples of types I, II1 and II2 in different basins.

5. The method for restoring original organic geochemical parameters of high-overmature source rocks based on FR-IR model according to claim 1, characterized in that, In S5, the specific steps of the thermal simulation experiment, TOC and pyrolysis experiment are as follows: S51: heating the dark mudstone and oil shale samples according to the standard of China Petroleum and Chemical Standard SH / T0508-92, 50 grams for each sample; S52: using a full-automatic heating device and a thermocouple feedback system to ensure the accuracy of each heating temperature; S53: when the heating temperature reaches 520℃, keeping constant temperature for 4 hours to ensure that the complete hydrocarbons in the sample are discharged; S54: respectively taking the unheated and heated dark mudstone and oil shale samples and grinding them into powders by a pulverizer; S55: adding hydrochloric acid to remove inorganic mineral carbon and washing with distilled water; S56: using a LECO CS-230 instrument to measure the total organic carbon TOC content of the unheated and heated samples; S57: using a Rock-Eval 6 instrument to perform rock pyrolysis on 50 mg of the unheated and heated samples according to the standard procedure; S58: heating each powder sample at a program rate of 300-550℃ in a helium environment to obtain S1, S2 and Tmax; S59: evaluating the hydrocarbon source rocks before and after heating.

6. The method for restoring original organic geochemical parameters of high-overmature source rocks based on FR-IR model according to claim 1, characterized in that, In S6, the formula of the conversion rate of TOC is as follows: wherein: δ is the hydrocarbon generation conversion, %; H TOC TOC is the amount of organic carbon after the thermal simulation, wt. %; TOC is the amount of organic carbon before the thermal simulation, wt. %; TOC o TOC is the amount of original organic carbon recovered, wt. %; TOC is the amount of present-day organic carbon, wt. %.

7. The method for restoring original organic geochemical parameters of high-overmature source rocks based on FR-IR model according to claim 1, characterized in that In S9, the recovery results of the FR and IR models are compared, and the correlation and coincidence between the recovery results are compared, and the average of the recovery results of the FR and IR is obtained to realize comprehensive recovery.

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