A method for evaluating resource quantity of hydrocarbon generation of high mature source rock in secondary burial depth

Abstract

The present disclosure belongs to the technical field of oil and gas resource exploration, and provides a resource quantity evaluation method for secondary burial hydrocarbon generation of high mature source rock. The method has a complete technical link of basic evaluation-parameter acquisition-model calibration-potential judgment-boundary definition-data quantification-resource accounting, solves the technical problem that the secondary hydrocarbon generation potential of high mature source rock cannot be accurately judged, greatly improves the accuracy of hydrocarbon generation history simulation through alternative sample thermal simulation + model calibration, fills the blank of non-quantitative standard of secondary hydrocarbon generation boundary of high mature source rock, and provides a clear reference basis for exploration in the depth and maturity range defined, and the calculated hydrocarbon generation quantity can accurately distinguish the primary and secondary hydrocarbon generation quantity, providing accurate resource quantity data support for the oil and gas exploration deployment of high mature source rock, and having strong practicality. The whole method process is standardized and reproducible, and can be popularized to all secondary burial hydrocarbon generation evaluation scenes of high mature source rock, and has a wide range of applications.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of oil and gas resource exploration, and particularly relates to a resource quantity evaluation method for secondary burial of hydrocarbon generation of high mature source rock. BACKGROUND

[0002] Resource quantity evaluation is a core link of hydrocarbon source rock exploration, and its result directly guides the direction and deployment of oil and gas exploration. At present, the mainstream oil and gas resource evaluation methods in the industry can be summarized into three categories: one is analogy method, which mainly estimates and calculates based on basic geological parameters such as sedimentary rock volume, sedimentation rate, basin area, source rock volume, etc., and is suitable for scenes with insufficient data in early exploration stage, but the evaluation precision and reliability are relatively low; two is statistical method, which covers various models such as oil and gas field size sequence method, oil and gas discovery process method, Pareto method, decline curve method, lognormal distribution method, Zipov method, and Weng-type life cycle method, and is the main means for western oil companies and governments to carry out resource evaluation, and the core advantage lies in the emphasis on the economy, dynamics and risk of resources; three is genetic method, which is the most widely used evaluation method in China, and its core is to determine the source rock volume (hydrocarbon expulsion volume, available accumulation volume) based on the principle of material balance, and then multiply a certain coefficient to carry out deterministic evaluation, and the specific methods include material balance method, natural profile evolution method, thermal simulation experiment method, and chemical kinetics method. The outstanding feature of this method is that it fully considers a series of genetic parameters in the process of oil and gas generation-migration-accumulation-preservation, and has clear geological significance, and is suitable for all exploration stages, but the accuracy of the evaluation result is highly dependent on the geological cognition degree of the characteristics of the source rock, the oil and gas migration and accumulation rules, and the preservation conditions, and the selection of some key parameters (such as migration coefficient) has certain artificial experience, which affects the accuracy of the evaluation result.

[0003] The oil and gas exploration in Binbei area of Songliao Basin has long focused on the shallow layer. With the decrease of the shallow layer oil and gas production year by year and the continuous increase of the exploration difficulty, the deep Carboniferous-Permian layer has gradually become an important potential target area for increasing reserves and production. The exploration results show that the source rock in the area has the characteristics of wide distribution, large thickness, medium to high organic matter abundance, the type of kerogen is mainly type II, and the thermal evolution degree has entered the high mature-over mature stage (the measured vitrinite reflectance Ro is greater than 2.0 %), which has good hydrocarbon generation basis and great exploration potential. However, the resource evaluation of the deep source rock faces many special difficulties. On the one hand, the exploration degree of the study area is low, the buried depth is large, the number of drilled wells encountering the Carboniferous-Permian layer is small, and the research foundation of the distribution characteristics and organic geochemical characteristics of the source rock is weak due to the limitation of high maturity. On the other hand, the source rock in the area has experienced the process of uplift and denudation, and a large amount of early generated oil and gas has been lost, which directly affects the accuracy of resource estimation. More importantly, the current deep oil and gas resource evaluation research has not fully paid attention to the core role of high mature source rock, especially the lack of resource evaluation method for secondary hydrocarbon generation in the secondary burial process of high mature source rock, which cannot meet the actual needs of the Carboniferous-Permian deep layer oil and gas exploration in Binbei area of Songliao Basin. Therefore, providing a hydrocarbon resource evaluation method suitable for the secondary burial process of high mature source rock has become a technical bottleneck to be solved in this field. SUMMARY

[0004] The present disclosure provides a resource evaluation method for secondary burial hydrocarbon generation of high mature source rock to at least solve the above technical problems in the prior art.

[0005] According to a first aspect of the present disclosure, a resource evaluation method for secondary burial hydrocarbon generation of high mature source rock is provided, comprising the following steps:

[0006] S1: statistics the organic matter abundance, organic matter type and organic matter maturity data of the target well in the study area, and comprehensively analyzes the hydrocarbon generation potential of the high mature source rock in the study area by combining with the corresponding geochemical characteristic analysis chart;

[0007] S2: selecting a substitute sample with similar sedimentary period and matching kerogen type of the high mature source rock in the study area, and using hydrocarbon generation thermal simulation experiment to qualitatively and quantitatively analyze each component of the output, and obtaining the yield-temperature curve and hydrocarbon generation kinetic parameters of each component;

[0008] S3: using a parallel first-order reaction model (MFF model) with different pre-exponential factors and discrete distribution activation energy, and according to the hydrocarbon generation kinetic parameters and conversion rate of each component in step S2, the kinetic model of gaseous hydrocarbon, total oil and total hydrocarbon of the substitute sample is calibrated;

[0009] S4: in combination with the sedimentary burial history-thermal history data of the target well in the study area and the calibrated kinetic parameters in step S3, the bottom layer and the top layer of the source rock base of the target well are subjected to hydrocarbon generation history simulation to determine the hydrocarbon generation evolution characteristics and judge the secondary hydrocarbon generation potential;

[0010] S5: for the target well with the secondary hydrocarbon generation potential, the hydrocarbon generation history of the full thickness layer position is simulated to determine the depth range of the secondary hydrocarbon generation limit and the equivalent vitrinite reflectance (EasyRo%) range corresponding to the 100% conversion rate before the secondary denudation;

[0011] S6: the logging total organic carbon content (TOC) data of the high-mature source rock in the study area are calculated, and in combination with the logging data, the sedimentary facies map and the previous exploration results, the original TOC contour map and the source rock thickness contour map are drawn;

[0012] S7: based on the genetic method, the original TOC contour map, the source rock thickness contour map, in combination with the set original hydrogen index, the organic matter conversion rate and the source rock density parameters, the total hydrocarbon generation amount and the secondary hydrocarbon generation amount of the high-mature source rock in the study area are calculated through grid division and accumulation.

[0013] Specifically, the present disclosure is aimed at the technical difficulty that the high-mature source rock cannot directly carry out thermal simulation experiment, and the alternative sample with similar deposition period and matching kerogen type is innovatively selected to obtain the hydrocarbon generation kinetic parameters through the hydrocarbon generation thermal simulation experiment, so as to solve the industry pain point that the hydrocarbon generation parameters of the high-mature source rock cannot be accurately obtained. The selection principle of the alternative sample is the core innovation, which is different from the random sampling mode in the prior art. Secondly, the MFF model with different pre-exponential factors + discrete distribution activation energy is innovatively combined with the kinetic parameters of the thermal simulation to be accurately calibrated to obtain the gaseous hydrocarbon / total oil / total hydrocarbon kinetic model suitable for the high-mature source rock; and the hydrocarbon generation history of the bottom layer + top layer of the source rock base is simulated respectively instead of the whole simulation, so as to accurately identify the influence of the denudation on the hydrocarbon generation and judge the secondary hydrocarbon generation potential. The simulation mode is unique. Thirdly, for the target well with the secondary hydrocarbon generation potential, the full thickness layer position hydrocarbon generation history simulation is carried out to determine the limit depth of the secondary hydrocarbon generation and the EasyRo% maturity range with the 100% organic matter conversion rate before the secondary denudation. The limit standard and method are the core innovation of the present disclosure. In addition, based on the genetic method, in combination with the source rock TOC contour map and the thickness contour map, the present disclosure innovatively splits the hydrocarbon generation amount into the total hydrocarbon generation amount and the secondary hydrocarbon generation amount to be respectively calculated instead of only calculating the total hydrocarbon generation amount, and in combination with the set hydrogen index, conversion rate and density parameters, the total hydrocarbon generation amount and the secondary hydrocarbon generation amount are calculated through grid division and accumulation, so as to greatly improve the calculation accuracy of the high-mature source rock hydrocarbon generation amount and fully adapt to the exploration actual demand.

[0014] The above seven steps form a complete technical link of basic evaluation-parameter acquisition-model calibration-potential judgment-boundary definition-data quantification-resource accounting, and are progressively and interrelatedly formed into an indivisible whole.

[0015] Specifically, the target well and the high-maturity source rock in step S1 are not specifically limited.

[0016] In an implementable manner, the high-maturity source rock in step S1 is the hydrocarbon source rock of the Carboniferous-Permian Linxi Formation in the Binbei area of the Songliao Basin, and the maturity Ro of the high-maturity source rock is greater than 2.0%.

[0017] Specifically, the Songliao Basin develops multiple sets of hydrocarbon source rock series such as the Nenjiang Formation, the Qingshankou Formation, the Yingcheng Formation, the Shaheshi Formation, and the Carboniferous-Permian Linxi Formation, and the types involve type I, type II1, type II2, type III kerogen and coal measure hydrocarbon source rock. Except the Nenjiang Formation, all the other horizons of source rock are in the gas generation stage, and the source rock of other horizons has large burial depth and high maturity. In particular, the Carboniferous-Permian is limited by high maturity, and there are less organic geochemical data. Therefore, the data of four wells of 4S1, Mg1, Du101 and Zs1 in this period are counted to analyze the organic matter abundance, organic matter type and organic matter maturity of the source rock in the region.

[0018] In an implementable manner, the geochemical characteristic analysis chart in step S1 includes the crossplot of organic matter maturity and burial depth, the frequency distribution chart of TOC, and the maceral discrimination chart.

[0019] Specifically, step S1 can quickly and accurately evaluate the hydrocarbon generation potential of the high-maturity source rock by comparing and analyzing the measured geochemical data of the target well in the above charts.

[0020] Specifically, the crossplot of organic matter maturity and burial depth (Ro-depth crossplot) is used to judge the change rule of the maturity of organic matter with the burial depth and identify the distribution horizon of the high-maturity source rock; the frequency distribution chart of TOC is used to count the distribution interval of the TOC value of the target well and determine the enrichment degree of the organic matter of the hydrocarbon source rock; and the maceral discrimination chart is used to distinguish the kerogen type and judge the hydrocarbon generation tendency (oil / gas) of the source rock.

[0021] In an implementable manner, in view of the fact that the organic geochemical characteristics show that the hydrocarbon source rock of the Carboniferous-Permian in the Binbei area of the Songliao Basin has hydrocarbon generation potential, but the maturity is generally high, which leads to the fact that the δ 13 C is heavier, the kerogen is mostly type III, there are fewer drilled wells of the Carboniferous-Permian, and there are less relevant organic geochemical analysis data. Therefore, step S2 selects the shale sample of the Permian Fengcheng Formation in the Mahu Sag as a substitute sample, which is close to the deposition period of the Carboniferous-Permian Linxi Formation in the Binbei area of the Songliao Basin and matches the kerogen type, so as to carry out the hydrocarbon generation thermal simulation experiment.

[0022] In one embodiment, the hydrocarbon generation thermal simulation experiment in step S2 adopts a closed system gold tube hydrocarbon generation thermal simulation experiment, wherein the pressure is 10~150MPa, the heating rate is 2~20℃ / h, and the temperature after heating is 300~600℃.

[0023] In one embodiment, the product of step S2 includes at least one of gaseous product and liquid product; the components of the liquid product include at least one of light components and heavy components.

[0024] In one embodiment, the formula for calculating the total hydrocarbon generation in the MFF model described in step S3 is: XKH = XKH = ( Q = S i (1-exp( - ))); where XKH is the total amount of hydrocarbons generated from organic matter; NKH is the number of parallel first-order reactions in the process of hydrocarbon generation from organic matter; XKH i Let ρ be the hydrocarbon generation potential of kerogen corresponding to the i-th reaction, i = 1 ~ NKH; T is the absolute temperature, T0 is the reference temperature; AKH i is the pre-exponential factor for the i-th reaction; D is the heating rate; EKH i Let be the activation energy of the i-th reaction; R is the gas constant.

[0025] Specifically, the basic idea of ​​the above model calibration is as follows: First, construct the objective function from the sum of squares of the differences between the calculated values ​​and the experimental values; construct the constraints from the physical meaning of the chemical kinetic parameters; then construct the penalty function from the objective function and the constraints, transforming the solution of the constrained extremum problem into the solution of the unconstrained extremum problem; finally, use the variable-scale optimization algorithm to solve the minimum point, thereby achieving the purpose of calibrating the model.

[0026] In one embodiment, in the hydrocarbon generation history simulation described in step S4, the factors affecting the hydrocarbon generation process include the burial depth, temperature difference, and erosion of the bottom and top layers of the source rock basement of the target well.

[0027] Specifically, since the source rock basement of the target well is thick and the amount of hydrocarbon generation at the bottom and top boundaries of the basement differs, the situation at the bottom and top layers must be considered separately during the hydrocarbon generation history simulation.

[0028] Specifically, the hydrocarbon generation capacity of source rocks is a key factor in determining the exploration potential of a region, and the study of the sedimentary burial-thermal evolution history of source rocks plays a crucial role in assessing hydrocarbon generation potential. It reflects the changes in the maturity of source rocks in the study area at different historical periods, providing important evidence for the migration, accumulation, and hydrocarbon accumulation processes. Hydrocarbon generation history analysis simulates the thermal evolution process of source rocks under different burial depths and temperature conditions to infer their hydrocarbon generation potential and hydrocarbon generation time. This process analysis can reveal the hydrocarbon generation periods of different source rocks, helping to assess oil and gas resource potential and guide exploration and development.

[0029] In one embodiment, the depth range of the secondary hydrocarbon generation limit in step S5 is 3479.3~4173.0m, and the corresponding EasyRo% range is 0.78~1.26%.

[0030] In one possible implementation, in step S6, given that the Carboniferous-Permian source rocks have a high degree of maturity, in order to accurately assess the hydrocarbon generation intensity of the source rocks, the characteristics of the source rocks are further quantitatively characterized according to the genetic method. Since the original hydrogen index is difficult to recover, in order to directly calculate the hydrocarbon generation of the source rocks, it is necessary to rely on reliable original TOC contour maps, source rock thickness contour maps, and other maps for analysis.

[0031] In one possible implementation, the formula for calculating the amount of hydrocarbons generated in step S7 is: • p i ·H i • TOC i • HI 0 Q / S 0 · X 0; where Q is the amount of hydrocarbons generated, in tons; S i The area of ​​the source rock is expressed in km². 2 H i ρ represents the thickness of the source rock, in meters (m). i This refers to the density of the source rock, expressed in kg / m³. 3 TOC0 is the original organic carbon content of the source rock, TOC0 = TOC × recovery coefficient; HI0 is the original hydrocarbon generation potential per unit mass of organic matter, in mg / g TOC; X0 is the hydrocarbon conversion rate of organic matter.

[0032] The corresponding formula for calculating hydrocarbon generation intensity is: Hydrocarbon generation intensity = • p i = H i • TOC i • HI 0 Figure 1 0 ·X 0.

[0033] Specifically, the hydrocarbon generation amount is a single grid hydrocarbon generation amount.

[0034] Specifically, the TOC0 is obtained by recovering the present TOC.

[0035] In an implementable manner, in step S7, the Q of each grid is accumulated by grid division to obtain the total hydrocarbon generation amount; based on the depth range and maturity interval corresponding to the secondary hydrocarbon generation bottom layer, the effective source rock distribution range of the secondary hydrocarbon generation is defined, and the secondary hydrocarbon generation amount is calculated by using the formula of the hydrocarbon generation amount and the hydrocarbon generation intensity.

[0036] Specifically, each divided grid has uniform hydrocarbon source rock volume, organic matter abundance, hydrogen index, hydrocarbon generation conversion rate and density.

[0037] Specifically, in the calculation of the secondary hydrocarbon generation amount, the formula of the hydrocarbon generation amount and the hydrocarbon generation intensity is used, and X0 is replaced by the organic matter conversion rate in the secondary hydrocarbon generation stage.

[0038] According to an implementable manner of the present disclosure, at least the following beneficial effects are achieved:

[0039] The present disclosure aims at the problem that the organic matter evolution degree of high-mature source rock is high and direct thermal simulation experiment cannot be carried out, and innovatively selects substitute samples with similar deposition period and matching kerogen type, and obtains hydrocarbon generation kinetic parameters by combining closed system gold tube thermal simulation experiment. This method avoids the problems of exhausted hydrocarbon potential and distorted parameters caused by directly using high-mature samples, makes the calibration of the kinetic model more consistent with the actual geological conditions, and reduces the simulation error of the hydrocarbon generation history. Secondly, for the first time, the organic matter conversion rate of 100% before the secondary denudation is taken as a threshold, and the depth range of the secondary hydrocarbon generation and the EasyRo% maturity interval are determined by combining the hydrocarbon generation history simulation, which solves the pain points of qualitative description and lack of quantitative standard of the secondary hydrocarbon generation boundary in the prior art. This quantitative standard can directly guide the selection of exploration target horizons, avoid invalid drilling, and greatly improve the exploration efficiency. In addition, based on the genetic formula, combined with the source rock TOC contour map, the thickness contour map and the grid division accumulation calculation, the hydrocarbon generation amount is innovatively divided into total hydrocarbon generation amount and secondary hydrocarbon generation amount for separate accounting. By distinguishing the primary cracking conversion rate and the secondary hydrocarbon conversion rate, the defects of the traditional method of only calculating the total hydrocarbon generation amount and being unable to distinguish the secondary contribution are solved, and the calculation result is more consistent with the hydrocarbon generation law of high-mature source rock, which provides accurate data support for resource classification evaluation.

[0040] The base data (logging TOC data, well logging data, sedimentary facies map) used in the present disclosure are all conventional data for oil and gas exploration. The steps of sample selection, thermal simulation experiment, model calibration, etc. are all general industry technologies, without the need for additional research and development of special equipment, with low operation threshold, which can be quickly promoted to similar high-mature source rock exploration areas such as Songliao Basin and Mahu Sag. In addition, the calculated secondary hydrocarbon generation amount can be directly used to guide the exploration deployment and development plan optimization of high-mature source rock areas, realizing the integration of exploration and development.

[0041] The present disclosure proves that part of the high-mature source rock which has experienced secondary burial still has effective hydrocarbon generation capacity by accurately evaluating the secondary hydrocarbon generation amount, which provides a theoretical basis for tapping the potential of old oilfields and new exploration in high-mature areas, and expands the exploration range of oil and gas resources. The constructed technical framework of alternative sample simulation + kinetic model calibration + boundary quantification + resource accounting can be used as a reference standard for the evaluation of secondary hydrocarbon generation of high-mature source rock in the industry, and promote the technical upgrading from experience judgment to quantitative evaluation in this field.

[0042] It should be understood that the content described in this part is not intended to identify key or important features of the embodiments of the present disclosure, nor to limit the scope of the present disclosure. Other features of the present disclosure will become apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0043] The above and other objects, features and advantages of the exemplary embodiments of the present disclosure will be more apparent from the following detailed description read in conjunction with the accompanying drawings, in which several embodiments of the present disclosure are shown by way of example, and in which:

[0044] In the drawings, identical or corresponding reference numerals indicate identical or corresponding parts.

[0045] Figure 2 A Ro-depth cross plot of the Carboniferous-Permian source rock in the Binbei area in Example 1 of the present disclosure is shown;

[0046] Figure 3 A TOC frequency distribution histogram of the Carboniferous-Permian source rock in the Binbei area in Example 1 of the present disclosure is shown;

[0047] Figure 4 A maceral composition triangle of the Carboniferous-Permian source rock in the Binbei area in Example 1 of the present disclosure is shown;

[0048] Figure 5 A kerogen δ 13 C frequency distribution histogram of the Carboniferous-Permian source rock in the Binbei area in Example 1 of the present disclosure is shown;

[0049] Figure 6 A Pr-nC17 Ph-nC 18 cross plot;

[0050] Figure 7 Fig. 8 shows a graph of the generation yield of each component of the YF1 hydrocarbon source rock thermal simulation experiment sample in Embodiment 1 of the present disclosure varying with temperature; wherein the temperature rising rate of (a) is 20℃ / h, and the temperature rising rate of (b) is 2℃ / h;

[0051] Figure 8 Fig. 9 shows a graph of the kinetic parameters and conversion rate of each component of the YF1 hydrocarbon source rock sample in Embodiment 1 of the present disclosure;

[0052] Figure 9 Fig. 10 shows a graph of the hydrocarbon generation history of the C-P Linxi Formation in Embodiment 1 of the present disclosure; wherein the left column is for Well 4S1, and the right column is for Well Du101;

[0053] Figure 10 Fig. 11 shows a graph of the related results of the secondary burial hydrocarbon conversion rate of Well 4S1 in Embodiment 1 of the present disclosure;

[0054] Figure 11 Fig. 12 shows a graph of the evaluation results of the source rock characteristics of the C-P Linxi Formation in Embodiment 1 of the present disclosure; wherein (a) is the original TOC contour map; and (b) is the hydrocarbon source rock thickness contour map;

[0055] Figure 12 Fig. 13 shows a graph of the hydrocarbon generation intensity contour map of the C-P Linxi Formation in the northern Songliao Basin in Embodiment 1 of the present disclosure;

[0056] Figure 1 Fig. 14 shows a graph of the secondary hydrocarbon generation intensity contour map of the C-P Linxi Formation in the northern Songliao Basin in Embodiment 1 of the present disclosure. DETAILED DESCRIPTION

[0057] In order to make the objectives, characteristics and advantages of the present disclosure more obvious and easy to understand, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below with reference to the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present disclosure.

[0058] Embodiment 1

[0059] In this embodiment, the resource quantity evaluation of the secondary burial hydrocarbon generation of high mature source rock is carried out, which is as follows:

[0060] (1) Evaluation of basic geochemical characteristics. The Songliao Basin contains multiple source rock strata, including the Nenjiang Formation, Qingshankou Formation, Yingcheng Formation, Shahezi Formation, and Linxi Formation of the Carboniferous-Permian System, involving Type I, Type II1, Type II2, and Type III kerogen and coal-bearing source rocks. Except for the Nenjiang Formation, all of them have entered the gas generation stage. The source rocks in other strata are buried at great depths and have high maturity. In particular, the Carboniferous-Permian (CP) system is limited by high maturity, and there is relatively little organic geochemical data. Therefore, data from four wells, 4S1, Mg1, Du101, and Zs1, during this period were analyzed to assess the abundance, type, and maturity of organic matter in the source rocks of this region.

[0061] Combined with corresponding geochemical characteristic analysis charts (cross-plot of organic matter maturity and burial depth, frequency distribution map of TOC, and micro-component discrimination map), Figure 2 The Ro-depth cross plot shows that the maturity is generally greater than 2, and according to the hydrocarbon source rock organic matter maturity evaluation index, the Carboniferous-Permian system in the Binbei area of ​​the Songliao Basin is currently in a high-overmature stage. Figure 3 The TOC frequency distribution histogram shows that the majority of TOC is between 1% and 2%. Referring to the SY / T5735-1995 source rock organic matter abundance index, the source rocks have high organic matter abundance, indicating they are primarily good source rocks. Microscopic component discrimination chart ( Figure 4 The data shows that the kerogen types are mainly type II1 and type III; due to the high maturity of the source rocks, the carbon isotopes are also affected, leading to... 12 C- 12 C breaks first. 13 C- 13 C fractures later, therefore δ 13 C-frequency distribution histogram ( Figure 5 The results show that kerogen δ 13 C > -25‰, belonging to Type III according to organic matter classification; for Carboniferous-Permian source rocks with high evolutionary degree, conventional methods cannot effectively reflect the type of organic matter kerogen, while the method of comparing biomarker compound parameters can effectively classify organic matter types, pterostilbene / nC 17 With phytane / nC 18 Relationship diagram ( Figure 6 The results show that the organic kerogen types are type II1 and type II2.

[0062] It is evident that the source rocks in this region have high organic matter abundance, deep thickness, high maturity, and good organic matter type. In summary, the Carboniferous-Permian basement layer in the study area has good hydrocarbon generation potential.

[0063] (2) Experimental Samples and Contents. Given that the organic geochemical characteristics indicate that the Carboniferous-Permian source rocks in the Binbei area of ​​the Songliao Basin possess hydrocarbon generation potential, but due to their generally high maturity, the δ¹⁴ ... 13C is heavier, the kerogen is mostly type III, and there are fewer wells drilled through the Carboniferous-Permian system, and there is even less organic geochemical analysis data. Therefore, shale samples from the Permian Fengcheng Formation in the Mahu Sag were selected as substitute samples, which were close to the deposition period of the Carboniferous-Permian Linxi Formation in the Binbei area of the Songliao Basin and had the same type of kerogen, so as to carry out simulation experiments of hydrocarbon generation.

[0064] Based on the method of thermal simulation experiment, the study of the characteristics of hydrocarbon generation of source rocks has become an essential technique and means for providing reliable parameters for the calculation of hydrocarbon resources. In order to accurately evaluate the secondary hydrocarbon resources of the C-P Linxi Formation, a gold tube hydrocarbon generation thermal simulation experiment in a closed system was carried out on the substitute samples, and the component yield-temperature curve and hydrocarbon generation kinetic parameters of the substitute sample kerogen during the generation process were further determined.

[0065] A muddy dolomite sample from well FN7 was selected, which is widely distributed in the study area and has great hydrocarbon potential, and is the main source rock of the Fengcheng Formation. The YF1 source rock sample has a low maturity with a Ro value of 0.6%, and a high organic matter abundance with a TOC value of 0.8563% (see Table 1).

[0066] Table 1

[0067]

[0068] The experimental instrument is a hydrocarbon generation kinetics thermal simulation experiment device developed by the Guangzhou Institute of Geochemistry of the Chinese Academy of Sciences, and the experimental process and standards follow the "Gold Tube Hydrocarbon Generation Thermal Simulation Experiment Method" of the Petroleum and Natural Gas Industry Standard. The thermal simulation experiment process is as follows: a. Under the condition of a pressure of 50 MPa, each sample is heated from room temperature to 600℃ at a heating rate of 2℃ / h and 20℃ / h, respectively. b. From 336℃ to 600℃, every 24℃, the gaseous output of the sample is qualitatively and quantitatively analyzed; the light components (C6~C 14 ) of the liquid output are qualitatively and quantitatively analyzed by gas chromatography (GC); the heavy components (C 14+ ) of the liquid output are analyzed by organic extraction and weighing; and the yield of the gaseous output of the thermal simulation hydrocarbon is quantitatively calculated and the hydrocarbon generation kinetic parameters are calculated.

[0069] During the hydrocarbon generation process of source rocks, heavy oil is generated earlier than light oil. Taking the YF1 rock sample with a 20℃ / h heating rate as an example, Figure 6 (a) of the figure shows that heavy oil (i.e. C 14+ ) and light oil (i.e. C 6-14The temperatures corresponding to the maximum yield are approximately 408℃ and 456℃, respectively. When the pyrolysis temperature exceeds 408℃, the yield of heavy oil decreases rapidly, while the yield of light oil continues to increase. In fact, liquid hydrocarbons or light oils mainly originate from the thermal decomposition of the early-stage heavy components. The pyrolysis of type I organic matter mainly produces oil, but after reaching the high-temperature stage of 504℃, the yield of methane (i.e., C1) in the closed system increases rapidly, which is due to the cracking of early-stage liquid products and moisture.

[0070] Throughout the entire thermal simulation experiment of YF1 source rock, the gaseous products were mainly methane. Figure 6 of (a) Figure 6 (b) shows that the methane yield gradually increases with increasing temperature, reaching a peak of 260.51 mg / (g·TOC) at a heating rate of 20 °C / h and a simulated temperature of 600 °C; and a peak of 299.26 mg / (g·TOC) at a heating rate of 2 °C / h and a simulated temperature of 600 °C. Total gas (i.e., C...) 1-5 The yield peaked at a heating rate of 20℃ / h and a simulated temperature of approximately 528℃, reaching 317.04 mg / (g·TOC); and at a heating rate of 2℃ / h and a simulated temperature of approximately 504℃, reaching 324.62 mg / (g·TOC). Total hydrocarbons (i.e., C...) 1+ The production rate peaked at a simulated temperature of approximately 432℃ and a heating rate of 20℃ / h, reaching 481.4 mg / (g·TOC); while at a simulated temperature of approximately 385℃ and a heating rate of 2℃ / h, it peaked at 503.08 mg / (g·TOC). The comparison of these two heating rates shows that different heating rates have some impact on natural gas production, but the differences are not significant; the lower the heating rate, the lower the corresponding gas production temperature.

[0071] Liquid hydrocarbon yield initially increases and then decreases with increasing temperature, as does total hydrocarbon yield, although the decrease is relatively small. This indicates that after the liquid hydrocarbon yield begins to decline, the gaseous hydrocarbon yield increases, slowing the rate of decline in total hydrocarbon yield. XKH = XKH It can be seen that the YF1 source rock sample contains liquid hydrocarbons (i.e., C24H2O) 6-14There is only one oil generation peak, and the sample reaches the peak of liquid hydrocarbon yield of 174.61 mg / (g·TOC) at a temperature of about 431.5℃ and a heating rate of 2℃ / h, and the sample reaches the peak of liquid hydrocarbon yield of 178.53 mg / (g·TOC) at a temperature of about 456℃ and a heating rate of 20℃ / h. The hydrocarbon yield of the source rock is different when the experimental heating rate is different. During the experiment, when the source rock is heated at a heating rate of 2℃ / h and 20℃ / h, it is found that when the yield is the same, the hydrocarbon generation temperature is lower when heated at a heating rate of 2℃ / h, which is consistent with the principle of time-temperature complementarity.

[0072] (3) Calibration of kinetic model. There are various reaction rate models for describing the chemical kinetic model of organic matter hydrocarbon generation, such as total package reaction, series reaction, parallel reaction, and consecutive reaction. In this embodiment, a parallel first-order reaction model with different pre-exponential factors and a discrete distribution of activation energy is used, which is referred to as MFF model. It is assumed that the process of organic matter hydrocarbon generation is composed of a series of (NKH) parallel first-order reactions, the activation energy of each reaction is EKH i , the pre-exponential factor is AKH i , and the hydrocarbon generation potential of kerogen corresponding to each reaction is XKH i , i=1,2,…,NKH. Thus, from the first-order reaction rate equation and the Arrhenius formula, it is not difficult to derive that the total hydrocarbon generation amount of the NKH parallel reactions is: Figure 7 = Figure 7 i (1-exp( - )));wherein XKH is the total hydrocarbon generation amount; T is the absolute temperature, T0 is the reference temperature; D is the heating rate; R is the gas constant. The basic idea of model calibration is as follows: first, construct an objective function from the square sum of the difference between the model calculation value and the experimental value, construct a constraint condition from the physical meaning of the chemical kinetic parameters, then construct a penalty function from the objective function and the constraint condition, convert the solution of the constrained extreme value problem into the solution of the unconstrained extreme value problem, and finally use the variable scale optimization algorithm to solve the minimum point to achieve the purpose of calibrating the model.

[0073] According to the conversion rates of each component obtained from the thermal simulation experiment of step (2), the kinetic model of gaseous hydrocarbon, total oil and total hydrocarbon of YF1 sample is calibrated by using the kinetic parameter calibration software. Figure 7 It can be seen from Table 1 that the pre-exponential factor of YF1 to generate gaseous hydrocarbon (i.e. C 1-5 ) is 6.8×10 14 S -1 , and the main frequency activation energy is 240 kJ / mol (240000 J / mol). Figure 7 ​(a); the pre-exponential factor for the generation of total oil is 3.59 x 10 15 S -1 (a); the pre-exponential factor for the generation of total oil is 3.59 x 10 Figure 8 (a); the pre-exponential factor for the generation of total oil is 3.59 x 10 15 S -1 (a); the pre-exponential factor for the generation of total oil is 3.59 x 10 Figure 8 (a); the pre-exponential factor for the generation of total oil is 3.59 x 10

[0074] (4) Build the sedimentary burial history-thermal history, and evaluate the hydrocarbon generation history. The hydrocarbon generation capacity of source rock is the key factor to judge whether an area has exploration potential, and the study of sedimentary burial-thermal evolution history of source rock plays a crucial role in assessing hydrocarbon generation potential. It can reflect the maturity changes of source rocks in different historical periods, and provide important basis for oil and gas migration, accumulation and reservoir forming process. Hydrocarbon generation history analysis is to simulate the thermal evolution process of source rocks under different burial depths and temperature conditions to predict their hydrocarbon generation potential and oil and gas generation time. This process analysis can reveal the hydrocarbon generation period of different source rocks, help to evaluate the potential of oil and gas resources, and guide exploration and development.

[0075] Because the C-P Linxi Formation has a wide sedimentary range and a thick sedimentary thickness, the hydrocarbon generation history experienced by different regions may not be consistent, so the hydrocarbon generation history evaluation is carried out for 4S1 well and Du101 well in different regions.

[0076] Firstly, according to the collected sedimentary burial history-thermal history of the target well in the study area, combined with the kinetic parameters, the evolution characteristics of the hydrocarbon generation history of 4S1 well and Du101 well are determined, and considering that the C-P Linxi Formation has a thick basement, the bottom and top of the basement have different hydrocarbon generation amounts, the hydrocarbon generation history simulation of the bottom and top of the basement is carried out respectively, and the results are shown in Figure 8 .

[0077] From the hydrocarbon generation history simulation results, for Du101 well, the burial depth is deep and the temperature is above 280℃ during the first hydrocarbon generation, the whole kerogen is completely converted and the oil and gas components are all generated, and they are basically completely lost due to the effect of denudation, so in the hydrocarbon generation history, before the denudation in the kerogen cracking stage, the EasyRo% of the bottom stratum reaches 4%, the kerogen is completely cracked, the EasyRo% of the top stratum is less than 4%, the kerogen cracking hydrocarbon generation has ended, and there is no secondary hydrocarbon generation, so there is no exploration potential (as shown in Figure 8 (b) and Figure 8(d)). In contrast, for well 4S1, the bottom formation temperature reached 180℃ at the initial burial depth, and the top formation temperature was even lower than 180℃. Therefore, the primary hydrocarbon generation stage is reflected in the hydrocarbon generation history. Before the erosion occurs during the initial cracking stage, when the EasyRo% of the bottom formation is close to 2%, the kerogen conversion ends, but the top formation is less than 1%. Therefore, the top kerogen is not completely converted. In the later secondary burial stage, the kerogen continues to convert and generate hydrocarbons, so some formations still have hydrocarbon generation potential (such as...). Figure 9 (a) and Figure 10 (c) Therefore, the boundary of secondary hydrocarbon generation is determined based on the above factors.

[0078] (5) Determine the bottom boundary of secondary hydrocarbon generation. The so-called secondary hydrocarbon generation threshold refers to the burial depth at which secondary hydrocarbon generation begins in the source rock, and determining the bottom boundary depth at which secondary hydrocarbon generation begins is crucial when calculating the amount of secondary hydrocarbon generation.

[0079] Due to the thick CP Linxi Formation, during the primary hydrocarbon generation in well 4S1, the kerogen conversion at the bottom layer ended before the erosion period. At this point, the top layer kerogen was not fully converted and continued to generate hydrocarbons during the later secondary burial stage. Further simulations of the hydrocarbon generation history of all layers of thickness in well 4S1 revealed that the depth range of the secondary hydrocarbon generation boundary with a 100% conversion rate before the second erosion occurred was 3479.2–4173.0 m, with a thickness of 693.7 m. The EasyRo% of the kerogen during the secondary hydrocarbon generation stage was 0.78–1.26% (e.g., ...). Figure 10 As shown in the figure, this provides a data foundation for the next step of calculating secondary hydrocarbon generation.

[0080] (6) Evaluation of the characteristics of the source rocks of the CP Linxi Formation. Given the high maturity of the Carboniferous-Permian source rocks, in order to accurately evaluate the hydrocarbon generation intensity of the source rocks, it is necessary to further quantitatively characterize the characteristics of the source rocks based on the genetic method. Since the original hydrogen index is difficult to recover, in order to directly calculate the hydrocarbon generation of the source rocks, it is necessary to rely on reliable original TOC contour maps, source rock thickness contour maps and other maps for analysis.

[0081] Therefore, the TOC data identified by well logging in the northern part of the Songliao Basin (Carboniferous-Permian) were used for prediction and calculation. The calculated TOC values ​​of 59 wells in the target area were obtained, and the TOC distribution of the northern part of the Songliao Basin (e.g., the Carboniferous-Permian) was analyzed. Q = S As shown in (a). The development of source rocks in the work area was obtained by statistically analyzing the logging data of the target area. Combined with the Carboniferous-Permian sedimentary facies map and previous exploration results, the thickness contour map of the Carboniferous-Permian source rocks in the northern part of the Songliao Basin was finally obtained (as shown in (a)). • p (as shown in (b)).

[0082] (7) Hydrocarbon generation calculation. The hydrocarbon generation intensity of the source rocks was evaluated using the genetic method. In order to accurately evaluate the hydrocarbon generation intensity of the source rocks, the analysis was based on the restored original TOC contour map and the source rock thickness contour map.

[0083] The formula for calculating hydrocarbon generation is: • TOC i ·H i • HI i Q / S 0 • p 0 ·X 0; where Q is the amount of hydrocarbons generated, in tons; S i The area of ​​the source rock is expressed in km². 2 H i ρ represents the thickness of the source rock, in meters (m). i This refers to the density of the source rock, expressed in kg / m³. 3 TOC0 represents the original organic carbon content of the source rock, TOC0 = TOC × recovery coefficient, and TOC0 is recovered from the current TOC; HI0 represents the original hydrocarbon generation potential per unit mass of organic matter, in mg / g TOC; X0 represents the hydrocarbon conversion rate of organic matter.

[0084] The corresponding formula for calculating hydrocarbon generation intensity is: Hydrocarbon generation intensity = • TOC i = H i • HI i Figure 11 0 Figure 12 0 ·X 0.

[0085] The northern part of the Songliao Basin is divided into m×n identical grids. Each grid has a uniform source rock volume, organic matter abundance, hydrogen index, hydrocarbon generation conversion rate, and density. The total hydrocarbon generation amount is obtained by summing the Q values ​​of each cell.

[0086] The hydrocarbon generation intensity of the CP Linxi Formation was calculated based on the above calculation method. The CP Linxi Formation is currently at a high maturity level, and rock pyrolysis data can no longer characterize its hydrocarbon generation potential. Based on the previously classified Type II1 and Type II2 kerogen, the original hydrogen index (HI0) was set to a constant value of 500 mg / g TOC. For the initial pyrolysis, the organic matter conversion rate is approximately 1. Based on the restored original TOC and thickness contour maps, a contour map depicting the hydrocarbon generation intensity of the Linxi Formation in the Binbei area was constructed. ​ The Linxi Formation is thick and mature, and calculations show that its hydrocarbon generation intensity is between 10,000 and 30,000 kt / km. 2Based on the established isopleth map of hydrocarbon generation intensity in the CP Linxi Formation, the total hydrocarbon generation of the CP Linxi Formation in the Binbei area is calculated to be 824.383 billion tons, with a natural gas density of 0.72 kg / m³. 3 This is equivalent to a gas volume of 1144.976 trillion cubic meters.

[0087] Based on the restored original TOC and thickness contour maps, a contour map of secondary hydrocarbon generation intensity in the Linxi Formation of the Binbei area was constructed. The secondary hydrocarbon generation thickness of the Linxi Formation is 693.7 m, with a maturity of 0.78–1.26% and an average conversion rate of 35%. Calculation results show that the hydrocarbon generation intensity ranges from 0 to 5500 kt / km². 2 Between; based on the already characterized CP Linxi Formation secondary hydrocarbon generation intensity contour map ( ​ The secondary hydrocarbon generation of the CP Linxi Formation in the Binbei area was calculated to be 22.326 billion tons, with a natural gas density of 0.72 kg / m³. 3 This is equivalent to a gas volume of 31 trillion cubic meters.

[0088] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this disclosure can be achieved, and this is not limited herein.

[0089] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this disclosure, "a plurality of" means two or more, unless otherwise explicitly specified.

[0090] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A method for evaluating the resource quantity of hydrocarbon generation from secondary burial depth in highly mature source rocks, characterized in that, Includes the following steps: S1: Statistically analyze the organic matter abundance, organic matter type, and organic matter maturity data of the target wells in the study area, and combine them with the corresponding geochemical characteristic analysis charts to comprehensively analyze the hydrocarbon generation potential of the highly mature source rocks in the study area. S2: Select substitute samples that are similar in depositional period and kerogen type to the high-maturity source rocks in the study area, and use hydrocarbon generation thermal simulation experiments to perform qualitative and quantitative analysis on each component of the product, and obtain the yield-temperature curves and hydrocarbon generation kinetic parameters of each component. S3: Using the MFF model, based on the hydrocarbon generation kinetic parameters and conversion rates of each component described in step S2, the kinetic models of gaseous hydrocarbons, total oil, and total hydrocarbons of the substitute sample are calibrated. S4: Combining the sedimentary burial history-thermal history data of the target well in the study area with the kinetic parameters calibrated in step S3, conduct hydrocarbon generation history simulation of the bottom and top layers of the source rock basement of the target well to clarify the hydrocarbon generation evolution characteristics and determine the secondary hydrocarbon generation potential; In the hydrocarbon generation history simulation, the factors affecting the hydrocarbon generation process include the burial depth, temperature difference and erosion of the bottom and top layers of the source rock basement of the target well; S5: For the target well with the aforementioned secondary hydrocarbon generation potential, simulate the hydrocarbon generation history of its full-thickness stratigraphy to determine the depth range and EasyRo% range of the secondary hydrocarbon generation limit before secondary erosion and when the conversion rate is 100%; the depth range of the secondary hydrocarbon generation limit is 3479.3~4173.0m, and the corresponding EasyRo% range is 0.78~1.26%; S6: Predict and calculate the TOC data of the high-mature source rocks in the study area, and draw the original TOC contour map and source rock thickness contour map by combining the well logging data, sedimentary facies map and previous exploration results. S7: Based on the genetic method, using the original TOC contour map and the source rock thickness contour map, combined with the set original hydrogen index, organic matter conversion rate, and source rock density parameters, the total hydrocarbon generation and secondary hydrocarbon generation of the highly mature source rocks in the study area are calculated by grid division and accumulation; the formula for calculating hydrocarbon generation is: Q=S i ·H i ·ρ i TOC 0 ·HI 0 ·X 0; where Q is the amount of hydrocarbons generated, in tons; S i The area of ​​the source rock is expressed in km². 2 H i ρ represents the thickness of the source rock, in meters (m). i This refers to the density of the source rock, expressed in kg / m³. 3 TOC0 represents the original organic carbon content of the source rock, TOC0 = TOC × recovery coefficient; HI0 represents the original hydrocarbon generation potential per unit mass of organic matter, in mg / g TOC; X0 represents the hydrocarbon conversion rate of organic matter; the corresponding formula for calculating hydrocarbon generation intensity is: Hydrocarbon generation intensity = Q / S i = H i ·ρ i TOC 0 ·HI 0 ·X 0; In step S7, the total hydrocarbon generation is obtained by summing the Q values ​​of each grid through grid division; based on the depth range and maturity interval corresponding to the secondary hydrocarbon generation bottom layer, the effective source rock distribution range of secondary hydrocarbon generation is defined, and the secondary hydrocarbon generation is calculated by summing the formulas for hydrocarbon generation and hydrocarbon generation intensity.

2. The resource quantity evaluation method according to claim 1, characterized in that, The highly mature source rock mentioned in step S1 is a hydrocarbon source rock of the Linxi Formation of the Carboniferous-Permian system in the Binbei area of ​​the Songliao Basin, and the maturity of the highly mature source rock is Ro > 2.0%.

3. The resource quantity evaluation method according to claim 1, characterized in that, The geochemical characteristic analysis charts mentioned in step S1 include a cross-plot of organic matter maturity versus burial depth, a frequency distribution plot of TOC, and a micro-component discrimination plot.

4. The resource quantity evaluation method according to claim 1, characterized in that, The hydrocarbon generation thermal simulation experiment described in step S2 adopts a closed system gold tube hydrocarbon generation thermal simulation experiment, wherein the pressure is 10~150MPa, the heating rate is 2~20℃ / h, and the temperature after heating is 300~600℃.

5. The resource quantity evaluation method according to claim 1, characterized in that, The product of step S2 includes at least one of gaseous product and liquid product; the components of the liquid product include at least one of light components and heavy components.

6. The resource quantity evaluation method according to claim 1, characterized in that, The formula for calculating the total hydrocarbon generation in the MFF model described in step S3 is as follows: XKH= = ( XKH i (1-exp( - ))); where XKH is the total amount of hydrocarbons generated from organic matter; NKH is the number of parallel first-order reactions in the process of hydrocarbon generation from organic matter; XKH i Let ρ be the hydrocarbon generation potential of kerogen corresponding to the i-th reaction, i = 1 ~ NKH; T is the absolute temperature, T0 is the reference temperature; AKH i is the pre-exponential factor for the i-th reaction; D is the heating rate; EKH i Let be the activation energy of the i-th reaction; R is the gas constant.

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