A method for determining the suitable maturity range of shale oil

Abstract

The present invention discloses a method for determining the suitable production maturity interval of shale oil, which includes the following steps: making graphs of the variation of oil-bearing index, shale oil density, and shale oil group components with burial depth and the relationship between burial depth and the degree of thermal evolution; determining the depth between the highest value of the oil-bearing index and the mobility parameter; and taking the corresponding thermal evolution degree interval as the shale oil maturity interval based on field practice; determining the shale oil maturity interval based on thermal simulation according to the graphs of the variation of gas-oil ratio, total oil, total gas, and total hydrocarbon content with the degree of thermal evolution; comparing and correcting the above two maturity intervals, and taking the intersection as the final suitable production maturity interval of shale oil. The present invention can effectively take into account the oil-bearing property of shale and the mobility of shale oil, make up for the deficiency in current exploration and development that only pays attention to the mobility of shale oil but ignores the movable resource amount of shale oil, and the obtained results can effectively solve the problem that the initial production of current shale oil wells is high but the decline is fast.

Description

Technical Field

[0001] The present invention relates to a method for determining the suitable maturity interval of shale oil, belonging to the technical field of oil development. Background Art

[0002] In recent years, with the gradual transformation and innovation of the concept of oil and gas exploration, against the background of the significant success of shale oil exploration and development in North America, shale oil and gas resources in shale formations have received extensive attention, and their proportion in the global energy structure has gradually increased. It has become one of the important alternative energy sources for future oil and gas resources, highlighting its energy security and strategic significance.

[0003] For continental shale, the degree of thermal evolution (Ro) is a key index for evaluating layers and selecting areas. It determines the properties and quality of oil and gas products and affects the fluidity and production effect of crude oil in the shale formation. A high maturity means a high gas-oil ratio (GOR, unit: m 3 / t), low density, low viscosity, high oil saturation, and small oil and gas molecules.

[0004] Generally, with the increase of burial depth, the physical and chemical properties of shale oil will change in the following two aspects: 1) Due to the increase of the degree of shale thermal evolution, the long chains of kerogen gradually disappear, the short alkyl side chains increase, and the H / C and O / C ratios decrease, resulting in the weakening of the adsorption capacity of kerogen for shale oil; 2) The saturated hydrocarbon content of shale oil increases, the viscosity and density decrease, the gas-oil ratio increases, and the fluidity increases. Exploration practice has proved that when the shale maturity is Ro > 0.9%, the GOR is relatively high, which is the main target area for shale oil. The GOR of successfully exploited shale oil in the United States is mostly greater than 100 m 3 / t, and the surface (20 °C) density is less than 0.87 g / cm 3 or the viscosity is less than 10 mPa·s. The Ro of three Jurassic shale oil wells (Ping'an 1 Well, Taiye 1 Well, and Fuye 10HF Well) in the Sichuan Basin even reached 1.4%, proving the important influence of higher maturity on the mobility of crude oil. Some studies have shown that in the high-temperature and high-pressure underground environment, part or all of the gaseous hydrocarbons are dissolved in the liquid hydrocarbons. When the formation is fractured, a large amount of gaseous hydrocarbons will be released due to the pressure reduction. On the one hand, it can drive the flow of liquid hydrocarbons, and on the other hand, it provides power for shale oil exploitation.

[0005] Regarding how to determine the suitable maturity interval of shale oil, previous studies and related literature mostly focus on the mobility of shale oil and pay less attention to the oil content of shale. This is also one of the reasons for the high initial production and rapid decline of daily production in a short time during the current shale oil exploitation process. Therefore, it is urgent to carry out relevant research to take into account both the oil content of shale and the mobility of shale oil, so as to provide guidance for the exploration and development of shale oil. Summary of the Invention

[0006] To overcome the problems in the prior art, the present invention provides a method for determining the suitable production maturity interval of shale oil.

[0007] The technical solution provided by the present invention to solve the above technical problems is: a method for determining the suitable production maturity interval of shale oil, comprising the following steps:

[0008] Step S1, respectively make graphs of the oiliness index, shale oil density, shale oil group components varying with burial depth, and the relationship between burial depth and thermal evolution degree according to the measured geochemical data;

[0009] Step S2, determine the depth interval between the oiliness index and the maximum value of the mobility parameter according to the graphs of the oiliness index, shale oil density, and shale oil group components varying with burial depth; and use the thermal evolution degree interval corresponding to this depth interval in the graph of the relationship between burial depth and thermal evolution degree as the suitable production maturity Ro interval of shale oil based on field practice;

[0010] Step S3, select low-maturity shale samples to conduct a gold tube thermal simulation experiment under a closed system to obtain the change situation of shale oil and gas enrichment products at different evolution stages;

[0011] Step S4, determine the graphs of the relationships between gas-oil ratio, total oil, total gas, and total hydrocarbon content varying with the evolution degree according to the change situation of shale oil and gas enrichment products at different evolution stages;

[0012] Step S5, determine the suitable production maturity easy Ro interval of shale oil based on thermal simulation according to the graphs of the relationships between gas-oil ratio, total oil, total gas, and total hydrocarbon content varying with the evolution degree;

[0013] Step S6, convert the suitable production maturity easy Ro interval of shale oil based on thermal simulation into the suitable production maturity Ro interval of shale oil based on thermal simulation according to the following formula;

[0014] Ro = 0.7034 * easy Ro + 0.2627

[0015] In the formula: Ro is the measured maturity; easy Ro is the thermal simulation maturity;

[0016] Step S7, compare and correct the converted suitable production maturity Ro interval of shale oil based on thermal simulation with the suitable production maturity Ro interval of shale oil based on field practice, and take the intersection of the two as the final suitable production maturity interval of shale oil.

[0017] A further technical solution is that the measured geochemical data in the step S1 is obtained through the following steps: conduct organic carbon and rock pyrolysis tests on the samples to respectively measure the organic carbon content TOC, free hydrocarbon S1, pyrolysis hydrocarbon S2, and the maximum pyrolysis temperature Tmax; and then obtain the oiliness index (S1 / TOC) through the above parameters.

[0018] A further technical solution is that in step S1, the core of the sample is crushed to less than 100 mesh before performing organic carbon testing and pyrolysis analysis.

[0019] A further technical solution is that in step S1, separation and quantitative experiments on the group components of shale oil are required. The operation process can be found in the petroleum and natural gas industry standard "Analysis of Soluble Organic Matter and Crude Oil Group Components in Rocks SY / T 5119 - 2016". According to the principle of liquid - solid adsorption equilibrium, after centrifuging the crude oil, it is placed in a chromatographic column and passed through solvents with different polarities such as n - hexane, chloroform, and benzene to obtain saturated hydrocarbons, aromatic hydrocarbons, and resins. The insoluble part remaining in the centrifuge tube is asphaltene.

[0020] A further technical solution is that in step S1, a densitometer is required to measure the density of shale oil. The densitometer is calibrated by density units with the density of pure water at 4°C being 1 g / cm 3 used as the standard calibration scale.

[0021] A further technical solution is that the specific process of the gold tube thermal simulation experiment under a closed system in step S3 is as follows: The sample is loaded into a gold tube sealed at one end, placed in a cold water bath, and the excess air in the gold tube is removed by argon. Using argon as the protective gas, the other end is sealed by argon arc welding; after loading the sample, weigh it again to check whether the gold tube leaks; then place the sample in a high - pressure autoclave, set relevant parameters, start the thermal simulation experimental device, set a programmed temperature increase, and after reaching the predetermined temperature point, take out the gold tube and quantitatively test the hydrocarbon products in it using gas chromatography.

[0022] A further technical solution is that the experimental conditions of the gold tube thermal simulation experiment under a closed system in step S3 are: pressure 50 Mpa, the experimental heating rates are 2°C / h and 20°C / h respectively, and the temperature range is 300 - 600°C.

[0023] A further technical solution is that the specific calibration process in step S7 is as follows: Based on the Ro interval of the suitable mining maturity of shale oil based on thermal simulation, take the intersection with the Ro interval of the suitable mining maturity of shale oil based on field practice as the final Ro interval of the suitable mining maturity of shale oil.

[0024] A further technical solution is that the specific calibration process in step S7 is:

[0025] When the Ro interval of the suitable mining maturity of shale oil based on thermal simulation is within the Ro interval of the suitable mining maturity of shale oil based on field practice, take the Ro interval of the suitable mining maturity of shale oil based on thermal simulation as the final Ro interval of the suitable mining maturity of shale oil;

[0026] When there is an intersection between the applicable maturity range of Ro for shale oil based on thermal simulation and the applicable maturity range of Ro for shale oil based on field practice, the intersection point of the two is taken as the final applicable maturity range of shale oil;

[0027] When the applicable maturity range of Ro for shale oil based on field practice is within the applicable maturity range of Ro for shale oil based on thermal simulation, the applicable maturity range of Ro for shale oil based on field practice is taken as the final applicable maturity range of shale oil.

[0028] The present invention has the following beneficial effects: The method of the present invention can effectively take into account the oil-bearing property of shale and the mobility of shale oil, making up for the deficiency in current exploration and development that only pays attention to the mobility of shale oil but ignores the movable resource volume of shale oil. The obtained results can effectively solve the problem that the initial production of current shale oil wells is high but the decline is fast. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic flow chart of the present invention;

[0030] Figure 2 is a graph showing the relationship between the burial depth of shale and the change in thermal evolution degree;

[0031] Figure 3 is a graph showing the change of oil-bearing index, shale oil density, and shale oil group components of shale with burial depth;

[0032] Figure 4 is a statistical graph of the thermal simulation experimental data of shale samples. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0034] As Figure 1 shown, a method for determining the applicable maturity range of shale oil of the present invention includes the following steps:

[0035] Step S1, respectively make graphs showing the change of oil-bearing index, shale oil density, and shale oil group components with burial depth and the relationship between burial depth and the change in thermal evolution degree according to the measured geochemical data;

[0036] Among them, the core of the sample is crushed to less than 100 meshes and then organic carbon testing and pyrolysis analysis are carried out, and the organic carbon content TOC, free hydrocarbon S1, pyrolysis hydrocarbon S2, and maximum pyrolysis temperature Tmax are measured respectively; then the oil-bearing index (S1 / TOC) is obtained through the above parameters;

[0037] Test the density of shale oil with a densitometer; the densitometer is calibrated by density units, with the density of pure water at 4°C being 1 g / cm 3 As the standard calibration is made based on the Archimedes' principle; the greater the density of the crude oil, the greater the buoyancy, and the higher the densitometer floats upright in it;

[0038] Carry out the separation and quantitative experiment of the group components of shale oil. The operation process is shown in the petroleum and natural gas industry standard "Analysis of Soluble Organic Matter in Rock and Group Components of Crude Oil SY / T 5119 - 2016". According to the principle of liquid - solid adsorption equilibrium, after centrifuging the crude oil, it is placed in a chromatography column and passed through solvents with different polarities such as n - hexane, chloroform, and benzene to obtain saturated hydrocarbons, aromatic hydrocarbons, and resins. The insoluble part remaining in the centrifuge tube is asphaltene;

[0039] Step S2: Determine the depth interval between the highest value of the oil - bearing index and the mobility parameter based on the variation diagrams of the oil - bearing index, shale oil density, and shale oil group components with burial depth; and take the thermal evolution degree interval in the relationship diagram between the burial depth corresponding to this depth interval and the thermal evolution degree as the Ro interval of the suitable mining maturity of shale oil based on field practice;

[0040] Step S3: Select low - maturity shale samples to conduct a gold tube thermal simulation experiment under a closed system to obtain the variation of shale oil and gas enrichment products at different evolution stages;

[0041] The specific process of this gold tube thermal simulation experiment under a closed system is as follows: Load the sample into a gold tube with one end sealed, place it in a cold water bath, remove the excess air in the gold tube through argon, and use argon as the protective gas. Seal the other end by argon arc welding; after loading the sample, weigh it again to check whether the gold tube leaks; then place the sample in a high - pressure autoclave, set relevant parameters (pressure 50 Mpa), start the thermal simulation experimental device, set a programmed temperature rise (the experimental heating rates are 2°C / h and 20°C / h respectively, and the temperature range is 300 - 600°C). After reaching the predetermined temperature point, take out the gold tube and quantitatively test the hydrocarbon products in it using gas chromatography;

[0042] Step S4: Determine the variation diagrams of gas - oil ratio, total oil, total gas, and total hydrocarbon content with the evolution degree based on the variation of shale oil and gas enrichment products at different evolution stages;

[0043] Step S5: Determine the easy Ro interval of the suitable mining maturity of shale oil based on thermal simulation according to the variation diagrams of gas - oil ratio, total oil, total gas, and total hydrocarbon content with the evolution degree;

[0044] Step S6: Convert the easy Ro interval of the suitable mining maturity of shale oil based on thermal simulation into the Ro interval of the suitable mining maturity of shale oil based on thermal simulation according to the following formula;

[0045] Ro = 0.7034 * easy Ro + 0.2627

[0046] Where: Ro is the measured maturity; easy Ro is the thermal simulation maturity;

[0047] Step S7: Compare and correct the Ro interval of the suitable production maturity of shale oil based on thermal simulation with the Ro interval of the suitable production maturity of shale oil based on field practice, and finally obtain the final Ro interval of the suitable production maturity of shale oil;

[0048] When the Ro interval of the suitable production maturity of shale oil based on thermal simulation is within the Ro interval of the suitable production maturity of shale oil based on field practice, take the Ro interval of the suitable production maturity of shale oil based on thermal simulation as the final Ro interval of the suitable production maturity of shale oil;

[0049] When the Ro interval of the suitable production maturity of shale oil based on thermal simulation intersects with the Ro interval of the suitable production maturity of shale oil based on field practice, take the intersection point of the two as the final Ro interval of the suitable production maturity of shale oil;

[0050] When the Ro interval of the suitable production maturity of shale oil based on field practice is within the Ro interval of the suitable production maturity of shale oil based on thermal simulation, take the Ro interval of the suitable production maturity of shale oil based on field practice as the final Ro interval of the suitable production maturity of shale oil.

[0051] Embodiment

[0052] (Taking the Daanzhai shale in the Sichuan Basin as an example), a method for determining the suitable production maturity interval of shale oil according to the present invention includes the following steps:

[0053] Step S1: Make a graph showing the variation of the oiliness index (OSI = S1 / TOC), shale oil density, and shale oil group components with burial depth (as shown in Figure 3 shown) and a graph showing the relationship between burial depth and thermal evolution degree (Ro) (as shown in Figure 2 shown) according to the measured geochemical data;

[0054] Step S2: Determine the depth between the highest value of the oiliness index and the mobility parameters (density, saturated hydrocarbon ratio) according to the graph showing the variation of the oiliness index, shale oil density, and shale oil group components with burial depth; and use the thermal evolution degree interval in the graph showing the relationship between the burial depth corresponding to the obtained depth interval and the thermal evolution degree as the Ro interval of the suitable production maturity of shale oil based on field practice;

[0055] Among them, considering the maturity range values of oiliness and mobility comprehensively, the suitable maturity interval is obtained comprehensively;

[0056] As shown in Figure 3 shown, as the burial depth increases, the oiliness index (OSI = S1 / TOC) of the shale first increases and then decreases, and at about 2800 m (Figure 2 At this depth, Ro = 0.9%) reaches its maximum, and the crude oil density continuously decreases with the increase of burial depth. The saturated hydrocarbon component in the crude oil reaches its maximum at about 3300m( Figure 2 where Ro = 1.3% corresponding to this depth); OSI starts to decline after a certain burial depth, reflecting the influence of the changes in the physical and chemical properties of shale oil caused by thermal evolution on the hydrocarbon expulsion efficiency of shale. Before Ro < 0.9%, the OSI of shale gradually increases with thermal evolution, showing the process of the pores in shale being gradually filled with the generated crude oil. When Ro = 0.9%, OSI reaches its maximum, and at this time, the pores in shale reach the maximum oil saturation adsorption state. After Ro > 0.9%, shale continues to generate hydrocarbons, and the density of shale oil continues to decrease. Due to the limited reservoir space of shale and the improved fluidity of crude oil, shale begins to expel a large amount of hydrocarbons, and the oiliness gradually decreases. Until Ro = 1.3%, the density of shale oil is less than 0.8g / cm 3 , the fluidity of crude oil is extremely strong, and the light components in the crude oil begin to decrease due to the influence of high hydrocarbon expulsion efficiency;

[0057] Generally, the density of crude oil is low and the components are light. The mobility of shale oil becomes better with the increase of the degree of thermal evolution. However, it is difficult to fully achieve both the mobility of shale oil (when Ro = 1.3%, the fluidity of crude oil is extremely strong) and the oiliness of shale (the best when Ro = 0.9%). Considering the maturity range values of shale oiliness and shale oil mobility comprehensively, it is preliminarily concluded that the suitable maturity interval is 0.9% - 1.3%; that is, the suitable production maturity Ro interval of shale oil based on field practice is 0.9% - 1.3%;

[0058] Step S3: Select low-maturity shale samples for gold tube thermal simulation experiments under a closed system to obtain the changes in shale oil and gas enrichment products at different evolution stages;

[0059] Step S4: Determine the relationship diagrams of gas-oil ratio, total oil, total gas, and total hydrocarbon content with the change of evolution degree easy Ro according to the changes in shale oil and gas enrichment products at different evolution stages (as Figure 4 shown);

[0060] Step S5: Taking into account the oiliness of shale and the mobility of shale oil, select the easy Ro interval in the relationship diagrams of gas-oil ratio, total oil, total gas, and total hydrocarbon content with the change of evolution degree (easy Ro) where the light hydrocarbon content (C 14- ) increases, the heavy hydrocarbon content (C 14+ ) decreases, but the total hydrocarbon content is high as the easy Ro interval of the suitable production maturity of shale oil based on thermal simulation;

[0061] The results show that the total hydrocarbon and total oil yields are relatively high (the intersection of the total oil and total gas yield curves means that crude oil begins to be massively cracked into gas), and the corresponding easy Ro ranges from 0.86% to 1.52% ( Figure 4 ); when easy Ro is between 0.96% and 1.47%, the heavy hydrocarbons decrease (C 14+ ) while the light hydrocarbons (C 6-14 ) increase ([[]] Figure 4 );

[0062] The above phenomena indicate that shale begins to produce a large amount of oil when easy Ro is about 0.86%; when it is between about 0.96% and 1.47%, the proportion of heavy hydrocarbons gradually decreases while the proportion of light hydrocarbons gradually increases, the gas-oil ratio of shale oil increases, and the fluidity enhances; when easy Ro is about 1.47%, the proportion of light hydrocarbons in shale oil approaches the maximum, and the mobility of shale oil is the best; after easy Ro is greater than 1.47%, the oil content and movable oil content of shale both begin to decrease; accordingly, it is concluded that the suitable easy Ro for shale oil recovery ranges from 0.96% to 1.47%; that is, the suitable maturity range of easy Ro for shale oil recovery based on thermal simulation is 0.96% to 1.47%;

[0063] Step S6: Convert the thermal simulation maturity easy Ro to Ro according to the following formula, and finally calculate that the suitable maturity range of Ro for shale oil recovery based on thermal simulation is 0.93% to 1.29%;

[0064] Ro = 0.7034 * easy Ro + 0.2627

[0065] In the formula: Ro is the measured maturity; easy Ro is the thermal simulation maturity;

[0066] Step S7: Then compare and correct the suitable maturity range of Ro for shale oil recovery based on thermal simulation, which is 0.93% to 1.29%, with the suitable maturity range of Ro for shale oil recovery based on field practice obtained in Step S2, which is 0.9% to 1.3%, to obtain the final suitable maturity range of shale oil recovery as 0.93% to 1.29%.

[0067] Taking Ro = 0.93% as the lower limit of the suitable maturity for shale oil recovery, and the suitable maturity range is 0.93% to 1.29%, which is beneficial to both the mobility and oil content of shale oil, and is consistent with the current production practice, and can be used as the boundary of the suitable maturity for shale oil recovery.

[0068] ​The above description is not intended to impose any form of limitation on the present invention. Although the present invention has been disclosed through the above embodiments, it is not intended to limit the present invention. Any person skilled in the relevant art can make some changes or modifications within the scope of the technical solution of the present invention by using the disclosed technical content to form equivalent embodiments of equivalent changes. However, as long as it does not depart from the technical solution of the present invention, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for determining the suitable production maturity range of shale oil, characterized in that, It includes the following steps: Step S1: Make graphs of the oiliness index, shale oil density, and changes in shale oil group components with burial depth, and the relationship between burial depth and thermal evolution degree based on the measured geochemical data respectively; Step S2: Determine the depth interval between the highest value of the oiliness index and the mobility parameter based on the graphs of the oiliness index, shale oil density, and changes in shale oil group components with burial depth; and take the thermal evolution degree interval in the relationship graph of burial depth and thermal evolution degree corresponding to this depth interval as the suitable extraction maturity Ro interval of shale oil based on field practice; Step S3: Select low-maturity shale samples for the gold tube thermal simulation experiment under a closed system to obtain the changes in shale oil and gas enrichment products at different evolution stages; The specific process of the gold tube thermal simulation experiment under a closed system is as follows: Put the sample into a gold tube with one end sealed, place it in a cold water bath, remove the excess air in the gold tube through argon gas, and use argon gas as the protective gas to seal the other end by argon arc welding; after loading the sample, weigh it again to check whether the gold tube leaks; then put the sample into an autoclave, set the relevant parameters, start the thermal simulation experimental device, set the programmed temperature increase, take out the gold tube after reaching the predetermined temperature point, and quantitatively test the hydrocarbon products in it using gas chromatography; The experimental conditions of the gold tube thermal simulation experiment under a closed system are: pressure 50 Mpa, the experimental heating rates are 2 °C / h and 20 °C / h respectively, and the temperature range is 300 - 600 °C; Step S4: Determine the graphs of the changes in gas-oil ratio, total oil, total gas, and total hydrocarbon content with the evolution degree based on the changes in shale oil and gas enrichment products at different evolution stages; Step S5: Determine the suitable extraction maturity easy Ro interval of shale oil based on thermal simulation according to the graphs of the changes in gas-oil ratio, total oil, total gas, and total hydrocarbon content with the evolution degree; Step S6: Convert the suitable extraction maturity easy Ro interval of shale oil based on thermal simulation to the suitable extraction maturity Ro interval of shale oil based on thermal simulation according to the following formula; Ro = 0.7034 * easy Ro + 0.2627 In the formula: Ro is the measured maturity; easy Ro is the thermal simulation maturity; Step S7: Compare and correct the converted suitable extraction maturity Ro interval of shale oil based on thermal simulation with the suitable extraction maturity Ro interval of shale oil based on field practice, and take the intersection of the two as the final suitable extraction maturity interval of shale oil.

2. The method for determining the suitable production maturity range of shale oil according to claim 1, characterized in that, The measured geochemical data in Step S1 is obtained through the following steps: Conduct organic carbon and rock pyrolysis tests on the sample to measure the organic carbon content TOC, free hydrocarbon S1, pyrolysis hydrocarbon S2, and the highest pyrolysis temperature Tmax respectively; then calculate the oiliness index through the above parameters.

3. The method for determining the suitable production maturity range of shale oil according to claim 2, characterized in that, In Step S1, the core of the sample is crushed to less than 100 meshes before conducting the organic carbon test and pyrolysis analysis.

4. The method for determining the suitable production maturity range of shale oil according to claim 2, characterized in that, In Step S1, it is necessary to conduct group component separation and quantitative experiments on shale oil.

5. The method for determining the suitable production maturity range of shale oil according to claim 2, characterized in that, In the step S1, a densitometer is needed to measure the density of shale oil. The densitometer is calibrated by density units with the density of pure water at 4 °C being 1 g / cm 3 as the standard calibration scale.

6. The method for determining the suitable production maturity range of shale oil according to claim 1, characterized in that, The specific correction process in Step S7 is as follows: Based on the suitable extraction maturity Ro interval of shale oil based on thermal simulation, take the intersection with the suitable extraction maturity Ro interval of shale oil based on field practice as the final suitable extraction maturity interval of shale oil.

7. The method for determining the suitable production maturity range of shale oil according to claim 1, characterized in that, The specific calibration process in step S7 is as follows: When the Ro interval of the applicable maturity of shale oil based on thermal simulation is within the range of the Ro interval of the applicable maturity of shale oil based on field practice, the Ro interval of the applicable maturity of shale oil based on thermal simulation is taken as the final applicable maturity interval of shale oil; When there is an intersection between the Ro interval of the applicable maturity of shale oil based on thermal simulation and the Ro interval of the applicable maturity of shale oil based on field practice, the intersection point of the two is taken as the final applicable maturity interval of shale oil; When the Ro interval of the applicable maturity of shale oil based on field practice is within the range of the Ro interval of the applicable maturity of shale oil based on thermal simulation, the Ro interval of the applicable maturity of shale oil based on field practice is taken as the final applicable maturity interval of shale oil.

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