Method and system for calculating density of crude oil in reservoir

Abstract

The invention discloses a method and system for calculating the density of crude oil in a reservoir, and the method comprises the steps: heating a plurality of core samples based on a to-be-researched reservoir, obtaining corresponding products, and measuring the yield data of the corresponding products, the products including cracking components and volatile components; according to the yield data of each core rock sample, determining the proportion of the cracking component in the product; measuring the crude oil density of the production oil of the production layer where each core rock sample is located, and establishing the correlation between the cracking component proportion and the crude oil density according to the measurement result and the cracking component proportion of each core rock sample, so as to obtain the crude oil density of different positions of the reservoir to be studied by using the correlation. Accurate acquisition of the reservoir crude oil density is realized, and technical support is provided for crude oil exploitation.

Description

Technical Field

[0001] The invention belongs to the field of crude oil geological evaluation, and in particular relates to a method and a system for calculating reservoir crude oil density. Background Art

[0002] Crude oil density can be used to determine the composition, type and fluid properties of crude oil, so the measurement of crude oil density has a certain indicative significance for crude oil production. The prior art generally measures crude oil density based on shale pyrolysis, and the main basis for the measurement is the correlation between the total yield index, oil yield index, residual hydrocarbon index and the light and heavy components of crude oil and crude oil density. In the process of realizing the present invention, the inventors found that the linear fitting correlation between the total yield index, oil yield index, residual hydrocarbon index and the light and heavy components of crude oil and crude oil density is usually poor (linear fitting degree R 2 <0.35). Therefore, there is a certain deviation between the crude oil density calculated based on the above correlation and the actual situation. Summary of the invention

[0003] In order to solve the above problems, an embodiment of the present invention provides a method for calculating the density of reservoir crude oil, comprising: heating a plurality of core samples based on the reservoir to be studied, obtaining corresponding outputs and measuring the production data of the corresponding outputs, wherein the outputs include cracking components and volatile components; determining the proportion of the cracking components in the outputs according to the production data of each core sample; measuring the crude oil density of the produced oil in the production layer where each core sample is located, and establishing a correlation between the cracking component ratio and the crude oil density based on the measurement results and in combination with the cracking component ratio of each core sample, thereby obtaining the crude oil density at different positions of the reservoir to be studied using the correlation.

[0004] Preferably, the step of obtaining the corresponding output includes: heating each core sample for the first time according to a heating condition at a heating temperature less than or equal to 350°C to obtain the corresponding volatile components; and heating each core sample that has completed the first heating for the second time according to a heating condition at a heating temperature greater than 350°C to obtain the corresponding cracking components.

[0005] Preferably, during the two consecutive heating processes, a programmed temperature rising method is adopted to uniformly raise the initial heating temperature to the target heating temperature according to a preset temperature rising rate, thereby completing the first heating and the second heating continuously, wherein the preset temperature rising rate is 25°C / min or 50°C / min, and the target heating temperature is greater than or equal to 650°C.

[0006] Preferably, the step of obtaining the corresponding output also includes: placing each core sample in a closed heating device for heating, and when the heating temperature rises to 50°C, extracting the product in the closed heating device as an invalid output for the first time; continuing to increase the heating temperature from 50°C to 350°C, and when the heating temperature rises to 350°C, extracting the product in the closed heating device as the volatile component for the second time; continuing to increase the heating temperature from 350°C to 650°C, and when the heating temperature rises to 650°C, extracting the product in the closed heating device as the cracking component for the third time.

[0007] Preferably, the enclosed heating device is a rock pyrolyzer or a thermal analyzer.

[0008] Preferably, before heating multiple core samples based on the reservoir to be studied, the method also includes: crushing each core sample in a specific low-temperature closed environment to ensure sufficient heating of each core sample, wherein the particle size of each core sample after crushing is less than or equal to 0.84 mm.

[0009] Preferably, the method further comprises: using a hydrogen flame ionization detector to measure the yield of the heating output of each core sample, wherein the yield data comprises: cracking component yield data and volatile component yield data.

[0010] On the other hand, the present invention also provides a system for calculating the density of reservoir crude oil, the system comprising: an output acquisition device, which is used to heat multiple core samples based on the reservoir to be studied, obtain corresponding outputs and measure the production data of the corresponding outputs, wherein the outputs include cracking components and volatile components; a data analysis device, which is used to determine the proportion of the cracking components in the output according to the production data of each core sample; a density generation device, which is used to measure the crude oil density of the production oil of the production layer where each core sample is located, and based on the measurement results and combined with the cracking component ratio of each core sample, establish a correlation between the cracking component ratio and the crude oil density, so as to use the correlation to obtain the crude oil density at different positions of the reservoir to be studied.

[0011] Preferably, the output acquisition device includes: a heating unit, which is used to heat each core sample for the first time according to a heating condition at a heating temperature less than or equal to 350°C to obtain corresponding volatile components, and to heat each core sample that has completed the first heating for a second time according to a heating condition at a heating temperature greater than 350°C to obtain corresponding cracking components.

[0012] Preferably, the system also includes: a rock sample preprocessing device, which is used to crush each core sample in a specific low-temperature closed environment before heating the multiple core samples based on the reservoir to be studied, so as to ensure the adequacy of heating of each core sample, wherein the particle size of each core sample after crushing is less than or equal to 0.84 mm.

[0013] Compared with the prior art, one or more embodiments of the above scheme may have the following advantages or beneficial effects:

[0014] The present invention proposes a method and system for calculating the density of reservoir crude oil. The method first collects core samples at a drilling site and heats them to obtain cracking components and volatile components of the heated rock samples; then, based on the characteristics that the hydrocarbon substances in the rock samples before heating are consistent with the hydrocarbon substances contained in the cracking components and volatile components, the proportion of the cracking components of each rock sample in the corresponding output is obtained; finally, the crude oil density of the production oil of the production layer where each core sample is located is measured respectively, and the crude oil density at the drilling site is estimated by establishing a correlation between the cracking component ratio and the crude oil density. The linear fitting accuracy of the correlation between the cracking component ratio and the crude oil density established by the present invention is high, which effectively improves the estimation accuracy of the crude oil density.

[0015] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0017] Figure 1 It is a step diagram of a method for calculating reservoir crude oil density according to an embodiment of the present application.

[0018] Figure 2 It is a linear relationship diagram between the cracking component ratio and the crude oil density in the method for calculating the reservoir crude oil density in an embodiment of the present application.

[0019] Figure 3 It is a schematic diagram of the overall structure of a system for calculating reservoir crude oil density according to an embodiment of the present application. DETAILED DESCRIPTION

[0020] The following will describe the implementation methods of the present invention in detail with reference to the accompanying drawings and embodiments, so that the implementation process of how the present invention applies technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly. It should be noted that as long as there is no conflict, the various embodiments of the present invention and the various features in the embodiments can be combined with each other, and the technical solutions formed are all within the protection scope of the present invention.

[0021] In addition, the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be performed in an order different from that shown here.

[0022] Crude oil density can be used to determine the composition, type and fluid properties of crude oil, so the measurement of crude oil density has a certain indicative significance for crude oil production. The prior art generally measures crude oil density based on shale pyrolysis, and the main basis for the measurement is the correlation between the total yield index, oil yield index, residual hydrocarbon index and the light and heavy components of crude oil and crude oil density. In the process of realizing the present invention, the inventors found that the linear fitting correlation between the total yield index, oil yield index, residual hydrocarbon index and the light and heavy components of crude oil and crude oil density is usually poor (linear fitting degree R 2 <0.35). Therefore, there is a certain deviation between the crude oil density calculated based on the above correlation and the actual situation.

[0023] Therefore, in order to solve the above problems, the embodiment of the present invention proposes a method and system for calculating the density of reservoir crude oil. The method first collects core samples at the drilling site and heats them to obtain the cracking components and volatile components of the heated rock samples; then, based on the characteristics that the hydrocarbon substances in the rock samples before heating are consistent with the hydrocarbon substances contained in the cracking components and volatile components, the proportion of the cracking components of each rock sample in the corresponding output is obtained; finally, the crude oil density of the production oil of the production layer where each core sample is located is measured respectively, and the crude oil density at the drilling site is estimated by establishing the correlation between the cracking component ratio and the crude oil density. The linear fitting accuracy of the correlation between the cracking component ratio and the crude oil density established by the present invention is high, which effectively improves the estimation accuracy of the crude oil density.

[0024] Embodiment 1

[0025] Figure 1 is a step diagram of a method for calculating reservoir crude oil density in an embodiment of the present application. Figure 1 To illustrate the various steps of this method.

[0026] like Figure 1As shown, in step S110, a plurality of core samples based on the reservoir to be studied are heated to obtain corresponding outputs and measure the production data of the corresponding outputs, wherein the outputs include cracking components and volatile components. The volatile components of the reservoir are mainly hydrocarbon substances generated by organic matter in the rock under geological conditions, including light and heavy components, and the cracking components are hydrocarbon substances that can be cracked and generated by residual organic matter in the rock under high temperature conditions. In other words, the hydrocarbon substances contained in the volatile components of the reservoir and the hydrocarbon substances contained in the cracking components are all hydrocarbon substances that can be generated by the organic matter in the reservoir. In this way, the ratio between the cracking components and the sum of the volatile components and the cracking components effectively reflects the degree of conversion of the organic matter in the reservoir into oil. Therefore, in this embodiment, a plurality of core samples are first collected from the reservoir to be studied. Then, a plurality of core samples based on the reservoir to be studied are heated, and the heated products are used as outputs. In the process of heating rock samples to obtain outputs, on the one hand, the volatile components of each rock sample are obtained based on the characteristics that the volatile components in the rock sample are very easy to evaporate; on the other hand, based on the characteristics that the rock sample will undergo cracking reactions under specific temperature conditions, the cracking components of each rock sample are obtained. Finally, the cracking component yield data and volatile component yield data of each rock sample are measured.

[0027] Furthermore, unlike the conventional rock pyrolysis method of placing samples in an open environment, this embodiment places multiple core samples based on the reservoir to be studied in a closed environment for heating, effectively avoiding evaporation loss of the output and obtaining accurate cracking component yield data and volatile component yield data.

[0028] Before heating multiple core samples based on the reservoir to be studied, the present invention crushes each core sample in a specific low-temperature closed environment to ensure the adequacy of heating of each core sample. In the embodiment of the present application, a low-temperature condition is created for a closed environment, and when a low-temperature closed environment is formed, the core sample is placed in the current low-temperature closed environment for crushing, so that the sample can be fully heated during the heating process. At the same time, since the crushing process of the rock sample will inevitably generate a certain amount of heat, the heat generated may cause the rock sample to generate the output of the heating process in advance during the crushing process. Therefore, the present invention places the core sample in a low-temperature closed environment for crushing, which, on the one hand, reduces the output of the heating process generated in advance; on the other hand, it ensures that the output of the heating process generated in advance can also be fully collected, thereby effectively improving the accuracy of the cracking component yield data and the volatile component yield data obtained. Among them, it is preferred that the low-temperature condition is created by liquid nitrogen, which not only achieves the purpose of forming low-temperature conditions, but also ensures that the output of the heating process generated in advance will not affect the accuracy of the yield data due to chemical reactions. Preferably, the particle size of each core rock sample after crushing is less than or equal to 0.84 mm.

[0029] In the step of obtaining the corresponding output, the present invention first heats each core sample for the first time according to the heating condition of the heating temperature being less than or equal to 350°C to obtain the corresponding volatile components; then, according to the heating condition of the heating temperature being greater than 350°C, each core sample that has completed the first heating is heated for the second time to obtain the corresponding cracking components. In practical applications, the boundary temperature of heating the rock sample to produce volatile components and cracking components is 350°C, that is, before the heating temperature of the rock sample reaches 350°C, the output only contains volatile components, and when the heating temperature reaches 350°C, the volatile components in the rock sample have been completely evaporated, and the output obtained by continuing to heat the rock sample at this time only contains cracking components, and the cracking completion node of the rock sample occurs when the heating temperature reaches 650°C. Therefore, this embodiment uses a heating condition of a heating temperature less than or equal to 350°C as a heating condition for obtaining volatile components. First, each core sample is heated for the first time according to the heating condition of a heating temperature less than or equal to 350°C, thereby collecting the volatile components of each rock sample. Then, after the heating temperature reaches 350°C, each core sample that has completed the first heating (and completed the collection of volatile components) is heated for the second time according to the heating condition of a heating temperature greater than 350°C, thereby collecting the cracking components of each rock sample. Accordingly, the present invention achieves the purpose of collecting volatile components and cracking components of each rock sample based on two heatings.

[0030] Further, in the two consecutive heating processes, the present invention adopts a programmed temperature increase method, and uniformly increases the initial heating temperature to the target heating temperature according to the preset temperature increase rate, thereby completing the continuous first heating and second heating. Specifically, the first heating process of the rock sample is a continuous process, and the second heating process is also a continuous process. Therefore, the present invention forms a continuous heating process that directly switches from the first heating to the second heating, including a complete first heating process and a complete second heating process, based on the boundary temperature of the volatile component and the cracking component. In an embodiment of the present application, the temperature increase rate is preset for the continuous heating process, and then the heating temperature is steadily increased according to the preset temperature increase rate, so as to achieve the purpose of uniformly increasing the initial heating temperature (ie: the initial heating temperature of the first heating or the initial heating temperature of the continuous heating process) to the target heating temperature (ie: the heating temperature at the end of the second heating or the heating temperature at the end of the continuous heating process). It can be seen that the present invention ensures the stability of the entire continuous heating process and effectively improves the generation efficiency of the output. Among them, the preset temperature increase rate is 25℃ / min or 50℃ / min, and the target heating temperature is greater than or equal to 650℃.

[0031] Next, the present invention first places each core sample in a closed heating device for heating, and when the heating temperature is raised to 50°C, the product in the closed heating device is used as an invalid output for the first output extraction; then, the heating temperature is continued to be increased from 50°C to 350°C, and when the heating temperature is raised to 350°C, the product in the closed heating device is used as a volatile component for the second output extraction; finally, the heating temperature is continued to be increased from 350°C to 650°C, and when the heating temperature is raised to 650°C, the product in the closed heating device is used as a cracking component for the third output extraction.

[0032] In this embodiment, each core sample is placed in a closed heating device for individual heating, so as to extract the output belonging to each core sample. Based on the characteristics that the rock sample has different outputs at different heating temperatures, in the process of steadily increasing the heating temperature, the critical temperature for generating different outputs is designated as the extraction node for the corresponding type of output. In a specific embodiment of the present application, 50°C is used as the critical temperature for the completion of the production of invalid outputs, 350°C is used as the critical temperature for the completion of the production of volatile components, and 650°C is used as the critical temperature for the completion of the production of cracking components. Therefore, in this embodiment, 50°C is used as the extraction node of the first output. When the heating temperature is 50°C, the output in the process of heating temperature rising from the initial heating temperature to 50°C is extracted as the first output; 350°C is used as the extraction node of the second output. When the heating temperature is 350°C, the output in the process of heating temperature rising from 50°C to 350°C is extracted as the second output, thereby obtaining volatile components; and 650°C is used as the extraction node of the third output. When the heating temperature is 650°C, the output in the process of heating temperature rising from 350°C to 650°C is extracted as the third output, thereby obtaining cracking components.

[0033] In a specific embodiment of the present application, the closed heating device has the ability to measure and record the changes in hydrocarbon components in the output of each heating process with temperature, and is preferably a rock pyrolyzer or a thermal analyzer.

[0034] Further, after obtaining the production data of each core sample output, in step S120, the proportion of the cracking component in the output is determined according to the production data of each core sample. Specifically, since the hydrocarbon components contained in the invalid output are relatively small and can be ignored, the present embodiment takes the volatile components and the cracking components as the total output of each rock sample, thereby calculating the ratio between the production data (e.g., mass) of the cracking component and the sum of the production data of the volatile component and the production data of the cracking component to obtain the proportion of the cracking component in the output of each rock sample (hereinafter referred to as "cracking component ratio"), that is, cracking component ratio = cracking component production data / (volatile component production data + cracking component production data).

[0035] In the embodiment of the present application, a hydrogen flame ionization detector is used to measure the yield of the heating output of each core sample, wherein the yield data includes: cracking component yield data and volatile component yield data.

[0036] Further, in step S130, the crude oil density of the production oil in the production layer where each core sample is located is measured respectively, and according to the measurement results, combined with the cracking component ratio of each core sample, the correlation between the cracking component ratio and the crude oil density is established, so as to obtain the crude oil density at different positions of the reservoir to be studied by using the correlation. In the embodiment of the present application, the conventional crude oil density determination method is used to measure the crude oil density of the production oil in the production layer where each core sample is located, and then based on the cracking component ratio and crude oil density of each rock sample, the correlation between the cracking component ratio and the crude oil density is fitted, so as to obtain the linear correlation between the cracking component ratio and the crude oil density, so as to achieve the purpose of establishing the correlation between the cracking component ratio and the crude oil density. Using the established correlation, combined with the cracking component ratio of the core samples at different positions of the reservoir to be studied, the crude oil density at the corresponding position can be obtained. The present invention uses closed pyrolysis analysis to detect hydrocarbon content at the drilling site, and the statistical formula with high linear fitting accuracy between the production crude oil density and the cracking component ratio is used to calculate the crude oil density, which effectively improves the accuracy of the crude oil density calculation result.

[0037] Embodiment 2

[0038] In a specific embodiment of the present application, the volatile components and cracking components of fresh core samples are measured by closed pyrolysis analysis at the drilling site according to the heating and measuring method described in Example 1, so as to obtain the volatile component production data and cracking component production data of the current drilling site, and then a programmed temperature is used to increase the temperature from the initial sample temperature to 650°C at a heating rate of 50°C / min, and the evaporated hydrocarbon content is calculated according to the experimental results in three temperature sections: heating temperature less than or equal to 50°C, heating temperature greater than 50°C and less than 350°C, and heating temperature greater than or equal to 350°C and less than or equal to 650°C.

[0039] In this embodiment, the above experiment was carried out in multiple wells at the same layer in a certain basin, the evaporated hydrocarbon content of the core samples of the production layer was obtained, and the cracking component ratio was calculated. At the same time, the oil production samples of the corresponding production layers of the drilling were collected and the crude oil density was measured, and the experimental data shown in Table 1 were obtained:

[0040] Table 1 Experimental data

[0041]

[0042] Further, based on the experimental results shown in Table 1, the following is fitted: Figure 2 The linear relationship between the cracking component ratio and crude oil density is shown in the figure ( Figure 2 is a linear relationship diagram between the cracking component ratio and the crude oil density of the method for calculating the reservoir crude oil density in the embodiment of the present application) wherein R 2 Represents the correlation coefficient. Based on the fitting image, the correlation between the cracking component ratio and the crude oil density (production oil density) can be established. The current correlation is expressed by the following expression:

[0043] y=0.4557x+0.6297 (1)

[0044] Where x represents the cracking component ratio and y represents the crude oil density.

[0045] It is measured that the cracking component ratio of the core of the same layer of a well in the current drilling site is 0.7. Based on the above correlation, the corresponding crude oil density is estimated to be about 0.948g / ml, and the actual crude oil density of the layer is basically consistent with the estimated result. It can be seen that there is a good linear correlation between the cracking component ratio and the crude oil density (production oil density). Using this correlation to estimate the crude oil density in the current drilling site can obtain accurate crude oil density estimation results.

[0046] Embodiment 3

[0047] Based on the method for calculating the density of reservoir crude oil described in the first embodiment, the embodiment of the present invention further provides a system for calculating the density of reservoir crude oil. Figure 3 The overall structure diagram of the system for calculating the density of crude oil in a reservoir according to an embodiment of the present application is shown in FIG. The structure and function of the system for calculating the density of crude oil in a reservoir are described in detail below in conjunction with the embodiment of the present application.

[0048] The system for calculating the density of reservoir crude oil described in the present invention at least includes: an output acquisition device 31, a data analysis device 32 and a density generation device 33. Specifically, the output acquisition device 31 is used to heat a plurality of core samples based on the reservoir to be studied, obtain corresponding outputs and measure the production data of the corresponding outputs, wherein the outputs include cracking components and volatile components. The data analysis device 32 is used to determine the proportion of cracking components in the output according to the production data of each core sample. The density generation device 33 is used to measure the crude oil density of the production oil of the production layer where each core sample is located, and establish a correlation between the cracking component ratio and the crude oil density based on the measurement results and the cracking component ratio of each core sample, so as to obtain the crude oil density at different positions of the reservoir to be studied using the correlation.

[0049] Furthermore, the output acquisition device 31 in the system for calculating the density of reservoir crude oil of the present invention includes a heating unit 311. The heating unit 311 is used to perform a first heating on each core sample under a heating condition of a heating temperature less than or equal to 350°C to obtain corresponding volatile components, and to perform a second heating on each core sample that has completed the first heating under a heating condition of a heating temperature greater than 350°C to obtain corresponding cracking components.

[0050] Furthermore, the system for calculating the density of reservoir crude oil of the present invention also includes a rock sample preprocessing device. The rock sample preprocessing device is used to crush each core sample in a specific low-temperature closed environment before heating the multiple core samples based on the reservoir to be studied, so as to ensure the adequacy of heating of each core sample, wherein the particle size of each core sample after crushing is less than or equal to 0.84 mm.

[0051] The present invention proposes a method and system for calculating the density of reservoir crude oil. The method first collects core samples at a drilling site and heats them to obtain cracking components and volatile components of the heated rock samples; then, based on the characteristics that the hydrocarbon substances in the rock samples before heating are consistent with the hydrocarbon substances contained in the cracking components and volatile components, the proportion of the cracking components of each rock sample in the corresponding output is obtained; finally, the crude oil density of the production oil of the production layer where each core sample is located is measured respectively, and the crude oil density at the drilling site is estimated by establishing a correlation between the cracking component ratio and the crude oil density. The linear fitting accuracy of the correlation between the cracking component ratio and the crude oil density established by the present invention is high, which effectively improves the estimation accuracy of the crude oil density.

[0052] The above description is only a specific implementation case of the present invention, and the protection scope of the present invention is not limited thereto. Any modification or replacement of the present invention by any technician familiar with the present technology within the technical specifications described in the present invention should be within the protection scope of the present invention.

[0053] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art may make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications should all fall within the scope of protection of the claims of the present invention.

[0054] It should be understood by those skilled in the art that the modules or steps of the present invention described above can be implemented by a general-purpose computing device, they can be concentrated on a single computing device, or distributed on a network composed of multiple computing devices, and optionally, they can be implemented by a program code executable by a computing device, so that they can be stored in a storage device and executed by the computing device, or they can be made into individual integrated circuit modules, or multiple modules or steps therein can be made into a single integrated circuit module for implementation. Thus, the present invention is not limited to any specific combination of hardware and software.

[0055] Although the embodiments disclosed in the present invention are as above, the above contents are only embodiments adopted for facilitating the understanding of the present invention and are not intended to limit the present invention. Any technician in the technical field to which the present invention belongs can make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed in the present invention, but the patent protection scope of the present invention shall still be subject to the scope defined in the attached claims.

Claims

1. A method for calculating the density of reservoir crude oil, characterized in that: include: Heating a plurality of core samples based on the reservoir to be studied, obtaining corresponding outputs and measuring the production data of the corresponding outputs, wherein the outputs include cracking components and volatile components; Determining the proportion of the cracking component in the output according to the production data of each core sample; The crude oil density of the produced oil in the production layer where each core sample is located is measured respectively, and based on the measurement results and the cracking component ratio of each core sample, a correlation between the cracking component ratio and the crude oil density is established, so as to obtain the crude oil density at different positions of the reservoir to be studied using the correlation.

2. The method according to claim 1, characterized in that The steps of obtaining the corresponding output include: Each core sample is heated for the first time under the heating condition of a heating temperature less than or equal to 350°C to obtain the corresponding volatile components; According to the heating condition that the heating temperature is greater than 350° C., each core sample that has completed the first heating is heated for the second time to obtain corresponding cracking components.

3. The method according to claim 2, characterized in that During the two consecutive heating processes, A programmed temperature rising method is adopted to uniformly raise the initial heating temperature to the target heating temperature according to a preset temperature rising speed, thereby completing the continuous first heating and the second heating, wherein the preset temperature rising speed is 25°C / min or 50°C / min, and the target heating temperature is greater than or equal to 650°C.

4. The method according to claim 2 or 3, characterized in that: The step of obtaining the corresponding output also includes: Each core rock sample is placed in a closed heating device for heating, and when the heating temperature is raised to 50° C., the product in the closed heating device is used as an invalid output for the first output extraction; Continue to increase the heating temperature from 50° C. to 350° C., and when the heating temperature reaches 350° C., extract the product in the sealed heating device as the volatile component for the second time; The heating temperature is continued to be increased from 350° C. to 650° C., and when the heating temperature is increased to 650° C., the product in the closed heating device is used as the cracking component for the third output extraction.

5. The method according to claim 4, characterized in that The enclosed heating device adopts a rock pyrolyzer or a thermal analyzer.

6. The method according to any one of claims 1 to 5, characterized in that: Before heating the plurality of core samples based on the reservoir to be studied, the method further comprises: Each core sample is crushed in a specific low-temperature closed environment to ensure that each core sample is sufficiently heated, wherein the particle size of each core sample after crushing is less than or equal to 0.84 mm.

7. The method according to any one of claims 1 to 6, characterized in that: The method further comprises: A hydrogen flame ionization detector is used to measure the yield of the heated output of each core sample, wherein the yield data includes: cracking component yield data and volatile component yield data.

8. A system for calculating the density of reservoir crude oil, characterized in that: The system is used to perform the method according to any one of claims 1 to 7, and the system comprises: An output acquisition device, which is used to heat a plurality of core rock samples based on the reservoir to be studied, obtain corresponding outputs and measure the production data of the corresponding outputs, wherein the outputs include cracking components and volatile components; A data analysis device, which is used to determine the proportion of the cracking component in the output according to the production data of each core sample; The density generating device is used to measure the crude oil density of the produced oil in the production layer where each core sample is located, and establish the correlation between the cracking component ratio and the crude oil density based on the measurement results and the cracking component ratio of each core sample, so as to obtain the crude oil density at different positions of the reservoir to be studied by using the correlation.

9. The system according to claim 8, characterized in that The output acquisition device comprises: The heating unit is used to heat each core sample for the first time according to the heating condition that the heating temperature is less than or equal to 350°C to obtain the corresponding volatile components, and to heat each core sample that has completed the first heating for the second time according to the heating condition that the heating temperature is greater than 350°C to obtain the corresponding cracking components.

10. The system according to claim 8 or 9, characterized in that The system further comprises: A rock sample pretreatment device is used to crush each core sample in a specific low-temperature closed environment before heating multiple core samples based on the reservoir to be studied, so as to ensure the adequacy of heating of each core sample, wherein the particle size of each core sample after crushing is less than or equal to 0.84mm.

Images