Method and device for obtaining maturity of shale organic matter

Abstract

The application discloses a shale organic matter maturity acquisition method and device, which is applied to a shale gas well to be predicted. First, regional reservoir characteristics are input into a shale gas reservoir rock physical volume model to calculate shale resistivity. Then, shale resistivity and logging resistivity are subjected to division operation to obtain a maturity factor. Finally, a relationship model of the maturity factor and shale organic matter maturity is established by means of a laser Raman experiment. When the maturity of organic matter of different shale gas wells to be predicted is quantitatively evaluated, the maturity factor can be calculated by means of logging data, and the corresponding relationship between the maturity factor and the shale organic matter maturity can be reflected by establishing the relationship model, so that the maturity of the high-mature marine shale organic matter can be quickly and relatively accurately calculated.

Description

Technical Field

[0001] This application relates to the field of natural gas exploration technology, and more specifically, to a method and apparatus for obtaining the maturity of shale organic matter. Background Technology

[0002] During deep burial, organic matter gradually evolves into a certain degree of maturity under the influence of energy conditions such as temperature; this is called organic matter maturity. There are two types of maturity parameters: the first type is used to indicate the stage of petroleum formation, including kerogen optical parameters, pyrolysis parameters, and soluble organic matter parameters; the second type is used to describe the relative intensity of temperature and time, such as vitrinite reflectance, maximum peak temperature, and maturity parameters of most biomarker compounds.

[0003] However, in existing technologies, since vitrinite is absent in Lower Paleozoic and Precambrian marine source rocks, the maturity of Lower Paleozoic source rocks cannot be evaluated using vitrinite reflectance, a second maturity parameter. Furthermore, laboratory methods for determining organic matter maturity rely on core samples, which are characterized by long experimental cycles and high core collection costs, leading to significant limitations and poor practical operability in real-world applications. Summary of the Invention

[0004] The purpose of this application is to overcome the shortcomings of existing technologies and provide a method and apparatus for obtaining the maturity of shale organic matter. By establishing a relationship model between maturity factor and shale organic matter maturity, the corresponding relationship between the two can be reflected. When carrying out quantitative evaluation of the organic matter maturity of different shale gas wells to be predicted, the organic matter maturity of marine shale with higher maturity can be calculated quickly and relatively accurately.

[0005] The objective of this application is achieved through the following technical solution:

[0006] Firstly, this application proposes a method for obtaining the maturity of shale organic matter, the method being applied to a shale gas well to be predicted, comprising:

[0007] Step 101: Input the regional reservoir characteristics into the shale gas reservoir rock physical volume model to calculate the shale resistivity R. ts The shale resistivity R ts Unaffected by the degree of thermal evolution of organic matter;

[0008] Step 102: The resistivity R of the shale ts and logging resistivity R t The maturity factor R is obtained by performing a division operation. ma The maturity factor R ma Reflects the degree of thermal evolution of shale;

[0009] Step 103: Establish the maturity factor R using laser Raman spectroscopy. ma A model relating shale organic matter maturity to the maturity factor R, wherein the model characterizes the maturity factor R. ma Relationship with the maturity of shale organic matter.

[0010] In one possible implementation, the method further includes the following after step S103:

[0011] Step 104: Calculate the maturity factor R of the shale gas well to be predicted. ma Based on the relationship model, the shale organic matter maturity of the shale gas well to be predicted is obtained, thus completing the maturity prediction of the shale gas well to be predicted.

[0012] In one possible implementation, the regional reservoir characteristics include: clay content, reservoir water saturation, mudstone resistivity, formation water resistivity, and reservoir porosity.

[0013] The shale resistivity R ts The calculation formula is:

[0014]

[0015] Among them, V sh For clay content, S w R represents the reservoir water saturation. sh R is the resistivity of mudstone. w φ represents the formation water resistivity, and φ represents the reservoir porosity.

[0016] In one possible implementation, the maturity factor R ma The calculation formula is:

[0017] Where R ts R is the resistivity of shale. t This refers to the well logging resistivity.

[0018] In one possible implementation, the formula for calculating the relational model is: R o =a·ln(R) ma )+b,R ma R is the maturity factor. o denoted as shale organic matter maturity, where a is the first coefficient and b is the second coefficient.

[0019] In one possible implementation, both the first coefficient a and the second coefficient b are obtained by experimentally fitting using the least squares method.

[0020] Secondly, this application also proposes a device for obtaining the maturity of shale organic matter, the device comprising:

[0021] The first calculation module is used to input regional reservoir characteristics into the shale gas reservoir rock physical volume model to calculate the shale resistivity R. ts The shale resistivity R ts Unaffected by the degree of thermal evolution of organic matter;

[0022] The second calculation module is used to calculate the shale resistivity R. ts and logging resistivity R t The maturity factor R is obtained by performing a division operation. ma The maturity factor R ma Reflects the degree of thermal evolution of shale;

[0023] The relationship establishment module is used to establish the maturity factor R using laser Raman experiments. ma A model relating shale organic matter maturity to the maturity factor R, wherein the model characterizes the maturity factor R. ma Relationship with the maturity of shale organic matter.

[0024] In one possible implementation, the device further includes:

[0025] The maturity prediction module is used to calculate the maturity factor R of the shale gas well to be predicted. ma Based on the relationship model, the shale organic matter maturity of the shale gas well to be predicted is obtained, thus completing the maturity prediction of the shale gas well to be predicted.

[0026] Thirdly, this application also proposes a computer device comprising a processor and a memory, wherein the memory stores a computer program, which is loaded and executed by the processor to implement the method for obtaining shale organic matter maturity as described in any of the first aspects.

[0027] Fourthly, this application also proposes a computer-readable storage medium storing a computer program that is loaded and executed by a processor to implement the method for obtaining the maturity of shale organic matter as described in any of the first aspects.

[0028] The main solution and its various further alternatives described above can be freely combined to form multiple solutions, all of which are solutions that can be adopted and are claimed in this application; furthermore, the (non-conflicting alternatives) can also be freely combined with each other and with other alternatives. Those skilled in the art, after understanding the solution of this application, will realize from the prior art and common general knowledge that there are many combinations, all of which are technical solutions to be protected by this application, and will not be exhaustively listed here.

[0029] This application discloses a method and apparatus for obtaining the maturity of shale organic matter. This method is applied to shale gas wells to be predicted. First, regional reservoir characteristics are input into a shale gas reservoir petrophysical volumetric model to calculate shale resistivity. Then, the shale resistivity and well logging resistivity are divided to obtain a maturity factor. Finally, a relationship model between the maturity factor and shale organic matter maturity is established using laser Raman spectroscopy. When quantitatively evaluating the maturity of organic matter in different shale gas wells to be predicted, only well logging data needs to be used to calculate the maturity factor. By establishing a relationship model between the maturity factor and shale organic matter maturity, the correspondence between the two can be reflected, enabling rapid and relatively accurate calculation of organic matter maturity in marine shale exceeding maturity. Attached Figure Description

[0030] Figure 1 A schematic diagram of the method for obtaining the maturity of shale organic matter according to an embodiment of this application is shown.

[0031] Figure 2 A schematic diagram of the relational model proposed in an embodiment of this application is shown.

[0032] Figure 3 The diagram shows the results of maturity assessment using the method for obtaining shale organic matter maturity. Detailed Implementation

[0033] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. This application can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, unless otherwise specified, the following embodiments and features in the embodiments can be combined with each other.

[0034] Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0035] In existing technologies, because vitrinite is absent in Lower Paleozoic and Precambrian marine source rocks, the maturity of Lower Paleozoic source rocks cannot be evaluated using vitrinite reflectance, a second maturity parameter. Furthermore, methods for characterizing shale organic matter maturity using laser Raman spectroscopy are currently in the exploratory and research stage. Due to the lack of unified methods (including sample preparation, testing conditions, spectral fitting, and parameter calculation), the comparability of test results from different institutions is poor. Simultaneously, laboratory methods for determining organic matter maturity rely on core samples, which are characterized by long experimental cycles and high core collection costs, leading to significant limitations and poor practical operability in real-world applications.

[0036] Therefore, in order to address the lack of effective means for predicting the organic matter maturity of highly mature marine shale reservoirs through well logging and the difficulty in quantitative evaluation, this application proposes a method and apparatus for obtaining shale organic matter maturity. By establishing a relationship model between maturity factors and shale organic matter maturity, the correspondence between the two is reflected, resulting in a high degree of agreement between the calculated results and the organic matter maturity obtained from core testing. This lays the foundation for evaluating the thermal evolution of highly mature marine shale reservoirs using well logging data.

[0037] The following section details the methods for obtaining the organic matter maturity of shale. Please refer to [link / reference]. Figure 1 , Figure 1 The diagram illustrates a method for obtaining the maturity of shale organic matter according to an embodiment of this application. This method is applied to shale gas wells to be predicted and includes:

[0038] Step 101: Input the regional reservoir characteristics into the shale gas reservoir rock physical volume model to calculate the shale resistivity R. ts .

[0039] Among them, the resistivity R of shale ts Unaffected by the degree of organic matter thermal evolution, regional reservoir characteristics include: clay content, reservoir water saturation, mudstone resistivity, formation water resistivity, and reservoir porosity.

[0040] Shale resistivity R ts The calculation formula is: Among them, V sh S represents the clay content (%). w R represents the reservoir water saturation (%). sh R is the resistivity of mudstone (Ω·m). w φ represents the formation water resistivity (Ω·m), and φ represents the reservoir porosity (%). Other parameters may also be included in the regional reservoir characteristics, and these parameters are calculated according to the methods specified in the standard "Shale Gas Logging Data Processing and Interpretation Specification SY / T6994-2014".

[0041] Step 102: Measure the resistivity R of the shale. ts and logging resistivity R t The maturity factor R is obtained by performing a division operation. ma .

[0042] Maturity Factor R ma The maturity factor R reflects the degree of thermal evolution of shale. ma The calculation formula is: Where R ts R is the shale resistivity (Ω·m). t The value is the logging resistivity (Ω·m).

[0043] Step 103: Establish the maturity factor R using laser Raman spectroscopy. ma A model relating shale organic matter maturity to shale organic matter maturity.

[0044] The relational model characterizes the maturity factor R ma The relationship between maturity factor and shale organic matter maturity was established using laser Raman experiments on shale rocks of different maturity levels. This model enables the implementation of the method proposed in this application. The calculation formula for the relationship model is: R o =a·ln(R) ma )+b,R ma R is the maturity factor. o Let denot , where 'a' represents the maturity of shale organic matter, and 'b' is the first coefficient and 'b' is the second coefficient. Both coefficients 'a' and 'b' were obtained through experimental fitting using the least squares method.

[0045] Step 104: For the shale gas well to be predicted, calculate the maturity factor of the shale gas well to be predicted, obtain the shale organic matter maturity of the shale gas well to be predicted according to the relational model, and complete the maturity prediction of the shale gas well to be predicted.

[0046] After obtaining the relational model, when faced with different shale gas wells to be predicted, it is only necessary to calculate the maturity factor using well logging data, and then the maturity of shale organic matter can be directly obtained through the relational model, thereby completing the maturity prediction of shale gas wells.

[0047] In one possible embodiment, the regional reservoir is a mature marine shale gas reservoir. Well logging data from drilled shale gas wells within the block are selected, and this data meets the quality requirements specified in the "Quality Specification for Original Petroleum Logging Data" (SY / T5132-2012). The logging data includes the regional reservoir characteristics of this application. First, the regional reservoir characteristics are input into the shale gas reservoir petrophysical volumetric model to calculate the shale resistivity R. ts Then the shale resistivity R ts and logging resistivity R t The maturity factor R is obtained by performing a division operation. ma Finally, the maturity factor R was established using laser Raman spectroscopy. ma A model relating shale organic matter maturity to shale organic matter maturity. Calculations show that the first coefficient 'a' can be 0.0774, and the second coefficient 'b' can be 3.4027. The relationship model is: R o =0.0774·ln(R) ma +3.4027. Please refer to... Figure 2 , Figure 2 A schematic diagram of the relational model proposed in the embodiments of this application is shown. Different shale gas wells were selected to obtain a fitting line of the relational model.

[0048] Please refer to the following. Figure 3 , Figure 3 The diagram shows the results of maturity evaluation using a method for obtaining shale organic matter maturity. In the diagram, the first channel is the geological stratification channel, the second is the lithology curve channel (natural gamma, uranium-reduced gamma, borehole diameter), the third is the conventional porosity curve (density, sonic transit time, and compensated neutrons), the fourth is the resistivity curve (deep and shallow resistivity), the fifth is the depth channel, the sixth is the structure resistivity and logging resistivity channel, and the seventh is the logging-predicted organic matter maturity channel. Structure resistivity and logging resistivity reflect increased organic matter maturity at depths of 3035–3076 m, exhibiting a high-maturity characteristic. Comparing the organic matter maturity provided in the embodiments of this application with the organic matter maturity from core analysis, the logging-predicted maturity is 3.52%, while the core maturity is 3.54%, with a relative error within 1%. This demonstrates that the method provided in the embodiments of this invention for obtaining high-maturity marine shale organic matter maturity based on logging data can accurately and reliably determine the organic matter maturity of high-maturity marine shale, and has good application effects in actual production.

[0049] Compared with the prior art, the embodiments of this application have the following beneficial effects:

[0050] First, it can evaluate the degree of thermal evolution of shale during the shale gas exploration stage, which is of great significance for identifying resource potential areas and core production areas.

[0051] Second, compared with traditional laboratory evaluation of organic matter maturity, this application starts with the analysis of the rock physical response characteristics of shale with different thermal evolution degrees, establishes a quantitative relationship between organic matter maturity and well logging resistivity, and does not rely on core analysis. It has the characteristics of being fast, intuitive, accurate, reliable and highly applicable to actual production.

[0052] This invention constructs shale resistivity unaffected by the degree of organic matter thermal evolution based on a shale gas reservoir rock physical volume model. It establishes a maturity factor RQ reflecting the degree of thermal evolution of marine shale by utilizing the difference between the actual measured resistivity and the constructed resistivity. Furthermore, it establishes a maturity factor Rm based on laser Raman experiments of shale with different maturity levels. ma A model relating organic matter maturity to shale organic matter maturity was developed, and quantitative evaluation of organic matter maturity was conducted using actual well logging. This model can accurately calculate the organic matter maturity of marine shale with higher than mature organic matter.

[0053] The following describes a possible implementation of a device for obtaining the maturity of shale organic matter, which is used to perform the various steps and corresponding technical effects of the method for obtaining the maturity of shale organic matter shown in the above embodiments and possible implementations. The device includes:

[0054] The first calculation module is used to input regional reservoir characteristics into the shale gas reservoir rock physical volume model to calculate the shale resistivity R. ts Shale resistivity R ts Unaffected by the degree of thermal evolution of organic matter;

[0055] The second calculation module is used to calculate the shale resistivity R. ts and logging resistivity R t The maturity factor R is obtained by performing a division operation. ma Maturity factor R ma Reflects the degree of thermal evolution of shale;

[0056] The relationship establishment module is used to establish the maturity factor R using laser Raman experiments. ma A model relating shale organic matter maturity to shale organic matter maturity, where the maturity factor R is represented. ma Relationship with the maturity of shale organic matter.

[0057] In one alternative embodiment, the device further includes:

[0058] The maturity prediction module is used to calculate the maturity factor R of the shale gas well to be predicted. ma Based on the relational model, the shale organic matter maturity of the shale gas well to be predicted is obtained, and the maturity prediction of the shale gas well to be predicted is completed.

[0059] This preferred embodiment provides a computer device that can implement the steps in any embodiment of the method for obtaining the maturity of shale organic matter provided in this application. Therefore, it can achieve the beneficial effects of the method for obtaining the maturity of shale organic matter provided in this application. For details, please refer to the previous embodiments, which will not be repeated here.

[0060] Those skilled in the art will understand that all or part of the steps in the various methods of the above embodiments can be implemented by instructions, or by instructions controlling related hardware. These instructions can be stored in a computer-readable storage medium and loaded and executed by a processor. Therefore, embodiments of this application provide a storage medium storing multiple instructions that can be loaded by a processor to execute the steps of any embodiment of the shale organic matter maturity acquisition method provided in this application.

[0061] The storage medium may include: read-only memory (ROM), random access memory (RAM), disk or optical disk, etc.

[0062] Since the instructions stored in the storage medium can execute the steps in any of the shale organic matter maturity acquisition method embodiments provided in this application, the beneficial effects that any of the shale organic matter maturity acquisition methods provided in this application can achieve can be realized, as detailed in the preceding embodiments, and will not be repeated here.

[0063] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for obtaining the maturity of shale organic matter, characterized in that, The method is applied to shale gas wells, including: Step 101: Input the regional reservoir characteristics into the shale gas reservoir rock physical volume model to calculate the shale resistivity R. ts The shale resistivity R ts Unaffected by the degree of thermal evolution of organic matter, the reservoir characteristics of the region include: clay content, reservoir water saturation, mudstone resistivity, formation water resistivity, and reservoir porosity. The shale resistivity R ts The calculation formula is: Among them, V sh For clay content, S w R represents the reservoir water saturation. sh R is the resistivity of mudstone. w φ represents the formation water resistivity, and φ represents the reservoir porosity. Step 102: The resistivity R of the shale ts and logging resistivity R t The maturity factor R is obtained by performing a division operation. ma The maturity factor R ma Reflects the degree of thermal evolution of shale; Step 103: Establish the maturity factor R using laser Raman spectroscopy. ma A model relating shale organic matter maturity to the maturity factor R, wherein the model characterizes the maturity factor R. ma The relationship between R and shale organic matter maturity is calculated using the following formula: R o =a·ln(R) ma )+b,R ma R is the maturity factor. o , where a represents the maturity of shale organic matter, and b represents the first coefficient and the second coefficient. Step 104: Calculate the maturity factor R of the shale gas well to be predicted. ma Based on the relationship model, the shale organic matter maturity of the shale gas well to be predicted is obtained, thus completing the maturity prediction of the shale gas well to be predicted.

2. The method for obtaining the maturity of shale organic matter as described in claim 1, characterized in that, The maturity factor R ma The calculation formula is: Where R ts R is the resistivity of shale. t This refers to the well logging resistivity.

3. The method for obtaining the maturity of shale organic matter as described in claim 1, characterized in that, The first coefficient a and the second coefficient b were both obtained by fitting the data using the least squares method in an experiment.

4. A device for obtaining the maturity of shale organic matter, characterized in that, The device includes: The first calculation module is used to input regional reservoir characteristics into the shale gas reservoir rock physical volume model to calculate the shale resistivity R. ts The shale resistivity R ts Unaffected by the degree of thermal evolution of organic matter, the reservoir characteristics of the region include: clay content, reservoir water saturation, mudstone resistivity, formation water resistivity, and reservoir porosity. The shale resistivity R ts The calculation formula is: Among them, V sh For clay content, S w R represents the reservoir water saturation. sh R is the resistivity of mudstone. w φ represents the formation water resistivity, and φ represents the reservoir porosity. The second calculation module is used to calculate the shale resistivity R. ts and logging resistivity R t The maturity factor R is obtained by performing a division operation. ma The maturity factor R ma Reflects the degree of thermal evolution of shale; The relationship establishment module is used to establish the maturity factor R using laser Raman experiments. ma A model relating shale organic matter maturity to the maturity factor R, wherein the model characterizes the maturity factor R. ma The relationship between R and shale organic matter maturity is calculated using the following formula: R o =a·ln(R) ma )+b,R ma R is the maturity factor. o , where a represents the maturity of shale organic matter, and b represents the first coefficient and the second coefficient. The maturity prediction module is used to calculate the maturity factor R of the shale gas well to be predicted. ma Based on the relationship model, the shale organic matter maturity of the shale gas well to be predicted is obtained, thus completing the maturity prediction of the shale gas well to be predicted.

5. A computer device, characterized in that, The computer device includes a processor and a memory, the memory storing a computer program, which is loaded and executed by the processor to implement the method for obtaining the maturity of shale organic matter as described in any one of claims 1-3.

6. A computer-readable storage medium, characterized in that, The storage medium stores a computer program, which is loaded and executed by a processor to implement the method for obtaining the maturity of shale organic matter as described in any one of claims 1-3.

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