Method and device for acquiring maturity of shale organic matters

Abstract

The invention discloses a shale organic matter maturity obtaining method and device, and the method is applied to a to-be-predicted shale gas well, and comprises the steps: inputting regional reservoir features into a shale gas reservoir rock physical volume model, and calculating the shale resistivity; performing division operation on the shale resistivity and the logging resistivity to obtain a maturity factor; and finally, establishing a relation model between the maturity factor and the shale organic matter maturity by utilizing a laser Raman experiment. When maturity quantitative evaluation is carried out on organic matters of different shale gas wells to be predicted, the maturity factor is calculated only by using logging information, and the corresponding relationship between the maturity factor and the shale organic matter maturity is reflected by establishing a relationship model between the maturity factor and the shale organic matter maturity; the method can quickly and accurately calculate the organic matter maturity of the high-over-maturity marine facies shale.

Description

Technical Field

[0001] The present application relates to the field of natural gas exploration technology, and in particular to a method and device for obtaining the maturity of shale organic matter. Background Art

[0002] During the deep burial process, organic matter gradually evolves to a mature degree under the influence of energy conditions such as temperature, which is called organic matter maturity. There are two types of maturity parameters: the first type is used to indicate the stage of oil formation, including kerogen optical parameters, pyrolysis parameters, and soluble organic matter parameters; the second type is the "thermal stress" parameter used to describe the relative intensity of temperature-time, such as vitrinite reflectance, maximum peak temperature, and most biomarker compound maturity parameters.

[0003] However, in the existing technology, since there is no vitrinite in the Lower Paleozoic and Precambrian marine source rocks, it is impossible to evaluate the maturity of the Lower Paleozoic source rocks through the vitrinite reflectance in the second maturity parameter. At the same time, the laboratory method for determining the maturity of organic matter relies on cores, which has the characteristics of long experimental cycle and high coring cost. In actual application, there will be great limitations and poor practical operability. Summary of the invention

[0004] The purpose of this application is to provide a method and device for obtaining shale organic matter maturity in order to overcome the existing technical defects. By establishing a relationship model between the maturity factor and the shale organic matter maturity to reflect the corresponding relationship between the two, the organic matter maturity of highly overmature marine shale can be calculated quickly and more accurately when conducting quantitative evaluation of the organic matter maturity of different shale gas wells to be predicted.

[0005] The purpose of this application is achieved through the following technical solutions:

[0006] In the first aspect, the present application proposes a method for obtaining shale organic matter maturity, which is applied to a shale gas well to be predicted, and comprises:

[0007] Step 101: Input the regional reservoir characteristics into the shale gas reservoir rock physics volume model to calculate the shale resistivity R ts , the shale resistivity R ts Not affected by the degree of thermal evolution of organic matter;

[0008] Step 102: The shale resistivity R ts and logging resistivity R t Perform division operation to obtain the maturity factor R ma , the maturity factor R ma Reflects the degree of shale thermal evolution;

[0009] Step 103: Establish the maturity factor R using laser Raman experiment ma A relationship model with shale organic matter maturity, wherein the relationship model represents the maturity factor R ma Relationship with shale organic matter maturity.

[0010] In a possible implementation manner, after step S103, the method further includes:

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

[0012] In a 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 is the clay content, S w is the reservoir water saturation, R sh is the resistivity of mudstone, R w is the formation water resistivity, and φ is the reservoir porosity.

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

[0017] Where R ts is the shale resistivity, R t is the logging resistivity.

[0018] In a possible implementation, the calculation formula of the relationship model is: o =a·ln(R ma )+b,R ma is the maturity factor, R o is the maturity of shale organic matter, a is the first coefficient, and b is the second coefficient.

[0019] In a possible implementation manner, the first coefficient a and the second coefficient b are both obtained by fitting using a least square method through experiments.

[0020] In a second aspect, the present application also proposes a device for obtaining shale organic matter maturity, the device comprising:

[0021] The first calculation module is used to 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 Not affected 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 Perform division operation to obtain the maturity factor R ma , the maturity factor R ma Reflects the degree of shale thermal evolution;

[0023] A relationship building module is used to establish the maturity factor R using laser Raman experiment ma A relationship model with shale organic matter maturity, wherein the relationship model represents the maturity factor R ma Relationship with shale organic matter maturity.

[0024] In a 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 , the maturity of shale organic matter of the shale gas well to be predicted is obtained according to the relationship model, and the maturity prediction of the shale gas well to be predicted is completed.

[0026] In a third aspect, the present application further proposes a computer device, comprising a processor and a memory, wherein the memory stores a computer program, and the computer program is loaded and executed by the processor to implement the method for obtaining shale organic matter maturity as described in any one of the first aspects.

[0027] In a fourth aspect, the present application further proposes a computer-readable storage medium, in which a computer program is stored. The computer program is loaded and executed by a processor to implement the method for obtaining shale organic matter maturity as described in any one of the first aspects.

[0028] The above-mentioned main scheme of the present application and its further options can be freely combined to form multiple schemes, all of which are schemes that can be adopted and claimed for protection in the present application; and in the present application, (non-conflicting options) options and other options can also be freely combined. After understanding the scheme of the present application, those skilled in the art can understand that there are multiple combinations based on the prior art and common knowledge, all of which are technical schemes to be protected by the present application, and they are not exhaustively listed here.

[0029] The present application discloses a method and device for obtaining the maturity of shale organic matter. The method is applied to shale gas wells to be predicted. First, the regional reservoir characteristics are input into the rock physical volume model of the shale gas reservoir to calculate the shale resistivity, and then the shale resistivity and the logging resistivity are divided to obtain the maturity factor. Finally, a relationship model between the maturity factor and the maturity of shale organic matter is established using a laser Raman experiment. When quantitatively evaluating the maturity of organic matter in different shale gas wells to be predicted, it is only necessary to calculate the maturity factor using logging data. By establishing a relationship model between the maturity factor and the maturity of shale organic matter, the corresponding relationship between the two can be reflected, and the maturity of highly over-mature marine shale organic matter can be quickly and accurately calculated. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A schematic flow chart of a method for obtaining shale organic matter maturity proposed in an embodiment of the present application is shown.

[0031] Figure 2 A schematic diagram of the relationship model proposed in the embodiment of the present application is shown.

[0032] Figure 3 The figure shows the result of the method for obtaining the maturity of shale organic matter and conducting maturity evaluation. DETAILED DESCRIPTION

[0033] The following describes the embodiments of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. The present application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0034] Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of this application.

[0035] In the existing technology, since there is no vitrinite in the Lower Paleozoic and Precambrian marine source rocks, it is impossible to evaluate the maturity of the Lower Paleozoic source rocks through the vitrinite reflectance in the second maturity parameter. In addition, the method of characterizing the maturity of shale organic matter using laser Raman spectroscopy parameters is still in the stage of free exploration and research. Due to the lack of a unified method (including sample preparation, test conditions, spectrum fitting and parameter calculation), the comparability of test results from different units is poor. At the same time, the laboratory method for determining the maturity of organic matter relies on cores, which has the characteristics of long experimental cycle and high coring cost. In actual application, there will be great limitations and poor practical operability.

[0036] Therefore, in order to solve the problem that there is a lack of effective means for logging prediction of organic matter maturity in highly overmature marine shale reservoirs and that quantitative evaluation is difficult, the embodiment of the present application proposes a method and device for obtaining shale organic matter maturity. By establishing a relationship model between maturity factor and shale organic matter maturity, the corresponding relationship between the two is reflected, so that the calculated results have a high consistency with the organic matter maturity of core testing, which lays a foundation for using logging data to evaluate the degree of thermal evolution of highly overmature marine shale reservoirs.

[0037] Next, the method of obtaining shale organic matter maturity is described in detail. Please refer to Figure 1 , Figure 1 The following is a flow chart of a method for obtaining shale organic matter maturity proposed in an embodiment of the present application. The method is applied to a shale gas well to be predicted, and includes:

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

[0039] The shale resistivity R ts Unaffected by the degree of thermal evolution of organic matter, 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 is the clay content (%), S w is the reservoir water saturation (%), R sh is the resistivity of mudstone (Ω·m), R w is the formation water resistivity (Ω·m), and φ is the reservoir porosity (%). In addition, regional reservoir characteristics can also include other parameters, and the calculation of parameters is carried out in accordance with the method specified in the "Shale Gas Logging Data Processing and Interpretation Specification SY / T6994-2014".

[0041] Step 102: Calculate the shale resistivity R ts and logging resistivity R t Perform division operation to obtain the maturity factor R ma .

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

[0043] Step 103: Establishing the maturity factor R using laser Raman experiment ma Relationship model with shale organic matter maturity.

[0044] Relationship model representation maturity factor R ma The relationship between the maturity factor and the maturity of shale organic matter is established by combining the laser Raman experiment of shales with different maturity levels to establish a relationship model between the maturity factor and the maturity of shale organic matter, which can realize the method proposed in this application. The calculation formula of the relationship model is: R o =a·ln(R ma )+b,R ma is the maturity factor, R o is the maturity of shale organic matter, a is the first coefficient, and b is the second coefficient. The first coefficient a and the second coefficient b are obtained by fitting the least square method through experiments.

[0045] Step 104: For the shale gas well to be predicted, the maturity factor of the shale gas well to be predicted is calculated, and the shale organic matter maturity of the shale gas well to be predicted is obtained according to the relationship model, so as to complete the maturity prediction of the shale gas well to be predicted.

[0046] After obtaining the relationship model, when faced with different shale gas wells to be predicted, we only need to use the logging data to calculate the maturity factor, and then we can directly obtain the maturity of shale organic matter through the relationship model, and then complete the maturity prediction of shale gas wells.

[0047] In a possible embodiment, the regional reservoir is a highly over-mature marine shale gas reservoir, and the logging data of the drilled shale gas wells in the block are selected. The logging data of the drilled wells meet the quality requirements of the "Petroleum Well Logging Raw Data Quality Specification" (SY / T5132-2012) standard. The logging data contains the regional reservoir characteristics of this application. First, the regional reservoir characteristics are input into the shale gas reservoir rock physical volume model to calculate the shale resistivity R ts , and then the shale resistivity R ts and logging resistivity R t Perform division operation to obtain the maturity factor R ma Finally, the laser Raman experiment was used to establish the maturity factor R ma The relationship model with shale organic matter maturity. After calculation, 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 relationship model proposed in the embodiment of the present application is shown, and different shale gas wells are selected to obtain a fitting line of the relationship model.

[0048] Please refer to the following Figure 3 , Figure 3 The result diagram of the method for obtaining the maturity of shale organic matter is shown. In the figure, the first track is the geological stratification track, the second track is the lithology curve track (natural gamma, deuranium gamma, well diameter), the third track is the conventional porosity curve (density, acoustic time difference and compensated neutron), the fourth track is the resistivity curve (deep and shallow resistivity), the fifth track is the depth track, the sixth track is the construction resistivity and logging resistivity track, and the seventh track is the logging prediction organic matter maturity track. The construction resistivity and logging resistivity reflect the increase in organic matter maturity at 3035-3076m, showing a high over-maturity feature. The organic matter maturity provided in the embodiment of the present application is compared with the organic matter maturity of the core analysis. The well logging predicted maturity is 3.52%, and the core maturity is 3.54%. The relative error between the two is within 1%, indicating that the method for obtaining the organic matter maturity of highly over-mature marine shale based on logging data provided in the embodiment of the present invention can accurately and reliably determine the organic matter maturity of highly over-mature marine shale, and has a good application effect in actual production.

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

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

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

[0052] The present invention constructs the shale resistivity that is not affected by the thermal evolution degree of organic matter based on the rock physical volume model of the shale gas reservoir, and establishes the maturity factor RQ reflecting the thermal evolution degree of marine shale by using the difference between the actually measured resistivity and the constructed resistivity. The maturity factor R is established by combining the laser Raman experiment of shales with different maturity. ma The relationship model between the organic matter maturity of shale and the actual well logging is used to carry out quantitative evaluation of organic matter maturity, which can more accurately calculate the organic matter maturity of highly mature marine shale.

[0053] A possible implementation of a device for acquiring shale organic matter maturity is provided below, which is used to execute the various steps and corresponding technical effects of the method for acquiring shale organic matter maturity shown in the above embodiments and possible implementations. The acquisition device includes:

[0054] The first calculation module is used to input the regional reservoir characteristics into the shale gas reservoir rock physical volume model to calculate the shale resistivity R ts , shale resistivity R ts Not affected 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 Perform division operation to obtain the maturity factor R ma , maturity factor R ma Reflects the degree of shale thermal evolution;

[0056] Relationship building module for establishing maturity factor R using laser Raman experiments ma The relationship model with shale organic matter maturity, the relationship model characterizes the maturity factor R ma Relationship with shale organic matter maturity.

[0057] In an optional manner, 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 , the maturity of shale organic matter of the shale gas well to be predicted is obtained according to the relationship model, and the maturity prediction of the shale gas well to be predicted is completed.

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

[0060] Those skilled in the art can understand that all or part of the steps in the various methods of the above embodiments can be completed by instructions, or by controlling related hardware through instructions, and the instructions can be stored in a computer-readable storage medium and loaded and executed by a processor. To this end, an embodiment of the present application provides a storage medium, which stores multiple instructions, and the instructions can be loaded by a processor to execute the steps of any embodiment of the method for obtaining shale organic matter maturity provided in the embodiment of the present application.

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

[0062] Since the instructions stored in the storage medium can execute the steps in any of the embodiments of the method for obtaining the maturity of shale organic matter provided in the embodiments of the present application, the beneficial effects that can be achieved by any of the methods for obtaining the maturity of shale organic matter provided in the embodiments of the present application can be achieved. For details, please refer to the previous embodiments and will not be repeated here.

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

Claims

1. A method for obtaining shale organic matter maturity, characterized in that: The method is applied to a shale gas well, comprising: Step 101: Input the regional reservoir characteristics into the shale gas reservoir rock physics volume model to calculate the shale resistivity R ts , the shale resistivity R ts Not affected by the degree of thermal evolution of organic matter; Step 102: The shale resistivity R ts and logging resistivity R t Perform division operation to obtain the maturity factor R ma , the maturity factor R ma Reflects the degree of shale thermal evolution; Step 103: Establish the maturity factor R using laser Raman experiment ma A relationship model with shale organic matter maturity, wherein the relationship model represents the maturity factor R ma Relationship with shale organic matter maturity.

2. The method for obtaining shale organic matter maturity according to claim 1, characterized in that: After step S103, the method further includes: Step 104: Calculate the maturity factor R of the shale gas well to be predicted. ma , the maturity of shale organic matter of the shale gas well to be predicted is obtained according to the relationship model, and the maturity prediction of the shale gas well to be predicted is completed.

3. The method for obtaining shale organic matter maturity according to claim 1, characterized in that: The regional reservoir characteristics 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 is the clay content, S w is the reservoir water saturation, R sh is the resistivity of mudstone, R w is the formation water resistivity, and φ is the reservoir porosity.

4. The method for obtaining shale organic matter maturity according to claim 1, characterized in that: The maturity factor R ma The calculation formula is: Where R ts is the shale resistivity, R t is the logging resistivity.

5. The method for obtaining shale organic matter maturity according to claim 1, characterized in that: The calculation formula of the relationship model is: o =a·ln(R ma )+b,R ma is the maturity factor, R o is the maturity of shale organic matter, a is the first coefficient, and b is the second coefficient.

6. The method for obtaining shale organic matter maturity according to claim 5, characterized in that: The first coefficient a and the second coefficient b are both obtained by fitting using the least square method through experiments.

7. A device for obtaining shale organic matter maturity, characterized in that: The device comprises: The first calculation module is used to 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 Not affected by the degree of thermal evolution of organic matter; The second calculation module is used to calculate the shale resistivity R ts and logging resistivity R t Perform division operation to obtain the maturity factor R ma , the maturity factor R ma Reflects the degree of shale thermal evolution; A relationship building module is used to establish the maturity factor R using laser Raman experiment ma A relationship model with shale organic matter maturity, wherein the relationship model represents the maturity factor R ma Relationship with shale organic matter maturity.

8. The device for obtaining shale organic matter maturity according to claim 7, characterized in that: The device also includes: The maturity prediction module is used to calculate the maturity factor R of the shale gas well to be predicted. ma , the maturity of shale organic matter of the shale gas well to be predicted is obtained according to the relationship model, and the maturity prediction of the shale gas well to be predicted is completed.

9. A computer device, characterized in that: The computer device includes a processor and a memory, wherein a computer program is stored in the memory, and the computer program is loaded and executed by the processor to implement the method for obtaining shale organic matter maturity according to any one of claims 1 to 6.

10. 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 shale organic matter maturity according to any one of claims 1 to 6.

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