Stratum lithology interface identification method and device

Abstract

The invention discloses a stratum lithology interface identification method and device. The method comprises the following steps: acquiring an earth crust electric field lithology test CYT curve obtained by measuring an underground target by using an electric field lithology detector; performing interface processing calculation on the obtained CYT curve to obtain a lithologic interface curve; and according to a preset cut-off value, identifying the corresponding stratum part greater than the cut-off value in the lithologic interface curve as a lithologic interface. According to the lithologic interface depth identification method, the deep and ultra-deep CYT detection technology is utilized, after data processing is carried out on the CYT curve, identification of the lithologic interface depth is achieved through a quantitative mode of setting cut-off value judgment, the implementation means is simple, and high precision can be achieved.

Description

Technical Field

[0001] This invention relates to the field of petroleum geological exploration technology, and in particular to a method and apparatus for identifying stratigraphic lithological interfaces. Background Technology

[0002] As oil exploration and development deepens, the exploration of reservoirs from structural to lithological traps requires not only detailed structural analysis but also reservoir prediction. In older oilfields, inconsistent well logging data limits geophysical exploration efforts. In particular, the velocity superposition of sandstone and mudstone in the target formation of the study area makes accurate prediction of lithological boundaries using seismic impedance inversion difficult. Existing methods primarily rely on well-seismic combined methods for lithological boundary identification. However, the limited resolution of deep and ultra-deep seismic data and the influence of multiples result in low depth resolution and consequently, low prediction accuracy, which remains a persistent challenge. Summary of the Invention

[0003] In view of the above problems, the present invention is proposed to provide a method and apparatus for identifying stratigraphic lithological interfaces that overcomes or at least partially solves the above problems.

[0004] In a first aspect, embodiments of the present invention provide a method for identifying stratigraphic lithological interfaces, comprising:

[0005] Obtain the CYT curve of crustal electric field lithology test obtained by measuring underground targets using an electric field lithology detector;

[0006] The obtained CYT curves are subjected to interface processing calculations to obtain lithological interface curves;

[0007] Based on a preset cutoff value, the strata portion of the lithological interface curve that is greater than the cutoff value is identified as a lithological interface.

[0008] In one embodiment, interface processing calculations are performed on the obtained CYT curve to obtain a lithological interface curve, including:

[0009] For each sampling point of the CYT curve measured by the electric field lithology detector, the ratio of the CYT value of each sampling point to the CYT value of the previous sampling point is calculated in the order from the surface to the subsurface to obtain the value of each point on the lithology interface curve.

[0010] The lithological interface curve is generated based on the values ​​of each point on the lithological interface curve.

[0011] In one embodiment, the formula for calculating the interface processing includes:

[0012]

[0013] Where i represents the number of sampling points measured by the instrument, and the value of i ranges from 1 to N. Starting from the ground, i represents the i-th sampling point, and i+1 represents the (i+1)-th sampling point. CYT(i) represents the CYT curve value corresponding to the i-th sampling point, and ith(i) is the i-th point on the lithological interface curve.

[0014] In one embodiment, based on a preset cutoff value, the stratum portion of the lithological interface curve exceeding the cutoff value is identified as a lithological interface, including:

[0015] The values ​​at each point on the lithological interface curve are compared with the preset cutoff value.

[0016] The values ​​of the lithological interface curves that are greater than the cutoff value are uniformly corrected to the first preset value;

[0017] The first preset value is used to characterize the stratum where the point is located as a lithological interface, and the depth corresponding to the point is the depth of the lithological interface.

[0018] In one embodiment, the method for identifying the stratigraphic lithological interface further includes:

[0019] The values ​​of the lithological interface curves that are less than or equal to the cutoff value are uniformly corrected to a second preset value; the second preset value is not equal to the first preset value;

[0020] The second preset value is used to characterize the stratum where the point is located as a non-lithological interface, and the depth corresponding to the point is the depth of the non-lithological interface.

[0021] In one embodiment, the cutoff value ranges from 2.5 to 10.

[0022] Secondly, embodiments of the present invention provide a device for identifying stratigraphic lithological interfaces, comprising:

[0023] The CYT curve acquisition module is used to acquire the crustal electric field lithology test CYT curve obtained by measuring underground targets using an electric field lithology detector;

[0024] The data processing module is used to perform interface processing calculations on the obtained CYT curve to obtain the lithological interface curve;

[0025] The identification module is used to identify the strata portion of the lithological interface curve that is greater than the preset cutoff value as a lithological interface, based on the preset cutoff value.

[0026] Thirdly, embodiments of the present invention provide a server, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the aforementioned method for identifying stratigraphic lithological interfaces.

[0027] Fourthly, embodiments of the present invention provide a computer-readable storage medium storing a computer program that, when executed by a processor, implements the aforementioned method for identifying stratigraphic lithological interfaces.

[0028] Fifthly, embodiments of the present invention provide a computer program product, the computer program product including a computer program, which, when executed by a processor, implements the aforementioned method for identifying stratigraphic lithological interfaces.

[0029] The beneficial effects of the above-described technical solutions provided in the embodiments of the present invention include at least the following:

[0030] This invention provides a method for identifying the depth of lithological interfaces by using deep and ultra-deep CYT detection technology, processing CYT curve data, and setting cutoff values ​​for quantitative analysis. The method is simple, and experiments have shown that it can achieve high accuracy.

[0031] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description, claims, and drawings.

[0032] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0033] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0034] Figure 1 This is a flowchart of a method for identifying stratigraphic lithological interfaces in an embodiment of the present invention;

[0035] Figure 2 This is a comparison diagram of the lithological interfaces identified by the lithological interface curve in Embodiment 1 of the present invention and the lithological interfaces in the actual logging curves.

[0036] Figure 3 This is a comparison diagram of the lithological interfaces identified by the lithological interface curve in Embodiment 2 of the present invention and the lithological interfaces in the actual logging curves.

[0037] Figure 4 This is a structural block diagram of the stratigraphic lithology interface identification device in an embodiment of the present invention. Detailed Implementation

[0038] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0039] To address the issue of low accuracy in lithological boundary prediction using well-seismic data combined with seismic data in existing technologies, this invention provides a method for identifying stratigraphic lithological interfaces, referring to... Figure 1 As shown, it includes the following steps:

[0040] S11. Obtain the crustal electric-field lithology testing (CYT) curve obtained by measuring the underground target using an electric field lithology detector;

[0041] S12. Perform interface processing calculations on the obtained CYT curves to obtain lithological interface curves;

[0042] S13. Based on the preset cutoff value, identify the stratum portion of the lithological interface curve that is greater than the cutoff value as a lithological interface.

[0043] CYT detection mainly refers to the detection of underground lithology using the principle of electric fields. It involves transmitting electric field signals of specific frequencies and intensities into the underground. When these signals propagate in the underground rock medium, they will produce different reflection, refraction, and scattering phenomena due to differences in the electrical properties of the rocks (such as resistivity, dielectric constant, etc.).

[0044] This invention utilizes the CYT curve obtained from crustal electric field lithology testing. Interface processing calculations are performed on the CYT curve to obtain a lithological interface curve. Then, by setting a cutoff value, the strata corresponding to points exceeding the cutoff value are identified as lithological interfaces. This invention provides a quantitative method for identifying the depth of lithological interfaces by using deep and ultra-deep CYT detection technology to process CYT curve data and then setting a cutoff value. The method is simple and can achieve high accuracy.

[0045] The inventors of this invention discovered that the CYT curve can intuitively reflect the combined changes in resistivity and lithology at different depths. For example, a sudden change in formation resistivity will also cause a sudden change in the CYT value; when the CYT curve suddenly rises or falls, it may indicate a change in lithology. Based on this characteristic, using the CYT curve for corresponding data processing can achieve quantitative identification of lithological interface data.

[0046] In one embodiment, the above steps perform interface processing calculations on the obtained CYT curve to obtain a lithological interface curve, which is specifically calculated in the following manner:

[0047] For each sampling point of the CYT curve measured by the electric field lithology detector, the ratio of the CYT value of each sampling point to the CYT value of the previous sampling point is calculated in the order from the surface to the subsurface to obtain the value of each point on the lithology interface curve.

[0048] The lithological interface curve is generated based on the values ​​of each point on the lithological interface curve.

[0049] By using the ratio between each sampling point and the previous sampling point, the depth points where sudden changes occur on the CYT curve can be intuitively reflected. These depth points may be the depth points where lithological changes occur, thus enabling accurate identification of lithological interfaces.

[0050] Specifically, interface processing calculations can be performed using, for example, the following formula:

[0051]

[0052] Where i represents the number of sampling points measured by the electric field lithology detector, and the value of i ranges from 1 to N. The measurement starts from the ground, i represents the i-th sampling point, and i+1 represents the (i+1)-th sampling point. CYT(i) represents the CYT curve value corresponding to the i-th sampling point, and ith(i) is the i-th point on the lithological interface curve.

[0053] If the sampling interval is set to 1m, and i = 100, the corresponding depth is 100m.

[0054] In one embodiment, in step S13 above, the stratum portion of the lithological interface curve that is greater than the cutoff value is identified as a lithological interface based on a preset cutoff value. This can be achieved in the following way:

[0055] The values ​​at each point on the lithological interface curve are compared with the preset cutoff value.

[0056] The values ​​of the lithological interface curves that are greater than the cutoff value are uniformly corrected to the first preset value;

[0057] The first preset value is used to characterize the stratum where the point is located as a lithological interface, and the depth corresponding to the point is the depth of the lithological interface.

[0058] Points on the lithological interface curve correspond to a certain formation depth; essentially, they are depth points. The CYT curve values ​​at each point are compared with preset cutoff values, and the values ​​of all lithological interface curves exceeding the cutoff values ​​are uniformly modified to, for example, 1.

[0059] A specific formula can be expressed as follows:

[0060] lith(i) = 1, lith(i) > M for i = 1…N - 1

[0061] The above M is a preset cut-off value.

[0062] Then modify the values of all lithology interface curves greater than the cut-off value to 1. 1 represents that this depth point is a lithology interface.

[0063] In one embodiment, the embodiment of the present invention also needs to uniformly modify the values of the lithology interface curves less than or equal to the cut-off value to a second preset value; the second preset value is not equal to the first preset value;

[0064] The second preset value is used to represent that the formation where the point is located is not a lithology interface, and the depth corresponding to this point is the depth of the non-lithology interface.

[0065] For example, the specific formula can be expressed as:

[0066] lith(i) = 0, lith(i) < M for i = 1…N - 1. M is the cut-off value, and the values of all lithology interface curves less than or equal to the cut-off value are uniformly modified to 0. 0 represents that this depth point is a non-lithology interface.

[0067] The value of the above M can be obtained according to empirical values. For example, the value range of M is 2.5 - 10.

[0068] For example, when M takes the value of 3, the method for judging the lithology interface is as follows:

[0069] ith(i) = 1, lith(i) > 3 for i = 1…N - 1

[0070] lith(i) = 0, lith(i) < 3 for i = 1…N - 1

[0071] After calculation, the lithology interface lith curve is obtained. According to the cut-off value, the lith curve is corrected. When the lith curve is less than 3, lith = 0, which is a non-lithology interface. When the Lith curve is greater than 3, lith = 1, which is a lithology interface point, and the corresponding depth point is the depth of the lithology interface.

[0072] The following uses a specific embodiment to illustrate the above method for identifying the formation lithology interface.

[0073] Embodiment 1:

[0074] Taking Well C in Area A as an example, the actual geological situation in this area is as follows:

[0075] The geology of this area is divided into Group A and Group B. Group A consists of a set of sandstone and mudstone strata (mainly composed of sandstone and mudstone), while Group B consists of a set of marine carbonate strata (marine facies indicates formation in a marine environment; the main components of carbonate rocks are calcite and dolomite. The formation of these rocks is usually due to biochemical processes or chemical precipitation in the ocean). At the boundary between the two strata, the lithology changes abruptly from mudstone to limestone, and its electrical properties change. The CYT curve measures the frequency information of electromagnetic waves, and the frequency of electromagnetic waves is closely related to resistivity; as the resistivity of the strata decreases, the frequency of electromagnetic waves also decreases. The lithological change interface identified in this study is the boundary between Group A and Group B; in other words, it is the bottom boundary of Group A or the top boundary of Group B.

[0076] Parameter acquisition: The CYT-VI type geodetic lithology instrument was used to measure the strata and obtain the CYT curve. The CYT curve is actually a processed value and is a dimensionless parameter. The processing involves converting the frequency into a period, multiplying the depth by 5, subtracting the period, and then dividing by 200 nanoseconds to obtain the value. The purpose is to amplify the differences because the frequency changes are very small. By changing the value, the tiny frequency differences are amplified by thousands of times, which can clearly identify the changes in the resistivity of the strata.

[0077] The specific steps for lithological interface identification are as follows:

[0078] Step 1: Calculate the lithological interface curve

[0079]

[0080] Step 2: Determine the depth of the lithological interface based on the cutoff value.

[0081] lith(i)=1, lith(i)>3i=1…N-1;

[0082] lith(i)=0, lith(i)<3i=1...N-1;

[0083] The lithological interface curve calculated in step 2 above is as follows: Figure 2 The black filling represents the lithological interface depth. Compared with the actual lithological changes and formation interfaces in the well logging, the actual lithological interface of Well C is 7297m, while the identified interface depth is 7296m, with an error of 1m. This shows that the formation lithological interface identification method provided by the embodiment of the present invention has high prediction accuracy.

[0084] Example 2:

[0085] Taking a geological group (hereinafter referred to as Group C) in area B as an example, and well Ding in area B as an example, the geological conditions of this area are described as follows:

[0086] In area B, Group C consists of a set of clastic rock strata. At the bottom of Group C, a set of conglomerate deposits is developed, beneath which lies Group D. The top of Group D consists of mudstone deposits. The boundary between Group C and Group D is the boundary between conglomerate and mudstone. This lithological interface results in a significant difference in resistivity, meaning that the electromagnetic wave frequencies measured by the instrument also differ considerably at this interface. The lithological change interface identified in this study is the boundary between Group C and Group D.

[0087] 2. Implementation steps:

[0088] Step 1: Calculate the lithological interface curve

[0089]

[0090] Step 2: Determine the depth of the lithological interface based on the cutoff value.

[0091] lith(i)=1,lith(i)>3i=1…N-1

[0092] lith(i)=0,lith(i)<3i=1…N-1

[0093] 3. Application Effect

[0094] Calculate the lithological interface curve based on step 2, such as Figure 3 The black filling indicates the depth of the lithological interface. Compared with the actual lithological changes and stratigraphic interfaces in the well logging, for the lithological interface between mudstone and conglomerate at the bottom of Group C, the lithological interface at the bottom of Group C in Well D at location B is 5909m, while the identified interface depth is 5908.5m, with an error of 0.5m. The interfaces of other lithologies are also basically consistent with the identified interface. This comparison result shows that the identification has high accuracy.

[0095] The technology was applied in locations A and B, and logging lithology verified its effectiveness. The identification error of the lithological interface between carbonate and clastic rocks was 0-5m, far exceeding the 20-30m resolution of seismic analysis. For clastic rock formations with interbedded sandstone and mudstone, there are numerous lithological interfaces. While this embodiment cannot identify all lithological interfaces, the identification rate is 100%, meaning that all identified lithological interfaces are actual lithological interfaces.

[0096] Based on the same inventive concept, this invention also provides a device for identifying stratigraphic lithological interfaces. Since the principle of the problem solved by this device is similar to the aforementioned method for identifying stratigraphic lithological interfaces, the implementation of this device can refer to the implementation of the aforementioned method, and the repeated parts will not be described again.

[0097] This invention provides a device for identifying stratigraphic lithological interfaces, referring to... Figure 4 As shown, it includes:

[0098] The CYT curve acquisition module 41 is used to acquire the crustal electric field lithology test CYT curve obtained by measuring the underground target using an electric field lithology detector;

[0099] Data processing module 42 is used to perform interface processing calculations on the obtained CYT curve to obtain a lithological interface curve;

[0100] The identification module 43 is used to identify the stratum portion of the lithological interface curve that is greater than the preset cutoff value as a lithological interface based on the preset cutoff value.

[0101] An embodiment of the present invention provides a server comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the aforementioned method for identifying stratigraphic lithological interfaces.

[0102] This invention provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the aforementioned method for identifying stratigraphic lithological interfaces.

[0103] This invention provides a computer program product, which includes a computer program that, when executed by a processor, implements the aforementioned method for identifying stratigraphic lithological interfaces.

[0104] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage and optical storage) containing computer-usable program code.

[0105] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0106] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0107] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0108] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for identifying stratigraphic lithological interfaces, characterized in that, include: ； Obtain the CYT curve of crustal electric field lithology test obtained by measuring underground targets using an electric field lithology detector; The obtained CYT curves are subjected to interface processing calculations to obtain lithological interface curves; Based on a preset cutoff value, the strata portion of the lithological interface curve that is greater than the cutoff value is identified as a lithological interface.

2. The method as described in claim 1, characterized in that, The obtained CYT curves are subjected to interface processing calculations to obtain lithological interface curves, including: For each sampling point of the CYT curve measured by the electric field lithology detector, the ratio of the CYT value of each sampling point to the CYT value of the previous sampling point is calculated in the order from the surface to the subsurface to obtain the value of each point on the lithology interface curve. The lithological interface curve is generated based on the values ​​of each point on the lithological interface curve.

3. The method as described in claim 1, characterized in that, The formulas for interface processing calculations include: Where i represents the number of sampling points measured by the instrument, and the value of i ranges from 1 to N. Starting from the ground, i represents the i-th sampling point, and i+1 represents the (i+1)-th sampling point. CYT(i) represents the CYT curve value corresponding to the i-th sampling point, and ith(i) is the i-th point on the lithological interface curve.

4. The method as described in claim 1, characterized in that, Based on a preset cutoff value, the strata portion of the lithological interface curve exceeding the cutoff value are identified as lithological interfaces, including: The values ​​at each point on the lithological interface curve are compared with the preset cutoff value. The values ​​of the lithological interface curves that are greater than the cutoff value are uniformly corrected to the first preset value; The first preset value is used to characterize the stratum where the point is located as a lithological interface, and the depth corresponding to the point is the depth of the lithological interface.

5. The method as described in claim 4, characterized in that, Also includes: The values ​​of the lithological interface curves that are less than or equal to the cutoff value are uniformly corrected to the second preset value; The second preset value is not equal to the first preset value; The second preset value is used to characterize the stratum where the point is located as a non-lithological interface, and the depth corresponding to the point is the depth of the non-lithological interface.

6. The method as described in claim 4, characterized in that, The cutoff value ranges from 2.5 to 10.

7. A device for identifying stratigraphic lithological interfaces, characterized in that, include: The crustal electric field lithology test CYT curve acquisition module is used to acquire the CYT curve obtained by measuring underground targets using an electric field lithology detector; The data processing module is used to perform interface processing calculations on the obtained CYT curve to obtain the lithological interface curve; The identification module is used to identify the strata portion of the lithological interface curve that is greater than the preset cutoff value as a lithological interface, based on the preset cutoff value.

8. A server, characterized in that, include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the program, implements the method for identifying stratigraphic lithological interfaces as described in any one of claims 1-6.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the method for identifying stratigraphic lithological interfaces as described in any one of claims 1-6.

10. A computer program product, characterized in that, The computer program product includes a computer program that, when executed by a processor, implements the method for identifying stratigraphic lithological interfaces as described in any one of claims 1-6.

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