Deep target layer gravity anomaly extraction method
By acquiring Bouguer gravity and magnetization anomaly data and combining them with seismic tectonic depth data, forward modeling and lithological correction were performed, solving the problem of inaccurate separation of deep gravity anomalies, achieving high-precision exploration of the Carboniferous system, and reducing seismic exploration costs.
Patent Information
- Application Number
- CN202410606444.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-16
- Publication Date
- 2025-11-18
AI Technical Summary
Existing technologies are insufficient to accurately separate and extract gravity anomalies in deep Carboniferous strata, resulting in low accuracy of lithological identification in Carboniferous exploration and weak resolution of inversion methods, making it difficult to meet the needs of fine exploration.
By acquiring Bouguer gravity anomaly and magnetization pole anomaly data, combined with shallow and medium-depth seismic tectonic depth and density data, forward modeling and delamination processing were performed to eliminate the influence of basement and lithological variations. The residual gravity anomaly of the Carboniferous target layer was obtained by processing with linear gravity anomalies and second derivatives.
It enables precise extraction of gravity anomalies in the Carboniferous system, improves identification accuracy, meets the needs of fine exploration of the Carboniferous system, and reduces seismic exploration costs.
Smart Images
Figure CN120972276A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the field of petroleum, natural gas geology and exploration and development engineering, and particularly relates to a deep target layer gravity anomaly extraction method. BACKGROUND
[0002] The Carboniferous system is an important exploration and development layer system in a basin, and the Carboniferous system has great exploration potential. Although a large amount of seismic exploration work has been carried out in some areas, the Carboniferous system is difficult to image, and the upper and lower stone systems and the bottom boundary of the Carboniferous system are difficult to determine, and need to be studied in combination with high-precision 1:50,000 gravity data. The Carboniferous system target layer is widely developed and has great depth variation, especially in the deep buried area of the depression, and lacks drilling calibration, and it is difficult to extract weak gravity anomalies in deep layers. In view of this, a method for effectively extracting deep Carboniferous system target gravity anomalies is needed to provide a supplement for the overall study of the Carboniferous system.
[0003] At present, the separation method of the deep target layer gravity anomaly is:
[0004] The first method is a qualitative separation method, that is, the spatial domain or frequency domain (such as interpolation cutting, trend analysis or upward extension of the remaining part) is used to qualitatively separate the deep target layer gravity anomaly. The above methods can only use the frequency characteristics of the data itself to separate by using the binary method, the multiple method, and the like, such as obtaining a high-frequency gravity anomaly map, or a low-frequency gravity anomaly map, or a gravity anomaly map of a certain frequency. However, due to the frequency superposition characteristics and the complexity of the gravity anomaly causes, the high frequency does not necessarily correspond to the shallow gravity anomaly, and the low frequency does not necessarily correspond to the deep gravity anomaly, and it is not said that a certain frequency can correspond to a certain layer. Therefore, it is ultimately not a quantitative separation method, and is seriously affected by the frequency characteristics of the shallow and deep basement, and has multiple solutions. The method usually only performs gravity anomaly filtering processing, the data processing process is simple, and the accuracy of lithology identification is not high.
[0005] The second method is an inversion method, that is, a gravity three-dimensional inversion is used to restore the underground three-dimensional density or three-dimensional interface depth information. However, due to the multiple solutions of inversion and the weak resolution of the deep layer, it is difficult to restore the density characteristics of the Carboniferous system, and the inversion itself is a difficult problem to solve, and its practicability is not high, and it is difficult to separate the Carboniferous system gravity anomaly by using it. SUMMARY
[0006] In view of the problems in the prior art, the present application provides a deep target layer gravity anomaly extraction method, and the technical problem to be solved by the present application is to improve the accuracy of Carboniferous system target gravity anomaly identification.
[0007] To solve the above technical problems, the present application provides a deep target layer gravity anomaly extraction method, comprising the following steps:
[0008] Step S1: obtaining Bouguer gravity anomaly data and magnetic polarizability anomaly data;
[0009] Step S2: obtaining seismic structure depth of each stratum to be stripped in the middle and shallow layer overlying the Carboniferous system and density data of each stratum statistics;
[0010] Step S3: using the seismic structure depth of the middle and shallow layer overlying the Carboniferous system and the density data to carry out forward stripping processing on the Bouguer gravity anomaly data, and obtaining the Bouguer gravity anomaly after stripping;
[0011] Step S4: obtaining the residual gravity anomaly of the Carboniferous target layer by calculating the regional anomaly of the Bouguer gravity anomaly after stripping;
[0012] Step S5: using the magnetic polarizability anomaly data to carry out lithology correction of the residual gravity anomaly of the Carboniferous target layer, and eliminating the influence of the basement and the internal lithology change of the Carboniferous system on the gravity anomaly.
[0013] Further, in the step S4, the regional gravity anomaly is obtained by using the upward continuation method or the low-pass filtering method and eliminating the deep gravity regional field from the Bouguer gravity anomaly after stripping.
[0014] Further, in the step S4, the regional anomaly is subtracted from the Bouguer gravity anomaly after stripping to obtain the residual gravity anomaly of the Carboniferous target layer.
[0015] Further, in the step S5, the residual gravity anomaly of the Carboniferous target layer is processed by gravity linear anomaly and gravity second derivative.
[0016] Further, in the step S5, the magnetic source pseudo-gravity anomaly is calculated by using the magnetic polarizability anomaly data, and is eliminated from the residual gravity anomaly of the Carboniferous target layer.
[0017] The present application provides a deep target layer gravity anomaly fine extraction method for the problem of deep Carboniferous target layer burial, lack of drilling calibration in the depression area, and difficulty in extracting gravity anomaly, which can effectively solve the problem of Carboniferous gravity anomaly extraction and provide data for the research of the Carboniferous system.
[0018] Compared with the residual gravity anomaly of the Carboniferous obtained from the stripping and lithologic correction and the residual gravity anomaly separated by the qualitative method, the Carboniferous gravity anomaly extracted by the present application has the characteristics of high coincidence rate with the data of drilling, earthquake and the like, and can meet the needs of the fine exploration of the Carboniferous. Meanwhile, the Carboniferous residual gravity anomaly extracted is processed by the subsequent gravity linear anomaly and gravity second derivative, and the Carboniferous uplift and depression structure, fracture distribution and combination relationship reflected are all reasonable to a certain extent, which provides an effective way for the research on the Carboniferous by using the gravity method.
[0019] The effective popularization of the method can provide technical support for the research on deep target by using gravity data and reduce the investment cost of seismic exploration. BRIEF DESCRIPTION OF DRAWINGS
[0020] Figure 1 is a flow chart of a deep target layer gravity anomaly extraction method of the present application.
[0021] Figure 2 is a middle-shallow layer seismic structure depth chart of a deep target layer gravity anomaly extraction method of the present application, and the unclear text in the chart does not affect the understanding of the present application. DETAILED DESCRIPTION
[0022] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.
[0023] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.
[0024] It should be noted that: similar reference numerals and letters represent similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.
[0025] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.
[0026] In order to better understand the purpose, structure and function of the present application, the deep target layer gravity anomaly extraction method of the present application is further described in detail below in combination with the drawings.
[0027] Embodiment 1:
[0028] As shown in Figure 1 , the deep target layer gravity anomaly extraction method of the present application comprises the following steps:
[0029] Step S1: obtaining Bouguer gravity anomaly data and magnetic polarization anomaly data;
[0030] Step S2: obtaining the seismic structure depth of each stratum to be stripped in the middle and shallow layer overlying the Carboniferous system in the region and the density data of each stratum statistics;
[0031] Step S3: using the seismic structure depth and density data of the middle and shallow layer overlying the Carboniferous system to perform forward stripping processing on the Bouguer gravity anomaly data, and obtaining the Bouguer gravity anomaly after stripping;
[0032] Step S4: obtaining the regional gravity anomaly of the Bouguer gravity anomaly after stripping, and obtaining the residual gravity anomaly of the Carboniferous target layer;
[0033] Step S5: using the magnetic polarized anomaly data to perform lithology correction of the residual gravity anomaly of the Carboniferous target layer, eliminating the influence of the basement and the internal lithology change of the Carboniferous system on the gravity anomaly, and finally obtaining the gravity anomaly reflecting the comprehensive depth and thickness of the Carboniferous system, and using it for Carboniferous exploration research;
[0034] Embodiment 2:
[0035] As shown in Figure 1 , the deep target layer gravity anomaly extraction method of the present application comprises the following steps:
[0036] Step S1: obtaining the Bouguer gravity anomaly data and the magnetic polarized anomaly data in the region by collecting or collecting.
[0037] Step S2: as Figure 2, the top boundary seismic structure depth of each stratum to be stripped in the overlying middle-shallow layer of the Carboniferous System (Paleogene System, Cretaceous System, Jurassic System, Triassic System, Permian System) in the acquisition area, and the density of each stratum (Paleogene System: 2.38 g / cm3, Cretaceous System: 2.47 g / cm3, Jurassic System: 2.53 g / cm3, Triassic System: 2.57 g / cm3, Permian System: 2.60 g / cm3) are obtained.
[0038] Step S3: The gravity responses of the Paleogene System, Cretaceous System, Jurassic System, Triassic System, and Permian System are calculated by using the top boundary seismic structure depth and density data of the overlying middle-shallow layer of the Carboniferous System, and the stripped Bouguer gravity anomaly is obtained by stripping the Bouguer gravity anomaly data. The stripped Bouguer gravity anomaly reflects the interface undulation and thickness change of the strata below the Carboniferous System in the study area to a certain extent.
[0039] Step S4: The regional anomaly is obtained by using the upward continuation method (or other low-pass filtering method) on the stripped Bouguer gravity anomaly, and the regional anomaly is subtracted from the stripped Bouguer gravity anomaly, so as to obtain the residual gravity anomaly after stripping, which basically reflects the gravity anomaly change caused by the Carboniferous System and the Carboniferous System.
[0040] Step S5: The magnetic pseudo-gravity anomaly is calculated by using the magnetic reduction-to-pole anomaly data, and the magnetic pseudo-gravity anomaly is eliminated from the residual gravity anomaly after stripping, so as to eliminate the influence of the basement and the lithological change in the Carboniferous System on the gravity anomaly, and finally obtain the residual gravity anomaly after stripping, which reflects the comprehensive depth and thickness of the Carboniferous System, and is used for the exploration and research of the Carboniferous System.
[0041] The difference between the embodiment and the first embodiment is that:
[0042] In step S4, the upward continuation method or the low-pass filtering method is used on the stripped Bouguer gravity anomaly, and the deep gravity regional field is eliminated, so as to obtain the regional gravity anomaly;
[0043] In step S4, the regional anomaly is subtracted from the stripped Bouguer gravity anomaly, so as to obtain the residual gravity anomaly of the Carboniferous System target layer;
[0044] In step S5, the residual gravity anomaly of the Carboniferous System target layer is processed by using the gravity linear anomaly and the gravity second derivative.
[0045] In step S5, the magnetic pseudo-gravity anomaly is calculated by using the magnetic reduction-to-pole anomaly data, and the magnetic pseudo-gravity anomaly is eliminated from the residual gravity anomaly of the Carboniferous System target layer, so as to eliminate the influence of the basement and the lithological change in the Carboniferous System on the gravity anomaly.
[0046] The above merely provides the preferred embodiments of the present application, and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the principles and technical scope of the present application shall fall into the scope of the present application.
Claims
1. A method for extracting gravity anomalies in deep target layers, characterized in that, Includes the following steps: Step S1: Obtain Bouguer gravity anomaly data and magnetization anomaly data; Step S2: Obtain the seismic tectonic depth and density data of the shallow to medium-depth strata overlying the Carboniferous system in the area; Step S3: Use the seismic tectonic depth and density data of the shallow to medium-depth layers overlying the Carboniferous system to perform forward modeling and layer stripping processing on the Bouguer gravity anomaly data to obtain the stripped Bouguer gravity anomaly. Step S4: Calculate the regional anomaly from the Bouguer gravity anomaly after delamination to obtain the residual gravity anomaly of the Carboniferous target layer; Step S5: Use magnetic polarization anomaly data to perform lithological correction of the residual gravity anomaly of the Carboniferous target layer, eliminating the influence of basement and internal Carboniferous lithological variations on the gravity anomaly.
2. The method for extracting gravity anomalies in deep target layers according to claim 1, characterized in that, In step S4, the Bouguer gravity anomaly after delamination is obtained by using the upward extension method or the low-pass filtering method and eliminating the deep gravity region field.
3. The method for extracting gravity anomalies in deep target layers according to claim 2, characterized in that, In step S4, the regional anomaly is subtracted from the Bouguer gravity anomaly after delamination to obtain the remaining gravity anomaly of the Carboniferous target layer.
4. The method for extracting gravity anomalies in deep target layers according to claim 3, characterized in that, In step S5, the residual gravity anomaly of the Carboniferous target layer is processed by gravity linear anomaly and gravity second derivative.
5. The method for extracting gravity anomalies in deep target layers according to claim 3, characterized in that, In step S5, the pseudo-gravity anomaly of the magnetic source is calculated using the magnetic polarization anomaly data and eliminated from the residual gravity anomaly of the Carboniferous target layer.