A method and apparatus for determining fault dip using gravity data

Abstract

This invention provides a method for determining fault dip using gravity data. The method calculates the total horizontal gravity gradient based on the Bouguer gravity anomaly values ​​at various gravity measurement points above the fault and plots a total horizontal gravity gradient profile. A semi-extreme line segment is then drawn on the profile, and the direction of the vector from the maximum point to the midpoint of the semi-extreme line segment is taken as the fault dip. This method for determining fault dip using gravity data is a simple, fast, and intuitive research approach. It enables the rapid acquisition of fault dip information using an economical and efficient gravity exploration method, providing a reliable basis for studying fault-related geological structures.

Description

Technical Field

[0001] This invention relates to the field of gravity exploration, and in particular to a method and apparatus for determining fault dip using gravity data. Background Technology

[0002] A fault, also known as a fracture, is a common geological phenomenon in nature where rocks or strata break apart and undergo relative displacement. The existence of faults is closely related to human activities and the formation and accumulation of energy and mineral resources, making fault research a crucial aspect of geological research. Faults include elements such as strike, dip, and displacement. When rocks or strata fracture, the relative displacement on both sides of the fault results in different rock types appearing on either side of the fault plane. Since different rocks generally have varying densities, differences in gravity anomalies will exist on the ground on either side of the fault. When the fault reaches a certain scale, the gravity anomaly becomes sufficiently significant, allowing the planar distribution of the fault and the strike to be identified through gravity measurements and data analysis. Researchers have yet to find a simple, effective, and intuitive method to determine the dip of a fault using gravity data.

[0003] Bouguer gravity anomalies are fundamental data for gravity exploration. Faults appear as gravity gradient zones (or gravity step zones) on these anomalies. The approximate location of a fault can be determined by observing the location of these gradient zones. However, due to the width of these gradient zones, the exact location of a fault cannot be directly determined from the gravity step zones. To obtain more accurate fault locations, the horizontal derivative of the Bouguer gravity anomaly is typically calculated, and the location of the fault is interpreted based on the maximum or minimum values ​​of the horizontal derivative. This method is accurate and effective in determining fault location, but it cannot directly provide information about the fault's dip.

[0004] According to gravity exploration theory, as the observation altitude increases, the gravity anomaly information of shallow geological structures attenuates relatively quickly, while the attenuation of deep structural information is relatively slow, making deep gravity information relatively prominent. For faults, this means that the shallower fault location information is stronger in gravity anomalies observed at ground level, while the deeper fault location information is stronger in gravity anomalies observed at greater altitudes. The direction from the shallow to the deep fault location indicates the fault dip, and this method is currently commonly used to determine fault dip. However, this method still requires gravity data extrapolation processing, which is relatively complex and has lower resolution. Summary of the Invention

[0005] In view of the above problems, the present invention is proposed to provide a method and apparatus for determining fault dip based on gravity data in order to overcome or at least partially solve the above problems.

[0006] In a first aspect, embodiments of the present invention provide a method for determining fault dip based on gravity data, comprising:

[0007] Based on the pre-acquired Bouguer gravity anomaly values ​​of each gravity measuring point, the total horizontal gradient value corresponding to the intermediate gravity measuring point is calculated; each gravity measuring point includes intermediate gravity measuring points and edge gravity measuring points; the intermediate gravity measuring point is the gravity measuring point other than the edge gravity measuring points among the gravity measuring points.

[0008] Choose one gravity measuring point from the gravity measuring points; take the chosen gravity measuring point as the origin of the coordinate system, and draw the total horizontal gradient curve of gravity based on the total horizontal gradient value corresponding to the intermediate gravity measuring point and the distance between the intermediate gravity measuring point and the chosen gravity measuring point to form a total horizontal gradient profile of gravity.

[0009] Draw the semi-extreme segment of the total horizontal gradient curve of gravity;

[0010] The direction of the vector from the maximum point of the total gravity gradient curve to the midpoint of the semi-extreme line segment is taken as the fault dip.

[0011] In one embodiment, based on the pre-acquired Bouguer gravity anomaly values ​​of each gravity measuring point, the total horizontal gradient value corresponding to the intermediate gravity measuring point is calculated, including:

[0012] The distance between two adjacent gravity measuring points of the intermediate gravity measuring point is obtained in advance;

[0013] The absolute value of the difference between the Bouguer gravity anomaly values ​​of two adjacent gravity measuring points of the intermediate gravity measuring point is divided by the distance between the two adjacent gravity measuring points of the intermediate gravity measuring point, and the result is used as the total horizontal gradient value corresponding to the intermediate gravity measuring point.

[0014] In one embodiment, the step of plotting the total horizontal gradient curve of gravity based on the total horizontal gradient value corresponding to the intermediate gravity measuring point and the distance between the intermediate gravity measuring point and the randomly selected gravity measuring point, to form a total horizontal gradient profile of gravity, includes:

[0015] Plot the coordinate axis using the distance value as the x-axis, the total horizontal gradient value as the y-axis, and the randomly selected gravity measurement point as the origin.

[0016] Based on the total horizontal gradient value of all intermediate gravity measuring points and the distance between the intermediate gravity measuring points and the randomly selected gravity measuring points, find the points corresponding to all intermediate gravity measuring points in the coordinate system formed by the coordinate axes, connect the points corresponding to all intermediate gravity measuring points, and obtain the total horizontal gradient curve of gravity, forming a total horizontal gradient profile of gravity.

[0017] In one embodiment, the selected gravity measuring point is an edge gravity measuring point.

[0018] In one embodiment, drawing the semi-extreme segment of the total gravity horizontal gradient curve includes:

[0019] Divide the ordinate of the maximum point of the total gravity gradient curve by 2 to obtain the semi-extreme ordinate.

[0020] Find the two points corresponding to the semi-extreme ordinate on the curve of the total gravity gradient profile, connect these two points, and take these two points as the endpoints of the semi-extreme line segment. The line segment connecting these two points is the semi-extreme line segment.

[0021] In one embodiment, the gravity measuring points are determined as follows:

[0022] The direction perpendicular to the fault is determined as the direction in which each gravity measuring point is deployed, and the following conditions are met: the distance between all gravity measuring points is less than or equal to the vertical fault displacement, and the distance from the two edge gravity measuring points to the pre-acquired fault location is greater than or equal to the pre-acquired average depth of the fault.

[0023] Secondly, embodiments of the present invention provide an apparatus for determining fault dip based on gravity data, comprising:

[0024] The horizontal total gradient calculation module is used to calculate the horizontal total gradient value corresponding to the intermediate gravity measuring point based on the pre-acquired Bouguer gravity anomaly values ​​of each gravity measuring point; the gravity measuring points include intermediate gravity measuring points and edge gravity measuring points; the intermediate gravity measuring points are the gravity measuring points other than the edge gravity measuring points among the gravity measuring points.

[0025] The profile drawing module is used to select one gravity measuring point from the gravity measuring points, take the selected gravity measuring point as the origin of the coordinate system, and draw the gravity horizontal total gradient curve based on the horizontal total gradient value corresponding to the intermediate gravity measuring point and the distance between the intermediate gravity measuring point and the selected gravity measuring point, thus forming a gravity horizontal total gradient profile.

[0026] The semi-extreme segment drawing module is used to draw the semi-extreme segments of the total horizontal gradient curve of gravity.

[0027] The fault dip determination module is used to determine the direction of the vector from the maximum point of the total gravity gradient curve to the midpoint of the semi-extreme line segment as the fault dip.

[0028] Thirdly, embodiments of the present invention provide a computing device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the program executed by the processor implements a method for determining fault dip based on gravity data.

[0029] Fourthly, embodiments of the present invention provide a computer-readable storage medium storing a computer program that, when executed by a processor, implements a method for determining fault dip from gravity data.

[0030] 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 a method for determining fault dip based on gravity data.

[0031] The beneficial effects of the above-described technical solutions provided in the embodiments of the present invention include at least the following:

[0032] This invention provides a method for determining fault dip using gravity data. The method calculates the total horizontal gravity gradient based on the Bouguer gravity anomaly values ​​at various gravity measurement points above the fault and plots a total horizontal gravity gradient profile. A semi-extreme line segment is then drawn on the profile, and the direction of the vector from the maximum point to the midpoint of the semi-extreme line segment is taken as the fault dip. This method for determining fault dip using gravity data is a simple, fast, and intuitive research approach. It enables the rapid acquisition of fault dip information using an economical and efficient gravity exploration method, providing a reliable basis for studying fault-related geological structures.

[0033] Other features and advantages of the invention will be set forth in the following description, 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.

[0034] 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

[0035] 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:

[0036] Figure 1 A method for determining fault dip based on gravity data provided in embodiments of the present invention;

[0037] Figure 2 The following diagrams are provided for embodiments of the present invention: (a) a 30° dip fault model, (b) a gravity level anomaly curve of the 30° dip fault model, and (c) a gravity level total gradient profile of the 30° dip fault model.

[0038] Figure 3The following diagrams are provided for embodiments of the present invention: (a) a 60° dip fault model, (b) a gravity level anomaly curve of the 60° dip fault model, and (c) a gravity level total gradient profile of the 60° dip fault model.

[0039] Figure 4 The following diagrams are provided for embodiments of the present invention: (a) a 90° dip fault model, (b) a gravity level anomaly curve of the 90° dip fault model, and (c) a gravity level total gradient profile of the 90° dip fault model.

[0040] Figure 5 The following diagrams are provided for embodiments of the present invention: (a) a 120° dip fault model, (b) a gravity level anomaly curve of the 120° dip fault model, and (c) a gravity level total gradient profile of the 120° dip fault model.

[0041] Figure 6 The following diagrams are provided for embodiments of the present invention: (a) a 150° dip fault model, (b) a gravity level anomaly curve of the 150° dip fault model, and (c) a gravity level total gradient profile of the 150° dip fault model.

[0042] Figure 7 The measured Bouguer gravity anomaly map (a) and total horizontal gravity gradient profile (b) of a target fault provided in an embodiment of the present invention;

[0043] Figure 8 A structural block diagram of the device for determining fault dip based on gravity data provided in an embodiment of the present invention. Detailed Implementation

[0044] 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.

[0045] This invention provides a method for determining fault dip based on gravity data, the flowchart of which is shown below. Figure 1 As shown, it includes:

[0046] S11. Based on the pre-acquired Bouguer gravity anomaly values ​​of each gravity measuring point, calculate the total horizontal gradient value corresponding to the intermediate gravity measuring point; each gravity measuring point includes intermediate gravity measuring points and edge gravity measuring points; the intermediate gravity measuring point is the gravity measuring point other than the edge gravity measuring points among all gravity measuring points.

[0047] S12. Select one gravity measuring point from all gravity measuring points; take the selected gravity measuring point as the origin of the coordinate system, and draw the gravity horizontal total gradient curve based on the horizontal total gradient value corresponding to the intermediate gravity measuring point and the distance between the intermediate gravity measuring point and the selected gravity measuring point to form a gravity horizontal total gradient profile.

[0048] S13. Draw the semi-extreme segment of the total horizontal gradient curve of gravity;

[0049] S14. The direction of the vector from the maximum point of the total gravity gradient curve to the midpoint of the semi-extreme segment is taken as the fault dip.

[0050] The method for determining fault dip using gravity data provided in this invention is a simple, fast, and intuitive research method. It can quickly obtain fault dip information using an economical and efficient gravity exploration method, providing a reliable basis for studying geological structures related to faults.

[0051] Before the aforementioned step S11, existing exploration data can be collected, the distribution characteristics of faults can be determined, and the main strike of the faults whose dip needs to be determined can be identified.

[0052] In the aforementioned step S11, at least three gravity measuring points form a gravity measuring line. The gravity measuring line can be deployed in the following manner, for example: the direction perpendicular to the fault is determined as the direction of the gravity measuring line, that is, the direction in which at least three gravity measuring points are deployed. The gravity measuring line extends from the fault location to both sides and satisfies the following conditions: the distance between all gravity measuring points of the gravity measuring line is less than or equal to the vertical fault displacement, and the sum of the distances between all gravity measuring points is greater than or equal to the average depth of the fault obtained in advance.

[0053] In the gravity measurement line deployment method provided in this embodiment of the invention, in the scenario of fault dip, the point spacing between gravity measurement points is designed with reference to the vertical displacement of the fault. The point spacing between gravity measurement points is less than or equal to the vertical displacement of the fault, which can ensure that the point spacing of gravity measurement points is small, and the gravity anomaly collected is more accurate, thereby reflecting the gravity information of fault dip more precisely.

[0054] In step S11, the Bouguer gravity anomaly is calculated by collecting gravity data through gravity survey lines deployed in the aforementioned manner, and then calculating the Bouguer gravity anomaly based on the collected gravity data.

[0055] Gravity data can be collected in the following ways: Organize a gravity exploration team to conduct gravity data collection along a gravity survey line; use the gravity values ​​measured by the gravimeter at each gravity measuring point as the observed gravity values ​​for that point; use the coordinates and elevations of each gravity measuring point measured by a positioning device as the elevation data for the gravity measuring point coordinates. A gravimeter is an instrument for measuring gravitational acceleration.

[0056] The Bouguer gravity anomaly is the gravity difference obtained by subtracting the normal gravity value from the gravimeter observations after latitude, altitude, mesosphere, and topographic corrections. It is generally obtained using relative gravity measurement methods, and its calculation formula can be, for example:

[0057] δ g =g 测 -g 高 -g 中 -g 纬 -g 形 -γ

[0058] Where: δ g This represents the Bouguer gravity anomaly; g 测 This is the measured gravity value; g 高 For height corrections; g 中 For intermediate layer corrections; g 纬 For latitude correction; g 形 γ represents the terrain correction term; γ represents the normal gravity value.

[0059] In step S11 above, the total horizontal gradient value corresponding to the intermediate gravity measuring point is calculated, which includes, for example, the following steps:

[0060] The distance between two adjacent gravity measuring points at the intermediate gravity measuring point is obtained in advance;

[0061] The absolute value of the difference between the Bouguer gravity anomaly values ​​of two adjacent gravity measuring points at the intermediate gravity measuring point is divided by the distance between the two adjacent gravity measuring points at the intermediate gravity measuring point. The result is taken as the total horizontal gradient value corresponding to the intermediate gravity measuring point.

[0062] Preferably, the gravity measuring point selected in step S12 is an edge gravity measuring point.

[0063] The aforementioned step S12 can be implemented, for example, in the following manner:

[0064] Plot the coordinate axis using the distance value as the x-axis, the total horizontal gradient value as the y-axis, and the randomly selected gravity measurement point as the origin.

[0065] Based on the total horizontal gradient value of all intermediate gravity measuring points and the distance between the intermediate gravity measuring points and the randomly selected gravity measuring points, find the points corresponding to all intermediate gravity measuring points in the coordinate system formed by the coordinate axes, connect the points corresponding to all intermediate gravity measuring points to obtain the total horizontal gradient curve of gravity, and form a total horizontal gradient profile of gravity.

[0066] For example, step S13 mentioned above can be performed in the following manner:

[0067] Divide the maximum value of the total horizontal gradient curve of gravity by 2 to obtain the semi-extreme ordinate.

[0068] Find two points on the total gravity gradient curve that correspond to the semi-extreme ordinate. Connect these two points and use them as the endpoints of the semi-extreme line segment. The line segment connecting these two points is the semi-extreme line segment.

[0069] The following two embodiments further describe the technical steps and effects of a method for determining fault dip based on gravity data provided by the present invention: Embodiment 1 determines the fault dip based on gravity forward modeling data of a fault model, which is used to describe the correctness of the present invention embodiment; Embodiment 2 determines the fault dip based on measured gravity data, which is used to describe the technical feasibility of the present invention embodiment.

[0070] Gravity forward modeling is an important method in gravity exploration. It refers to the process of predicting the gravity anomalies that these geological bodies will produce on the ground or other observation points based on known information such as the shape, size, density distribution, and spatial location of underground geological bodies, using physical laws and mathematical calculations. Simply put, it is to start from the underground geological body model and calculate the theoretical gravity response in a forward manner.

[0071] Example 1:

[0072] The fault model in Example 1 includes two sets of horizontal strata, with the lower strata having a density 0.1 g / cm³ greater than the upper strata. 3 Before the fault occurred, the interface depth between the two strata was -500m. The fault occurred at coordinate 0. After the fault occurred, the strata on the left side of the fault subsided, with a vertical displacement of 2000m, and the interface depth between the two strata decreased to -2500m, while the interface depth on the right side of the fault remained unchanged. To demonstrate the general applicability of this method, five representative fault models with dip angles of 30°, 60°, 90°, 120°, and 150° were calculated. The fault models are shown below. Figure 2 a~ Figure 6 a, where fault models with dip angles of 30° and 60° represent normal faults, fault models with dip angles of 90° represent vertical faults, and fault models with dip angles of 120° and 150° represent reverse faults. The above fault dip angles represent the main cases of fault dip angles.

[0073] In the field of geology, "set" is a conventional term used to describe a group of stratigraphic units with independent characteristics.

[0074] A normal fault is a fault in which the upper strata relatively subside and the lower strata relatively rise. It plays an important role in geological research. Its fault plane is usually steep, with an angle generally between 45° and 90°, most often around 60° to 70°. A vertical fault is a fault with a nearly vertical fault plane (usually between 80° and 90°). The upper and lower strata of this type undergo relative displacement in the vertical direction. It is a special case of fault type, differing from normal and reverse faults in its dip angle. A reverse fault is a fault in which the upper strata relatively rise and the lower strata relatively subside. The angle of the fault plane is generally between 45° and 90°, and its movement direction is opposite to that of a normal fault.

[0075] Step 1: Design the gravity measurement line, including: determining the direction of the gravity measurement line, the distance between gravity measurement points, and the length of the gravity measurement line.

[0076] In actual exploration work, before designing gravity survey lines, it is necessary to collect and analyze existing gravity exploration data in the study area, determine the distribution characteristics of faults in the study area, identify the target faults for which fault dip research is to be carried out, and determine their main strike.

[0077] In this example of the target fault model, the direction of the gravity survey line is chosen to be perpendicular to the target fault. The direction of the gravity forward modeling calculation points of the target fault model is equivalent to the direction of the gravity survey line. The distance between gravity survey points is less than or equal to the vertical fault displacement of the target fault. The smaller the distance between survey points, the more accurate the location of the maximum value of the horizontal gravity gradient. In the study of the target fault model in this example, the distance between gravity survey points is 100m. The gravity survey line should extend from the fault location to both sides, with an extension length not less than the estimated average depth of the target fault. The estimated average depth of the target fault is 1500m, that is, the length of the gravity survey line is greater than 3000m to ensure sufficient gravity data in subsequent studies. In this example, to show the complete shape of the gravity curve, the gravity survey line in this example extends 10000m from the fault location to both sides.

[0078] In gravity exploration, gravity forward modeling points refer to the calculation locations selected to simulate gravity anomalies generated by underground geological bodies. Simply put, they are points set on the ground or within a certain spatial range to calculate gravity values. These points form a calculation network, and by performing theoretical calculations at these points, the gravity distribution corresponding to different geological body models can be predicted.

[0079] Step 2: Collect gravity data, including the following steps:

[0080] A gravity exploration team was organized to conduct gravity data collection operations. Gravity meters were used to measure the gravity values ​​at each gravity measurement point, and positioning devices were used to determine the coordinates and elevations of each point. For gravity studies of the target fault model, the gravity values ​​at each gravity forward modeling point can be obtained through gravity forward modeling. The distance between the coordinates of these points is the distance value set during the forward modeling of the target fault model. The coordinates and elevation of a gravity measurement point refer to the planar position coordinates (such as latitude and longitude or a Cartesian coordinate system) of each gravity measurement point in a specific coordinate system, as well as its altitude. This accurately determines the spatial location of the gravity measurement point.

[0081] Step 3: Calculate the Bouguer gravity anomaly.

[0082] Based on the coordinates and elevations of the gravity measuring points, Bouguer and normal field corrections are applied to the observed gravity values ​​at each point. These corrections are then applied using the coordinates, elevations, and topographic data of the gravity measuring points, resulting in Bouguer gravity anomaly data for each point. For model-based gravity studies, the elevation of the gravity measuring points is set to 0; therefore, the Bouguer, normal field, and topographic correction values ​​for each point are all 0. Thus, the gravity anomaly data calculated by the model is equivalent to the Bouguer gravity anomaly. (See...) Figure 2 b- Figure 6 b.

[0083] The Bouguer gravity anomaly value obtained by gravity forward modeling of the target fault model is equivalent to the Bouguer gravity anomaly obtained by implementing step three of this procedure. The purpose of both is to obtain the basic gravity data for studying the fault dip, and it does not affect the correctness of the method of determining the fault dip using gravity data. In fact, it can verify the correctness of the method of determining the fault dip using gravity data.

[0084] Step 4: Calculate the total horizontal gradient value of gravity.

[0085] In the example, through the Figure 2 b- Figure 6 The horizontal gradient value of the gravity anomaly in the target fault model in b is calculated, and the absolute value is obtained to obtain the total horizontal gradient value of gravity.

[0086] Step 5: Plot the total horizontal gradient curve of gravity to form a profile of the total horizontal gradient of gravity.

[0087] Based on the distance or coordinate value of each gravity measuring point from the origin, and the total horizontal gradient value of each gravity measuring point, these points are marked on the profile diagram. Connecting these points forms the total horizontal gradient curve of gravity, thus obtaining the profile diagram of the total horizontal gradient of gravity, as shown below. Figure 2 c- Figure 6 As shown in c.

[0088] Step Six: Plot the half-extreme segment of the total horizontal gradient curve of gravity.

[0089] Read the maximum value of the total horizontal gradient curve from the total horizontal gradient profile. Figure 2 c- Figure 6 The maxima of the total horizontal gradient curve in c are 1.52, 2.03, 2.15, 2.03, and 1.52, respectively, in units of 10^10. -8 s -2 ;therefore, Figure 2 c- Figure 6 The ordinates of the c-segment extreme values ​​are 0.76, 1.02, 1.08, 1.02, and 0.76, respectively, in units of 10. -8 s -2 .

[0090] Step 7: Plot the midpoint of the semi-extreme segment of the total horizontal gradient curve of gravity.

[0091] Read the x-coordinates of the intersection points of the semi-extreme line segment and the total horizontal gradient curve of gravity, and take the average of the x-coordinates of the intersection points to obtain the x-coordinate of the midpoint of the semi-extreme line segment. Figure 2 c- Figure 6 The x-coordinates of the intersection points of the semi-extreme segment of c with the total horizontal gradient curve of gravity are -3300 and 500, -1650 and 790, -1180 and 1180, -790 and 1650, and -500 and 3300, respectively. Therefore, Figure 2 c- Figure 6 The x-coordinates of the midpoints of the semi-extreme segment c are -1400, -430, 0, 430, and 1400, respectively. Based on the obtained x-coordinates of the midpoints of the semi-extreme segment, mark the midpoints of the semi-extreme segment on the total horizontal gradient of gravity, as shown below. Figure 2 c- Figure 6 As shown in c. Figure 2 c- Figure 6 The position of the "+" sign on the semi-extreme line segment in line c is the midpoint of the semi-extreme line segment.

[0092] Step 8: Draw the vector from the maximum point of the total gravity gradient curve to the midpoint of the semi-extreme segment.

[0093] Locate the maximum value on the total gravity gradient curve and mark the maximum value with a "+", such as... Figure 2 c- Figure 6 As shown in c; draw an arrow pointing from the "+" sign at the maximum value position to the "+" sign at the midpoint of the semi-extreme segment, as shown in c. Figure 2 c~ Figure 6 As shown in diagram c, the direction of the vector indicates the fault's dip. This allows for the determination of the fault dip using gravity data. The arrows in the diagram point to... Figure 2 a~ Figure 6The consistency between the target fault model and the fault dip angle reflects the high reliability of this method; the consistency between the vector dip angle and the target fault model dip angle reflects that the method for determining fault dip angle using gravity data provided in this embodiment can qualitatively reflect the relative magnitude of the fault dip angle; the five representative fault dip angles provided in this embodiment, including normal faults, vertical faults, and reverse faults, reflect that the method for determining fault dip angle using gravity data provided in this embodiment is applicable to fault dip studies with various dip angles.

[0094] Example 2:

[0095] To determine fault dip using actual gravity exploration data, the study area in Example 2 is located in a basin in my country. To investigate the development of faults along the southern margin of this basin, gravity exploration was conducted. Using this actual gravity data, the method for determining fault dip based on gravity data provided in this embodiment of the invention was employed, yielding results consistent with other gravity data. The specific implementation steps are as follows:

[0096] Step 1: Design the gravity survey line

[0097] Prior to the project, regional gravity data was collected, revealing that the southern boundary fault of the basin generally trends east-west. To conduct structural research, a detailed study of the southern boundary fault was necessary, including determining its dip. Therefore, area gravity measurements were deployed, with gravity survey lines laid out in a north-south direction, spaced 250m apart at points and 1000m apart at lines. The survey area for this gravity exploration was quite large, extending over 4000m from the fault to both sides.

[0098] Step 2: Collect gravity data. Since this has been described in detail in Example 1, it will not be repeated here.

[0099] Step 3: Calculate the Bouguer gravity anomaly

[0100] Figure 7 Figure a shows the Bouguer gravity anomaly curve of a gravity survey line in the central part of the study area, with the direction being west at the top, east at the bottom, south on the left, and north on the right. From Figure 7 As can be seen from the profile, within the range, the gravity anomaly value continuously decreases from left to right (geographically from south to north), with a significant rapid decrease in gravity anomaly between 2000m and 3000m. Based on gravity exploration knowledge, the main fault location is within this range. However, from the Bouguer gravity anomaly (… Figure 7 a) The tendency of the fault cannot be directly identified.

[0101] Step 4: Calculate the total horizontal gradient value of gravity. Since this step is described in detail in Example 1, it will not be repeated in Example 2.

[0102] Step 5: Plot the total horizontal gradient curve of gravity to form a profile of the total horizontal gradient of gravity. For example, the profile of the total horizontal gradient of gravity in Example 2 can be shown as follows: Figure 7 As shown in b.

[0103] Step Six: Plot the half-extreme segment of the total horizontal gradient curve of gravity.

[0104] Gravity level total gradient profile ( Figure 7 b) On the upper part, a clear maximum of the total horizontal gradient of gravity was found at 2250m, with a maximum value of approximately 24.0 × 10⁻⁶. -8 s -2 Then draw the semi-extreme line segment, the total horizontal gradient of gravity for which is 12.0 × 10⁻⁶. -8 s -2 The semi-extreme segment intersects the total gradient curve of gravity on both the left and right sides of the maximum value, meaning there are two intersection points, for example... Figure 7 As shown in b.

[0105] Step 7: Plot the midpoint of the semi-extreme segment of the total horizontal gradient curve of gravity.

[0106] Read the x-coordinates of the left and right intersection points of the semi-extreme line segment and the total horizontal gradient curve of gravity, take the average of the x-coordinates of the left and right intersection points, and obtain the x-coordinate of the midpoint of the semi-extreme line segment. Figure 7 In section b, the x-coordinates of the intersection points of the semi-extreme line segment and the total horizontal gradient curve are 800m and 3500m, respectively. Therefore, the x-coordinate of the midpoint of the semi-extreme line segment is 2150m. Using the obtained x-coordinate of the midpoint of the semi-extreme line segment, mark the position of the midpoint on the semi-extreme line segment of the total horizontal gradient curve, as shown in section b. Figure 7 The "+" on the semi-extreme line segment in b.

[0107] Step 8: Draw the vector from the maximum point of the total gravity gradient curve to the midpoint of the semi-extreme segment.

[0108] Locate the maximum value on the total gravity gradient curve. The x-coordinate of the maximum value is approximately 2250m. Mark the maximum value with a "+". Figure 7 b; Draw an arrow pointing from the "+" position of the maximum value to the "+" position of the midpoint of the semi-maximum segment. The direction of the vector indicates the fault's tendency.

[0109] Based on the same inventive concept, embodiments of the present invention provide a device for determining fault dip using gravity data, the structural block diagram of which is shown below. Figure 8 As shown, it includes:

[0110] The horizontal total gradient calculation module 81 is used to calculate the horizontal total gradient value corresponding to the intermediate gravity measuring point based on the pre-acquired Bouguer gravity anomaly values ​​of each gravity measuring point; the gravity measuring points include intermediate gravity measuring points and edge gravity measuring points; the intermediate gravity measuring points are the gravity measuring points other than the edge gravity measuring points among the gravity measuring points.

[0111] The profile drawing module 82 is used to select one gravity measuring point from the gravity measuring points, take the selected gravity measuring point as the origin of the coordinate system, and draw the gravity horizontal total gradient curve based on the horizontal total gradient value corresponding to the intermediate gravity measuring point and the distance between the intermediate gravity measuring point and the selected gravity measuring point, so as to form a gravity horizontal total gradient profile.

[0112] The semi-extreme segment drawing module 83 is used to draw the semi-extreme segments of the total horizontal gradient curve of gravity.

[0113] The fault dip determination module 84 is used to take the direction of the vector from the maximum point of the total gravity gradient curve to the midpoint of the semi-extreme line segment as the fault dip.

[0114] Based on the same inventive concept, embodiments of the present invention also provide a computing device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the program executed by the processor implements a method for determining fault dip from gravity data.

[0115] Based on the same inventive concept, embodiments of the present invention also provide a computer-readable storage medium storing a computer program, which, when executed by a processor, implements a method for determining fault dip from gravity data.

[0116] Based on the same inventive concept, embodiments of the present invention also provide a computer program product, which includes a computer program that, when executed by a processor, implements a method for determining fault dip from gravity data.

[0117] Since the principle by which these devices solve the problem is similar to the aforementioned method for determining fault dip using gravity data, the implementation of these devices can be found in the implementation of the aforementioned method, and the repetitions will not be repeated.

[0118] 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.

[0119] 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.

[0120] 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.

[0121] 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 functions specified in one or more boxes. Obviously, those skilled in the art can make various modifications and variations to this invention without departing from the spirit and scope of the invention. Therefore, if these modifications and variations of the invention fall within the scope of the claims of the invention and their equivalents, the invention is also intended to include these modifications and variations.

Claims

1. A method for determining fault dip based on gravity data, characterized in that, include: Based on the pre-acquired Bouguer gravity anomaly values ​​of each gravity measuring point, calculate the total horizontal gradient value corresponding to the intermediate gravity measuring point; Each gravity measuring point includes an intermediate gravity measuring point and an edge gravity measuring point; The intermediate gravity measuring point is the gravity measuring point other than the edge gravity measuring point among all the gravity measuring points; Choose any one of the gravity measuring points from the aforementioned gravity measuring points; Using the randomly selected gravity measuring point as the origin of the coordinate system, and based on the total horizontal gradient value corresponding to the intermediate gravity measuring point and the distance between the intermediate gravity measuring point and the randomly selected gravity measuring point, a total horizontal gradient curve of gravity is plotted to form a total horizontal gradient profile of gravity. Draw the semi-extreme segment of the total horizontal gradient curve of gravity; The direction of the vector from the maximum point of the total gravity gradient curve to the midpoint of the semi-extreme line segment is taken as the fault dip.

2. The method as described in claim 1, characterized in that, Based on the pre-acquired Bouguer gravity anomaly values ​​at each gravity measuring point, calculate the total horizontal gradient value corresponding to the intermediate gravity measuring point, including: The distance between two adjacent gravity measuring points of the intermediate gravity measuring point is obtained in advance; The absolute value of the difference between the Bouguer gravity anomaly values ​​of two adjacent gravity measuring points of the intermediate gravity measuring point is divided by the distance between the two adjacent gravity measuring points of the intermediate gravity measuring point, and the result is used as the total horizontal gradient value corresponding to the intermediate gravity measuring point.

3. The method as described in claim 1, characterized in that, The step of plotting the total horizontal gradient curve of gravity based on the total horizontal gradient value corresponding to the intermediate gravity measuring point and the distance between the intermediate gravity measuring point and the randomly selected gravity measuring point, to form a total horizontal gradient profile of gravity, includes: Plot the coordinate axis using the distance value as the x-axis, the total horizontal gradient value as the y-axis, and the randomly selected gravity measurement point as the origin. Based on the total horizontal gradient value of all intermediate gravity measuring points and the distance between the intermediate gravity measuring points and the randomly selected gravity measuring points, find the points corresponding to all intermediate gravity measuring points in the coordinate system formed by the coordinate axes, connect the points corresponding to all intermediate gravity measuring points, and obtain the total horizontal gradient curve of gravity, forming a total horizontal gradient profile of gravity.

4. The method as described in claim 1 or 3, characterized in that, The selected gravity measurement points are edge gravity measurement points.

5. The method as described in claim 1, characterized in that, The process of plotting the semi-extreme segment of the total horizontal gradient curve of gravity includes: Divide the maximum value of the total gravity gradient curve by 2 to obtain the semi-extreme ordinate. Find two points on the total gravity gradient curve that correspond to the semi-extreme ordinate, connect these two points, and use these two points as the endpoints of the semi-extreme line segment. The line segment connecting these two points is the semi-extreme line segment.

6. The method as described in claim 1, characterized in that, The gravity measuring points are determined in the following manner: The direction perpendicular to the fault is determined as the direction in which each gravity measuring point is deployed, and the following conditions are met: the distance between all gravity measuring points is less than or equal to the vertical fault displacement, and the distance from the two edge gravity measuring points to the pre-acquired fault location is greater than or equal to the pre-acquired average depth of the fault.

7. An apparatus for determining fault dip based on gravity data, characterized in that, include: The horizontal total gradient calculation module is used to calculate the horizontal total gradient value corresponding to the intermediate gravity measuring point based on the pre-acquired Bouguer gravity anomaly values ​​of each gravity measuring point. Each gravity measuring point includes an intermediate gravity measuring point and an edge gravity measuring point; The intermediate gravity measuring point is the gravity measuring point other than the edge gravity measuring point among all the gravity measuring points; The profile drawing module is used to select one gravity measuring point from the gravity measuring points, take the selected gravity measuring point as the origin of the coordinate system, and draw the gravity horizontal total gradient curve based on the horizontal total gradient value corresponding to the intermediate gravity measuring point and the distance between the intermediate gravity measuring point and the selected gravity measuring point, thus forming a gravity horizontal total gradient profile. The semi-extreme segment drawing module is used to draw the semi-extreme segments of the total horizontal gradient curve of gravity. The fault dip determination module is used to determine the direction of the vector from the maximum point of the total gravity gradient curve to the midpoint of the semi-extreme line segment as the fault dip.

8. A computing device, characterized in that, include: The memory, the processor, and the computer program stored in the memory and executable on the processor, wherein the program executed by the processor implements the method for determining fault dip from gravity data 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 determining fault dip based on gravity data 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 a method for determining fault dip based on gravity data as described in any one of claims 1-6.

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