A qualitative method for predicting fissure and water conducting channel of coal seam roof based on five-dimensional seismic interpretation subsystem

Abstract

The application discloses a fissure prediction and coal seam roof water-conducting channel qualitative method based on a five-dimensional seismic interpretation subsystem, and comprises the following steps: after five-dimensional gather data is loaded through a GeoEast five-dimensional seismic interpretation subsystem, quality control inspection is conducted on the five-dimensional gather data; the difference of the amplitude and the time difference of a coal seam target horizon in different directions is utilized to conduct coal seam fissure prediction, and the coal seam fissure prediction is conducted by using the azimuth instantaneous attribute of the coal seam target horizon; the horizon of sandstone of the coal seam roof and the coal seam floor is determined, the fissure development condition of the sandstone horizon of the coal seam roof and the coal seam floor is further obtained, and comprehensive analysis is conducted to qualitatively explain the possible water-conducting channel. The application is used to solve the technical problems that the prior art cannot realize the accurate prediction of the fissure in the coal seam and the accurate determination of the water-conducting channel of the coal seam roof, so that the accurate prediction of the fissure in the coal seam and the accurate determination of the water-conducting channel of the coal seam roof are achieved.

Description

Technical Field

[0001] This invention relates to the field of fracture prediction and water-conducting channel characterization, specifically to a method for fracture prediction and coal seam roof water-conducting channel characterization based on a five-dimensional seismic interpretation subsystem. Background Technology

[0002] The stability of the coal seam roof plays a crucial role in the safe production of coal mines. Well-developed mudstone fissures in the roof may form water-conducting channels, connecting water-bearing sandstone and coal seams, thus affecting the safe production of coal mines.

[0003] Wide-azimuth seismic exploration technology refers to an integrated technology for the acquisition, processing, and interpretation of three-dimensional seismic data with an aspect ratio greater than 0.5. First, high-quality seismic data volumes are acquired through a wide-azimuth observation system. Then, OVT (Optical Vibration Transmission) fine processing technology is used to provide high-quality "five-dimensional" common reflection point gathers, containing five-dimensional information including three-dimensional coordinates, shot-receiver distance, and azimuth. The shot-receiver distance information is correlated with the scale, lithology, and fluid composition of the target geological body, while the azimuth information is correlated with the development characteristics of faults and fractures in the strata.

[0004] Wide-azimuth seismic exploration technology provides relatively ideal basic data for the interpretation of small faults in coal seams. However, existing technologies based on this basic data still cannot achieve accurate prediction of fractures in coal seams or accurate characterization of water-conducting channels in the roof of coal seams. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this invention provides a method for predicting fractures and characterizing water-conducting channels in coal seams based on a five-dimensional seismic interpretation subsystem. This method addresses the technical problem that existing technologies cannot accurately predict fractures in coal seams and accurately characterize water-conducting channels in coal seams, thereby achieving the goal of accurately predicting fractures in coal seams and accurately characterizing water-conducting channels in coal seams.

[0006] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0007] A method for fracture prediction and qualitative analysis of water-conducting channels in coal seam roof based on a five-dimensional seismic interpretation subsystem includes the following steps:

[0008] After loading the five-dimensional gather data through the GeoEast five-dimensional seismic interpretation subsystem, the five-dimensional gather data is subjected to quality control checks.

[0009] Coal seam fracture prediction is performed by utilizing the differences in amplitude and time difference of the target stratum in different orientations, and by utilizing the instantaneous orientation attributes of the target stratum in coal seam.

[0010] The stratigraphic positions of the sandstone in the top and bottom of the coal seam are determined, and the fracture development of the sandstone in the top and bottom of the coal seam is further obtained. A comprehensive analysis is then conducted to qualitatively interpret the possible water-conducting channels.

[0011] In a preferred embodiment of the present invention, the quality control check of the five-dimensional gather data includes:

[0012] The azimuth and offset of the five-dimensional gather data are checked.

[0013] Perform a gather data check on the five-dimensional gather data;

[0014] The template view and the fracture prediction fitted ellipse are displayed on the five-dimensional gather data.

[0015] In a preferred embodiment of the present invention, the azimuth and offset checks performed on the five-dimensional gather data include:

[0016] The five-dimensional gather data is loaded into the main interface of the GeoEast five-dimensional seismic interpretation subsystem for display, and the target coal seam horizon and fault structure to be interpreted are loaded at the same time.

[0017] Based on the range of azimuth and offset distance displayed in the template view of the main interface, check whether the range of azimuth and offset distance is accurate.

[0018] In a preferred embodiment of the present invention, the process of performing a gather data check on the five-dimensional gather data includes:

[0019] The GeoEast five-dimensional seismic interpretation subsystem is used to display the gather profile of the five-dimensional gather data.

[0020] Examine the target coal seam horizons and the amplitude variation curves contained in the gathered profile.

[0021] In a preferred embodiment of the present invention, the display of the template view and the fracture prediction fitting ellipse on the five-dimensional gather data includes:

[0022] The GeoEast five-dimensional seismic interpretation subsystem displays the amplitude information, spectrum, and fracture prediction fitted ellipse of a single point within the work area.

[0023] Adjust the range of the offset distance in the template view and check whether the crack prediction fitting ellipse can meet the prediction conditions.

[0024] The prediction conditions include: the flatness of the crack prediction fitting ellipse is within a threshold, the distance between the fitting point and the crack prediction fitting ellipse is within a threshold, the number of superpositions of changing the azimuth angle in the selected area, and the change in the direction of the crack prediction fitting ellipse is within a threshold.

[0025] As a preferred embodiment of the present invention, when predicting coal seam fractures by utilizing the differences in the amplitude and time difference of the target stratum in different orientations, the method includes:

[0026] Feasibility analysis, determination of template view, fitting of crack prediction elliptical template, and results analysis.

[0027] In a preferred embodiment of the present invention, determining the template view includes:

[0028] The template view is determined based on the main direction of tectonic development in the study area;

[0029] The fitted crack prediction ellipse template includes:

[0030] When the target layer energy and the data signal-to-noise ratio of the coal seam are both greater than the threshold, the maximum amplitude of the fracture calculation module in the GeoEast five-dimensional seismic interpretation subsystem is used to fit the fracture prediction elliptical template.

[0031] When the target layer energy and the data signal-to-noise ratio of the coal seam are both less than the threshold, the root mean square amplitude of the fracture calculation module in the GeoEast five-dimensional seismic interpretation subsystem is used to fit the fracture prediction ellipse template.

[0032] When there is a reflective layer with an intensity greater than the threshold above the target coal seam, the fracture prediction ellipse template is obtained by fitting the travel time of the fracture calculation module in the GeoEast five-dimensional seismic interpretation subsystem.

[0033] The analysis of the results includes:

[0034] The fitted crack prediction ellipse template generates the corresponding crack result map, and at the same time generates three attributes: intensity, confidence and azimuth.

[0035] The results are analyzed based on the fracture map and the three attributes, and the fracture map and the coal seam ant attribute slices are overlaid and displayed.

[0036] The crack result diagram includes: a result diagram showing the development of cracks, a result diagram showing the crack situation with short lines, and a result diagram reflecting the intensity and degree of crack development.

[0037] As a preferred embodiment of the present invention, when using the instantaneous attributes of the target stratum orientation of a coal seam to predict coal seam fractures, the method includes:

[0038] Feasibility analysis, determination of template view, fitting of crack prediction elliptical template, and results analysis.

[0039] In a preferred embodiment of the present invention, determining the template view includes:

[0040] The template view is determined based on the main direction of tectonic development in the study area;

[0041] The fitted crack prediction ellipse template includes:

[0042] When the target layer energy and data signal-to-noise ratio of the coal seam are both greater than the threshold, the maximum amplitude of the fracture prediction ellipse template is fitted by the instantaneous attribute calculation module of the GeoEast five-dimensional seismic interpretation subsystem.

[0043] When the target layer energy and data signal-to-noise ratio of the coal seam are both less than the threshold, the root mean square amplitude of the instantaneous attribute calculation module of the GeoEast five-dimensional seismic interpretation subsystem is used to fit the crack prediction ellipse template.

[0044] When there is a reflective layer with an intensity greater than the threshold above the target coal seam, the travel time fitting of the fracture prediction ellipse template is obtained through the instantaneous attribute calculation module of the GeoEast five-dimensional seismic interpretation subsystem.

[0045] The analysis of the results includes:

[0046] Based on the fitted crack prediction ellipse template, an azimuth instantaneous amplitude crack result map or an azimuth instantaneous frequency result map is obtained, and the result analysis is performed based on the azimuth instantaneous amplitude crack result map or the azimuth instantaneous frequency result map.

[0047] In a preferred embodiment of the present invention, the determination and qualitative interpretation of the fracture development and strata of the sandstone in the coal seam roof and floor include:

[0048] By using borehole logging curves to create synthetic seismic records, the stratigraphic positions of the sandstone in the coal seam roof and floor are calibrated. Then, fine stratigraphic tracing is performed to determine the stratigraphic positions of the sandstone in the coal seam roof and floor, and further, the fracture development of the stratigraphic positions of the sandstone in the coal seam roof and floor is obtained.

[0049] Based on a comprehensive analysis of the fracture development of the sandstone strata in the top and bottom of the coal seam and the fracture development of the target strata of the coal seam, a qualitative interpretation of the possible water-conducting channels is made.

[0050] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0051] (1) The method provided by this invention makes full use of the azimuth information in the OVT gather to predict the development of coal seam roof fractures, and makes full use of the OVT domain seismic data to predict fractures to improve the prediction accuracy and reliability of the prediction results of coal seam roof fractures. This has important practical significance for ensuring safe production in coal mines. At the same time, it expands the application scope of wide azimuth seismic exploration technology by improving the five-dimensional seismic interpretation technology.

[0052] (2) The method provided by the present invention fully mines the information of five-dimensional seismic data in the five-dimensional interpretation subsystem, and conducts research on fracture prediction and the characterization of water-conducting channels in the roof of coal seams, thereby further improving the accuracy of fracture prediction and the accuracy of characterization of water-conducting channels in the roof of coal seams.

[0053] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0054] Figure 1 - This is a flowchart illustrating the steps of the method for fracture prediction and qualitative analysis of water-conducting channels in the roof of a coal seam based on a five-dimensional seismic interpretation subsystem, according to an embodiment of the present invention.

[0055] Figure 2 - This is a schematic diagram showing the spatial location of the 7253 working face and the 85-87 high-density seismic work area in an embodiment of the present invention;

[0056] Figure 3 - This is a diagram showing the results of the multi-attribute comprehensive analysis of the 7253 working surface in an embodiment of the present invention;

[0057] Figure 4 - This is a schematic diagram of the plane location of fault 7253 as interpreted from seismic data according to an embodiment of the present invention;

[0058] Figure 5 - is an ellipse diagram fitting the orientational properties of the fracture medium in an embodiment of the present invention;

[0059] Figure 6 - This is a technical roadmap for crack prediction and analysis according to an embodiment of the present invention;

[0060] Figure 7 - This is a diagram showing the main interface of loading pre-stack gathers into the five-dimensional seismic interpretation subsystem according to an embodiment of the present invention;

[0061] Figure 8 - This is a schematic diagram illustrating how the azimuth angle and offset distance change with the view template in an embodiment of the present invention;

[0062] Figure 9 - is a display diagram of gather profile data according to an embodiment of the present invention;

[0063] Figure 10 - This is an interface display diagram of the five-dimensional seismic interpretation subsystem in an embodiment of the present invention;

[0064] Figure 11 - is the corresponding diagram of the view template and the fitted ellipse determined in the embodiment of the present invention;

[0065] Figure 12 - is a schematic diagram of the fracture calculation interface according to an embodiment of the present invention;

[0066] Figure 13 - This is a diagram showing the fracture distribution of coal seam 7 calculated based on the maximum amplitude according to an embodiment of the present invention;

[0067] Figure 14 - This is a diagram showing the fracture strength, reliability, and azimuth results of the 7th coal seam in this embodiment of the invention;

[0068] Figure 15 - is an overlay diagram of the crack results and ant attributes in an embodiment of the present invention;

[0069] Figure 16 - is a schematic diagram of the orientation instantaneous attribute calculation interface according to an embodiment of the present invention;

[0070] Figure 17 - This is a diagram showing the fracture development results calculated from the azimuth instantaneous amplitude and frequency of an embodiment of the present invention;

[0071] Figure 18 - This is a comprehensive analysis diagram of the fracture development results at 50m and 30m of the coal seam roof and at the coal seam in an embodiment of the present invention;

[0072] Figure 19 - This is a comprehensive analysis diagram of the intensity of fracture development at 50m and 30m of the coal seam roof and at the coal seam in an embodiment of the present invention;

[0073] Figure 20 - This is a comprehensive analysis diagram of the coal seam floor at 50m and 30m and the fracture development results at the coal seam in an embodiment of the present invention;

[0074] Figure 21 - This is a comprehensive analysis diagram of the coal seam floor at 50m and 30m and the fracture development intensity at the coal seam, according to an embodiment of the present invention. Detailed Implementation

[0075] The method for fracture prediction and qualitative analysis of water-conducting channels in coal seam roof based on a five-dimensional seismic interpretation subsystem provided by this invention, such as... Figure 1 As shown, it includes the following steps:

[0076] Step S1: After loading the five-dimensional gather data through the GeoEast five-dimensional seismic interpretation subsystem, perform quality control checks on the five-dimensional gather data;

[0077] Step S2: Utilize the differences in amplitude and time difference of the target stratum in the coal seam at different orientations to predict coal seam fractures, and utilize the instantaneous attributes of the target stratum orientation to predict coal seam fractures.

[0078] Step S3: Determine the stratigraphic position of the sandstone in the roof and floor of the coal seam, further obtain the fracture development status of the sandstone stratigraphic position in the roof and floor of the coal seam, and conduct a comprehensive analysis to qualitatively interpret the possible water-conducting channels.

[0079] In step S1 above, the quality control check of the five-dimensional gather data includes:

[0080] Perform azimuth and offset checks on the five-dimensional gather data;

[0081] Perform a data check on the five-dimensional data collection data;

[0082] The template view and the fitted ellipse for crack prediction are displayed on the five-dimensional gather data.

[0083] Furthermore, when performing azimuth and offset checks on the five-dimensional gather data, the following steps are included:

[0084] The five-dimensional gather data is loaded into the main interface of the GeoEast five-dimensional seismic interpretation subsystem for display, and the target coal seam horizon and fault structure to be interpreted are loaded at the same time.

[0085] Based on the range of azimuth and offset displayed in the template view of the main interface, check whether the range of azimuth and offset is accurate.

[0086] Furthermore, when performing gather data checks on the five-dimensional gather data, the following are included:

[0087] Displaying gather profiles of five-dimensional gather data using the GeoEast five-dimensional seismic interpretation subsystem;

[0088] Examine the target coal seam horizons and the amplitude variation curves contained in the gather profile.

[0089] Furthermore, when displaying the template view and the fracture prediction fitted ellipse on the five-dimensional gather data, the following is included:

[0090] The GeoEast five-dimensional seismic interpretation subsystem displays the amplitude information, spectrum, and fracture prediction fitted ellipse of a single point within the work area.

[0091] Adjust the range of offset in the template view and check whether the crack prediction fitted ellipse can meet the prediction conditions.

[0092] The prediction conditions include: the flatness of the crack prediction fitting ellipse is within a threshold, the distance between the fitting point and the crack prediction fitting ellipse is within a threshold, and the direction change of the crack prediction fitting ellipse is within a threshold when the number of superpositions of azimuth angles is changed in the selected area.

[0093] In step S2 above, when using the differences in the amplitude and time difference of the target coal seam at different azimuths to predict coal seam fractures, the following steps are included:

[0094] Feasibility analysis, determination of template view, fitting of crack prediction elliptical template, and results analysis.

[0095] Furthermore, the feasibility analysis includes:

[0096] Adjust the range of offset in the template view and check whether the crack prediction fitted ellipse can meet the prediction conditions.

[0097] If so, then coal seam fracture prediction is considered feasible;

[0098] If not, then coal seam fracture prediction is not feasible;

[0099] The prediction conditions include: the flatness of the crack prediction fitting ellipse is within a threshold, the distance between the fitting point and the crack prediction fitting ellipse is within a threshold, and the direction change of the crack prediction fitting ellipse is within a threshold when the number of superpositions of azimuth angles is changed in the selected area.

[0100] Determine the template view, including:

[0101] The template view is determined based on the main direction of tectonic development in the study area.

[0102] Furthermore, fitting the crack prediction ellipse template includes:

[0103] When the target layer energy and data signal-to-noise ratio of the coal seam are both greater than the threshold, the maximum amplitude of the fracture calculation module in the GeoEast five-dimensional seismic interpretation subsystem is used to fit the fracture prediction elliptical template.

[0104] When the target layer energy and data signal-to-noise ratio of the coal seam are both less than the threshold, the root mean square amplitude of the fracture calculation module in the GeoEast five-dimensional seismic interpretation subsystem is used to fit the fracture prediction elliptical template.

[0105] When there is a reflective layer with an intensity greater than the threshold above the target coal seam, the fracture prediction ellipse template is obtained by fitting the travel time of the fracture calculation module in the GeoEast five-dimensional seismic interpretation subsystem.

[0106] Results analysis, including:

[0107] The fitted crack prediction ellipse template generates the corresponding crack result map, and at the same time generates three attributes: intensity, confidence and azimuth.

[0108] The results are analyzed based on the fracture map and three attributes, and the fracture map and coal seam ant attributes are overlaid and displayed along the layer slices.

[0109] The crack results map includes: a results map showing the development of cracks, a results map showing the crack situation with short lines, and a results map reflecting the intensity and degree of crack development.

[0110] In step S2 above, when using the instantaneous attribute of the target stratum orientation of the coal seam to predict coal seam fractures, the following steps are included:

[0111] Feasibility analysis, determination of template view, fitting of crack prediction elliptical template, and results analysis.

[0112] Furthermore, the feasibility analysis includes:

[0113] Adjust the range of offset in the template view and check whether the crack prediction fitted ellipse can meet the prediction conditions.

[0114] If so, then coal seam fracture prediction is considered feasible;

[0115] If not, then coal seam fracture prediction is not feasible;

[0116] The prediction conditions include: the flatness of the crack prediction fitting ellipse is within a threshold, the distance between the fitting point and the crack prediction fitting ellipse is within a threshold, and the direction change of the crack prediction fitting ellipse is within a threshold when the number of superpositions of azimuth angles is changed in the selected area.

[0117] Determine the template view, including:

[0118] The template view is determined based on the main direction of tectonic development in the study area.

[0119] Furthermore, fitting the crack prediction ellipse template includes:

[0120] When the target layer energy and data signal-to-noise ratio of the coal seam are both greater than the threshold, the maximum amplitude of the fracture prediction ellipse template is fitted by the instantaneous attribute calculation module of the GeoEast five-dimensional seismic interpretation subsystem.

[0121] When the target layer energy and data signal-to-noise ratio of the coal seam are both less than the threshold, the root mean square amplitude of the instantaneous attribute calculation module of the GeoEast five-dimensional seismic interpretation subsystem is used to fit the crack prediction ellipse template.

[0122] When there is a reflective layer with an intensity greater than the threshold above the target coal seam, the travel time fitting of the fracture prediction ellipse template is used by the GeoEast five-dimensional seismic interpretation subsystem's instantaneous attribute calculation module.

[0123] Results analysis, including:

[0124] Based on the fitted crack prediction ellipse template, the instantaneous amplitude crack result map or the instantaneous frequency crack result map of azimuth is obtained, and the result analysis is carried out based on the instantaneous amplitude crack result map or the instantaneous frequency crack result map of azimuth.

[0125] In step S3 above, determining the fracture development and qualitative interpretation of the sandstone strata in the coal seam roof and floor includes:

[0126] By using borehole logging curves to create synthetic seismic records, the stratigraphic positions of the sandstone in the coal seam roof and floor are determined. Then, fine stratigraphic tracing is performed to determine the stratigraphic positions of the sandstone in the coal seam roof and floor, and further, the fracture development of the stratigraphic positions of the sandstone in the coal seam roof and floor is obtained.

[0127] Based on a comprehensive analysis of the fracture development of the sandstone strata in the coal seam roof and floor and the fracture development of the target strata in the coal seam, a qualitative interpretation of the possible water-conducting channels is provided.

[0128] The following embodiments are further illustrations of the present invention, but the scope of the present invention is not limited thereto.

[0129] The geological conditions of the study area in this embodiment will be briefly described first, as follows:

[0130] 7253 working face location

[0131] The 7253 working face is located in the south-central part of the 85 mining area, primarily mining the 72 coal seam. It is bordered by the F10 fault to the east, the F9 fault to the west, the WF4-4 fault to the south, and the main roadway safety coal pillar line to the north. The working face has a strike length of 780m, a dip length of 219.5m, an average coal thickness of 2.99m, and recoverable reserves of 680,900 tons. This working face is located in the northeast corner of the high-density 3D seismic survey area 85-87, with the in-line direction of the area being due north. The specific location is as follows: Figure 2 As shown.

[0132] Geological conditions of working face 7253

[0133] I. Coal Seam Occurrence

[0134] The coal seam being mined in this working face is No. 72 coal seam, belonging to the Lower Permian Lower Shihezi Formation. It is a semi-bright coal with a weak vitreous luster, and is in powder, flake, or fragmented form with well-developed endogenous fractures. The No. 72 coal seam is 1.42–4.21 m thick, with an average of 2.99 m. The coal seam structure is simple, and locally contains one layer of interbedded gangue.

[0135] II. Geological Structure

[0136] The working face is a monoclinal structure, dipping northward. The bottom elevation of coal seam 72 is -530m to -750m. The dip angle of the coal (rock) strata is relatively steep, ranging from 11° to 20°, with an average of 15°.

[0137] III. Drilling Data Collection

[0138] The boreholes around the 7253 working face were sorted out and analyzed, as shown in Table 1 below.

[0139] Table 4-1-1 Summary of Drilling Statistics Around Working Face 7253

[0140]

[0141] Analysis of the interlayer spacing between coal seams 72 and 82: Of the 17 boreholes, 6 boreholes did not find coal seam 8. The interlayer spacing ranged from 3.7 to 23.52 m, with an average of 15.9 m. Preliminary analysis suggests that: ① Coal seam 8 is not well developed in some areas around this facet; ② The interlayer spacing between coal seams 8 and 7 is small, which will form a composite reflection wave on the seismic time profile.

[0142] Comprehensive analysis of earthquake geological data

[0143] Figure 3 This is a multi-attribute comprehensive analysis result diagram of the 7253 working face. The attribute diagram shows the planar distribution of faults F9, F10, and WF4-4. Figure 4 This is a schematic diagram of the plane location of the 7253 fault as interpreted from seismic data.

[0144] The following is a brief discussion of the principle and technical roadmap of crack prediction in this embodiment:

[0145] Principles and technical roadmap of crack prediction

[0146] OVT gathers, after being migrated in the OVT domain, retain azimuth information, allowing for fracture characteristic analysis using azimuth anisotropy or AVO gradient anisotropy. For a set of vertically parallel fractures, the eccentricity of an ellipse can indicate fracture density, while the major axis indicates fracture orientation. By selecting different shot-receiver distances and different numbers of gather azimuth subdivisions, and extracting attributes such as maximum amplitude, root-mean-square amplitude, and travel time along the target layer through time windows, the anisotropy variation of the gather profile is analyzed. Ellipse fitting is then performed, and the most suitable parameters are selected to predict fractures. Fracture prediction has progressed from azimuth-based prediction to prediction using spiral gathers (five-dimensional), significantly improving prediction direction and accuracy.

[0147] like Figure 5 As shown, the eccentricity of the ellipse reflects the crack density. The larger the eccentricity, the greater the crack density, and the smaller the eccentricity, the smaller the crack density. The direction of the major axis of the fitted ellipse is the crack orientation.

[0148] This embodiment aims to meet the needs of wide-azimuth seismic data interpretation and analysis, and to fully exploit the information in five-dimensional seismic data. It applies the GeoEast five-dimensional seismic interpretation subsystem to conduct research on fracture prediction. The fracture prediction technical approach in this embodiment is as follows: Figure 6 As shown.

[0149] Daoji Data Quality Control Inspection

[0150] After the five-dimensional gather data is loaded, pre-stack gather analysis is performed first. The correctness of the loaded gather is analyzed by checking the work area information (trace number range), azimuth angle, and offset distance (incident angle range).

[0151] I. Azimuth and Offset Distance (Angle of Incidence) Range Check

[0152] Figure 7 This is the main interface display diagram for loading pre-stack gathers into the five-dimensional seismic interpretation subsystem. The target coal seam horizons and fault structures to be interpreted are also loaded. Figure 7 The medium gray area displays roadway information, strata, and coal seam intersections. Figure 7 As the azimuth and offset ranges change in the template view, the offset and azimuth ranges circled in the lower right image also change accordingly. Check if the offset and azimuth ranges are accurate, specifically as follows: Figure 8 As shown.

[0153] II. Gathering Data Inspection (Gathering Profile, Target Layer Strata)

[0154] Figure 9 The image shows the Daoji profile. The upper line in the Daoji profile represents the interpreted No. 7 coal seam, and the lower line in the Daoji profile represents the amplitude variation curve.

[0155] III. Display of Template View and Fitted Ellipse for Crack Prediction

[0156] Figure 10 This is an interface display diagram of the five-dimensional seismic interpretation subsystem. Figure 10 The image displays information such as amplitude, spectrum, and fitted ellipse at a single point within the work area. Adjust the offset range in the template view to ensure the fitted ellipse for crack prediction meets the following conditions:

[0157] 1. The ellipse is relatively flat;

[0158] 2. The fitting point is near the boundary of the ellipse;

[0159] 3. In areas with good data quality, changing the number of superimposed azimuth angles results in minimal changes to the ellipse direction.

[0160] Coal seam fracture prediction

[0161] Fracture prediction involves analyzing the differences in amplitude and time difference of the target stratum in a coal seam at different azimuths to make predictions. The fracture prediction process mainly includes feasibility analysis, determining the template view (using omnidirectional information for fracture prediction, adjusting only the offset range), fracture calculation, and result analysis.

[0162] I. Feasibility Analysis

[0163] Adjust the range of the offset in the template view so that the fitted ellipse for crack prediction satisfies the following conditions:

[0164] 1. The ellipse is relatively flat;

[0165] 2. The fitting point is near the boundary of the ellipse;

[0166] 3. In areas with good data quality, changing the number of superimposed azimuth angles results in minimal changes to the ellipse direction.

[0167] II. Determine the template view

[0168] In this embodiment, geological understanding was incorporated into the study, and the actual geological characteristics were analyzed. Based on the fact that the main tectonic development direction of the study area is NE-NNE, a template view was determined, as shown below. Figure 11 As shown.

[0169] III. Crack Calculation

[0170] The corresponding calculations are performed using the crack calculation module. Figure 12 This is a schematic diagram of the crack calculation interface, which includes three calculation methods: maximum amplitude, root mean square amplitude, and travel time.

[0171] The maximum amplitude is the amplitude of the target layer read from the gather. A fracture prediction ellipse template is fitted, and this method is chosen when the target layer has high energy and the data has a high signal-to-noise ratio. In this embodiment, the reflected wave amplitude of coal seam 7 has high energy and a high signal-to-noise ratio, therefore this method was chosen.

[0172] The root mean square amplitude is the root mean square amplitude of the target layer within the layer thickness range read from the gather. It is then fitted with a crack prediction ellipse template. This method is used when the target layer energy is weak and the data signal-to-noise ratio is low.

[0173] The time-travel algorithm fits an ellipse based on the time difference between the target layer and the standard layer. This method is chosen when there is a strong reflection layer above the target layer.

[0174] IV. Results Analysis

[0175] Figure 13 The images show the fracture distribution results of coal seam No. 7 calculated based on the maximum amplitude. The left image shows the fracture development as a small rose diagram, the middle image shows the fractures as short lines, and the right image is a rose diagram. Figure 13 It can be seen that the intensity of fracture development is correlated with the fracture, and the degree of fracture development is higher near the fault.

[0176] Along with generating the fracture planar map, three attributes—intensity, confidence level, and azimuth—are generated to aid in the analysis of fracture development. Specifically, `intensity.den` represents the eccentricity of the fitted ellipse, i.e., the ratio of its major axis to its minor axis; `confidence.con` represents the dispersion of the fitted ellipse; and `azimuth.ori` represents the direction of the major axis of the fitted ellipse, generally used qualitatively to indicate the fracture direction, as shown in the example below. Figure 14 As shown.

[0177] Simultaneously, the results of ant attribute slices along the seam of coal seam 7 were overlaid with the fracture prediction results for display, such as... Figure 15As shown.

[0178] Instantaneous Attribute Prediction of Coal Seam Orientation

[0179] Azimuth instantaneous attribute prediction is a crack prediction method performed in the frequency domain, including two calculation methods: azimuth instantaneous amplitude and azimuth instantaneous frequency. The process of using azimuth instantaneous attributes for crack prediction mainly includes four steps: feasibility analysis, determining the template view (using all-angle information for crack prediction, only adjusting the offset range), crack calculation, and result analysis.

[0180] The corresponding calculations are performed using the instantaneous orientation attribute calculation module. Figure 16 This is a schematic diagram of the interface for calculating the instantaneous azimuth attribute, which includes three calculation methods: maximum amplitude, root mean square amplitude, and travel time. Figure 17 The image shows the fracture development results calculated from the azimuth instantaneous amplitude and frequency.

[0181] Analysis of fissures or water-conducting channels

[0182] The fracture prediction work carried out above mainly followed the target stratum of the coal seam and analyzed the development of fractures in the coal seam. The following analysis will analyze the fracture development of the sandstone strata in the top and bottom of the coal seam, and then comprehensively analyze the fracture development results of multiple strata to qualitatively explain the possible water-conducting channels.

[0183] In this example, the sandstone strata of the coal seam roof are located at 30m and 50m from the coal seam roof, and the sandstone strata of the coal seam floor are located at 30m and 50m from the coal seam floor.

[0184] Fracturing within 30m and 50m of the coal seam roof

[0185] The target coal seam horizons were shifted upwards by time to obtain horizons 50m and 30m from the coal seam roof. Then, calculations were performed based on these target horizons to determine the fracture development of each target layer. The resulting diagram is shown below. Figure 18 As shown, by Figure 18 It can be seen that, in addition to the relatively concentrated development of fractures near the fault structure, two fracture development zones, YC1 and YC2, were delineated within the 7253 working face. These two anomalous areas show anomalies in three layers and may form water-conducting channels, such as... Figure 18 The circular and rectangular frames are shown. Figure 19 This is a comprehensive analysis diagram of the fracture development intensity at 50m and 30m in the coal seam roof and at the coal seam location.

[0186] Fracturation development within 30m and 50m of the coal seam floor

[0187] The target coal seam strata were shifted downwards by time to obtain strata 50m and 30m from the coal seam floor. Then, calculations were performed based on these target strata to determine the fracture development of each stratum. The resulting diagram is shown below. Figure 20 As shown, by Figure 20 It can be seen that, in addition to the relatively concentrated development of fractures near the fault structure, two fracture development zones, YC3 and YC4, were delineated within the 7253 working face. These two anomalous areas show anomalies in all layers and may form water-conducting channels, such as... Figure 20 The circular and rectangular frames are shown. Figure 21 This is a comprehensive analysis diagram of the fracture development intensity at 50m and 30m of the coal seam floor and at the coal seam level.

[0188] Based on the above research, this embodiment has achieved the following results:

[0189] This embodiment utilizes the GeoEast five-dimensional seismic interpretation subsystem to perform tasks such as fracture prediction and qualitative description of water-conducting channels in the coal seam roof. From Figure 13 It can be seen that the fracture development intensity of coal seam 7 is related to the fault, and the degree of fracture development is relatively high near the fault.

[0190] Two fracture development zones, YC1 and YC2, were delineated within the 7253 working face. These two anomalous areas show abnormalities at 30m and 50m above the coal seam roof and at the target stratum of the coal seam, which may form water-conducting channels.

[0191] Two fracture development zones, YC3 and YC4, were delineated within the 7253 working face. These two anomalous areas showed abnormalities at 30m and 50m of the coal seam floor and at the target coal seam level, which may form water-conducting channels.

[0192] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A method for fracture prediction and qualitative analysis of water-conducting channels in coal seam roof based on a five-dimensional seismic interpretation subsystem, characterized in that, Includes the following steps: After loading the five-dimensional gather data through the GeoEast five-dimensional seismic interpretation subsystem, the five-dimensional gather data is subjected to quality control checks. Coal seam fracture prediction is performed by utilizing the differences in amplitude and time difference of the target stratum in different orientations, and by utilizing the instantaneous orientation attributes of the target stratum in coal seam. The stratigraphic positions of the sandstone in the roof and floor of the coal seam are determined, and the fracture development of the sandstone in the roof and floor of the coal seam is further obtained. A comprehensive analysis is conducted to qualitatively interpret the possible water-conducting channels, including: there are anomalies in the sandstone in the roof of the coal seam and the target stratum of the coal seam, which may form water-conducting channels. Alternatively, anomalies may be observed in the sandstone strata at the bottom of the coal seam and in the target strata of the coal seam, which could potentially form water-conducting channels.

2. The method for fracture prediction and qualitative analysis of water-conducting channels in coal seam roof based on a five-dimensional seismic interpretation subsystem as described in claim 1, characterized in that, The quality control check of the five-dimensional gather data includes: The azimuth and offset of the five-dimensional gather data are checked. Perform a gather data check on the five-dimensional gather data; The template view and the fracture prediction fitted ellipse are displayed on the five-dimensional gather data.

3. The method for fracture prediction and qualitative analysis of water-conducting channels in coal seam roof based on a five-dimensional seismic interpretation subsystem as described in claim 2, is characterized in that... When performing azimuth and offset checks on the five-dimensional gather data, the following steps are included: The five-dimensional gather data is loaded into the main interface of the GeoEast five-dimensional seismic interpretation subsystem for display, and the target coal seam horizon and fault structure to be interpreted are loaded at the same time. Based on the range of azimuth and offset distance displayed in the template view of the main interface, check whether the range of azimuth and offset distance is accurate.

4. The method for fracture prediction and qualitative analysis of water-conducting channels in coal seam roof based on a five-dimensional seismic interpretation subsystem as described in claim 2, characterized in that, The process of performing gather data inspection on the five-dimensional gather data includes: The GeoEast five-dimensional seismic interpretation subsystem is used to display the gather profile of the five-dimensional gather data. Examine the target coal seam horizons and the amplitude variation curves contained in the gathered profile.

5. The method for fracture prediction and qualitative analysis of water-conducting channels in coal seam roof based on a five-dimensional seismic interpretation subsystem as described in claim 2, characterized in that, When displaying the template view and the fracture prediction fitted ellipse on the five-dimensional gather data, the following steps are included: The GeoEast five-dimensional seismic interpretation subsystem displays the amplitude information, spectrum, and fracture prediction fitted ellipse of a single point within the work area. Adjust the range of the offset distance in the template view and check whether the crack prediction fitting ellipse can meet the prediction conditions. The prediction conditions include: the flatness of the crack prediction fitting ellipse is within a threshold, the distance between the fitting point and the crack prediction fitting ellipse is within a threshold, the number of superpositions of changing the azimuth angle in the selected area, and the change in the direction of the crack prediction fitting ellipse is within a threshold.

6. The method for fracture prediction and qualitative analysis of water-conducting channels in coal seam roof based on a five-dimensional seismic interpretation subsystem as described in claim 1, characterized in that, When using the differences in amplitude and time difference of the target stratum in a coal seam at different azimuths to predict coal seam fractures, the following are included: Feasibility analysis, determination of template view, fitting of crack prediction elliptical template, and results analysis.

7. The method for fracture prediction and qualitative analysis of water-conducting channels in coal seam roof based on a five-dimensional seismic interpretation subsystem as described in claim 6, characterized in that, The process of determining the template view includes: The template view is determined based on the main direction of tectonic development in the study area; The fitted crack prediction ellipse template includes: When the target layer energy and the data signal-to-noise ratio of the coal seam are both greater than the threshold, the maximum amplitude of the fracture calculation module in the GeoEast five-dimensional seismic interpretation subsystem is used to fit the fracture prediction elliptical template. When the target layer energy and the data signal-to-noise ratio of the coal seam are both less than the threshold, the root mean square amplitude of the fracture calculation module in the GeoEast five-dimensional seismic interpretation subsystem is used to fit the fracture prediction ellipse template. When there is a reflective layer with an intensity greater than the threshold above the target coal seam, the fracture prediction ellipse template is obtained by fitting the travel time of the fracture calculation module in the GeoEast five-dimensional seismic interpretation subsystem. The analysis of the results includes: The fitted crack prediction ellipse template generates the corresponding crack result map, and at the same time generates three attributes: intensity, confidence and azimuth. The results are analyzed based on the fracture map and the three attributes, and the fracture map and the coal seam ant attribute slices are overlaid and displayed. The crack result diagram includes: a result diagram showing the development of cracks, a result diagram showing the crack situation with short lines, and a result diagram reflecting the intensity and degree of crack development.

8. The method for fracture prediction and qualitative analysis of water-conducting channels in coal seam roof based on a five-dimensional seismic interpretation subsystem as described in claim 1, characterized in that, When using the instantaneous attributes of the target stratum orientation of a coal seam to predict coal seam fractures, the following are included: Feasibility analysis, determination of template view, fitting of crack prediction elliptical template, and results analysis.

9. The method for fracture prediction and qualitative analysis of water-conducting channels in coal seam roof based on a five-dimensional seismic interpretation subsystem as described in claim 8, characterized in that, The process of determining the template view includes: The template view is determined based on the main direction of tectonic development in the study area; The fitted crack prediction ellipse template includes: When the target layer energy and data signal-to-noise ratio of the coal seam are both greater than the threshold, the maximum amplitude of the fracture prediction ellipse template is fitted by the instantaneous attribute calculation module of the GeoEast five-dimensional seismic interpretation subsystem. When the target layer energy and data signal-to-noise ratio of the coal seam are both less than the threshold, the root mean square amplitude of the instantaneous attribute calculation module of the GeoEast five-dimensional seismic interpretation subsystem is used to fit the crack prediction ellipse template. When there is a reflective layer with an intensity greater than the threshold above the target coal seam, the travel time fitting of the fracture prediction ellipse template is obtained through the instantaneous attribute calculation module of the GeoEast five-dimensional seismic interpretation subsystem. The analysis of the results includes: Based on the fitted crack prediction ellipse template, an azimuth instantaneous amplitude crack result map or an azimuth instantaneous frequency result map is obtained, and the result analysis is performed based on the azimuth instantaneous amplitude crack result map or the azimuth instantaneous frequency result map.

10. The method for fracture prediction and qualitative analysis of water-conducting channels in coal seam roof based on a five-dimensional seismic interpretation subsystem as described in claim 1, characterized in that, In determining and qualitatively interpreting the fracture development of the sandstone strata in the coal seam roof and floor, the following should be included: By using borehole logging curves to create synthetic seismic records, the stratigraphic positions of the sandstone in the coal seam roof and floor are calibrated. Then, fine stratigraphic tracing is performed to determine the stratigraphic positions of the sandstone in the coal seam roof and floor, and further, the fracture development of the stratigraphic positions of the sandstone in the coal seam roof and floor is obtained. Based on a comprehensive analysis of the fracture development of the sandstone strata in the top and bottom of the coal seam and the fracture development of the target strata of the coal seam, a qualitative interpretation of the possible water-conducting channels is made.

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