Method and device for determining water-bearing property and connectivity of crack based on well-ground electromagnetic detection system, medium and product

Abstract

The invention discloses a method and device for determining the water content and connectivity of a crack based on a well-ground electromagnetic detection system, a medium and a product, and relates to the technical field of geophysical exploration, and the method comprises the steps: obtaining a plurality of groups of historical data; based on each group of historical data, determining layout parameters of the well-ground electromagnetic detection system; arranging a well-ground electromagnetic detection system based on the arrangement parameters, and collecting original field time sequence data; determining frequency data based on the original field time sequence data; carrying out current normalization processing based on the frequency data to obtain amplitude and phases under different harmonic waves; determining a three-dimensional data volume of the excitation section based on the amplitude and the phase under each harmonic wave; the three-dimensional data volume comprises a three-dimensional space differential phase data volume, a three-dimensional resistivity inversion data volume and a three-dimensional space differential resistivity data volume; and based on the three-dimensional data volume, determining the water-containing property and the fracture communication condition of the excitation section. According to the invention, the capability of distinguishing the artificial crack is improved.

Description

Technical Field

[0001] The present application relates to the field of geophysical survey technology, and in particular to a method, device, medium and product for determining water content and connectivity of fractures based on a well-to-ground electromagnetic detection system. Background Art

[0002] Artificial reservoir creation is a method commonly used in the development of resources such as oil, natural gas, shale gas, and geothermal (hot dry rock). The method is to inject a large amount of high-pressure liquid into the target area, and transform the reservoir fracture structure through hydraulic fracturing, forming one or more main fractures while expanding natural fractures or secondary fractures. At the same time, secondary fractures continue to branch out to form secondary secondary fractures and more levels of secondary fractures, forming a fracture network in which natural fractures and artificial fractures are intertwined, thereby increasing the seepage area and conductivity, and improving the recovery rate or heat exchange rate.

[0003] A deep understanding of the geometry and extension of fine hydraulic fractures is crucial to improving the effectiveness of hydraulic fracturing and production stimulation operations in low-permeability reservoirs, improving fracture (well group) connectivity and increasing recovery or heat exchange rates.

[0004] However, the cracks and crack clusters formed by reservoir fracturing are very complex, with poor regularity, irregular cracks, small crack widths and limited lengths. Conventional ground active electromagnetic methods and natural source electromagnetic methods have little response to cracks in hot dry rocks. In addition, in areas with severe human activities, mechanical vibrations and power interference, it is difficult to obtain high-quality monitoring data when detecting targets such as original or hydraulic fracturing cracks in reservoirs using traditional electromagnetic methods. There are limitations such as weak anti-interference ability, limited detection depth, and insufficient detection accuracy, which results in low resolution of artificial cracks. Summary of the invention

[0005] The purpose of the present application is to provide a method, device, medium and product for determining the water content and connectivity of fractures based on a well-ground electromagnetic detection system, so as to solve the problem of low resolution of artificial fractures.

[0006] To achieve the above objectives, this application provides the following solutions:

[0007] In a first aspect, the present application provides a method for determining the water content and connectivity of fractures based on a well-ground electromagnetic detection system, wherein the well-ground electromagnetic detection system comprises: a ground transmitting source, a ground excitation source electrode, an in-well excitation source electrode, and a ground observation network; the ground observation network comprises a plurality of ground receiving electrodes;

[0008] The method for determining the water content and connectivity of fractures based on the well-ground electromagnetic detection system includes:

[0009] Acquire multiple sets of historical data; the historical data include: drilling geological stratification information, logging curves, fracturing section location information and fracturing fluid resistivity;

[0010] Based on each set of historical data, the layout parameters of the well-ground electromagnetic detection system are determined; the layout parameters include: the position of the ground excitation source electrode, the excitation current, the excitation point in the well, the excitation signal period, the number of single frequency point periods, and the range of the ground observation network, the point-line distance and the electrode distance of the ground receiving electrode;

[0011] Based on the deployment parameters, deploy the well-ground electromagnetic detection system and collect original field time series data;

[0012] Based on the original field time series data, frequency data is determined; the frequency data includes: real components, imaginary components and coordinate data of all frequencies of each measuring point and real components, imaginary components and coordinate data of the excitation current; the measuring point is the midpoint between two ground receiving electrodes;

[0013] Based on the frequency data, current normalization processing is performed to obtain the amplitude and phase under different harmonics;

[0014] Based on the amplitude and the phase under each harmonic, determine the three-dimensional data volume of the excitation segment; the three-dimensional data volume includes: a three-dimensional spatial differential phase data volume, a three-dimensional resistivity inversion data volume and a three-dimensional spatial differential resistivity data volume; the excitation segment includes the formations corresponding to the excitation points in all wells;

[0015] Based on the three-dimensional data volume, the water content and fracture connectivity of the excitation section are determined.

[0016] Optionally, based on each set of historical data, determining the deployment parameters of the well-ground electromagnetic detection system includes:

[0017] Based on each set of historical data, a corresponding fracture model is constructed;

[0018] Carrying out forward modeling for each of the fracture models under different ground observation networks, and drawing forward modeling result diagrams for each of the ground observation networks for each of the fracture models;

[0019] Based on each of the forward modeling result diagrams, the layout parameters are determined.

[0020] Optionally, the ground transmitting source, the ground excitation source electrode and each of the ground receiving electrodes are arranged on the ground, and the in-well excitation source electrode is arranged in the excitation well.

[0021] Optionally, a corresponding fracture model is constructed based on each set of historical data, including:

[0022] According to the drilling geological stratification information and logging curves in each group of historical data, the formation resistivity layered model corresponding to each group of historical data is constructed;

[0023] A fracture model corresponding to each set of historical data is constructed according to the formation resistivity layered model, fracturing section location information and fracturing fluid resistivity corresponding to each set of historical data; the fracture model includes a horizontal plate model and a vertical plate model.

[0024] Optionally, based on the deployment parameters, deploying the well-to-ground electromagnetic detection system and collecting original field time series data include:

[0025] According to the position of the ground excitation source electrode, burying the ground excitation source electrode in the ground;

[0026] Deploy the ground observation network in the ground monitoring area according to the scope of the ground observation network, the distance between points and lines, and the electrode distance between ground receiving electrodes;

[0027] According to the excitation point in the well, the excitation signal cycle and the number of single frequency point cycles, the excitation point in the well is moved upward from deep to shallow in the excitation well, and the excitation source electrodes in the well are set in sequence;

[0028] During the upward movement, the excitation source electrode flow in the well continuously emits excitation current underground, and the ground observation network collects radial horizontal electric field components to obtain the original field time series data.

[0029] Optionally, determining frequency data based on the original field time series data includes:

[0030] Performing spectrum analysis and filtering on the original field time series data to obtain filtered field time series data;

[0031] The filtered field time series data are superimposed and Fourier transformed to obtain the frequency data.

[0032] Optionally, based on the amplitude and the phase of each harmonic, a three-dimensional data volume of the excitation segment is determined, including:

[0033] According to the phase of each harmonic, the differential phase anomaly of the formation between the excitation points in each adjacent well is calculated;

[0034] According to the differential phase anomaly of the formation between the excitation points in each adjacent well, a corresponding differential phase anomaly plane map is drawn;

[0035] Determining the three-dimensional spatial differential phase data volume according to all differential phase anomaly plane images in the excitation segment;

[0036] Calculating the apparent resistivity of the formation corresponding to the excitation point in each well according to the geometric coefficient of the apparent resistivity corresponding to the excitation point in each well and the amplitude;

[0037] According to the apparent resistivity of the formation corresponding to the excitation point in each well, draw the corresponding apparent resistivity plane diagram;

[0038] Determine the three-dimensional resistivity inversion data volume according to all apparent resistivity plane maps in the excitation segment;

[0039] Determine the differential resistivity between the formations corresponding to the excitation points in the adjacent wells according to the apparent resistivity of the formations corresponding to the excitation points in the adjacent wells;

[0040] According to the differential resistivity between the formations corresponding to the excitation points in each adjacent well, a corresponding differential resistivity plane diagram is drawn;

[0041] The three-dimensional spatial differential resistivity data volume is determined according to all differential resistivity plane images in the excitation segment.

[0042] In a second aspect, the present application provides a computer device comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement any of the above-mentioned methods for determining the water content and connectivity of fractures based on a well-to-ground electromagnetic detection system.

[0043] In a third aspect, the present application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements any of the above-mentioned methods for determining water content and connectivity of fractures based on a well-to-ground electromagnetic detection system.

[0044] In a fourth aspect, the present application provides a computer program product, including a computer program, which, when executed by a processor, implements any of the above-mentioned methods for determining fracture water content and connectivity based on a well-to-ground electromagnetic detection system.

[0045] According to the specific embodiments provided in this application, this application discloses the following technical effects:

[0046] The present application discloses a method, device, medium and product for determining the water content and connectivity of fractures based on a well-ground electromagnetic detection system. First, multiple groups of historical data are obtained; the historical data include: borehole geological stratification information, logging curves, fracturing section location information and fracturing fluid resistivity; based on each group of historical data, the layout parameters of the well-ground electromagnetic detection system are determined; then, based on the layout parameters, the well-ground electromagnetic detection system is deployed, and original field time series data are collected; secondly, based on the original field time series data, frequency data is determined; the frequency data includes: real components, imaginary components and coordinate data of all frequencies of each measuring point and real components, imaginary components and coordinate data of the excitation current; the measuring point is the midpoint between two ground receiving electrodes; then, based on the frequency data, current normalization processing is carried out to obtain the amplitude and phase under different harmonics; thirdly, based on the amplitude and phase under each harmonic, the three-dimensional data body of the excitation section is determined; finally, based on the three-dimensional data body, the water content and fracture connectivity of the excitation section are determined. After the well-to-ground electromagnetic detection system is deployed based on the deployment parameters, the original field time series data is collected, and the three-dimensional data body is determined according to the original field time series data, so as to obtain the water content and fracture connectivity of the excitation section, which greatly overcomes the interference of human activities, mechanical vibrations, and power facilities on the electromagnetic data, improves the signal-to-noise ratio of the original field time series data, can detect the formation resistivity distribution in a larger range around the fracturing well, improves the resolution of artificial reservoir fractures, provides information on formation structure, fracture extension, wellbore offset or target orientation, and realizes a comprehensive evaluation of reservoir transformation and fracture connectivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0048] Figure 1 A schematic flow chart of a method for determining water content and connectivity of fractures based on a well-to-ground electromagnetic detection system provided in one embodiment of the present application;

[0049] Figure 2 A schematic diagram of the framework of the method for determining the water content and connectivity of fractures;

[0050] Figure 3 This is a schematic diagram of the structure of the well-ground electromagnetic detection system;

[0051] Figure 4 This is a schematic diagram of the layered model of formation resistivity;

[0052] Figure 5 is a schematic diagram of the total longitudinal conductance curve;

[0053] Figure 6 It is a schematic diagram of the horizontal plate model;

[0054] Figure 7 It is a schematic diagram of the vertical plate model;

[0055] Figure 8 This is the forward modeling result diagram of the horizontal plate-shaped model under the 5m×5m ground observation network;

[0056] Fig. 9 This is the forward modeling result diagram of the horizontal plate-shaped model under the 10m×10m ground observation network;

[0057] Fig.10 This is the forward modeling result diagram of the horizontal plate-shaped model under the 20m×20m ground observation network;

[0058] Fig.11 This is the x-direction component diagram of the forward modeling results of the vertical plate-shaped model under the 10m×20m ground observation network;

[0059] Fig.12 The y-direction component diagram of the forward modeling results of the vertical plate-shaped model under the 10m×20m ground observation network;

[0060] Fig.13 This is the first structural diagram of the ground observation network;

[0061] Fig.14 This is a second structural diagram of the ground observation network;

[0062] Fig.15 It is the differential phase anomaly plane diagram corresponding to AB2-AB3;

[0063] Fig.16 It is a schematic diagram of a three-dimensional space differential phase data volume;

[0064] Fig.17 It is a three-dimensional display of the slice direction of the differential phase survey line;

[0065] Fig.18 is the apparent resistivity plane diagram corresponding to AB1;

[0066] Fig.19 It is a schematic diagram of the three-dimensional resistivity inversion data volume;

[0067] Fig. 20 It is a three-dimensional resistivity depth slice stereogram;

[0068] Fig.21 It is the differential resistivity plane diagram corresponding to AB2-AB3;

[0069] Fig. 22 It is a schematic diagram of volume difference of three-dimensional spatial differential resistivity data;

[0070] Fig.23 It is a three-dimensional display diagram of the longitudinal slice of resistivity;

[0071] Fig.24 It is a three-dimensional display diagram of the spatial distribution of low-resistance anomalies;

[0072] Fig.25 A schematic diagram of the structure of a computer device provided in one embodiment of the present application.

[0073] Reference numerals:

[0074] Ground transmitting source—1, ground excitation source electrode—2, well excitation source electrode—3, ground observation network—4, ground receiving electrode—5. DETAILED DESCRIPTION

[0075] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0076] The purpose of this application is to provide a method, device, medium and product for determining the water content and connectivity of fractures based on a well-ground electromagnetic detection system, aiming to improve the ability to distinguish artificial fractures.

[0077] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0078] In an exemplary embodiment, Figure 1 and Figure 2 As shown, a method for determining the water content and connectivity of fractures based on a well-ground electromagnetic detection system is provided, such as Figure 3 As shown, the well-ground electromagnetic detection system includes: a ground transmitting source 1, a ground excitation source electrode 2, an in-well excitation source electrode 3 and a ground observation network 4; the ground observation network includes a plurality of ground receiving electrodes 5.

[0079] Specifically, Figure 3 In the borehole-to-ground electromagnetic detection system using borehole-to-ground electromagnetic method (BSEM), the ground excitation source electrode A and the borehole excitation source electrode B together constitute an excitation electrode, and B1 and B2 are the positions of different borehole excitation points of the borehole excitation source electrode. The ground receiving electrode is MN. The ground excitation source electrode is connected to the borehole excitation source electrode and the ground transmitting source through power supply cables.

[0080] During field work, one power supply electrode (i.e., the in-well excitation source electrode) is placed in the well, and the other power supply electrode (i.e., the ground excitation source electrode) is placed on the surface near the wellhead. During data collection, the power supply electrode excites an alternating electromagnetic field signal, and the potential difference and phase between any two ground receiving electrodes are observed through the collection station arranged on the ground.

[0081] As an optional implementation, the ground transmitting source, the ground excitation source electrode and each ground receiving electrode are all arranged on the ground, and the in-well excitation source electrode is arranged in the excitation well.

[0082] The ground observation network is centered on the ground projection of the bottom of the stimulation well, and is mostly a radioactive measurement network or a regular measurement network. The monitoring area can be flexibly adjusted according to the trajectory of the fracturing well and the construction progress; the ground observation network contains multiple survey lines and multiple measurement points. All measurement points are determined by real-time differential positioning and clearly marked; the survey line direction is generally perpendicular to the main structural direction of the site, and the point-line distance is determined comprehensively based on the depth and scale of the detected small cracks, which can be selected on demand between 10m and 20m. The electrode spacing is determined based on forward simulation and can be flexibly adjusted according to actual needs. It does not have to be evenly distributed and can be selectively encrypted in key monitoring areas; on-site real-time differential positioning must ensure that the survey line direction, measurement point location, electrode spacing and design error do not exceed 1%, and the survey line number and measurement point number are clearly marked.

[0083] The waveform of the excitation current is a square wave with a duty cycle of 1 and no zero crossing. The optimal excitation frequency must ensure that the maximum monitoring depth is reached. In order to ensure the processing and interpretation effect, the actual excitation signal frequency is generally expanded; the area of ​​the power supply electrode of the ground excitation source electrode is increased, and the grounding resistance is reduced to ensure the energy intensity of the excitation source. It is recommended that the power supply current be no less than 30A, and the square wave signal of a single excitation frequency be repeated no less than 30 times. A high-power constant current generator set and a constant current time-frequency electromagnetic transmitter must be used to ensure that the power supply current and the excitation frequency are consistent at different time periods. When the number of collection stations is not enough to cover the entire ground observation network at the same time, a rolling mode of multiple excitations and multiple groups of simultaneous collections should be adopted.

[0084] The methods for determining the water content and connectivity of fractures based on the well-ground electromagnetic detection system include:

[0085] Step 1: Acquire multiple sets of historical data; the historical data include: borehole geological stratification information, logging curves, fracturing section location information and fracturing fluid resistivity.

[0086] Step 2: Based on each set of historical data, determine the layout parameters of the well-ground electromagnetic detection system.

[0087] The layout parameters include: the position of the ground excitation source electrode, the excitation current, the excitation point in the well, the excitation signal period, the number of single frequency point periods, the range of the ground observation network, the point-line distance and the electrode distance of the ground receiving electrode.

[0088] As an optional implementation, step 2 includes:

[0089] Step 21: Construct corresponding crack models based on each set of historical data.

[0090] As an optional implementation, step 21 includes:

[0091] Step 211: constructing a formation resistivity layered model corresponding to each set of historical data according to the borehole geological stratification information and logging curves in each set of historical data.

[0092] Step 212: constructing a fracture model corresponding to each set of historical data according to the formation resistivity layered model, fracturing section location information and fracturing fluid resistivity corresponding to each set of historical data; the fracture model includes a horizontal plate model and a vertical plate model.

[0093] Step 22: Carry out forward modeling for each fracture model under different ground observation networks, and draw forward modeling result diagrams for each fracture model under different ground observation networks.

[0094] Specifically, the forward modeling diagram refers to the differential resistivity processing result diagram of different ground observation networks for different fracture models.

[0095] Step 23: Determine the layout parameters based on the forward modeling result diagrams.

[0096] Specifically, the layout parameters are determined based on the forward modeling result diagrams, the buried depth of the fracturing section, the total amount of injected fracturing fluid, and the planar distribution of microseismic events.

[0097] Step 3: Based on the deployment parameters, deploy the well-ground electromagnetic detection system and collect original field time series data.

[0098] As an optional implementation, step 3 includes:

[0099] Step 31: Bury the ground excitation source electrode on the ground according to the position of the ground excitation source electrode.

[0100] Step 32: Deploy a ground observation network in the ground monitoring area according to the range of the ground observation network, the point-line distance and the electrode distance of the ground receiving electrodes.

[0101] Specifically, the area of ​​the ground observation network needs to be larger than the estimated distribution range of the fracturing fluid; the measuring points in the ground observation network collect radial horizontal electric field components, the orientation is the direction of the well, the M pole is the near well point, the N pole is the far well point, and the measuring point is the midpoint of the two ground receiving electrodes MN.

[0102] Step 33: According to the excitation point in the well, the excitation signal cycle and the number of single frequency point cycles, in the excitation well, the excitation points in the well are moved up from deep to shallow, and the excitation source electrodes in the well are set in sequence.

[0103] Specifically, the excitation section of the excitation source electrode in the excitation well must be larger than the fracturing section, that is, the excitation point in the deepest well is deeper than the deepest fracturing point, and the excitation point in the shallowest well is shallower than the shallowest fracturing point.

[0104] Step 34: During the upward movement, the excitation source electrode flow in the well continuously emits excitation current underground, and the ground observation network collects radial horizontal electric field components to obtain original field time series data.

[0105] Specifically, the excitation source electrode in the well continuously emits high-power pulse excitation current into the ground, and stimulates an induced electromagnetic field in the ground, causing the underground medium to generate induced eddy currents, where the induced eddy currents gradually diffuse and decay into the underground half-space. The diffusion speed and attenuation amplitude are related to the electrical conductivity of the underground medium.

[0106] Step 4: Determine the frequency data based on the original field time series data.

[0107] The frequency data include: real components, imaginary components and coordinate data of all frequencies of each measuring point and real components, imaginary components and coordinate data of the excitation current; the measuring point is the midpoint between two ground receiving electrodes.

[0108] As an optional implementation, step 4 includes:

[0109] Step 41: Perform spectrum analysis and filtering on the original field time series data to obtain filtered field time series data.

[0110] Specifically, after checking that the header information in the original field time series data is correct, the Age format file is intercepted and converted, noise analysis is performed, spectrum analysis and filtering are carried out, and filtered field time series data are obtained.

[0111] Step 42: Superimpose and Fourier transform the filtered field time series data to obtain frequency data.

[0112] Step 5: Based on the frequency data, perform current normalization processing to obtain the amplitude and phase of different harmonics.

[0113] Step 6: Based on the amplitude and phase of each harmonic, determine the three-dimensional data volume of the excitation segment.

[0114] The three-dimensional data volume includes: a three-dimensional spatial differential phase data volume, a three-dimensional resistivity inversion data volume and a three-dimensional spatial differential resistivity data volume; the excitation section includes the formations corresponding to the excitation points in all wells.

[0115] As an optional implementation, step 6 includes:

[0116] Step 61: Calculate the differential phase anomaly of the formation between the excitation points in each adjacent well according to the phase of each harmonic.

[0117] Specifically, the calculation formula of the differential phase anomaly includes:

[0118]

[0119] in, Php is the differential phase anomaly of the formation between the excitation point in the i-th well and the excitation point in the i+1-th well; i Php is the dual-frequency phase corresponding to the excitation electrode corresponding to the excitation point in the i-th well; i+1 is the dual-frequency phase corresponding to the excitation electrode corresponding to the excitation point in the i+1th well; F 1i is the phase value of the first harmonic corresponding to the excitation point in the i-th well; ω 3i is the frequency of the third harmonic corresponding to the excitation point in the i-th well; F 3i is the phase value of the third harmonic corresponding to the excitation point in the i-th well; ω 1i is the frequency of the first harmonic corresponding to the excitation point in the i-th well.

[0120] The differential phase anomaly reflects the changing characteristics of the water-bearing boundary zone of the formation corresponding to the excitation point in the well.

[0121] Step 62: Draw a corresponding differential phase anomaly plane diagram according to the differential phase anomaly of the formation between the excitation points in each adjacent well.

[0122] Specifically, the high anomaly in the differential phase anomaly plane map can qualitatively reflect the water-bearing characteristics between the excitation points in two adjacent wells of the reservoir.

[0123] Step 63: Determine a three-dimensional spatial differential phase data volume based on all differential phase anomaly plane images in the excitation segment.

[0124] Specifically, the three-dimensional spatial differential phase data volume can intuitively reflect the water content characteristics of the reservoir at different depths.

[0125] Step 64: Calculate the apparent resistivity of the formation corresponding to the excitation point in each well according to the geometric coefficient and amplitude of the apparent resistivity corresponding to the excitation point in each well.

[0126] Specifically, the calculation formula for apparent resistivity includes:

[0127] Ro_w i =K i ×A 1 .

[0128]

[0129] Among them, Row i is the apparent resistivity (abbreviated as resistivity) of the formation corresponding to the excitation point in the i-th well; K i is the geometric coefficient of apparent resistivity corresponding to the excitation point in the ith well; A 1 is the amplitude; r is the distance between the ground excitation source electrode A and the measuring point; T i is the distance between the excitation source electrode in the well and the measuring point corresponding to the excitation point in the i-th well.

[0130] Specifically, apparent resistivity mainly reflects the relative change characteristics of the resistivity of the formation corresponding to the excitation point in the well.

[0131] Step 65: Draw a corresponding apparent resistivity plane diagram according to the apparent resistivity of the formation corresponding to the excitation point in each well.

[0132] Specifically, the low resistivity area in the apparent resistivity plane map can be displayed as a water-rich area with developed fractures and good connectivity within a specific depth of the reservoir.

[0133] Step 66: Determine a three-dimensional resistivity inversion data volume based on all apparent resistivity plane maps in the excitation segment.

[0134] Furthermore, the three-dimensional resistivity inversion data volume is sliced ​​at any depth, and then the spatial distribution characteristics of resistivity in the survey area are analyzed.

[0135] Step 67: Determine the differential resistivity between the formations corresponding to the excitation points in the adjacent wells based on the apparent resistivity of the formations corresponding to the excitation points in the adjacent wells.

[0136] Specifically, the calculation formula for differential resistivity includes:

[0137] ρ si,i+1 =R i,i+1 ×k j .

[0138] R i,i+1 =Ro_w i / Ro_w i+1 .

[0139] Among them, ρ si,i+1 is the differential resistivity between the formation corresponding to the excitation point in the i-th well and the formation corresponding to the excitation point in the i+1-th well; R i,i+1 k is the apparent resistivity ratio of the formation corresponding to the excitation point in the i-th well to the formation corresponding to the excitation point in the i+1-th well; j is the apparent resistivity correction factor, which is calibrated according to the average apparent resistivity obtained from the measuring point closest to the excitation well; Ro_w i+1is the apparent resistivity of the formation corresponding to the excitation point in the i+1th well.

[0140] Differential resistivity reflects the relative resistivity change characteristics between the formations corresponding to the excitation points in adjacent wells.

[0141] Step 68: Draw a corresponding differential resistivity plane diagram according to the differential resistivity between the formations corresponding to the excitation points in each adjacent well.

[0142] Specifically, the low resistivity area in the differential resistivity plane map is inferred to be a water-rich area with developed fractures and good connectivity between the excitation points in two adjacent wells of the reservoir.

[0143] Step 69: Determine a three-dimensional spatial differential resistivity data volume based on all differential resistivity plane images in the excitation segment.

[0144] Specifically, the three-dimensional differential resistivity data volume can intuitively display the fracture development and connectivity of the reservoir excitation section and predict the water-rich area.

[0145] Step 7: Based on the 3D data volume, determine the water content and fracture connectivity of the excitation section.

[0146] Furthermore, the method of the present application is described in detail, and the implementation content includes:

[0147] Step 1: Obtain multiple sets of historical data; the historical data include: drilling geological stratification information, logging curves, fracturing section location information and fracturing fluid resistivity.

[0148] Step 2: Construct the formation resistivity layered model corresponding to each set of historical data based on the drilling geological stratification information and logging curves in each set of historical data. Figure 4 The blue curve in the figure is the well logging curve, and the green curve is the formation resistivity layered model. The total longitudinal conductivity can be calculated based on the well logging curve and the formation resistivity layered model (corresponding to Figure 5 The blue curve and green curve in the figure are consistent with each other, which proves that the established formation resistivity layered model can represent the real formation structure. Figure 4 The relevant data of the layered model of the formation resistivity are shown in Table 1.

[0149] Table 1. Relevant data of formation resistivity layered model

[0150]

[0151]

[0152] Step 3: According to the formation resistivity layered model, fracturing section location information and fracturing fluid resistivity corresponding to each set of historical data, a fracture model for simulating low-resistance fracture bodies corresponding to each set of historical data is constructed; the fracture model includes: Figure 6 The horizontal plate model shown and Figure 7 The vertical plate model shown in Figure 1 is shown in Figure 2. Figure 6 The geometric dimensions of the horizontal plate model shown are 20m (x direction) × 30m (y direction) × 10m (z direction), the depth is 3900m-3910m, the excitation well is 120m away from the anomaly, the excitation points in the well are 3900m and 3910m, the resistivity of the anomaly is 10Ω·m, and the excitation current is 30A. Figure 7 The geometric dimensions of the vertical plate model shown are 5m (x direction) × 20m (y direction) × 30m (z direction), with a depth of 3900m-3930m. The excitation well is 120m away from the anomaly. The excitation points in the well are 3900m, 3910m, 3920m and 3930m. The resistivity of the anomaly is 10Ω·m, and the excitation current is 30A.

[0153] Step 4: Figure 8-Figure 10 These are the results of processing using 5m×5m, 10m×10m and 20m×20m ground observation networks. It can be seen that the spacing of different ground observation networks can effectively identify the position of the target body, and the abnormal bodies processed by different ground observation networks can be accurately located; the differential resistivity processing results can directly reflect the range of the abnormal body through the 0 value, and the values ​​of the abnormal body are all greater than 0; among them, the 5m×5m and 10m×10m ground observation networks are basically consistent in the characterization of the position and morphology of the abnormal body; the 20m×20m ground observation network can accurately locate the abnormal position, the density of the ground observation network is relatively large, and the morphology of the abnormal body is slightly different, which can meet the detection needs. From the processing results of ground observation networks with different densities, it can be confirmed that the greater the density of the ground observation network, the better the characterization of the abnormal body. However, during field construction, factors such as geological tasks and construction costs need to be considered comprehensively. This embodiment uses a 10×20m ground observation network for data collection. Figure 11-Figure 12 The results are processed using a 10m×20m ground observation network. The position of the anomaly is consistent with the model, the anomaly values ​​are all greater than 0, and there are relatively good anomaly displays in both the x and y directions, which can meet the detection needs.

[0154] Refer to Table 2, combined with the buried depth of the main fracturing section, the total amount of injected fracturing fluid and the plane distribution of microseismic events, determine the location of the excitation source electrode, the excitation current, the excitation point in the well, the excitation signal period, the number of single frequency point cycles, the range of the ground observation network, the point-line distance and the electrode distance of the ground receiving electrode, etc. The excitation signal period and the number of single frequency point cycles should be determined based on the formation resistivity layered model and the depth of the fracturing section. The monitoring network area needs to be larger than the estimated distribution range of the fracturing fluid, and the electrode distance of the ground receiving electrode should be determined based on the signal-to-noise ratio of the collected original signal being greater than 5.

[0155] Table 2 Layout parameters

[0156]

[0157] Step 5: According to the location of the ground excitation source electrode, bury the ground excitation source electrode in the ground. According to the scope of the ground observation network, the point-line distance and the electrode distance of the ground receiving electrode, lay out the ground observation network in the ground monitoring area. The ground observation network is as follows: Fig.13 and Fig.14 The regular ground observation network is shown.

[0158] Step 6: According to the excitation point in the well, the excitation signal cycle and the number of single frequency point cycles, in the excitation well, the excitation point in the well is moved up from deep to shallow, and the excitation source electrodes in the well are set in sequence. The excitation source electrode in the well continuously emits high-power pulse excitation current to the ground, and excites the induced electromagnetic field in the ground, so that the underground medium generates induced eddy currents, in which the induced eddy currents gradually diffuse and decay in the underground half space. The diffusion speed and attenuation amplitude are related to the conductivity of the underground medium.

[0159] Step 7: The ground observation network collects radial horizontal electric field components to obtain original field time series data.

[0160] Step 8: After checking that the header information in the original field time series data is correct, intercept and convert the Age format file, perform noise analysis, spectrum analysis and filtering, and obtain the filtered field time series data. Superimpose and Fourier transform the filtered field time series data to obtain frequency data. Establish a database based on the frequency data, perform current normalization processing, and obtain the amplitude and phase under different harmonics.

[0161] Step 9: Calculate the differential phase anomaly of the formation between the excitation points in each adjacent well according to the phase under each harmonic. Draw the corresponding differential phase anomaly plane diagram according to the differential phase anomaly of the formation between the excitation points in each adjacent well. Among them, the differential phase anomaly plane diagram corresponding to AB2-AB3 is as follows: Fig.15As shown, it reflects the changing characteristics of the water-bearing boundary zone in the strata between the excitation points in Wells 2 and 3 (depth 3917m-3909m). The high phase anomaly is distributed in the southern part of Well 01, which is speculated to be an area where fluid may be enriched.

[0162] Step 10: According to all the differential phase anomaly planes in the excitation segment, the three-dimensional differential phase data volume is determined, and the phase depth slice can be obtained along the survey line direction, which can intuitively reflect the water content characteristics of the reservoir within the depth range of 3925 meters to 3637 meters. Fig.16 As shown, the three-dimensional display of the differential phase line direction slice is as follows Fig.17 shown.

[0163] Step 11: Calculate the apparent resistivity of the formation corresponding to the excitation point in each well according to the geometric coefficient and amplitude of the apparent resistivity of the excitation point in each well. Draw the corresponding apparent resistivity plane diagram according to the apparent resistivity of the formation corresponding to the excitation point in each well. The apparent resistivity plane diagram corresponding to AB1 is as follows: Fig.18 As shown in the figure, it mainly reflects the relative change characteristics of the resistivity of the formation (3925m) corresponding to the excitation point in Well No. 1. There are mainly two low-resistance areas: ① The low-resistance area is located at the bottom of Well 01 and its periphery, and the shape is a lens with the long axis in the NW direction. The low-resistance anomaly in the NW direction extends to the bottom of Well 02, and the low-resistance anomaly in the SE direction changes to a near SN direction. The center of the low-resistance anomaly is located at the southeast direction of the bottom of Well 01; ② The low-resistance area is distributed on the west and southwest sides of Well 01. The low-resistance anomaly is overall in the shape of a NW-trending belt and extends to the central low-resistance anomaly.

[0164] Step 12: Determine the three-dimensional resistivity inversion data volume based on all apparent resistivity plane maps in the excitation segment. Slices can be made at any depth to analyze the spatial distribution characteristics of the resistivity in the measurement area. The three-dimensional resistivity inversion data volume is as follows: Fig.19 As shown, the three-dimensional resistivity depth slice stereogram is as follows Fig. 20 shown.

[0165] Step 13: Determine the differential resistivity between the formations corresponding to the excitation points in the adjacent wells according to the apparent resistivity of the formations corresponding to the excitation points in the adjacent wells. Draw the corresponding differential resistivity plane diagram according to the differential resistivity between the formations corresponding to the excitation points in the adjacent wells. The differential resistivity plane diagram corresponding to AB2-AB3 is shown in Fig.21 As shown, it mainly reflects the relative resistivity change characteristics of the strata between the excitation points in Wells 2 and 3 (depth 3917m-3909m). The low resistivity area is distributed in the southern part of Well 01, which is presumed to be a water-rich area with developed fractures and good connectivity.

[0166] Step 14: Determine the three-dimensional space differential resistivity data volume based on all differential resistivity plane maps in the excitation segment. A longitudinal slice is obtained along any direction, which reflects the relative electrical property change characteristics of the formation in the longitudinal direction, and intuitively displays the fracture development, water abundance and connectivity within the depth range of 3925m-3637m of the reservoir. The three-dimensional space differential resistivity data volume is as follows: Fig. 22 As shown, the three-dimensional display of the differential resistivity longitudinal slice is as follows Fig.23 shown.

[0167] Step 15: The spatial distribution of low-resistance anomalies is displayed in three dimensions. Fig.24 Combined with microseismic monitoring, geophysical exploration results around the well and logging information, the appropriate low-resistance anomaly boundary value is selected, the spatial distribution characteristics of the low-resistance anomaly are displayed in three dimensions, and the water content and fracture connectivity are predicted.

[0168] In this embodiment, the 2000Ω·m contour line is selected as the outer boundary of the low-resistance anomaly, and the area below 2000Ω·m is an area where cracks and crack clusters are developed and have a certain degree of water filling. Fig.24 The medium and low resistivity anomalies are mainly distributed around Wells 01 and 02 and in the southern part of the work area. They are the main water-filled areas with good fracture connectivity and relatively sufficient transformation. The low resistivity anomaly at the bottom of Well 01 presents a barreled feature, which is developed from shallow to deep; the low resistivity anomaly in the southern part of the work area is layered and distributed vertically at a depth of 3750m or less. Local low resistivity anomalies are developed on the east and west sides of Well 02. The scale of the anomaly gradually decreases from shallow to deep, and the shape is an inverted cone, which is mainly distributed at a depth of 3800m or less.

[0169] Comprehensive analysis shows that the fracture networks of Wells 01 and 02 have certain connectivity, with the best connectivity at 3700m-3740m; the fracture networks of Wells 01 and 03 have poor connectivity.

[0170] In an exemplary embodiment, a computer device is provided, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement a method for determining water content and connectivity of fractures based on a well-ground electromagnetic detection system.

[0171] In an exemplary embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, a method for determining water content and connectivity of fractures based on a well-to-ground electromagnetic detection system is implemented.

[0172] In an exemplary embodiment, a computer program product is provided, including a computer program, which, when executed by a processor, implements a method for determining water content and connectivity of fractures based on a well-to-ground electromagnetic detection system.

[0173] In an exemplary embodiment, a computer device is provided. The computer device may be a server or a terminal. The internal structure diagram thereof may be as follows: Fig.25 As shown. The computer device includes a processor, a memory, an input / output interface (Input / Output, referred to as I / O) and a communication interface. The processor, the memory and the input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The input / output interface of the computer device is used to exchange information between the processor and an external device. The communication interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, a method for determining the water content and connectivity of fractures based on a well-ground electromagnetic detection system is implemented.

[0174] Those skilled in the art will understand that Fig.25 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0175] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with relevant regulations.

[0176] Those of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in the present application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM may be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0177] The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. The non-relational database may include a distributed database based on blockchain, etc., but is not limited thereto. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., but is not limited thereto.

[0178] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0179] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A method for determining fracture water content and connectivity based on a well-ground electromagnetic detection system, characterized in that: The well-ground electromagnetic detection system comprises: a ground transmitting source, a ground excitation source electrode, an in-well excitation source electrode and a ground observation network; the ground observation network comprises a plurality of ground receiving electrodes; The method for determining the water content and connectivity of fractures based on the well-ground electromagnetic detection system includes: Acquire multiple sets of historical data; the historical data include: drilling geological stratification information, logging curves, fracturing section location information and fracturing fluid resistivity; Based on each set of historical data, the layout parameters of the well-ground electromagnetic detection system are determined; the layout parameters include: the position of the ground excitation source electrode, the excitation current, the excitation point in the well, the excitation signal period, the number of single frequency point periods, and the range of the ground observation network, the point-line distance and the electrode distance of the ground receiving electrode; Based on the deployment parameters, deploy the well-ground electromagnetic detection system and collect original field time series data; Based on the original field time series data, frequency data is determined; the frequency data includes: real components, imaginary components and coordinate data of all frequencies of each measuring point and real components, imaginary components and coordinate data of the excitation current; the measuring point is the midpoint between two ground receiving electrodes; Based on the frequency data, current normalization processing is performed to obtain the amplitude and phase under different harmonics; Based on the amplitude and the phase under each harmonic, determine the three-dimensional data volume of the excitation segment; the three-dimensional data volume includes: a three-dimensional spatial differential phase data volume, a three-dimensional resistivity inversion data volume and a three-dimensional spatial differential resistivity data volume; the excitation segment includes the formations corresponding to the excitation points in all wells; Based on the three-dimensional data volume, the water content and fracture connectivity of the excitation section are determined.

2. The method for determining fracture water content and connectivity based on a well-ground electromagnetic detection system according to claim 1, characterized in that: Based on each set of historical data, the layout parameters of the well-ground electromagnetic detection system are determined, including: Based on each set of historical data, a corresponding fracture model is constructed; Carrying out forward modeling for each of the fracture models under different ground observation networks, and drawing forward modeling result diagrams for each of the ground observation networks for each of the fracture models; Based on each of the forward modeling result diagrams, the layout parameters are determined.

3. The method for determining fracture water content and connectivity based on a well-ground electromagnetic detection system according to claim 2, characterized in that: The ground transmitting source, the ground excitation source electrode and each ground receiving electrode are all arranged on the ground, and the in-well excitation source electrode is arranged in the excitation well.

4. The method for determining fracture water content and connectivity based on a well-ground electromagnetic detection system according to claim 2, characterized in that: Based on each set of historical data, the corresponding fracture model is constructed, including: According to the logging curves described in the drilling geological stratification information in each group of historical data, a formation resistivity layered model corresponding to each group of historical data is constructed; A fracture model corresponding to each set of historical data is constructed according to the formation resistivity layered model, fracturing section location information and fracturing fluid resistivity corresponding to each set of historical data; the fracture model includes a horizontal plate model and a vertical plate model.

5. The method for determining fracture water content and connectivity based on a well-ground electromagnetic detection system according to claim 1, characterized in that: Based on the deployment parameters, the well-ground electromagnetic detection system is deployed, and original field time series data is collected, including: According to the position of the ground excitation source electrode, burying the ground excitation source electrode in the ground; Deploy the ground observation network in the ground monitoring area according to the scope of the ground observation network, the distance between points and lines, and the electrode distance between ground receiving electrodes; According to the excitation point in the well, the excitation signal cycle and the number of single frequency point cycles, the excitation point in the well is moved upward from deep to shallow in the excitation well, and the excitation source electrodes in the well are set in sequence; During the upward movement, the excitation source electrode flow in the well continuously emits excitation current underground, and the ground observation network collects radial horizontal electric field components to obtain the original field time series data.

6. The method for determining fracture water content and connectivity based on a well-ground electromagnetic detection system according to claim 1, characterized in that: Based on the original field time series data, determining frequency data includes: Performing spectrum analysis and filtering on the original field time series data to obtain filtered field time series data; The filtered field time series data are superimposed and Fourier transformed to obtain the frequency data.

7. The method for determining fracture water content and connectivity based on a well-ground electromagnetic detection system according to claim 1, characterized in that: Based on the amplitude and phase of each harmonic, the three-dimensional data volume of the excitation segment is determined, including: According to the phase of each harmonic, the differential phase anomaly of the formation between the excitation points in each adjacent well is calculated; According to the differential phase anomaly of the formation between the excitation points in each adjacent well, a corresponding differential phase anomaly plane map is drawn; Determining the three-dimensional spatial differential phase data volume according to all differential phase anomaly plane images in the excitation segment; Calculating the apparent resistivity of the formation corresponding to the excitation point in each well according to the geometric coefficient of the apparent resistivity corresponding to the excitation point in each well and the amplitude; According to the apparent resistivity of the formation corresponding to the excitation point in each well, draw the corresponding apparent resistivity plane diagram; Determine the three-dimensional resistivity inversion data volume according to all apparent resistivity plane maps in the excitation segment; Determine the differential resistivity between the formations corresponding to the excitation points in the adjacent wells according to the apparent resistivity of the formations corresponding to the excitation points in the adjacent wells; According to the differential resistivity between the formations corresponding to the excitation points in each adjacent well, a corresponding differential resistivity plane diagram is drawn; The three-dimensional spatial differential resistivity data volume is determined according to all differential resistivity plane images in the excitation segment.

8. A computer device comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the method for determining the water content and connectivity of fractures based on a well-to-ground electromagnetic detection system as described in any one of claims 1 to 7.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method for determining the water content and connectivity of fractures based on a well-to-ground electromagnetic detection system as described in any one of claims 1 to 7 is implemented.

10. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the method for determining the water content and connectivity of fractures based on a well-to-ground electromagnetic detection system as described in any one of claims 1 to 7 is implemented.

Images