CN-121702890-B - Fracturing crack imaging physical simulation method and system combined with non-uniform contact electrode

CN121702890BCN 121702890 BCN121702890 BCN 121702890BCN-121702890-B

Abstract

The invention relates to the technical field of oilfield reservoir research, in particular to a fracturing fracture imaging physical simulation method and a fracturing fracture imaging physical simulation system combined with non-uniform contact electrodes, wherein the fracturing fracture imaging physical simulation method and the fracturing fracture imaging physical simulation system comprise the steps of performing resistance modal detection at the current time by utilizing a low-frequency excitation signal in a fracture expansion simulation process to obtain corresponding electric signals; and carrying out fitting comparison on the electric field distribution result of the current time step and the conductive fluid distribution result of the current time step, and outputting the crack parameters and the conductive fluid distribution result of the core fracturing test piece at the current time step based on the fitting comparison result. The invention directly and in-situ senses the change of the electrical characteristics caused by the natural cracks and the fluid contained therein, acquires the electrical signals, reduces the response delay, combines priori knowledge and deep learning to construct the inversion model of the conductive fluid distribution, and effectively improves the accuracy and the reliability of inversion of the conductive fluid distribution.

Inventors

TAN YAWEN
MU ZONGJIE
FANG JINGYI
ZHANG PANPAN
TIAN SHOUCENG
Sheng mao
DAI JIACHENG
ZHOU RONGHAO
XU PENG

Assignees

中国石油大学(北京)克拉玛依校区

Dates

Publication Date: 20260505
Application Date: 20260212

Claims (10)

1. A fracturing crack imaging physical simulation method combined with non-uniform contact electrodes is characterized by comprising the following steps of: Performing crack extension simulation on a rock core fracturing test piece clamped in a rock core clamping device, and performing resistance mode detection at the current time by using a low-frequency excitation signal in the crack extension simulation process to obtain a corresponding electric signal; Inputting the core effective porosity, initial electric field distribution and Darcy equation pre-calculated flow field data of the core fracturing test piece as priori knowledge of a conductive fluid distribution inversion model, and inputting the electric signal as original data of the conductive fluid distribution inversion model to obtain a conductive fluid distribution result of the core fracturing test piece at the current time step; And taking the conductive fluid distribution result of the core fracturing test piece in the previous time step as an initial field of the current time step, determining the core internal crack morphology distribution of the current time step, performing fitting comparison on the core internal crack morphology distribution of the current time step and the conductive fluid distribution result of the current time step, and outputting the core internal crack morphology distribution of the core fracturing test piece in the current time step and the conductive fluid distribution result based on the fitting comparison result.
2. The method for physically simulating fracture imaging by combining non-uniformly distributed contact electrodes according to claim 1, wherein the process for constructing the inversion model of the conductive fluid distribution comprises the following steps: Obtaining a plurality of samples, and dividing the samples into a training sample set and a test sample set according to a proportion, wherein each sample comprises identification information of a conductive fluid distribution result, core effective porosity of a historical core fracturing test piece, initial electric field distribution and flow field data pre-calculated by a Darcy equation, and an electric signal corresponding to a certain time step in crack expansion simulation of the historical core fracturing test piece; Training an initial model by using a training sample set, introducing a loss function during training, ending training when the value of the loss function is stable, and obtaining a conductive fluid distribution inversion model, wherein the initial model is a double-channel U-Net network introducing residual connection and attention mechanism, and comprises a double channel, a feature fusion module, an encoder, a physical constraint module and a decoder, wherein the double channel comprises a priori knowledge input channel and an original data input channel which are parallel, the priori knowledge input channel and the original data input channel are respectively used for inputting priori knowledge and an electric signal, the feature fusion module performs feature fusion and tensor construction on the priori knowledge and the electric signal, the encoder performs 4-level downsampling on the input fusion features, reserves microscopic boundary features through residual connection, performs physical constraint by using the physical constraint module in the encoding process, and the decoder performs feature recovery on the encoded fusion features; And respectively testing the conductive fluid distribution inversion model by using the test sample set, optimizing model parameters of the conductive fluid distribution inversion model, and outputting the conductive fluid distribution inversion model meeting the test evaluation requirement.
3. The method for imaging physical simulation of fracturing cracks by combining non-uniformly distributed contact electrodes according to claim 1 or 2, wherein the method for imaging physical simulation of fracturing cracks by combining non-uniformly distributed contact electrodes is characterized in that a conductive fluid distribution result of a core fracturing test piece in a previous time step is used as an initial field of a current time step, the morphological distribution of the cracks in the core in the current time step is determined, the morphological distribution of the cracks in the core in the current time step is subjected to fitting comparison with the conductive fluid distribution result in the current time step, and the morphological distribution of the cracks and the conductive fluid distribution result of the core fracturing test piece in the core in the current time step are output based on the fitting comparison result, and comprises the following steps: Taking the conductive fluid distribution result of the core fracturing test piece in the previous time step as an initial field of the current time step, and determining the distribution of the morphology of the cracks in the core in the current time step; Fitting and comparing the distribution of the crack morphology in the core of the current time step with the distribution result of the conductive fluid of the current time step to obtain a corresponding fitting error, and judging whether the fitting error is larger than a set value or not; Responding, randomly adjusting the initial field of the previous time step in a set adjustment interval, and returning to redetermine the distribution of the crack morphology in the core of the current time step; and if not, outputting a conductive fluid distribution result of the current time step and the distribution of the crack morphology in the core.
4. The fracturing fracture imaging physical simulation method combining non-uniform contact electrodes according to claim 1 or 2, wherein the core clamping device comprises a clamping body and two end covers, the two end covers are respectively arranged at the front end and the rear end of the clamping body, fluid inlets/outlets are respectively arranged on the two end covers, the clamping body comprises a clamping part and a modal sensing array part which are identical in length and are of hollow quadrangular prism-shaped structures, the modal sensing array part is sleeved in the clamping part, the modal sensing array part comprises five layers of modal sensing array measuring layers which are sequentially arranged from top to bottom, each modal sensing array measuring layer comprises four sections of sensing array measuring sections with identical structures, adjacent sensing array measuring sections are connected through an insulating rubber block to form a closed modal sensing array measuring layer, each section of sensing array measuring section comprises seven resistance electrodes which are arranged at intervals, an insulating rubber block is arranged between the adjacent resistance electrodes, and four stress loading modules are respectively arranged on the outer sides of the five layers of the sensing array measuring layers.
5. The method for imaging physical simulation of a fracturing fracture combined with non-uniform contact electrodes according to claim 4, wherein the method for imaging physical simulation of the fracturing fracture combined with the non-uniform contact electrodes is characterized by performing fracture propagation simulation on a core fracturing test piece clamped in a core clamping device, performing resistance mode detection at the current time by using a low-frequency excitation signal in the process of fracture propagation simulation to obtain a corresponding electrical signal, and comprises the following steps: processing a rock core into a rock core fracturing test piece, wherein a simulated wellbore is arranged in the center of the rock core fracturing test piece, and the size of the rock core fracturing test piece is set according to the size of a rock core clamping device; Placing a core fracturing test piece in a modal sensing array component, placing the modal sensing array component in a clamping assembly, filling insulating silicone oil between the clamping assembly and the modal sensing array component through an external pump, pressurizing a stress loading module through the outside, compacting the modal sensing array component while providing stress for the core fracturing test piece, and enabling a resistance electrode on the modal sensing array component to be in full contact with the core fracturing test piece; And injecting conductive fluid into the core fracturing test piece clamped in the core clamping device in a mode of setting displacement or constant pressure, and performing resistance mode detection at the current time by utilizing a low-frequency excitation signal in the process of injecting the conductive fluid and driving cracks to expand so as to obtain a corresponding electric signal.
6. The method for imaging physical simulation of a fracture combined with a non-uniformly distributed contact electrode according to claim 1, 2 or 5, wherein the process of detecting the resistance mode comprises the following steps: Injecting a low-frequency excitation signal into the diagonal resistance electrode pair in the modal sensing array component, measuring the potential difference between the other adjacent resistance electrodes to obtain a corresponding voltage gradient, and calculating to obtain an equivalent resistance value; and (3) circulating the steps, sequentially applying current layer by layer, and determining the equivalent resistance of each multi-mode sensing array measuring layer.
7. A physical simulation system for imaging a fracture by combining non-uniform contact electrodes by using the method as set forth in any one of claims 1 to 6, which comprises a simulation detection part and a dynamic inversion part; The simulation detection part comprises a core clamping device and an excitation and detection device, wherein the core clamping device is used for fracturing a test piece, crack expansion simulation is carried out on the core fracturing test piece clamped in the core clamping device, and the excitation and detection device is used for carrying out resistance mode detection at the current time by utilizing a low-frequency excitation signal in the crack expansion simulation process to obtain a corresponding electric signal; a dynamic inversion section comprising: The dynamic inversion unit inputs the core effective porosity, initial electric field distribution and flow field data pre-calculated by a Darcy equation of the core fracturing test piece as priori knowledge of a conductive fluid distribution inversion model, and inputs the electric signal as raw data of the conductive fluid distribution inversion model to obtain a conductive fluid distribution result of the core fracturing test piece at the current time step; And the crack fitting unit is used for taking the conductive fluid distribution result of the core fracturing test piece in the previous time step as an initial field of the current time step, determining the core internal crack morphology distribution of the current time step, performing fitting comparison on the core internal crack morphology distribution of the current time step and the conductive fluid distribution result of the current time step, and outputting the core internal crack morphology distribution of the core fracturing test piece in the current time step and the conductive fluid distribution result based on the fitting comparison result.
8. The fracturing fracture imaging physical simulation system combining non-uniform contact electrodes according to claim 7, wherein the core clamping device comprises a clamping body and two end covers, the two end covers are respectively arranged at the front end and the rear end of the clamping body, fluid inlets/outlets are respectively arranged on the two end covers, the clamping body comprises a clamping component and a modal sensing array component which are identical in length and are of hollow quadrangular prism-shaped structures, the modal sensing array component is sleeved in the clamping component, the modal sensing array component comprises five layers of modal sensing array measuring layers which are sequentially arranged from top to bottom, each modal sensing array measuring layer comprises four sections of sensing array measuring sections with identical structures, adjacent sensing array measuring sections are connected through an insulating rubber block to form a closed modal sensing array measuring layer, each section of sensing array measuring section comprises seven resistance electrodes which are arranged at intervals, an insulating rubber block is arranged between the adjacent resistance electrodes, and four stress loading modules are respectively arranged on the outer sides of the five layers of the modal sensing array measuring layers; or/and the combination of the two, The excitation and detection device comprises an excitation source module and a detection module; The excitation source module is provided with a frequency resistance excitation channel, outputs 10Hz-100kHz square wave current, has a maximum current of less than or equal to 20mA, and supports the axial and radial resistance gradient measurement of the core; the detection module comprises a resistance gradient measurement module and performs resistance mode detection.
9. The fracturing fracture imaging physical simulation system of claim 7 or 8, further comprising a model construction unit for conducting fluid distribution inversion model construction process, comprising: The sample acquisition module is used for acquiring a plurality of samples, and dividing the samples into a training sample set and a test sample set according to a proportion, wherein each sample comprises identification information of a conductive fluid distribution result, core effective porosity of a historical core fracturing test piece, initial electric field distribution and flow field data pre-calculated by a Darcy equation, and an electric signal corresponding to a certain time step in crack expansion simulation of the historical core fracturing test piece; The training module is used for training an initial model by utilizing a training sample set, introducing a loss function during training, finishing training when the value of the loss function is stable, obtaining a conductive fluid distribution inversion model, wherein the initial model is a double-channel U-Net network introducing residual connection and an attention mechanism, and comprises a double channel, a feature fusion module, an encoder, a physical constraint module and a decoder, the double channel comprises a priori knowledge input channel and an original data input channel which are parallel, the priori knowledge input channel and the original data input channel are respectively used for inputting priori knowledge and an electric signal, the feature fusion module performs feature fusion and tensor construction on the priori knowledge and the electric signal, the encoder performs 4-level downsampling on the input fusion features, reserves microscopic boundary features through residual connection, performs physical constraint on the encoded fusion features in the encoding process, and the decoder performs feature recovery on the encoded fusion features; the testing module is used for testing the conductive fluid distribution inversion model respectively by using the testing sample set, optimizing model parameters of the conductive fluid distribution inversion model and outputting the conductive fluid distribution inversion model meeting the testing and evaluating requirements.
10. The fracturing fracture imaging physical simulation system of claim 7 or 8, in combination with non-uniformly distributed contact electrodes, wherein the fracturing fitting unit comprises: The solving module is used for taking the conductive fluid distribution result of the core fracturing test piece in the previous time step as an initial field of the current time step and determining the distribution of the crack morphology in the core in the current time step; The fitting module is used for carrying out fitting comparison on the distribution of the crack morphology in the core of the current time step and the distribution result of the conductive fluid of the current time step to obtain a corresponding fitting error, and judging whether the fitting error is larger than a set value or not; and the fitting output module is used for randomly adjusting the initial field of the previous time step in a set adjustment interval and returning to redetermine the distribution of the crack morphology in the core of the current time step in response to the response, and outputting the conductive fluid distribution result and the distribution of the crack morphology in the core of the current time step in response to the response.

Description

Fracturing crack imaging physical simulation method and system combined with non-uniform contact electrode Technical Field The invention relates to the technical field of oilfield reservoir research, in particular to a fracturing fracture imaging physical simulation method and system combined with non-uniform contact electrodes. Background The crack morphology is an important representation of the fracturing development effect of the oil and gas reservoir, and is important for rapidly and accurately obtaining the crack development condition and evaluating the fracturing development effect of the oil and gas reservoir. At present, the indoor test and the numerical simulation are main methods for acquiring the development form of the crack, and specifically: The physical simulation test can visually reflect the cracking, expansion and morphological characteristics of the crack by carrying out fracturing on a small-scale rock core, and is a key means for researching the complex crack network formation mechanism and evaluating the fracturing scheme effect. However, the existing physical simulation crack monitoring technology has remarkable limitations that 1, an acoustic emission technology locates a crack event point by capturing elastic waves generated by rock fracture, but is difficult to accurately depict a continuous crack geometric form, has insufficient spatial resolution and limited sensitivity to microcracks or non-brittle fractures and is easy to be interfered by background noise, 2, a CT technology can provide three-dimensional structural information with high resolution, but has low scanning speed, is difficult to capture a transient process of rapid dynamic expansion of the crack in the fracturing process, so that morphological information of a key expansion stage is lost or blurred, and 3, CT, nuclear magnetic resonance imaging equipment has high purchase and maintenance cost and special working environment requirements limit the integrated application of the imaging equipment in a conventional autoclave simulation device; Numerical simulation methods for predicting fracture morphology are highly dependent on input constitutive models, fracture criteria, and parameters, which are often difficult to accurately acquire or calibrate, and the simulation of complex geomechanical interactions remains a challenge. Existing fracture imaging simulation inversion methods, for example: The first published patent document, publication number is CN114239431B, discloses a simulation method, device and equipment for water flooding of a fracture development reservoir, based on water flooding displacement streamline characteristics of fracture cores of different production in the fractured reservoir, a matrix is divided into a plurality of linear subareas, a water flooding two-dimensional problem is converted into a one-dimensional linear subarea coupling solution problem, a research area is divided into an injection area, a fracture area and a production area, corresponding linear flow models are respectively established, each linear flow model is sequentially solved, linear displacement analytical solution of a matrix area at the injection end, linear diversion numerical solution of the fracture, linear displacement analytical solution of the matrix at the outlet end and linear flow of a fracture system are coupled, the water flooding two-dimensional problem is converted into a one-dimensional linear subarea coupling solution problem, linear flow half analytical solution of three areas with the fracture flooding water is obtained, and then pressure distribution and saturation distribution of the fracture development reservoir are obtained, and accurate simulation of the water process of the fracture development reservoir is realized. The method does not relate to a fracturing fracture imaging physical simulation method combining non-uniform contact electrodes for constructing resistance mode detection, conductive fluid distribution inversion and fracture fitting, and can not combine resistance mode detection, priori knowledge and deep learning to dynamically analyze the geometric forms and conductivity distribution of non-planar seams and branch seams. The prior published patent document No. CN116068662A discloses a crack random simulation method and device based on a crack development intensity trend, the method comprises the steps of establishing a crack development intensity distribution map, conducting physical simulation based on preset crack simulation parameters, randomly generating a crack simulation center and corresponding crack probability parameters, extracting the crack intensity corresponding to the corresponding crack center from the crack development intensity distribution map based on the crack simulation center, verifying the crack probability parameters based on the crack intensity, calculating the starting point and the end point coordinates of a crack to which the crack simulation center cor