Detonation fracturing monitoring method and device based on tracer monitoring and distributed optical fiber sensing monitoring

Abstract

The invention belongs to the field of oil and gas development and energy utilization, particularly relates to a detonation fracturing monitoring method and device based on tracer monitoring and distributed optical fiber sensing monitoring, and aims to solve the problems that in the prior art, detonation fracturing rapid dynamic change monitoring is insufficient, and exertion of the advantages of environmental protection and resource saving is restricted. The method comprises the following steps: calculating the volume of a hydraulic fracturing crack according to the volume of a flowback tracer agent; calculating the volume of the liquid explosive required by the hydraulic fracturing fracture volume; the liquid explosive with the adjusted viscosity is pumped into a hydraulic fracturing crack in the horizontal well; based on distributed optical fiber monitoring equipment, monitoring data obtained after the liquid explosive is detonated are obtained, inversion calculation is conducted on the monitoring data, the reservoir transformation effect of detonation fracturing is evaluated, and the stress-strain state of the reservoir after detonation fracturing is detected. According to the invention, real-time accurate monitoring of temperature, pressure and strain change in the detonation fracturing process is realized, and resource saving is realized.

Description

Technical Field

[0001] The present invention belongs to the field of oil and gas development and energy utilization, and in particular relates to a detonation fracturing monitoring method and device based on tracer monitoring and distributed optical fiber sensing monitoring. Background Art

[0002] Hydraulic fracturing is a widely used technology in shale oil and gas development. Since the 1950s, it has played a key role in the development of shale gas, tight gas, and other difficult-to-extract resources. The core principle of hydraulic fracturing is to inject high-pressure fluid into underground rock formations to create and expand fractures, thereby increasing the rock's permeability and allowing oil and gas to flow more easily to the wellbore and be extracted. The fluid, typically composed of water, sand, and various chemical additives, is injected into the underground rock formation under high pressure, creating and maintaining open fractures, thereby enhancing the flow of oil and gas. This technology has the advantage of increasing well production and is applicable to deep reservoirs. After decades of development, the technology has become relatively mature. However, hydraulic fracturing has several significant drawbacks: First, its ability to stimulate reservoirs is limited, particularly in low- and ultra-low-permeability reservoirs. Second, and this is a key limitation in major shale oil producing areas in my country, such as Xinjiang and Ordos, due to its significant water consumption. These areas are already severely water-scarce. Large-scale hydraulic fracturing operations (a single well can consume tens of thousands of tons of water) not only exacerbate local water shortages, but also bring about environmental impacts such as fracturing fluid flowback, wastewater treatment, and potential groundwater contamination, greatly limiting the sustainable application and economic viability of this technology.

[0003] In recent years, explosive fracturing, a new technology with significant resource-saving and environmental advantages, has gained traction. This technology utilizes shock waves and stress waves generated by explosive detonations within reservoir fractures to disrupt the rock mass surrounding the wellbore, creating a network of densely distributed, fine fractures. This significantly increases reservoir permeability, thereby boosting shale oil and gas production. Its core advantage is its radical departure from traditional fracturing's dependence on water resources. In particular, explosive fracturing eliminates the need for water as a fracturing fluid, fundamentally eliminating the need for large amounts of freshwater for hydraulic fracturing. This is revolutionary for shale oil development in severely water-scarce regions of my country, such as Xinjiang and Ordos. It directly addresses water resource bottlenecks and significantly reduces environmental pressures and costs. Furthermore, this technology avoids the use of proppants and large amounts of chemical additives, further demonstrating its material savings.

[0004] Because explosive fracturing is a dynamic fracturing process that releases energy in an extremely short period of time, some fracture networks develop even more quickly during the reservoir stimulation process. Microseismic monitoring techniques, widely used in hydraulic fracturing to assess reservoir stimulation and fracture propagation, are no longer applicable in this situation. The principle behind microseismic monitoring is that human engineering activities (geological exploration, oil and gas extraction) damage the surrounding rock structure, leading to localized stress concentrations within it. Due to the inherent strength of the surrounding rock, this localized accumulation of large amounts of energy can cause microscopic damage or plastic deformation. Microdamage gradually accumulates, forming macroscopic cracks. During the formation and propagation of cracks, energy is released in the form of elastic waves. The low-frequency (generally below 1 kHz) rock acoustic emissions generated by this process are called microseismic events, also known as small-magnitude events. Microseismic monitoring technology uses the microseismic activity generated by reservoir fracturing during oil well production to assess the formation and propagation of fracture systems, and thus the effectiveness of reservoir stimulation.

[0005] Since explosive fracturing releases extremely high energy in a very short period of time, traditional microseismic monitoring technology used for hydraulic fracturing cannot capture the changes in rapidly formed fracture networks. Microseismic monitoring requires the deployment of a large number of sensors on the surface, and even so, it is difficult to capture high-frequency explosive fracturing events, making it difficult to accurately evaluate the effect of reservoir transformation.

[0006] Existing monitoring technologies are primarily based on static or relatively slow-moving designs. These methods are insufficient for the instantaneous, dynamic nature of detonation fracturing, severely impacting its enormous potential to save time, materials (water, proppant, chemicals), and costs. There is an urgent need to develop new, efficient, dynamic, and real-time monitoring methods to fully leverage the advantages of detonation fracturing: efficiency, economy, and environmental friendliness, while avoiding the waste of resources and loss of efficiency caused by monitoring failures.

[0007] Based on this, the present invention proposes a detonation fracturing monitoring method and device based on tracer monitoring and distributed optical fiber sensing monitoring. Summary of the Invention

[0008] In order to solve the above-mentioned problems in the existing technology, namely, the defects of the existing monitoring technology such as response lag and inability to adapt to instantaneous dynamic processes, which make it impossible to effectively evaluate the effect of detonation fracturing, and seriously restrict the technology from exerting its key environmental protection and resource conservation advantages such as water saving, material saving, and efficiency improvement, the present invention proposes a detonation fracturing monitoring method and device based on tracer monitoring and distributed optical fiber sensing monitoring.

[0009] In a first aspect, the present invention provides a detonation fracturing monitoring method based on tracer monitoring and distributed optical fiber sensing monitoring, the method comprising the following steps: Step S1: After drilling is completed, a tracer is injected into the horizontal well, and the hydraulic fracture volume is calculated based on the tracer volume returned; Step S2, calculating the volume of liquid explosive required for the hydraulic fracturing crack volume and adjusting the viscosity of the liquid explosive; Step S3, pumping the liquid explosive with adjusted viscosity into the hydraulic fracturing crack in the horizontal well; Step S4: obtaining monitoring data after detonating the liquid explosive using the distributed optical fiber monitoring equipment, evaluating the reservoir stimulation effect of the detonation fracturing by performing inversion calculations on the monitoring data, and detecting the stress-strain state of the reservoir after the detonation fracturing; The distributed optical fiber monitoring equipment is installed on a detonation fracturing monitoring device based on tracer monitoring and distributed optical fiber sensing monitoring.

[0010] Furthermore, the volume of the liquid explosive is calculated as follows: Step S21, calculating the height of the main fracture according to the volume of the fracturing fluid injected for hydraulic fracturing; Step S22, calculating the maximum crack width of the main crack based on the fluid pressure, formation elastic modulus, Poisson's ratio and the height of the main crack during the construction phase; Step S23, calculating the length of the liquid explosive at the critical detonation diameter according to the maximum crack width, the critical detonation diameter of the liquid explosive, and the half crack length of the hydraulic fracturing design; Step S24 , calculating the volume of the liquid explosive based on the length of the liquid explosive at the critical detonation diameter, the maximum crack width, and the critical detonation diameter of the liquid explosive.

[0011] Furthermore, the maximum crack width , which is calculated as follows: ; in, v is Poisson's ratio, E is the formation elastic modulus, H is the height of the main crack, P 0 is the fluid pressure during the construction phase.

[0012] Furthermore, the length of the liquid explosive at the critical detonation diameter L d , which is calculated as follows: ; in, is the critical detonation diameter of liquid explosives, L Half crack length designed for hydraulic fractures.

[0013] Furthermore, the volume of liquid explosives , which is calculated as follows: .

[0014] Furthermore, the distributed optical fiber monitoring device includes one or more of a distributed temperature optical fiber sensor, a distributed acoustic wave optical fiber sensor, and a distributed strain optical fiber sensor.

[0015] Furthermore, the distributed optical fiber monitoring device is installed on one side of the outer circumference of the casing close to each perforation opening.

[0016] Furthermore, the distributed optical fiber monitoring device is installed in an optical fiber collection column, and the optical fiber collection column is installed on the outer circumference of the casing near the edge of each perforation port.

[0017] Furthermore, the axial direction of the optical fiber collection column is perpendicular to the axial direction of the sleeve.

[0018] Another aspect of the present invention provides a detonation fracturing monitoring device based on tracer monitoring and distributed optical fiber sensing monitoring, and a detonation fracturing monitoring method based on tracer monitoring and distributed optical fiber sensing monitoring. The device includes a bridge plug, an initiator, a safety gun, a centralizer, a packer, an optical fiber collection column, a perforation port, and a casing; A horizontally placed casing is lowered into the horizontal well. A plurality of perforations are evenly opened on both sides of the casing along its length, wherein the perforations on one side are staggered with the perforations on the other side. An optical fiber collection column is provided at the edge of each perforation, and the optical fiber collection column is fixed on the outer surface of the casing. A plurality of centralizers are coaxially mounted on the outer surface of the casing, and the centralizers are used to centralize the casing; A packer, a detonator, and a safety gun are sequentially arranged in the casing from the end close to one side of the vertical well to the other end; the detonator is used to detonate the liquid explosive, and the safety gun is used to transmit a detonation signal to the detonator; A bridge plug is provided on the well wall of the horizontal well on the side close to the vertical well, and the bridge plug is used to prevent the backflow of liquid explosives and fluid during the hydraulic fracturing process.

[0019] Beneficial effects of the present invention: By combining tracer monitoring with distributed fiber optic sensing technology, this invention can acquire key dynamic data (temperature, pressure, and strain) during explosive fracturing in real time, enabling precise assessment of reservoir stimulation effectiveness. This not only provides a scientific basis for production optimization, but more importantly, accurate assessment avoids repeated fracturing or ineffective interventions due to unclear results, thereby fundamentally eliminating unnecessary consumption of explosives, labor, and energy, embodying the core value of resource conservation.

[0020] Flowback tracers are used to accurately calculate fracture volume, which is then used to optimize the amount and viscosity of liquid explosives, ensuring efficient use of explosives. This precise control minimizes explosive waste, significantly reducing construction costs and potential environmental risks (such as unexploded explosive residue), demonstrating resource conservation and environmental friendliness.

[0021] The method (detonation fracturing + monitoring) offers a very short overall operation time, from injection to detonation to effect evaluation, all in one go. Compared to the lengthy construction and flowback waiting periods of traditional hydraulic fracturing, this significantly shortens the time-to-production cycle. This not only significantly improves operational efficiency but also directly saves significant time, equipment, and labor costs, making it a model of efficiency savings.

[0022] The self-supporting fracture network created by explosive fracturing completely eliminates the massive amounts of proppants (such as sand) and fracturing fluid (water) required to carry them, as required by traditional hydraulic fracturing. This directly achieves zero water consumption, avoiding the environmental footprint of proppant extraction, transportation, and injection, as well as the risk of chemical contamination associated with the preparation and use of fracturing fluids. This represents a revolutionary breakthrough in environmental protection and material conservation.

[0023] Distributed fiber-optic sensing technology replaces traditional microseismic monitoring, effectively resolving the latter's failure during high-speed detonation. Fiber-optic sensing eliminates the need for numerous surface sensors, reducing equipment investment and enabling more efficient and real-time data acquisition. This efficient and low-cost monitoring method inherently conserves resources, while its precise assessment capabilities ensure savings throughout the entire operation.

[0024] The design of integrating distributed fiber optic monitoring equipment into a dedicated perforating gun not only ensures stable and reliable monitoring and construction safety, but also avoids the manpower, material resources and time investment required by traditional monitoring methods (such as the deployment of a large number of detectors), further demonstrating efficiency and economy at the equipment deployment level. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Other features, objects and advantages of the present application will become more apparent upon reading the detailed description of non-limiting embodiments made with reference to the following drawings: Figure 1 1 is a flow chart of a detonation fracturing monitoring method based on tracer monitoring and distributed optical fiber sensing monitoring provided by the first embodiment of the present invention; Figure 2 Schematic diagram of the structure of a detonation fracturing monitoring device based on tracer monitoring and distributed optical fiber sensing monitoring provided by the second embodiment of the present invention. DETAILED DESCRIPTION

[0026] The present application will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are intended only to illustrate the relevant invention and are not intended to limit the invention. It should also be noted that, for ease of description, only portions relevant to the relevant invention are shown in the accompanying drawings.

[0027] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0028] The present invention provides a detonation fracturing monitoring method based on tracer monitoring and distributed optical fiber sensing monitoring, the method comprising the following steps: Step S1: After drilling is completed, a tracer is injected into the horizontal well, and the hydraulic fracture volume is calculated based on the tracer volume returned; Step S2, calculating the volume of liquid explosive required for the hydraulic fracturing crack volume and adjusting the viscosity of the liquid explosive; Step S3, pumping the liquid explosive with adjusted viscosity into the hydraulic fracturing crack in the horizontal well; Step S4: obtaining monitoring data after detonating the liquid explosive using the distributed optical fiber monitoring equipment, evaluating the reservoir stimulation effect of the detonation fracturing by performing inversion calculations on the monitoring data, and detecting the stress-strain state of the reservoir after the detonation fracturing; The distributed optical fiber monitoring equipment is installed on a detonation fracturing monitoring device based on tracer monitoring and distributed optical fiber sensing monitoring.

[0029] In order to more clearly explain the detonation fracturing monitoring method based on tracer monitoring and distributed optical fiber sensing monitoring of the present invention, the following is combined with Figure 1 Each step in the embodiment of the present invention is described in detail.

[0030] A detonation fracturing monitoring method based on tracer monitoring and distributed optical fiber sensing monitoring according to a first embodiment of the present invention includes steps S1 to S4, each of which is described in detail as follows: Step S1: After drilling is completed, a tracer is injected into the horizontal well, and the hydraulic fracture volume is calculated based on the tracer volume returned; In this method, horizontal wells are typically 2000-2500 m long, with a single hydraulic fracturing stage length of 40-50 m, 6-8 clusters per stage, and 5-8 m spacing between clusters. Perforation is performed using constant-aperture perforating charges (effective aperture ≥ 10 mm) and an 89-type perforating gun, with a perforation rate of 0.5-2 m per cluster and 3-16 holes per cluster. The main hydraulic fracture width is typically 2 mm.

[0031] In this embodiment, a suitable tracer is selected based on the reservoir characteristics (such as permeability, temperature, pressure, etc.) and the target monitoring requirements. After the drilling operation is completed, the selected tracer is injected into the horizontal well section using a dedicated pump. The injection location should cover the area where explosive fracturing is planned. During the injection process, the injection pressure and flow rate need to be monitored to ensure that the tracer is evenly distributed throughout the target interval. After the injection is completed, the injection pump is turned off and the liquid in the formation is allowed to flow back naturally. This process may take a certain amount of time, depending on the pressure and permeability of the formation. During the flowback period, the flow rate and composition changes of the return fluid are continuously monitored, especially the appearance time and concentration changes of the tracer.

[0032] Surface or downhole sensors collect tracer information from flowback fluids. These sensors detect the presence and concentration of tracers. The collected data is transmitted to a surface control system for processing. Based on the tracer concentration curve in the flowback fluid and known formation parameters (such as porosity, permeability, and fluid loss coefficient), the volume of the fracture network formed after hydraulic fracturing is estimated based on the law of mass conservation.

[0033] The tracer is insoluble in water and has a certain volume (say 100 microns), which prevents the tracer from entering the pores of the rock.

[0034] Method for calculating fracture network volume based on flowback tracer information: Monitor the flowback flow rate of tracers over time Q ( t ) and concentration C ( t ), the average concentration of the return fluid is calculated according to the following formula: ; in t For time, T is the total time of fracturing fluid flowback.

[0035] The total volume of the fracture network V f It can be estimated according to the following formula: ; in C initial is the average concentration of the tracer when the tracer-containing fracturing fluid is injected; V inj is the total volume of injected fracturing fluid; η s is the retention coefficient of the tracer ( η s ≤1).

[0036] Step S2, calculating the volume of liquid explosive required for the hydraulic fracturing crack volume and adjusting the viscosity of the liquid explosive; The present invention adjusts the viscosity of the liquid explosive to approach the viscosity of slickwater, a commonly used proppant, which ranges from 1 to 270 mPa·s. By precisely calculating and adjusting the viscosity before pumping the explosive into the cracks, the liquid explosive can be more evenly distributed within the cracks, significantly enhancing the crack expansion effect and increasing the production of oil and gas wells.

[0037] The volume of the liquid explosive is calculated as follows: Step S21, calculating the height of the main fracture according to the volume of the fracturing fluid injected for hydraulic fracturing; Step S22, calculate the maximum crack width of the main crack according to the fluid pressure, formation elastic modulus, Poisson's ratio and the height of the main crack during the construction phase : ; in, v is Poisson's ratio, E is the formation elastic modulus, H is the height of the main crack, P 0 is the fluid pressure during the construction phase; Step S23, calculating the length of the liquid explosive at the critical detonation diameter according to the maximum crack width, the liquid explosive critical detonation diameter and the half crack length of the hydraulic fracturing design L d : ; in, is the critical detonation diameter of liquid explosives, L Half crack length designed for hydraulic fractures; Step S24, based on the length of the liquid explosive at the critical detonation diameter, the maximum crack width and the liquid explosive critical detonation diameter, the volume of the liquid explosive is calculated. : .

[0038] Step S3, pumping the liquid explosive with adjusted viscosity into the hydraulic fracturing crack in the horizontal well; This embodiment uses a fracturing pump (minimum displacement 0.5m 3 / min) into the horizontal well, and the liquid explosives enter the hydraulic fracturing cracks under strong pumping pressure.

[0039] Step S4: obtaining monitoring data after detonating the liquid explosive using the distributed optical fiber monitoring equipment, evaluating the reservoir stimulation effect of the detonation fracturing by performing inversion calculations on the monitoring data, and detecting the stress-strain state of the reservoir after the detonation fracturing; The distributed fiber optic monitoring equipment is installed on a detonation fracturing monitoring device based on tracer monitoring and distributed fiber optic sensing monitoring. According to the monitoring requirements, appropriate distributed fiber optic sensor types are selected and installed. These sensors may include but are not limited to: Distributed Temperature Fiber Sensor (DTS): Detects the reservoir temperature increase caused by the large amount of heat generated during the detonation fracturing process and is used to monitor temperature change data in the wellbore.

[0040] Distributed acoustic fiber sensor (DAS): monitors the acoustic wave signals of the dynamic expansion of cracks during detonation fracturing and obtains vibration data to capture the stress waves and microseismic activities generated by the detonation.

[0041] Distributed strain fiber sensor (DFS): monitors reservoir deformation after explosive fracturing and obtains strain data, which is used to measure strain changes in rock formations and assess crack expansion.

[0042] Based on the comprehensive processing and analysis of the above three signals (vibration, temperature, and strain), the signal intensity distributed along the optical fiber is obtained, and then the location, direction, and density of crack expansion are determined.

[0043] The distributed fiber optic monitoring device is installed on the outer circumference of the casing near each perforation opening. It is housed within a fiber optic collection column, which is installed on the outer circumference of the casing near the edge of each perforation opening. The axial direction of the fiber optic collection column is perpendicular to the axial direction of the casing, ensuring that the sensor can accurately monitor dynamic changes near each perforation opening.

[0044] Among them, the present invention proposes the concept of tracer monitoring and distributed optical fiber transformation to conduct hydraulic fracturing crack volume assessment and detonation fracturing stress-strain monitoring on the reservoir section that needs to be transformed.

[0045] Based on the monitoring data of distributed fiber optic sensors, the production profile is inverted by combining various inversion methods such as the gradient method and the random method. Inversion calculations are performed on parameters such as fracture characteristics to evaluate the reservoir stimulation effect of explosive fracturing and provide data support for the next stimulation of other reservoir sections in the same horizontal well.

[0046] In this embodiment, step S4 includes the following steps: Step S41: Multimodal sensing data during the detonation process are synchronously collected through a distributed optical fiber sensing system, including strain field fluctuations, acoustic vibration spectrum, and temperature field migration parameters, to construct a spatiotemporally aligned fusion data set. At the moment of detonation, the multimodal synchronous acquisition module of the distributed fiber optic sensing system is activated to synchronously capture the following fused data with millisecond-level time resolution: Distributed strain fiber optic sensors are used to analyze the dynamic strain propagation characteristics of the detonation shock wave at the wellbore-fracture-stratum interface and distinguish the coupling effects of longitudinal waves, shear waves, and surface waves. Distributed acoustic fiber optic sensors are used to record rock fracture acoustic emission events caused by the release of detonation energy within the crack network, and a mapping relationship between acoustic pattern characteristics and crack propagation rate is established. Distributed fiber optic temperature sensors are used to monitor local temperature gradient changes caused by detonation heat release and fracture fluid seepage, thereby locating the fluid migration path in newly formed fractures. A time-space synchronous coordinate system is constructed to dynamically bind the three-dimensional parameters of optical fiber axial distance, detonation timing, and formation depth to generate a time-space aligned fusion data set.

[0047] Step S42: Based on the fused data set, a signal unmixing algorithm is used to separate the characteristics of the dynamic crack expansion event, and the detonation energy propagation path and the crack network topology are inverted in combination with the physical driving model: Based on the fused data set in step S41, a deep learning-driven signal unmixing algorithm is used to separate the low-frequency vibration signals of the reopening of the original fractures, the high-frequency microseismic event clusters of the new fracture extension, and the nonlinear pressure oscillations of the secondary deflagration of the liquid explosive residue; The anisotropic propagation path of detonation energy in heterogeneous formations is inverted based on the arrival time difference of strain wave fronts, and an energy attenuation coefficient matrix is ​​established to quantify the dissipation effect of crack roughness on shock wave energy. The separated multi-source data are input into the crack propagation simulation model to simulate the fractal propagation process of the crack in real time, analyze the fluid-solid coupling behavior of the main crack intersection area and the stress shadow zone, and generate the crack network topology structure.

[0048] Step S43: The fracture network topology and energy propagation path are integrated, and the reservoir transformation volume, fracture permeability, and ground stress field distribution are inverted through multi-parameter coupling analysis to generate a three-dimensional transformation sweet spot index distribution map: By integrating the acoustic emission event density, strain disturbance range, and temperature anomaly area, a time-varying probability cloud map of the transformation volume is constructed, and boundary determination errors are corrected through cross-scale data correlation. A machine learning model for fracture aperture and permeability tensors is established based on the harmonic resonance effect of acoustic signals and the fluid convection velocity derived from temperature field inversion. The strain reconstruction algorithm is used to extract the deflection characteristics of the maximum horizontal principal stress direction in the near-wellbore area. Combined with the fracture network topology, a dynamic geomechanical model is constructed to predict the interference effect of the detonation-induced stress field on the propagation of fractures in adjacent wells. A three-dimensional sweet spot index distribution map is generated to quantify the production capacity contribution weight.

[0049] Step S44: Establish a detonation parameter optimization strategy based on the inversion results, and implement model parameter self-correction through cross-physical field data verification: Establish a knowledge graph associating detonation parameters with fiber response characteristics, and generate dynamic fracturing strategies through reinforcement learning algorithms; The real-time inversion results are coupled with the tracer monitoring data across physical fields for verification, and the energy attenuation coefficient matrix and geomechanical model parameters are corrected to form a self-correcting optimization closed loop.

[0050] Among them, a unified millisecond-level timestamp is added to the distributed strain fiber (DFS), acoustic fiber (DAS), and temperature fiber (DTS) data, and the time synchronization error is less than 0.1ms; According to the formation depth-fiber distance mapping table (calibrated by cable magnetic markers), the DFS strain data, DAS acoustic wave data, and DTS temperature data are spatially interpolated and aligned in segments of one meter.

[0051] The DFS raw strain data were denoised using wavelet thresholding (using the sym8 wavelet basis and soft thresholding); Acoustic spectrum extraction: Perform short-time Fourier transform (STFT) on the DAS acoustic wave signal with a window length of 10ms and a step length of 1ms to generate a time-frequency spectrum matrix; Temperature gradient calculation: Calculate the temperature gradient field of DTS temperature data using the spatial derivative method.

[0052] In this embodiment, the GAN network architecture includes: constructing a generative adversarial network consisting of a generator (U-Net structure) and a discriminator (5-layer CNN), with the DAS time-frequency matrix as input and the separated low-frequency crack re-opening signal (10-100Hz) and high-frequency new crack signal (1-10kHz) as output; Training data: 200 sets of historical fracturing data (including manually annotated fracture type labels) are used for supervised training. The DFS strain waveform was subjected to Hilbert-Huang transform (HHT) to extract the instantaneous frequency of the nonlinear oscillation component. When the frequency suddenly changed to 200-500 Hz, it was determined to be a secondary deflagration event.

[0053] In this embodiment, the time delay of the DFS strain wavefront reaching different optical fiber segments is calculated by a cross-correlation algorithm to invert the wave velocity field.

[0054] In this embodiment, the attenuation coefficient matrix is ​​constructed as follows: Based on DAS signal attenuation rate , fitting frequency-dependent attenuation coefficient α ( f )=0.02 f +0.1 ( f is the frequency, unit is kHz; d is the propagation distance, in m).

[0055] Among them, the crack extension simulation specifically includes: LatticeBoltzmann model parameters: set the grid resolution to 0.1 m × 0.1 m, the fluid viscosity to 5 mPa·s, the rock Young's modulus to 20 GPa, and the Poisson's ratio to 0.25; Adaptive mesh refinement: When the local stress gradient exceeds 10 MPa / m, the mesh is subdivided to 0.05 m × 0.05 m to capture the shear slip effect at the intersection of the main cracks.

[0056] In this embodiment, the specific method for reservoir parameter inversion and sweet spot index calculation is as follows: Quantification of the remodeling volume (SRV): Probabilistic fusion rule: Define the SRV probability as: ;in, is the acoustic emission event density (number of events / m³), normalized to [0,1]; is the strain disturbance amplitude (με), normalized to [0,1]; is the temperature anomaly value (℃), normalized to [0,1].

[0057] Boundary correction: The fiber SRV probability cloud map is aligned with the previous microseismic monitoring point cloud data through transfer learning, and the boundary contour is optimized using Chamfer distance. :

[0058] in, A collection of 3D point clouds generated for distributed fiber-optic monitoring data, representing the spatial and temporal locations of strain, temperature, or acoustic events in the reservoir. p A point in a 3D point cloud generated from distributed fiber optic monitoring data.

[0059] is a three-dimensional point cloud collection of microseismic monitoring data, representing the location of crack propagation events. q It is a point in the three-dimensional point cloud set of microseismic monitoring data.

[0060] Fracture permeability inversion: Harmonic Resonance Frequency Shift Model: Establishing Crack Aperture w ( mm ) and the resonance frequency offset Δf ( Hz ) relationship: ; Where L is the crack length (unit: m), indicating the horizontal extension distance of the crack; E is the elastic modulus of rock, and h is the thickness of the rock layer.

[0061] Permeability tensor calculation: fluid velocity field based on DTS inversion v ( x , z ), and the permeability is inverted by Darcy’s law.

[0062] In this embodiment, the strain-stress conversion is performed by calculating the ground stress components using the generalized Hooke's law.

[0063] In this embodiment, the sweet spot index is calculated as follows: Define the sweet spot index: ,in, is the stress shadow area suppression coefficient (0-1).

[0064] In this embodiment, the detonation parameter optimization engine includes: Reinforcement learning framework: Using the Deep Deterministic Policy Gradient (DDPG) algorithm, define: State space: including SRV distribution, sweet spot index, and interference intensity of adjacent wells; Action space: charge (50-200kg), detonation velocity (3000-6000m / s), pumping timing (0-60s); Reward function: ;in, To quantify the degree of stress disturbance caused by explosive fracturing on adjacent production wells (e.g., the decline in production capacity caused by the extension of fractures to adjacent wells).

[0065] Policy iteration: Update the policy network weights after each round of fracturing until the reward function converges (change rate <1%).

[0066] The present invention uses the millisecond-level high-time resolution data acquisition capability of the distributed fiber optic sensing system (DTS, DAS, DFS) to capture transient events such as shock wave propagation, dynamic crack expansion, and fluid seepage during the detonation fracturing process in real time. This solves the problem that traditional microseismic monitoring technology cannot capture the formation of high-frequency and rapid crack networks due to low-frequency response and surface layout limitations, and provides monitoring support for the dynamic fracturing process at all time and space scales.

[0067] This invention is based on the deep fusion of multimodal fiber optic data (strain field, acoustic spectrum, temperature field), combined with physical driving models and machine learning algorithms, to accurately decouple the characteristics of complex events such as the re-opening of original fractures, the expansion of new fractures and energy dissipation, breaking through the limitations of traditional single-parameter inversion and significantly improving the accuracy of reconstruction of fracture network morphology, permeability distribution and ground stress field.

[0068] By constructing a time-varying probability cloud map of the reconstructed volume (SRV), a fracture permeability grading model, and a three-dimensional distribution map of the "sweet spot index", the present invention directly converts fiber optic monitoring data into quantifiable engineering parameters (such as fracture conductivity and production increase potential areas), providing a visual decision-making basis for detonation parameter optimization and avoiding reliance on empirical adjustments.

[0069] Based on a reinforcement learning algorithm and cross-physical field verification (such as tracer-fiber data matching), the present invention dynamically modifies the energy attenuation coefficient, permeability model, and geostress field parameters, enabling the detonation fracturing scheme to adapt to reservoir heterogeneity and interference effects from adjacent wells, significantly improving reconstruction efficiency and long-term stable production capabilities.

[0070] The present invention reduces the dependence of traditional hydraulic fracturing on chemical additives and proppants, thereby alleviating environmental risks, by verifying the self-supporting effect of proppant-free fracture networks and providing real-time monitoring feedback. At the same time, the characteristics of rapid transformation and immediate production, combined with precise assessment methods, provide technical support for the efficient development of low-permeability and ultra-low-permeability reservoirs.

[0071] Although the various steps in the above embodiment are described in the above-mentioned order, those skilled in the art will understand that in order to achieve the effect of this embodiment, different steps do not have to be executed in such an order. They can be executed simultaneously (in parallel) or in a reverse order. These simple changes are within the scope of protection of the present invention.

[0072] like Figure 2 As shown, the second embodiment of the present invention provides a detonation fracturing monitoring device based on tracer monitoring and distributed optical fiber sensing monitoring, which is based on the detonation fracturing monitoring method based on tracer monitoring and distributed optical fiber sensing monitoring of the first embodiment. The device includes a bridge plug 1, an initiator 2, a safety gun 3, a centralizer 4, a packer 5, an optical fiber collection column 6, a perforation port 7, and a casing 8. A horizontally placed casing 8 is lowered into the horizontal well. A plurality of perforations 7 are evenly formed on both sides of the surface of the casing 8 along its length, wherein the perforations 7 on one side are staggered with the perforations 7 on the other side. An optical fiber collection column 6 is provided at the edge of each perforation 7, and the optical fiber collection column 6 is fixed on the outer surface of the casing 8. A plurality of centralizers 4 are coaxially mounted on the outer surface of the casing 8, and the centralizers 4 are used to centralize the casing 8; Inside the casing 8, from the end close to one side of the vertical well to the other end, a packer 5, an initiator 2 and a safety gun 3 are sequentially arranged; the initiator 2 is used to detonate the liquid explosive, and the safety gun 3 is used to transmit a detonation signal to the initiator 2; A bridge plug 1 is provided on the well wall of the horizontal well on the side close to the vertical well, and the bridge plug 1 is used to prevent the backflow of liquid explosives and fluids during the hydraulic fracturing process.

[0073] Before hydraulic fracturing is performed, the present invention first isolates the target layer from other layers by using the bridge plug 1 to prevent the fracturing fluid from entering other layers.

[0074] Then, the selected fractured section is further sealed using the packer 5 in preparation for subsequent high-pressure injection.

[0075] An appropriate amount of chemical tracers is mixed into the fracturing fluid. These tracers will not affect the performance of the fracturing fluid, but can help track the path and extent of crack propagation in subsequent monitoring.

[0076] The selection of tracers should be based on their unique physical or chemical properties, such as fluorescence, radioactivity, etc., so that they can be clearly distinguished in subsequent detection.

[0077] The fracturing fluid containing tracers is injected into the target layer through a pumping system, opening natural fractures in the formation or forming new fractures under high pressure.

[0078] At the same time, distributed fiber optic sensors are used to monitor temperature, pressure and strain changes in real time and record dynamic parameters during crack formation and development.

[0079] Data from distributed fiber optic sensors is received by ground equipment and analyzed to evaluate the distribution of the crack network.

[0080] Based on the migration trajectory of the tracer, the actual direction and connectivity of the fracture can be determined, thereby optimizing the subsequent production strategy.

[0081] Before starting any operation, ensure that all personnel have evacuated to a safe area and that all equipment is in good condition.

[0082] Confirm that the detonator 2, the safety gun 3 and the bridge plug 1 function normally, especially the bridge plug 1, which is used to prevent the backflow of liquid explosives and fluids generated in the subsequent hydraulic fracturing process.

[0083] The selected fractured section is further sealed with a packer 5 in preparation for subsequent high-pressure injection. This step ensures that the liquid explosive acts only on the intended target layer, avoiding unnecessary impact on other formations.

[0084] Fracturing pumps are used to transport liquid explosives from the surface to a designated location underground. The pipeline must be resistant to high pressure and corrosion to ensure safe and efficient transportation.

[0085] The delivery pressure of liquid explosives should be adjusted according to the well depth and geological conditions to ensure that they can reach the predetermined depth smoothly without leakage or premature detonation.

[0086] Before pumping, key parameters such as pump pressure and flow rate are set to ensure that the liquid explosive can be evenly distributed throughout the target layer.

[0087] The speed of the pump is adjusted so that the liquid explosive can completely fill the rock formation gaps around the perforation opening 7 within a suitable time, thereby forming an effective blasting environment.

[0088] The fracturing pump is activated to pump the liquid explosive downhole through the channel in the casing 8. A displacement fluid is then pumped in to displace the liquid explosive from the wellbore into the reservoir. Because liquid explosives have a certain viscosity, a steady pumping speed is required to avoid blockages and other problems.

[0089] Monitor pressure changes during the pumping process and take immediate action if any abnormality is detected, such as slowing down the pump or stopping pumping for inspection.

[0090] Real-time monitoring of various parameters during the pumping process, including but not limited to pump pressure, flow rate, and temperature and pressure changes in the well.

[0091] Distributed fiber optic sensors (such as DTS, DAS, and DFS) are used to monitor dynamic changes in the well in real time to ensure that liquid explosives correctly fill hydraulic fractures and achieve optimal results. In addition, it is necessary to ensure that there is no liquid explosive in the wellbore or the liquid explosive concentration is far below the explosion threshold.

[0092] After the liquid explosive is pumped in, the distributed optical fiber sensor is used to further confirm whether the liquid explosive has been evenly distributed, with particular attention paid to the filling condition near the perforation opening 7 .

[0093] If you find that some areas are not filled enough, you can consider increasing the pumping volume or adjusting the pumping strategy appropriately.

[0094] When all preparations are completed, a detonation command is issued, and a signal is sent to the detonator 2 through the safety gun 3 to trigger the explosion of the liquid explosive.

[0095] The explosion instantly generates a powerful shock wave and high temperature, which quickly penetrates the rock formation, forming a large number of tiny cracks and increasing the permeability of the reservoir.

[0096] At the moment of detonation, the fracturing pump uses distributed fiber optic sensors such as DTS, DAS and DFS to synchronously record the temperature, acoustic waves and strain changes in the well, capturing the detonation event and the propagation path of the stress wave it triggers.

[0097] The ground working platform quickly processes and performs inversion calculations on the collected data to reconstruct the spatial distribution and temporal evolution of crack expansion during detonation fracturing and evaluate the effect of detonation fracturing. Effect evaluation: Combining temperature, acoustic wave and strain data, a comprehensive assessment was made of the effect of detonation fracturing on reservoir reconstruction, especially whether the newly formed fracture network significantly improved reservoir connectivity and oil and gas mobility.

[0098] The terms "first", "second", etc. are used to distinguish similar objects, rather than to describe or indicate a particular order or sequence.

[0099] The term "comprise" or any other similar term is intended to cover non-exclusive inclusion such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0100] Thus far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present invention.

Claims

1. A detonation fracturing monitoring method based on tracer monitoring and distributed optical fiber sensing monitoring, characterized in that: The method comprises the following steps: Step S1: After drilling is completed, a tracer is injected into the horizontal well, and the hydraulic fracture volume is calculated based on the tracer volume returned; Step S2, calculating the volume of liquid explosive required for the hydraulic fracturing crack volume and adjusting the viscosity of the liquid explosive; Step S3, pumping the liquid explosive with adjusted viscosity into the hydraulic fracturing crack in the horizontal well; Step S4: obtaining monitoring data after detonating the liquid explosive using the distributed optical fiber monitoring equipment, evaluating the reservoir stimulation effect of the detonation fracturing by performing inversion calculations on the monitoring data, and detecting the stress-strain state of the reservoir after the detonation fracturing; The distributed optical fiber monitoring equipment is installed on a detonation fracturing monitoring device based on tracer monitoring and distributed optical fiber sensing monitoring.

2. The detonation fracturing monitoring method based on tracer monitoring and distributed optical fiber sensing monitoring according to claim 1, characterized in that: The volume of the liquid explosive is calculated as follows: Step S21, calculating the height of the main fracture according to the volume of the fracturing fluid injected for hydraulic fracturing; Step S22, calculating the maximum crack width of the main crack based on the fluid pressure, formation elastic modulus, Poisson's ratio and the height of the main crack during the construction phase; Step S23, calculating the length of the liquid explosive at the critical detonation diameter according to the maximum crack width, the critical detonation diameter of the liquid explosive, and the half crack length of the hydraulic fracturing design; Step S24 , calculating the volume of the liquid explosive based on the length of the liquid explosive at the critical detonation diameter, the maximum crack width, and the critical detonation diameter of the liquid explosive.

3. The detonation fracturing monitoring method based on tracer monitoring and distributed optical fiber sensing monitoring according to claim 2, characterized in that: Maximum crack width , which is calculated as follows: ； in, v is Poisson's ratio, E is the formation elastic modulus, H is the height of the main crack, P 0 is the fluid pressure during the construction phase.

4. The detonation fracturing monitoring method based on tracer monitoring and distributed optical fiber sensing monitoring according to claim 3, characterized in that: Length of liquid explosive at critical detonation diameter L d , which is calculated as follows: ； in, is the critical detonation diameter of liquid explosives, L Half crack length designed for hydraulic fractures.

5. The detonation fracturing monitoring method based on tracer monitoring and distributed optical fiber sensing monitoring according to claim 4, characterized in that: Volume of liquid explosive , which is calculated as follows: 。 6. The detonation fracturing monitoring method based on tracer monitoring and distributed optical fiber sensing monitoring according to claim 1, characterized in that: The distributed optical fiber monitoring device includes one or more of a distributed temperature optical fiber sensor, a distributed acoustic wave optical fiber sensor, and a distributed strain optical fiber sensor.

7. The detonation fracturing monitoring method based on tracer monitoring and distributed optical fiber sensing monitoring according to claim 1, characterized in that: The distributed optical fiber monitoring device is installed on one side of the outer circumference of the casing close to each perforation opening.

8. The detonation fracturing monitoring method based on tracer monitoring and distributed optical fiber sensing monitoring according to claim 7, characterized in that: The distributed optical fiber monitoring device is installed in an optical fiber collection column, and the optical fiber collection column is installed on the outer circumference of the casing near the edge of each perforation port.

9. The detonation fracturing monitoring method based on tracer monitoring and distributed optical fiber sensing monitoring according to claim 8, characterized in that: The axial direction of the optical fiber collection column is perpendicular to the axial direction of the sleeve.

10. A detonation fracturing monitoring device based on tracer monitoring and distributed optical fiber sensing monitoring, based on the detonation fracturing monitoring method based on tracer monitoring and distributed optical fiber sensing monitoring according to any one of claims 1 to 9, characterized in that: The device comprises a bridge plug (1), a detonator (2), a safety gun (3), a centralizer (4), a packer (5), an optical fiber collection column (6), a perforation port (7) and a casing (8); A horizontally placed casing (8) is lowered into the horizontal well, and a plurality of perforations (7) are evenly opened on both sides of the surface of the casing (8) along its length direction, wherein the perforations (7) on one side are staggered with the perforations (7) on the other side, and an optical fiber collection column (6) is provided at the edge of each perforation (7), and the optical fiber collection column (6) is fixed on the outer surface of the casing (8); A plurality of centralizers (4) are coaxially mounted on the outer surface of the casing (8), and the centralizers (4) are used to centralize the casing (8); A packer (5), a detonator (2) and a safety gun (3) are sequentially arranged in the casing (8) from the end close to one side of the vertical well to the other end; the detonator (2) is used to detonate the liquid explosive, and the safety gun (3) is used to transmit a detonation signal to the detonator (2); A bridge plug (1) is provided on the well wall of the horizontal well on a side close to the vertical well, and the bridge plug (1) is used to prevent backflow of liquid explosives and fluid during hydraulic fracturing.

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