CN115324567A - Method and device for monitoring stratum fracturing effect by using distributed optical fiber - Google Patents

Abstract

The invention discloses a method and a device for monitoring formation fracturing effect by using distributed optical fibers. The method includes: acquiring dynamic parameters of production layers in the fracturing operation process and the oil and gas production process during the experiment of an oil and gas well measuring device; Collect the ground measurement signals collected by the optical fiber sensor; establish the mapping relationship between the dynamic parameters of the production layer and the surface measurement signals to form a database; monitor the oil and gas well site according to the mapping relationship and the database, and obtain the monitoring data of the formation fracturing effect. Results chart. By analyzing the ground measurement signal detected by the optical fiber sensor, and using the obtained characteristics of frequency, tone, volume, etc., to establish a mapping relationship with the production layer output parameters, real-time, dynamic, and full-cycle monitoring of the formation fracturing process and effect is realized. , through the accumulation of data to achieve accurate judgments.

Description

Method and device for monitoring formation fracturing effect by using distributed optical fiber

technical field

The invention relates to the technical field of oil and gas exploitation, in particular to a method and a device for monitoring formation fracturing effects by using distributed optical fibers.

Background technique

In order to improve and increase the permeability and productivity of oil and gas reservoirs, the oil and gas industry generally adopts fracturing methods to expand rock fractures and proppants to support the fractures. However, the effectiveness of fracturing and propping can only be roughly evaluated by changes in production capacity measured at the surface for a long time in the past.

With the increasing application of optical fiber sensing technology in the oil and gas exploration and development industry, more and more production layer status monitoring work is expected to be improved and broken through methods based on optical fiber sensing technology. Then, in the process of using optical fiber sensing technology for detection, the fiber optic temperature measurement technology is mostly used for data acquisition and analysis, and the data obtained by the temperature measurement method has a great influence on temperature, and the resulting error is inevitable, resulting in a decrease in detection accuracy. .

Based on the existing optical fiber sensing technology, the present invention proposes a method and a device for monitoring the process and effect of fracturing in oil and gas producing formations. Through the method and device, real-time, dynamic and full-period monitoring of formation fracturing process and effect can be realized.

Contents of the invention

Therefore, the object of the present invention is to provide a method and device for monitoring formation fracturing effect by using distributed optical fiber. Through the method and device, real-time, dynamic and full-period monitoring of formation fracturing process and effect can be realized.

In order to achieve the above object, a method of utilizing distributed optical fiber to monitor formation fracturing effect of the present invention comprises the following steps:

S1. Acquire the dynamic parameters of the production layer during the fracturing operation and oil and gas production during the experiment of the oil and gas well measurement device, and collect the ground measurement signals collected by the optical fiber sensor;

S2. Establish a mapping relationship between the dynamic parameters of production layers and ground measurement signals to form a database;

S3. According to the mapping relationship and the database, monitor the oil and gas well site, and obtain a result map of formation fracturing effect monitoring.

Preferably in any one of the above embodiments, in S1, the production layer dynamic parameters include production layer injection parameters and production layer output parameters; the production layer injection parameters include liquid injection speed, liquid injection volume, sand injection Volume and pump pressure characteristic values; the production layer output parameters include oil, gas and water flow velocity and flow characteristic values; the ground measurement signal includes ground optical signal strength, tone color characteristics, frequency band, and frequency characteristic values after analysis.

Preferably in any one of the above embodiments, in S1, the ground measurement signal analysis process includes: performing Fourier transform on the ground measurement signal to complete the conversion from time domain to frequency domain; The measurement signal is divided into frequency bands according to the preset frequency range; the frequency domain ground measurement signal is segmented and bandpass filtered to obtain frequency bands; the frequency feature identification and timbre feature identification are performed on the filtered segmented frequency domain ground measurement signal; Get the frequency characteristic value and the timbre characteristic.

Preferably in any one of the above embodiments, in S2, the establishment of the mapping relationship between the dynamic parameters of the production layer and the ground measurement signal includes the following methods:

S201. Adjust the pump pressure in the injection parameters of the production layer to form a pump pressure characteristic array containing multiple pump pressure characteristic values, obtain the corresponding ground light signal intensity during the pump pressure adjustment process, and correspond to a ground light signal according to each pump pressure characteristic value Corresponding relationship of signal intensity, establishing the mapping relationship between production layer injection parameters and ground optical signal intensity;

S202. Adjust the flow in the output parameters of the production layer, form a flow array containing multiple flow values, obtain the corresponding ground optical signal strength during the flow adjustment process, and establish a corresponding relationship according to each flow value corresponding to a ground light signal intensity The mapping relationship between production layer output parameters and ground optical signal intensity;

S203, repeating the above S201-S202, respectively establishing the relationship between the production layer injection parameters and the timbre characteristics and the relationship between the production layer output parameters and the timbre characteristics;

S204. According to the frequency change and frequency band change of the corresponding ground measurement signal when adjusting the pump pressure change in the production layer injection parameters, establish the mapping relationship between the production layer injection parameters and the frequency band and frequency characteristic value;

S205. Establish a mapping relationship between the production layer output parameter, the frequency band, and the frequency characteristic value according to the frequency change and the frequency band change of the corresponding ground measurement signal when the flow rate change in the production layer output parameter is adjusted.

The present invention also provides a device for monitoring formation fracturing effects by using distributed optical fibers, including an optical fiber sensor, a main control computer, and a ground signal generation and acquisition panel;

When conducting laboratory simulation experiments, it also includes oil and gas well fracturing simulation actuators; oil and gas well fracturing simulation actuators are used to perform formation fracturing actions during the experiment and generate simulated production layer dynamic parameters;

When performing on-site fracturing operations, it also includes a logging operation vehicle and an on-site fracturing mechanism. The on-site fracturing mechanism is used to perform stratum fracturing actions during the operation; Predetermined position in well logging;

The optical fiber sensor is used to obtain ground measurement signals during oil and gas well fracturing operations;

The ground signal generation and collection panel is used to send an optical signal to the optical fiber and receive the ground measurement signal returned by the optical fiber sensor;

The main control computer is used to use the mapping relationship between the dynamic parameters of the production layer established during the simulation experiment and the ground measurement signal to monitor the oil and gas well site according to the ground measurement signal obtained during the field operation, and obtain the formation fracturing effect Monitoring results map.

Preferably, in any one of the above embodiments, the oil and gas well fracturing simulation actuator includes a fracturing fluid tank, a sand tank, a mixing tank, a pump, and a liquid volume sand volume pump pressure adjustment unit; The fracturing fluid and proppant are injected during operation, and the output layer injection parameters include fluid injection speed, fluid injection volume, sand injection volume, and pump pressure characteristic values; the production layer output parameters include flow velocity and flow characteristic value of oil, gas and water

The on-site fracturing mechanism includes a fracturing vehicle, a sand mixing vehicle, a fracturing instrument vehicle and a manifold vehicle; the on-site fracturing mechanism is used to perform stratum fracturing operations.

In any one of the above embodiments, preferably, the main control computer further includes analyzing the ground measurement signal acquired by the optical fiber sensor to obtain ground light signal strength, timbre feature, frequency band, and frequency feature values.

Preferably in any one of the above embodiments, the ground measurement signal analysis process includes: performing Fourier transform on the ground measurement signal to complete the conversion from the time domain to the frequency domain; The frequency range is set, and the frequency band is divided; the frequency domain ground measurement signal is segmented and bandpass filtered to obtain the frequency band; the frequency feature identification and timbre feature identification are performed on the filtered segmented frequency domain ground measurement signal; the frequency feature value is obtained and tone characteristics.

Preferably in any one of the above embodiments, the establishment of the mapping relationship between the dynamic parameters of the production layer and the ground measurement signal includes:

Adjust the pump pressure in the production layer injection parameters to form a pump pressure characteristic array containing multiple pump pressure characteristic values, obtain the corresponding ground optical signal strength during the pump pressure adjustment process, and correspond to a ground optical signal strength according to each pump pressure characteristic value The mapping relationship between production layer injection parameters and ground optical signal intensity is established;

Adjust the flow in the output parameters of the production layer to form a flow array containing multiple flow values, obtain the corresponding ground optical signal strength during the flow adjustment process, and establish the production layer according to the corresponding relationship between each flow value corresponding to a ground optical signal intensity The mapping relationship between output parameters and ground optical signal strength;

Repeat the above process to establish the relationship between production layer injection parameters and timbre characteristics and the relationship between production layer output parameters and timbre characteristics;

According to the frequency change and frequency band change of the corresponding ground measurement signal when the pump pressure change in the production layer injection parameters is adjusted, the mapping relationship between the production layer injection parameters and the frequency band and frequency characteristic value is established;

According to the frequency change and frequency band change of the corresponding surface measurement signal when the flow rate change in the production layer output parameter is adjusted, the mapping relationship between the production layer output parameter, the frequency band and the frequency characteristic value is established.

A method and device for monitoring formation fracturing effects using distributed optical fibers disclosed in this application has at least the following advantages compared with the prior art:

1. By analyzing the ground measurement signal detected by the optical fiber sensor, using the obtained characteristics such as frequency, timbre, volume, etc., to establish a mapping relationship with the output parameters of the production layer, to realize real-time, dynamic and comprehensive analysis of the fracturing process and effect of the formation. Periodic monitoring realizes accurate judgment through the accumulation of data. Compared with temperature measurement and other methods, it reduces the generation of errors and improves the measurement accuracy.

Description of drawings

Fig. 1 is the flowchart of the method for monitoring formation fracturing effect using distributed optical fiber in the present invention;

Fig. 2 is a schematic structural diagram of a device for monitoring formation fracturing effects using distributed optical fibers in the present invention;

Fig. 3 is a schematic diagram of the specific structure of the device for monitoring formation fracturing effects using distributed optical fibers in the present invention

Fig. 4 is the flowchart of the on-site data collection and processing software of the embodiment of the present invention;

Fig. 5 is the measurement signal spectrum diagram of the embodiment of the present invention;

Fig. 6 is an evaluation diagram of the fracturing results of the embodiment of the present invention.

Detailed ways

The present invention will be further described in detail through the accompanying drawings and specific embodiments below.

The principle of this application is that the light wave emitted by the laser propagates along the distributed optical fiber to the depth of the oil and gas well. During the propagation process, the photons collide with the sound wave particles along the propagation path. The collision produces backscattered waves (Brillouin scattering), and the scattered waves return to the ground along the optical fiber and are captured by the receiving and measuring device. Compared with the source signal sent by the laser, the measured signal has changed in intensity, frequency, phase, wavelength, polarization state and other characteristics. This change is related to the characteristics of the acoustic signal generated in the oil and gas well and in the formation, and the characteristics of the acoustic signal It is also closely related to the dynamic parameters of oil and gas wells or formations (injection profile, pump pressure, production profile). Realize that during the fracturing process, relevant data on the fracturing process and effect can be obtained on the ground.

Any kind of sound has three basic properties: pitch, volume and timbre. The pitch reflects the frequency of the sound, the volume reflects the amplitude of the sound, and the timbre reflects the vibration of the sound. The sounds emitted by different vibration sources (materials, components, structures) may be very similar, but they cannot be exactly the same. The difference lies in the three basic properties of the sound. When the dynamic parameters of the production layer (injection profile, pump pressure, production profile) change, the sound signal emitted changes accordingly, and the optical signal measured by the equipment on the ground changes accordingly.

In physics, sound includes two kinds of music and noise. The sound emitted by the wellbore and the formation environment is a physical noise. The main differences between it and the physical noise include:

①The sound with regular, simple vibration and accurate height is musical sound; the sound with irregular and chaotic vibration and without a certain height is noise.

② The vibration frequency ratio of different vibration sources in music can be reduced to a simple ratio, such as 3:7; the vibration frequency ratio of different vibration sources in noise cannot be reduced to a simple ratio, such as 201:388. (discovered by Pythagoras)

The method for analyzing and processing the downhole sound wave signal of the oil and gas well involved in the present invention is called the noise analysis method. The main principles of this method are:

① The sound signal of the production layer is a mixed noise composed of sounds with different vibration frequencies from different vibration sources.

②The sound signal of production layer has no definite pitch, but it can be described by statistical method.

③The greater the flow rate and the faster the flow rate of the fluid in the production layer, the greater the volume of the sound signal, that is, there is a linear relationship between the dynamic parameters of the production layer (injection profile, pump pressure, and production profile) and the volume, and this relationship can be verified through experiments. inferred.

④Compared with the timbre of musical tones, the timbre of the production layer sound signal is more chaotic, but it can still be analyzed by using statistics and computer software analysis methods.

Therefore, as shown in FIG. 1 , a method for monitoring formation fracturing effects using distributed optical fibers provided by an embodiment of the present invention includes the following steps:

S1. Acquire the dynamic parameters of the production layer during the fracturing operation and oil and gas production during the experiment of the oil and gas well measurement device, and collect the ground measurement signals collected by the optical fiber sensor;

S2. Establish a mapping relationship between the dynamic parameters of production layers and ground measurement signals to form a database;

S3. According to the mapping relationship and the database, monitor the oil and gas well site, and obtain a result map of formation fracturing effect monitoring.

Specifically, in S1, the production layer dynamic parameters include production layer injection parameters and production layer output parameters; the production layer injection parameters include liquid injection speed, liquid injection volume, sand injection volume, and pump pressure characteristic values; The output parameters of the production layer include the flow velocity and flow characteristic value of oil, gas and water; the ground measurement signal includes ground optical signal intensity, tone color characteristic, frequency band, and frequency characteristic value after analysis.

In S1, the ground measurement signal analysis process includes: performing the Fourier transform on the ground measurement signal to complete the conversion from the time domain to the frequency domain; for the transformed frequency domain ground measurement signal according to the preset frequency range, which is the following table As shown in 1, frequency band division is carried out; the frequency domain ground measurement signal is carried out to segmental bandpass filtering, and the frequency band is obtained: the frequency domain ground measurement signal of the segmented frequency domain after filtering is carried out frequency feature identification and timbre feature identification; the frequency feature value and Timbre characteristics.

serial number Band name Frequency Range 1 very low frequency 20-40Hz 2 low frequency 40-80Hz 3 Medium and low frequency 80-160Hz 4 IF 160-1280Hz 5 Medium and high frequency 1280-2560Hz

Table 1: Division of measured noise frequency bands

In S2, the establishment of the mapping relationship between the dynamic parameters of the production layer and the ground measurement signal includes the following methods:

S201. Adjust the pump pressure in the injection parameters of the production layer, form a pump pressure characteristic array including multiple pump pressure characteristic values, obtain the corresponding ground light signal intensity during the pump pressure adjustment process, and correspond to a ground light signal according to each pump pressure characteristic value For the corresponding relationship of signal intensity, the mapping relationship between production layer injection parameters and ground optical signal intensity is established as shown in Table 2 below;

Table 2: Correspondence between dynamic parameters of production layers and frequency statistical characteristics of ground measurement signals

S202. Adjust the flow in the output parameters of the production layer, form a flow array containing multiple flow values, obtain the corresponding ground optical signal strength during the flow adjustment process, and establish a corresponding relationship according to each flow value corresponding to a ground light signal intensity The mapping relationship between production layer output parameters and ground optical signal intensity;

serial number Production Layer Output Parameters Ground light signal strength 1 Velocity and flow rate of oil, gas and water1 volume 1 ... Velocity and flow rate of oil, gas and water 2 ... no Velocity and flow rate of oil, gas and water n volume n

Table 3: Correspondence between the dynamic parameters of the production layer and the surface optical signal intensity of the ground measurement signal

S203, repeating the above S201-S202, respectively establishing the relationship between the production layer injection parameters and the timbre characteristics and the relationship between the production layer output parameters and the timbre characteristics;

serial number Production Layer Injection Parameters Timbre characteristics 1 Liquid injection speed, liquid injection volume, sand injection volume, pump pressure characteristic parameters 1 Time and amplitude eigenvalue group 1 ... Liquid injection speed, liquid injection volume, sand injection volume, pump pressure characteristic parameters 2 ... no Liquid injection speed, liquid injection volume, sand injection volume, characteristic parameters of pump pressure n time and magnitude eigenvalue group n serial number Production Layer Output Parameters Timbre characteristics 1 Velocity and flow rate of oil, gas and water1 Time and amplitude eigenvalue group 1 ... Velocity and flow rate of oil, gas and water 2 ... no Velocity and flow rate of oil, gas and water n time and magnitude eigenvalue group n

Table 4 Correspondence between waveform characteristics of measured signals and dynamic parameters of production layers.

S204. According to the frequency change and frequency band change of the corresponding surface measurement signal when adjusting the pump pressure change in the production layer injection parameters, establish the mapping relationship between the production layer injection parameters and the frequency band and frequency characteristic value;

S205. Establish a mapping relationship between the production layer output parameter, the frequency band, and the frequency characteristic value according to the frequency change and the frequency band change of the corresponding surface measurement signal when the flow rate change in the production layer output parameter is adjusted.

As shown in Figures 2-3, the present invention also provides a device for monitoring formation fracturing effects using distributed optical fibers to implement the above monitoring method, including optical fiber sensors, a main control computer, and a ground signal generation and acquisition panel;

When conducting laboratory simulation experiments, it also includes oil and gas well fracturing simulation actuators; oil and gas well fracturing simulation actuators are used to perform formation fracturing actions during the experiment and generate simulated production layer dynamic parameters;

When performing on-site fracturing operations, it also includes a logging operation vehicle and an on-site fracturing mechanism. The on-site fracturing mechanism is used to perform stratum fracturing actions during the operation; Predetermined position in well logging;

The optical fiber sensor is used to obtain ground measurement signals during oil and gas well fracturing operations;

The ground signal generation and collection panel is used to send an optical signal to the optical fiber and receive the ground measurement signal returned by the optical fiber sensor;

The main control computer is used to obtain the dynamic parameters of the production layer during the fracturing operation process and the oil and gas production process during the simulation experiment, and according to the mapping relationship between the dynamic parameters of the production layer established during the simulation experiment and the ground measurement signal, A database is formed; the ground measurement signals of the field operation are monitored on the oil and gas well site according to the mapping relationship and the database, and a result map of formation fracturing effect monitoring is obtained.

The oil and gas well fracturing simulation actuator includes a fracturing fluid tank, a sand tank, a mixing tank, a pump, and a liquid volume sand volume pump pressure adjustment unit; it is used to inject fracturing fluid and proppant when simulating a fracturing operation, and output The production layer injection parameters include liquid injection speed, liquid injection volume, sand injection volume, and characteristic values of pump pressure;

The on-site fracturing mechanism includes a fracturing vehicle, a sand mixing vehicle, a fracturing instrument vehicle, and a manifold vehicle; the on-site fracturing mechanism is used to perform stratum fracturing operations and generate production layer output parameters; the production layer Production parameters include flow velocity and flow characteristic values of oil, gas and water.

The main control computer also includes analyzing the ground measurement signal acquired by the optical fiber sensor to obtain ground optical signal strength, timbre feature, frequency band, and frequency feature value.

The ground measurement signal analysis process includes: converting the ground measurement signal from the time domain to the frequency domain through Fourier transform; dividing the converted frequency domain ground measurement signal into frequency bands according to the preset frequency range; The frequency domain ground measurement signal is segmented and band-pass filtered to obtain frequency bands; the frequency feature identification and timbre feature identification are performed on the filtered segmented frequency domain ground measurement signal; the frequency feature value and timbre feature are obtained.

The establishment of the mapping relationship between the dynamic parameters of the production layer and the ground measurement signal includes:

Adjust the pump pressure in the production layer injection parameters to form a pump pressure characteristic array containing multiple pump pressure characteristic values, obtain the corresponding ground optical signal strength during the pump pressure adjustment process, and correspond to a ground optical signal strength according to each pump pressure characteristic value The mapping relationship between production layer injection parameters and ground optical signal intensity is established;

Adjust the flow in the output parameters of the production layer to form a flow array containing multiple flow values, obtain the corresponding ground optical signal strength during the flow adjustment process, and establish the production layer according to the corresponding relationship between each flow value corresponding to a ground optical signal intensity The mapping relationship between output parameters and ground optical signal strength;

Repeat the above process to establish the relationship between production layer injection parameters and timbre characteristics and the relationship between production layer output parameters and timbre characteristics;

According to the frequency change and frequency band change of the corresponding ground measurement signal when the pump pressure change in the production layer injection parameters is adjusted, the mapping relationship between the production layer injection parameters and the frequency band and frequency characteristic value is established;

According to the frequency change and frequency band change of the corresponding surface measurement signal when the flow rate change in the production layer output parameter is adjusted, the mapping relationship between the production layer output parameter, the frequency band and the frequency characteristic value is established.

In this application, the specific mapping function can also be obtained by linearly fitting the mapping relationship between the above-mentioned production layer output parameters and production layer injection parameters and the analytical data of the ground measurement signal, thereby realizing the Signal, you can get the results of specific monitoring data.

In a specific embodiment, data collection and processing is divided into two parts: one part is laboratory data collection and processing, and the other part is field data collection and processing.

Laboratory data collection and processing is to use the experimental device described above, under the automatic control of the computer, to simulate the fracturing operation process and oil and gas production process, and to preset different production layer injection parameters and production layer output parameters. Next, the scattered light data collection is completed, and through software analysis and processing (noise analysis method), the corresponding relationship between the measurement signal and the production layer injection parameters (production parameters) is established, and a database is formed.

On-site data acquisition and processing is to use the oil and gas well on-site measurement device described above to run distributed optical fibers in the same well or adjacent wells at the same time as the fracturing operation to complete the data acquisition process, and through software analysis and processing, the formation pressure can be obtained. The result map of cracking effect monitoring. These result graphs include: measurement signal spectrum graph, measurement signal strength distribution graph, and measurement signal timbre waveform graph.

As shown in Figure 5, this is the spectrum diagram of the measured signal under certain depth conditions at a certain time. The x-axis represents time, the z-axis represents depth, and the y-axis represents the frequency spectral line of the measurement signal, which is the frequency band and frequency characteristic value obtained after the ground software analyzes a certain measurement signal (noise analysis method) in the form of a curve form presented. Combining these values or curves with the database we have formed, we can obtain parameter values such as injection profile, pump pressure, and production profile.

In the past, parameter values such as injection profiles, pump pressures, and production profiles were obtained mainly by means of simulation calculations based on production data obtained from surface measurement.

This method is implemented on the basis of big data through a large number of simulation experiments combined with actual logging data, so that the accuracy of the measurement results is higher.

As shown in Figure 6, this figure presents the situation of each perforation cluster in a certain perforation section in the production layer entering fluid (fluid production) during the fracturing implementation process (after fracturing), and the abscissa represents the perforation cluster , the ordinate represents the perforation section. In the image, the magnitude of the amplitude represents the amount of liquid/sand input (liquid production/sand production), and the depth of the color represents the speed of liquid/sand injection (liquid production/sand production). size. The result map has raised the evaluation of fracturing effect from a qualitative level to a quantitative level.

The details are explained in Table 5 below:

Table 5: Correspondence between charts and images

Apparently, the above-mentioned embodiments are only examples for clear description, rather than limiting the implementation. For those of ordinary skill in the art, other changes or changes in different forms can be made on the basis of the above description. It is not necessary and impossible to exhaustively list all the implementation manners here. And the obvious changes or changes derived therefrom are still within the scope of protection of the present invention.

Claims (9)

1. A method for monitoring stratum fracturing effect by using a distributed optical fiber is characterized by comprising the following steps:

s1, acquiring dynamic parameters of a producing zone in a fracturing operation process and an oil and gas production process in an experimental process of an oil and gas well measuring device, and collecting ground measuring signals acquired by an optical fiber sensor;

s2, establishing a mapping relation between the dynamic parameters of the production zone and the ground measurement signals to form a database;

and S3, monitoring the oil and gas well field according to the mapping relation and the database to obtain a result diagram of stratum fracturing effect monitoring.

2. The method for monitoring the effect of fracturing on a formation using a distributed optical fiber according to claim 1, wherein in S1, the dynamic parameters of the production zone comprise injection parameters of the production zone and production parameters of the production zone; the production zone injection parameters comprise injection speed, injection amount, sand injection amount and pumping pressure characteristic values; the production parameters of the production zone comprise the flow velocity and the flow characteristic value of oil, gas and water; the ground measurement signal comprises ground light signal intensity, tone characteristics, frequency bands and frequency characteristic values after being analyzed.

3. The method for monitoring the effect of fracturing on a formation using a distributed optical fiber according to claim 2, wherein in S1, the process of analyzing the surface measurement signal comprises:

performing Fourier transform on the ground measurement signal to complete the conversion from a time domain to a frequency domain;

carrying out frequency band division on the transformed frequency domain ground measurement signal according to a preset frequency range; carrying out segmented band-pass filtering on the frequency domain ground measurement signal to obtain a frequency band;

carrying out frequency characteristic identification and tone characteristic identification on the filtered segmented frequency domain ground measurement signals; and obtaining a frequency characteristic value and a tone characteristic.

4. The method for monitoring the effect of stratum fracturing by using the distributed optical fiber as claimed in claim 2, wherein in S2, the establishing of the mapping relationship between the dynamic parameters of the producing zone and the surface measurement signals comprises the following steps:

s201, adjusting the pump pressure in the production zone injection parameters to form a pump pressure characteristic array containing a plurality of pump pressure characteristic values, acquiring corresponding ground optical signal intensity in the pump pressure adjustment process, and establishing a mapping relation between the production zone injection parameters and the ground optical signal intensity according to the corresponding relation of each pump pressure characteristic value corresponding to one ground optical signal intensity;

s202, adjusting flow in production zone output parameters to form a flow array comprising a plurality of flow values, acquiring corresponding ground optical signal intensity in the flow adjustment process, and establishing a mapping relation between the production zone output parameters and the ground optical signal intensity according to a corresponding relation of each flow value corresponding to one ground optical signal intensity;

s203, repeating the steps S201-S202, and respectively establishing a relation between a production zone injection parameter and a tone characteristic and a relation between a production zone output parameter and the tone characteristic;

s204, establishing a mapping relation between the injection parameters of the production zone and frequency bands and frequency characteristic values according to frequency changes and frequency band changes of corresponding ground measurement signals when pump pressure changes in the injection parameters of the production zone are adjusted;

s205, establishing a mapping relation between the production zone output parameters and the frequency bands and the frequency characteristic values according to the frequency change and the frequency band change of the corresponding ground measurement signals when the flow change in the production zone output parameters is adjusted.

5. A device for monitoring stratum fracturing effect by using distributed optical fibers is characterized by comprising an optical fiber sensor, a ground signal generation and acquisition panel and a main control computer;

when a laboratory simulation experiment is carried out, the system also comprises an oil-gas well fracturing simulation executing mechanism; the oil-gas well fracturing simulation executing mechanism is used for executing formation fracturing actions in the experimental process and generating simulated dynamic parameters of a producing zone;

when the on-site fracturing operation is carried out, the system also comprises a logging operation vehicle and an on-site fracturing mechanism, wherein the on-site fracturing mechanism is used for executing stratum fracturing action in the operation process; the well logging operation vehicle is used for placing the optical fiber into a preset position in a well to be logged;

the optical fiber sensor is used for acquiring a ground measurement signal when an oil-gas well is fractured;

the ground signal generating and collecting panel is used for sending light signals to the optical fibers and receiving ground measuring signals returned by the optical fiber sensors;

and the main control computer is used for monitoring the oil and gas well site by utilizing the mapping relation between the dynamic parameters of the producing zone and the ground measuring signals established in the simulation experiment according to the ground measuring signals acquired in the field operation, and obtaining a result diagram for monitoring the formation fracturing effect.

6. The device for monitoring the effect of fracturing on formations according to claim 5,

the oil-gas well fracturing simulation executing mechanism comprises a fracturing fluid tank, a sand tank, a mixing tank, a pump and a fluid quantity sand pump pressure adjusting unit; the fracturing fluid and proppant injection device is used for injecting fracturing fluid and proppant during the simulated fracturing operation, and the output production layer injection parameters comprise injection speed, injection amount, sand injection amount and pumping pressure characteristic values; the production parameters of the producing zone comprise the flow velocity and the flow characteristic value of oil, gas and water;

the on-site fracturing mechanism comprises a fracturing truck, a sand mulling truck, a fracturing instrument truck and a manifold truck; the in situ fracturing mechanism is used for executing formation fracturing actions.

7. The apparatus of claim 5, wherein the main control computer further analyzes the ground measurement signal obtained by the optical fiber sensor to obtain a ground light signal intensity, a tone characteristic, a frequency band, and a frequency characteristic value.

8. The apparatus of claim 7, wherein the surface measurement signal analysis process comprises:

performing Fourier transform on the ground measurement signal to complete the conversion from a time domain to a frequency domain;

dividing the frequency range of the transformed frequency domain ground measurement signal according to a preset frequency range; carrying out segmented band-pass filtering on the frequency domain ground measurement signal to obtain a frequency band;

carrying out frequency characteristic identification and tone characteristic identification on the filtered segmented frequency domain ground measurement signals; and obtaining a frequency characteristic value and a tone characteristic.

9. The device for monitoring the effect of fracturing on formations according to claim 5, wherein the mapping relationship between the dynamic parameters of the producing zone and the ground measuring signals is established by:

adjusting the pump pressure in the production layer injection parameters to form a pump pressure characteristic array containing a plurality of pump pressure characteristic values, acquiring the corresponding ground optical signal intensity in the pump pressure adjustment process, and establishing a mapping relation between the production layer injection parameters and the ground optical signal intensity according to the corresponding relation of each pump pressure characteristic value corresponding to one ground optical signal intensity;

adjusting the flow in the production layer output parameters to form a flow array comprising a plurality of flow values, acquiring the corresponding ground optical signal intensity in the flow adjustment process, and establishing a mapping relation between the production layer output parameters and the ground optical signal intensity according to the corresponding relation of each flow value corresponding to one ground optical signal intensity;

repeating the process, and respectively establishing the relationship between the production zone injection parameters and the tone characteristics and the relationship between the production zone output parameters and the tone characteristics;

establishing a mapping relation between the injection parameters of the production zone and frequency bands and frequency characteristic values according to the frequency change and frequency band change of corresponding ground measurement signals when the pump pressure in the injection parameters of the production zone is adjusted;

and establishing a mapping relation between the production layer output parameters and the frequency band and the frequency characteristic value according to the frequency change and the frequency band change of the corresponding ground measurement signals when the flow change in the production layer output parameters is adjusted.

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