Active source microseismic monitoring method based on phase change energy storage material

Abstract

The method relates to the technical field of vibration detection, and specifically discloses an active source microseismic monitoring method based on phase change energy storage materials, which comprises the following steps: step S1: collecting geological data and using the same to establish a regional velocity model, performing geothermal field analysis according to the geological data, and evaluating temperature change of the controllable vibration proppant after entering a well; step S2: optimizing the phase change energy storage material and constructing the controllable vibration proppant, wherein the controllable vibration proppant is jointly constructed by the phase change energy storage material and a coating material; step S3: injecting the constructed controllable vibration proppant into a reservoir, receiving an active source microseismic signal through a microseismic detector; and step S4: simplifying a seismic source model, positioning the seismic source through the active source microseismic signal, and simulating a controllable vibration proppant laying range, so that the problems of weak and random signals, low signal-to-noise ratio of collected data and difficulty in evaluating an effective transformation volume in traditional microseismic monitoring technology are solved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of vibration detection, and particularly discloses an active source microseismic monitoring method based on phase change energy storage materials. BACKGROUND

[0002] It is an important link to improve productivity to determine the reservoir producing effect, however, the remaining oil space distribution of the reservoir in the high water cut stage is very complex, and the fracturing reconstruction and production effect of unconventional resources are difficult to prove. Microseismic monitoring is a key technology for scientifically evaluating the reservoir producing effect, but the traditional microseismic monitoring technology listens to passive source signals with non-steady, weak and random characteristics, and there is a natural bottleneck of low signal-to-noise ratio of collected data, which leads to a series of problems such as difficulty in picking up effective signals, low efficiency of seismic source positioning, and overestimation of effective reconstruction volume.

[0003] The active seismic source can avoid the inherent limitations brought by the passive seismic source. The phase change energy storage material is used to store and release heat energy through the conversion between different phase states by using the high energy storage density characteristics of the material itself. According to the research and analysis of the American Dow Chemical Company, there are more than 20,000 kinds of phase change materials. The phase change microcapsule technology melts and disperses the phase change energy storage material into micron-sized droplets, and uses film-forming materials to build micron-millimeter-sized microcapsules. After more than 30 years of development, this technology has been widely used in many fields, but no related research has been found in the field of oilfield development.

[0004] Therefore, it is of great significance to develop a new microseismic monitoring method by using the phase change energy storage material as the basic material of the active seismic source to meet the urgent needs of the development of efficient and high-precision microseismic monitoring technology and the national energy supply security strategy.

[0005] Therefore, the inventor provides an active source microseismic monitoring method based on phase change energy storage materials to solve the above problems. SUMMARY

[0006] The purpose of the method is to solve the problems of weak and random signals, low signal-to-noise ratio of collected data, and difficulty in evaluating the effective fracturing volume in the traditional microseismic monitoring technology.

[0007] In order to achieve the above purpose, the basic scheme of the method provides an active source microseismic monitoring method based on phase change energy storage materials, which comprises the following steps:

[0008] Step S1: Collecting geological data and using the data to establish a regional velocity model, and analyzing the geothermal field and evaluating the temperature change of the controllable vibration proppant after entering the well according to the geological data;

[0009] Step S2: Selecting the phase change energy storage material and constructing the controllable vibration proppant, wherein the controllable vibration proppant is constructed by the phase change energy storage material and the coating material.

[0010] Step S3: injecting the constructed controllable vibration proppant into the reservoir, and receiving the active source microseismic signal through a microseismic detector;

[0011] Step S4: simplifying the source model, and positioning the source and simulating the controllable vibration proppant placement range through the active source microseismic signal.

[0012] Further, in step S1, the collected geological data includes stratum information, structure information and surface geological conditions of the studied area, and the collected geological data is integrated to establish a regional velocity model.

[0013] Further, in step S2, the phase change energy storage material is one of four categories of solid-solid phase change, solid-liquid phase change, solid-gas phase change and liquid-gas phase change.

[0014] Further, in step S2, the selection process includes the following steps:

[0015] The salt resistance and specific gravity required by the controllable vibration proppant are determined according to the previous geological data collection and geothermal field analysis, and the microseismic signal energy generated by the heat explosion of the proppant constructed by different phase change energy storage materials is analyzed to select the applicable phase change energy storage material.

[0016] Further, in step S3, the controllable vibration proppant is carried by a high-pressure fluid to the bottom of the well.

[0017] Further, in step S3, the microseismic detector can be placed in the well.

[0018] Further, in step S3, the microseismic detector can be placed on the ground.

[0019] Further, in step S4, the source positioning is performed by simplifying the source model and using the equivalent source principle to position the source in a limited space.

[0020] Further, the equivalent source principle refers to the assumption that the sources, i.e. the controllable vibration proppant, are densely distributed and have the same vibration time and direction in a small range, and considering the positioning accuracy and microseismic signal intensity factors, all sources in a small range of space are processed as a single source.

[0021] The principle and effect of the present scheme are:

[0022] The application provides a kind of active source microseismic monitoring method based on phase change energy storage material, compared with traditional microseismic monitoring technology, the application proposes the idea of "rock rupture initiation" to "controllable vibration proppant active excitation", controllable vibration proppant is constructed using phase change energy storage material, uncontrollable "passive source" signal is converted into controllable enhanced "active source" signal, and the space laying range of controllable vibration proppant is used as monitoring interpretation result, the monitoring interpretation precision and timeliness are improved, and the proppant laying range simulation result can be used to represent the spatial distribution range of remaining oil, and can also be used to guide fracturing effect evaluation and optimization decision, solve the problems of weak and random signal, low signal-to-noise ratio of collected data and difficult evaluation of effective transformation volume in traditional microseismic monitoring technology. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0024] Figure 1 A flow chart of the active source microseismic monitoring method based on phase change energy storage material proposed by the embodiments of the present application is shown;

[0025] Figure 2 A specific implementation schematic diagram of the active source microseismic monitoring method based on phase change energy storage material proposed by the embodiments of the present application is shown;

[0026] Figure 3 A specific implementation schematic diagram of the active source microseismic monitoring method based on phase change energy storage material proposed by the embodiments of the present application is shown;

[0027] Figure 4 A schematic diagram of the uniform isotropic model of the active source microseismic monitoring method based on phase change energy storage material proposed by the embodiments of the present application is shown;

[0028] Figure 5 A schematic diagram of the uniform isotropic model of the active source microseismic monitoring method based on phase change energy storage material proposed by the embodiments of the present application is shown;

[0029] Figure 6 A schematic diagram of the active source microseismic monitoring method based on phase change energy storage material proposed by the embodiments of the present application is shown;

[0030] Figure 7 A schematic diagram of the active source microseismic monitoring method based on phase change energy storage material proposed by the embodiments of the present application is shown;

[0031] Figure 8 A data processing flowchart of an active source microseismic monitoring method based on phase change energy storage material is shown. DETAILED DESCRIPTION

[0032] To further illustrate the technical means and effects taken by the method to achieve the predetermined method purpose, the specific embodiments, structures, features and effects according to the method are described in detail as follows in combination with preferred embodiments.

[0033] An active source microseismic monitoring method based on phase change energy storage material is implemented as shown in Figure 1

[0034] The active source microseismic detection method mainly includes the following four steps:

[0035] Step S1: Collect geological data and use it to establish a regional velocity model, analyze the geothermal field according to the geological data and evaluate the temperature change after the controllable vibration proppant enters the well;

[0036] Step S2: Optimize the phase change energy storage material and construct the controllable vibration proppant, wherein the controllable vibration proppant is constructed based on salt resistance, specific gravity and compression resistance, and has a spherical shape and a small size with a particle size of hundreds of microns to millimeters;

[0037] Step S3: Inject the constructed controllable vibration proppant into the reservoir, and receive the active source microseismic signal through the microseismic detector;

[0038] Step S4: Simplify the source model, and perform source positioning and controllable vibration proppant placement range simulation based on the active source microseismic signal.

[0039] In step S1, the collected geological data includes stratum information, structure information and surface geological conditions of the study area, and the collected geological data is integrated to establish a regional velocity model.

[0040] As shown in Figures 4 to 8 The embodiment constructs a uniform isotropic model with a P-wave (P-wave) velocity of 3000 m / s and an S-wave (S-wave) velocity of 1796 m / s, and the model size is 200 m x 200 m x 200 m (excluding the thickness of the boundary layer);

[0041] In step S2, the phase change energy storage material includes four categories of solid-solid phase change, solid-liquid phase change, solid-gas phase change and liquid-gas phase change;

[0042] In the optimization process of the phase change energy storage material, the following screening steps are included: ​

[0043] According to the previous geological data collection and geothermal field analysis, the salt resistance and specific gravity required by the controllable vibration proppant are determined, and the microseismic signal energy generated by the thermal explosion of the proppant constructed by different phase change energy storage materials is considered and analyzed, and the applicable phase change energy storage material is selected, and the controllable vibration proppant is constructed by combining the film material, so that the active source microseismic signal is controlled and enhanced;

[0044] As shown in Figure 2 and Figure 3 , in step S3, the controllable vibration proppant is carried to the bottom of the well by the high-pressure fluid, and under the heating of the geothermal temperature, the phase change material in the vibration proppant is excited to produce phase change, including one of solid-solid phase change or solid-gas phase change, further causing the expansion of the film inside, when reaching a certain critical point, the controllable vibration proppant explodes and generates microseismic signals, in this embodiment, it is a single seismic source, the frequency is 60Hz, and the seismic source position is the center of the bottom of the model, by collecting and analyzing the frequency characteristics of the active source microseismic signal, and using time-frequency analysis methods such as Fourier transform and wavelet transform, the signal pickup is realized.

[0045] And the microseismic detector can be placed in the well or on the ground, in this embodiment Figure 4 is ground monitoring, Figure 5 is well monitoring, and the measuring lines are located at the center. Figure 6 and Figure 7 are schematic diagrams of microseismic signals obtained by ground monitoring (y component) and well monitoring (z component) respectively, in Figure 6 and Figure 7 , the P wave is a kind of longitudinal wave, and the S wave is a kind of transverse wave. Figure 8 is the basic process of active source microseismic monitoring data processing, including active source microseismic signal pickup and seismic source positioning, according to the travel time and waveform information of P wave and S wave, after effective signal pickup, the seismic source position can be obtained by optimizing the seismic source positioning method.

[0046] In step S4, the seismic source positioning is carried out by simplifying the seismic source model and using the equivalent seismic source principle for seismic source positioning in a limited space;

[0047] The equivalent seismic source principle refers to: considering positioning accuracy and microseismic signal strength and other factors, all seismic sources in a small range of space are processed as a single seismic source by using the assumption condition that the seismic sources (controllable vibration proppants) are densely distributed and have the same vibration time and direction in a small range.

[0048] The controllable vibration proppant laying range simulation is to obtain the spatial distribution of the controllable vibration proppant by using the assumption condition that the controllable vibration proppant corresponds to the positioned seismic source one by one, and by comprehensively considering the seismic source position, seismic time, and seismic source intensity and other related seismic source information.

[0049] The application provides a kind of active source microseismic monitoring method based on phase change energy storage material, compared with traditional microseismic monitoring technology, the application proposes the idea of source signal from "rock rupture induced" to "controllable vibration proppant active excitation", controllable vibration proppant is constructed using phase change energy storage material, uncontrollable "passive source" signal is converted into controllable enhanced "active source" signal, and the space laying range of controllable vibration proppant is used as monitoring interpretation result, the monitoring interpretation precision and timeliness are improved, and the proppant laying range simulation result can be used to represent the spatial distribution range of remaining oil, and can also be used to guide fracturing effect evaluation and optimization decision, solve the problems of weak and random signal, low signal-to-noise ratio of collected data and difficult evaluation of effective transformation volume in traditional microseismic monitoring technology.

[0050] The above is only a preferred embodiment of the method, and does not limit the method in any form. Although the method has been disclosed as above, it is not intended to limit the method. Any person skilled in the art can make slight changes or modifications to the disclosed technical content to obtain equivalent embodiments with equivalent changes without departing from the technical solution of the method. Any modification, equivalent change and modification of the above embodiments according to the technical essence of the method are still within the scope of the technical solution of the method.

Claims

1. A method of active source microseismic monitoring based on phase change energy storage material, characterized in that: It comprises the following steps: Step S1: Collecting geological data and using it to establish a regional velocity model, conducting geothermal field analysis according to the geological data and evaluating the temperature change of the controlled vibration proppant after entering the well; Step S2: Selecting the phase change energy storage material and constructing the controlled vibration proppant, wherein the controlled vibration proppant is constructed by the phase change energy storage material and the coating material; Step S3: Injecting the constructed controlled vibration proppant into the reservoir, and receiving the active source microseismic signal through the microseismic detector; Step S4: Constructing a simplified seismic source model, and positioning the seismic source and simulating the placement range of the controlled vibration proppant through the active source microseismic signal; The model has a longitudinal wave velocity of 3000 m / s, a transverse wave velocity of 1796 m / s, and a model size of 200 m x 200 m x 200 m; The phase change energy storage material is one of the four categories of solid-solid phase change, solid-liquid phase change, solid-gas phase change, and liquid-gas phase change, which is encapsulated inside the proppant through a coating process to form the controlled vibration proppant; The controlled vibration proppant is carried to the bottom of the well by a high-pressure fluid, and the microseismic detector is placed anywhere in the well or on the ground; Under the heating of the geothermal temperature, the phase change material inside the vibrating proppant is excited to produce a phase change, which further causes the expansion of the coating inside, and when a certain critical point is reached, the controlled vibration proppant bursts and generates a microseismic signal, which is a single seismic source with a frequency of 60 Hz and a source location at the center of the bottom of the model. The signal is picked up by collecting and analyzing the frequency characteristics of the active source microseismic signal and using the time-frequency analysis method; the time-frequency analysis method includes Fourier transform and wavelet transform; In step S1, the collected geological data includes the stratigraphic information, structural information and surface geological conditions of the study area, and the collected geological data is integrated to establish a regional velocity model; In step S2, during the selection of the phase change energy storage material, the following screening steps are included: The required salt resistance and specific gravity of the controlled vibration proppant are determined based on the previous geological data collection and geothermal field analysis, and the microseismic signal energy generated by the proppant constructed by different phase change energy storage materials is analyzed to select the suitable phase change energy storage material; In step S4, the seismic source positioning is performed through the simplified seismic source model and the equivalent seismic source principle in a limited space; The equivalent seismic source principle refers to the assumption that the seismic source, i.e. the controlled vibration proppant, is densely distributed and has the same vibration time and direction in a small range, and considering the positioning accuracy and microseismic signal intensity factors, all seismic sources in a small range of space are processed as a single seismic source.

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