CN116500673A - Artificial island micro-seismic monitoring method, equipment and medium based on distributed optical fiber acoustic wave sensing - Google Patents
Artificial island micro-seismic monitoring method, equipment and medium based on distributed optical fiber acoustic wave sensing Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V1/00—Seismology; Seismic or acoustic prospecting or detecting
- G01V1/28—Processing seismic data, e.g. analysis, for interpretation, for correction
- G01V1/282—Application of seismic models, synthetic seismograms
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H9/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means
- G01H9/004—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means using fibre optic sensors
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V1/00—Seismology; Seismic or acoustic prospecting or detecting
- G01V1/28—Processing seismic data, e.g. analysis, for interpretation, for correction
- G01V1/288—Event detection in seismic signals, e.g. microseismics
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- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
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- G01V1/30—Analysis
- G01V1/303—Analysis for determining velocity profiles or travel times
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- G01V1/00—Seismology; Seismic or acoustic prospecting or detecting
- G01V1/28—Processing seismic data, e.g. analysis, for interpretation, for correction
- G01V1/30—Analysis
- G01V1/307—Analysis for determining seismic attributes, e.g. amplitude, instantaneous phase or frequency, reflection strength or polarity
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- G—PHYSICS
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- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V1/00—Seismology; Seismic or acoustic prospecting or detecting
- G01V1/28—Processing seismic data, e.g. analysis, for interpretation, for correction
- G01V1/36—Effecting static or dynamic corrections on records, e.g. correcting spread; Correlating seismic signals; Eliminating effects of unwanted energy
Abstract
The invention relates to the field of artificial island micro-seismic monitoring, and discloses an artificial island micro-seismic monitoring method, equipment and medium based on distributed optical fiber acoustic wave sensing, wherein the method comprises the following steps: distributed optical fiber acoustic wave sensing monitoring equipment is circumferentially distributed in island land and shallow water and deep water areas around the island land, and an optical cable in the equipment is coupled with water sediment and sand matrixes; continuously observing the microseism signals in the stratum with meter-scale space precision; picking up microseism signals based on a long-short time window ratio method, picking up the relative arrival time of DAS (data acquisition system) earthquake signals by using a cross correlation method, and constructing a time difference matrix; establishing a three-dimensional initial speed model of the artificial island by using a measuring means; dividing a research area into coarse grids, and obtaining the initial position of the microseism signal by using a grid searching method; and carrying out joint updating on the initial velocity model and the initial position of the microseism event by adopting a simulated annealing method to obtain the optimal velocity model and the optimal position of the microseism event.
Description
Technical Field
The invention relates to the field of artificial island micro-seismic monitoring, in particular to an artificial island micro-seismic monitoring method, equipment and medium based on distributed optical fiber acoustic wave sensing.
Background
The geological profile of the artificial island study area can be obtained by using geological data and geophysical data. For example, the in-situ measurement or laboratory measurement is carried out on the data such as rock, sediment, drilling core and the like on the surface layer of the artificial island, so that the stratum ordering and the internal crack development condition of the artificial island can be obtained. But limited by technology and cost, island information obtained by the method is less, and only partial points can be described. Conventional marine seismic methods, such as Ocean Bottom Cables (OBC) or Ocean Bottom Seismometers (OBS), may also perform marine formation imaging. The OBS method is that hundreds or thousands of detectors are connected to a submarine cable, one end of the submarine cable is connected to a fixed instrument ship, the other seismic source ship is used for blasting according to a designed route to perform seismic operation, and the submarine cable receives reflected wave signals of a marine bottom stratum. OBS is the placement of seismometers in the deep sea, monitoring of ocean bottom seismic signals. However, on one hand, the island water level is shallow, which affects the implementation of the actual project. On the other hand, the OBC and OBS have higher cost, and the defect of the traditional method is one of the main difficulties for restricting the island security evaluation in China.
Fiber optic microseism monitoring techniques provide dawn for island security assessment. The distributed optical fiber acoustic wave sensing (DAS) technology can detect deformation caused by micro seismic waves and can reflect the change of the structural characteristics of the underground stratum. Meanwhile, the DAS seismic data has the advantages of low acquisition cost, wide frequency spectrum, high stratum resolution, convenience in arrangement, capability of carrying out real-time transmission and the like. These advantages have the potential to replace traditional marine seismometers. At present, the DAS technology is not practically applied in the field of artificial island micro-seismic monitoring, and development space exists for data acquisition, processing, imaging algorithms and equipment.
Therefore, the research proposes a novel method for monitoring the micro-earthquake of the artificial island based on DAS.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides an artificial island micro-seismic monitoring method, equipment and medium based on distributed optical fiber acoustic wave sensing, which aim to solve the real-time monitoring and quantitative evaluation of marine island seismic disasters.
In order to achieve the above purpose, the present invention may be performed by the following technical scheme:
in a first aspect, the invention provides an artificial island micro-seismic monitoring method, comprising the following steps:
distributed optical fiber acoustic wave sensing monitoring equipment is circumferentially distributed in island land and shallow water and deep water areas around the island land, an optical cable in the equipment is coupled with water sediment and sand matrixes, and the specific position of the optical cable is calculated through GPS and active source signals;
continuously observing the microseism signals in the stratum with meter-scale space precision; picking up microseism signals based on a long-short time window ratio method, picking up the relative arrival time of DAS (data acquisition system) earthquake signals by using a cross correlation method, and constructing a time difference matrix;
establishing a three-dimensional initial speed model of the artificial island by using a measuring means;
dividing a research area into coarse grids, and obtaining the initial position of the microseism signal by using a grid searching method;
the initial velocity model and the initial position of the microseism event are updated in a combined mode by adopting a simulated annealing method, and the optimal velocity model and the optimal microseism event position are obtained;
and (3) synthesizing DAS microseism signal acquisition, processing and inversion means, and determining the accurate position of the artificial island microseism.
In a second aspect, the present invention provides an electronic device comprising a processor and a memory, the memory storing at least one instruction, at least one program, code set or instruction set, the at least one instruction, the at least one program, the code set or instruction set being loaded and executed by the processor to implement an artificial island microseismic monitoring method as described above.
In a third aspect, the present invention provides a computer readable storage medium having stored therein at least one instruction, at least one program, code set or instruction set loaded and executed by a processor to implement an artificial island microseismic monitoring method as described above.
Compared with the prior art, the invention has the beneficial effects that: the invention provides a novel method for monitoring an artificial island micro-earthquake, which comprises the steps of obtaining meter-scale space precision continuous observation micro-earthquake signals by arranging distributed optical fiber acoustic wave sensing monitoring equipment around island lands and shallow water and deep water areas around the island lands; accurately picking up the relative arrival time of DAS seismic signals based on a long-short time window comparison method and a cross correlation method, and constructing a time difference matrix; establishing a three-dimensional initial speed model of the artificial island by means of laboratory measurement, in-situ measurement, geophysical measurement and the like; obtaining the initial position of the microseism signal by using a grid searching method; and updating inversion by adopting a simulated annealing method to obtain an optimal speed model and a microseism event position. According to the method, the monitoring cost of the artificial island is reduced, a new thought is provided for evaluating the geological safety of the artificial island, the real-time accurate characterization of the stratum activity condition of the island is facilitated, and a good technical monitoring means is provided for the geological steady-state safety of the artificial island.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following description will briefly explain the drawings needed in the embodiments, and it is obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of an artificial island microseism monitoring method based on distributed optical fiber acoustic wave sensing according to an embodiment of the invention;
FIG. 2 is a schematic diagram of monitoring island microseism signals by using a distributed acoustic sensing optical fiber according to an embodiment of the present invention;
FIG. 3 is a flow chart for updating velocity models and microseismic event locations using simulated annealing.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present disclosure.
Examples:
it should be noted that the terms "first," "second," and the like in the description and the claims of the present invention and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments of the invention described herein may be implemented in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed or inherent to such process, method, article, or apparatus.
In the description of the present invention, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise. Furthermore, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.
The word "exemplary" is used hereinafter to mean "serving as an example, embodiment, or illustration. Any embodiment described as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.
In order to better understand the technical solution provided by the embodiments of the present invention, the following description is given for some simple descriptions of the technical background of the technical solution provided by the embodiments of the present invention, so as to better understand the technical concept of the present invention.
The artificial island geological safety steady state monitoring has important significance for future ocean development in China. Traditional laboratory or field measurement methods are costly, time-efficient, and difficult to monitor for long periods of formation conditions. The activities of sediment and fault zones in the island often cause secondary disasters such as collapse, landslide, debris flow and the like, and the security of substances and people life and property on the island is seriously affected. Therefore, the island steady state real-time safety monitoring system with low cost, high efficiency and high precision is developed, and is beneficial to the long-term development of the ocean in China in the future. According to the invention, the island-reef land and underwater microseism signals are continuously monitored by utilizing the sea-land integrated distributed optical fiber sound wave sensing monitoring system, so that real-time stratum activity conditions are obtained. Meanwhile, a long-short time window comparison method and a cross correlation method are used for picking up the relative arrival time of DAS microseism signals, and effective microseism signals are identified. And obtaining an initial speed model of the island and the position of the microseism event based on the original geology and geophysical data, and further obtaining a more accurate development condition of the underground fault zone by using a simulated annealing method. Based on the method, the invention provides a novel artificial island geological steady-state safety evaluation means.
Referring to fig. 1, the artificial island micro-seismic monitoring method based on distributed optical fiber acoustic wave sensing of the present invention may include the following steps:
step one: distributed optical fiber acoustic wave sensing monitoring equipment is circumferentially distributed in island land and shallow water and deep water areas around the island land, and optical cables in the equipment are well coupled with matrixes such as underwater sediment and sand; and calculating the specific position of the optical cable through the GPS and the active source signals.
Specifically, the distributed optical fiber acoustic wave sensing monitoring equipment is circumferentially arranged in the island land and the shallow water and deep water areas around the island land, and an optical cable in the equipment is well coupled with matrixes such as water sediment and sand, and the specific steps comprise:
(1) Pouring the land cable directly into cement; and the soil can be directly buried in a deep ditch which is not less than fifty centimeters under the condition of not having pouring, and the soil needs to be compacted after the soil is buried.
(2) Digging a groove at the bottom of the water by a barge method in a shallow water environment, burying a sensitized submarine cable in the groove, and covering and compacting a filler.
(3) In the deep water environment, a sensitized sea cable is directly laid by utilizing a gravity sedimentation method, and a weight is tied at intervals of one hundred meters to sink into the sea bottom along with the sea cable in order to ensure good coupling between the sea cable and sediment at the bottom.
Further, the calculating the specific position of the optical cable through the GPS and the active source signal specifically comprises the following steps:
(1) In the process of laying the land cable and the sea cable, the specific spatial position of the optical cable is recorded through GPS dotting.
(2) And manually knocking a weight above the land optical cable, and recording DAS signals in the optical cable and corresponding GPS positions of the land hammering.
(3) A movable air gun is adopted to emit signals in water, and the relative positions of air gun sources are recorded through sea cables.
(4) And obtaining the space layout path of each section of optical cable through the one-to-one correspondence between the GPS position, the active source position and the DAS signal position.
Step two: continuously observing the microseism signals in the stratum with meter-scale space precision; and picking up microseism signals based on a long-short time window ratio method, picking up the relative arrival time of DAS (data acquisition system) earthquake signals by using a cross-correlation method, and constructing a time difference matrix.
Specifically, the method for continuously observing the microseism signals in the stratum with meter-scale space precision specifically comprises the following steps:
(1) The DAS demodulator is connected in series with land cable, shallow water and deep water sea cable.
(2) Transmitting laser light inside the demodulator and receiving the reflected lightBased on the laser signal of (2)The OTDR principle resolves the strain caused by micro-earthquakes outside the cable in the laser path.
(3) Setting the optical cable monitoring strain gauge length to be 1 meter, and setting the time sampling rate to be 250Hz; microseismic signals were continuously monitored and recorded 24 hours a day.
In detail, referring to fig. 2, fig. 2 is a schematic diagram of monitoring an artificial island microseismic signal by a distributed optical fiber sensing device. It mainly comprises the following components:
(1) Distributed optical fiber monitoring equipment is arranged in land, shallow water and deep water environments of the artificial island. The land cable is directly poured into cement or embedded into a deep trench of not less than fifty centimeters; burying the optical fiber in a water bottom groove by a barge method in a shallow water environment; in the deepwater environment, the submarine cable is directly paved by utilizing a gravity sedimentation method, and the submarine cable and the seabed are ensured to be coupled by attaching a weight.
(2) And the optical cable signal demodulator is placed in a land machine room or other safe positions, so that stable power supply of the demodulator is ensured. The demodulator interface is connected in series with the land cable and the sea cable. Based onThe OTDR principle resolves the strain induced by the seismic waves felt by the land and sea cables.
(3) The strain sensitivity of the optical fiber space monitoring is set to be one meter, the time sampling rate is 250Hz, and the continuous wave field of the microseismic propagation to the surface is monitored continuously every day.
Further, the method for picking up microseism signals based on the long-short time window ratio method picks up the relative arrival time of DAS earthquake signals by using a cross-correlation method, and constructs a time difference matrix, which comprises the following specific steps:
first, a long-short window ratio method is used to pick up the effective microseism event. The long term window (LTA) is an Average value of energy of a longer time signal sampling length, and the short term window (Short Term Average, STA) is an Average value of energy of a shorter time signal sampling length:
wherein S (N) is the signal amplitude obtained by DAS monitoring, N is the number of long-time window signal samples, M is the number of short-time window signal samples, and N > M. Ratio is the average energy Ratio of the shorter time signal to the longer time signal obtained by recording. When it is greater than a threshold, it may be determined that the monitored signal is caused by a seismic event.
And secondly, picking up accurate relative arrival time of different optical fiber monitoring channels by using a cross-correlation method, and constructing a time difference matrix. The cross-correlation method formula can be expressed as:
wherein x is 1 And x 2 The seismic traces are monitored for different DASs,is a similarity coefficient. And precisely obtaining similarity coefficients of the seismic events extracted by Ratio among different optical fiber channels by using a cross-correlation formula, and selecting a time difference with the maximum similarity coefficient of the seismic channels to form a time difference matrix.
Step three: and establishing a three-dimensional initial speed model of the artificial island by using a measuring means.
Specifically, the method for establishing the artificial island three-dimensional initial speed model by using the measuring means comprises the following specific steps:
obtaining the speed of an artificial island rock and sediment sample by laboratory measurement, wherein the speed is used as a speed background; obtaining the speed of rock and sediment at a specific point location through in-situ measurement, and taking the speed as regional stratum speed constraint; by combining the data, the three-dimensional speed field of the artificial island in the research area is established by means of geophysical methods such as well logging, seismic data inversion and the like. The velocity model obtained based on the above limited data has a certain gap from the real model, but can reflect the basic velocity structure.
By way of example, the measurement means may be laboratory measurements, in situ measurements, geophysical measurements and the like.
Step four: dividing the research area into coarse grids, and obtaining the initial position of the microseism signal by using a grid searching method.
Specifically, the method for dividing the research area into coarse grids and obtaining the initial position of the microseism signal by using a grid searching method specifically comprises the following steps:
(1) The investigation region is divided into larger three-dimensional rectangular grids according to the obtained uniformity of the three-dimensional velocity model, and the center point of each grid represents one possible source location.
(2) And calculating the travel time of each grid seismic source to the DAS optical cable by using a ray tracing method, and establishing an arrival time difference matrix of each seismic source in the optical cable signal based on a cross correlation method.
(3) And differencing the recorded optical cable arrival time difference matrix and the real observed arrival time difference matrix to form a double-difference matrix.
(4) The seismic source corresponding to the double difference matrix with the smallest mode is the position of the micro-seismic signal.
Step five: and carrying out joint updating on the initial velocity model and the initial position of the microseism event by adopting a simulated annealing method to obtain the optimal velocity model and the optimal position of the microseism event.
Specifically, the method for updating the initial velocity model and the initial position of the microseism event by adopting the simulated annealing method in a combined way to obtain the optimal velocity model and microseism event position comprises the following specific steps:
(1) Setting a higher initial temperature of a simulated annealing method, taking microseism signals obtained by optical cable observation to a time difference matrix as constraint data, taking a three-dimensional initial velocity model and a microseism initial position as initial conditions, and updating the velocity model and the microseism event position at the temperature.
(2) After a certain number of iterations is reached, the temperature of the simulated annealing method is reduced, the combination of the time difference calculated by forward modeling of the velocity model and the microseism position in the last temperature and the real time difference is used as an initial condition, and the temperature is updated again in an iteration mode in the new temperature.
(3) Gradually reducing the temperature of the simulated annealing method, and stopping iteration when the obtained position change range of the microseism event is smaller than 2 meters.
(4) The velocity model at this time is the optimal velocity model, and the inversion position is the final microseism event position.
In detail, referring to fig. 3, fig. 3 is a flow chart for correcting velocity models and microseismic event locations using simulated annealing.
The method mainly comprises the following steps:
the three-dimensional speed model of the research area is determined as follows:
m v ＝[V 1 ,V 2 ,...,V M ]
the microseism event positions obtained according to the grid search method are as follows:
m s ＝[S 1 ,S 2 ,...,S N ]
wherein M is the grid point number of the three-dimensional velocity model, and N is the number of microseism events. The joint inversion model parameters at this time are:
m＝m v +m s
determining the initial temperature of the simulated annealing method as T 0 The energy function at this time is composed of microseismic signal-to-moveout matrix:
where nr represents the number of DAS traces, t=o+te, t is the arrival time of DAS recordings, O is the start time of a seismic event, and Te is the travel time from the source point to the trace.And->Representing observationsTravel times of the arriving seismic traces r to event i and event j. />And->Representing the travel times of the detector r to event i and event j obtained by the forward calculation. The obs and cal represent observed and calculated values.
The simulated annealing method is mainly divided into two path optimization model parameters of internal circulation and external circulation. The main flow of the internal circulation is as follows:
in the process of updating model parameters by a simulated annealing method, aiming at updating the speed model and the microseism event position, the following formula is adopted:
in the method, in the process of the invention,is T k Speed value at temperature, +.>Is T k Updated speed values at temperature. V (V) max Maximum speed value, V min Is the minimum speed value. />Is T k Microseismic event location at temperature, +.>Is T k And updating the positions of the microseismic events at the temperature. S is S max Take the value of the maximum position, S min Take the value of the minimum position. x is a random number, and its value can be expressed as:
where u is a random number between 0, 1.
After the model parameters are updated, if the changed energy value delta E is smaller than 0, the new model parameter forward calculation data are proved to be more approximate to the observation data, and the new model parameters are received at the moment; if ΔE > 0, then the reception probability is calculated:
if P > a, a is a random number between [0,1], the new model is still acceptable; otherwise, the original model enters the next cycle.
The main flow of the external circulation is as follows:
the temperature change function of the simulated annealing method is determined as follows:
T k ＝T 0 exp(-ck 1/2n )
wherein c is a control parameter, k is an outer loop iteration parameter, and n=m+n is the number of model parameters.
After each inner loop is completed, it is queried whether an outer loop is needed. If the external circulation needs to be continued, the temperature is updated, a speed model with the optimal temperature and a microseism event position combination are selected as initial conditions, and model parameters are continuously updated. Otherwise, judging whether the positioning precision of the microseism event meets the requirement, if so, outputting a result, otherwise, continuously updating the position of the microseism event at the temperature until a stop condition is reached.
According to the calculation method, the island micro-seismic event occurrence position can be finally obtained. The extension condition of the underground fault zone can be finally described by a large number of microseism event positioning results, and a plurality of tiny hidden fault structures are found.
Step six: and (3) synthesizing DAS microseism signal acquisition, processing and inversion means, and determining the accurate position of the artificial island microseism.
Based on the same inventive concept, the embodiment of the invention further provides an electronic device, which comprises a processor and a memory, wherein at least one instruction, at least one section of program, a code set or an instruction set is stored in the memory, and the at least one instruction, the at least one section of program, the code set or the instruction set is loaded and executed by the processor so as to realize the artificial island micro-seismic monitoring method.
It is understood that the memory may include random access memory (Random Access Memory, RAM) or Read-only memory (Read-only memory). Optionally, the memory includes a non-transitory computer readable medium (non-transitory computer-readable storage medium). The memory may be used to store instructions, programs, code sets, or instruction sets. The memory may include a stored program area and a stored data area, wherein the stored program area may store instructions for implementing an operating system, instructions for at least one function, instructions for implementing the various method embodiments described above, and the like; the storage data area may store data created according to the use of the server, etc.
The processor may include one or more processing cores. The processor uses various interfaces and lines to connect various portions of the overall server, perform various functions of the server, and process data by executing or executing instructions, programs, code sets, or instruction sets stored in memory, and invoking data stored in memory. Alternatively, the processor may be implemented in hardware in at least one of digital signal processing (Digital Signal Processing, DSP), field programmable gate array (Field-Programmable Gate Array, FPGA), programmable logic array (Programmable Logic Array, PLA). The processor may integrate one or a combination of several of a central processing unit (Central Processing Unit, CPU) and a modem etc. Wherein, the CPU mainly processes an operating system, application programs and the like; the modem is used to handle wireless communications. It will be appreciated that the modem may not be integrated into the processor and may be implemented by a single chip.
Because the electronic device is the electronic device corresponding to the artificial island microseism monitoring method according to the embodiment of the invention, and the principle of solving the problem of the electronic device is similar to that of the method, the implementation of the electronic device can refer to the implementation process of the embodiment of the method, and the repetition is omitted.
Based on the same inventive concept, the embodiments of the present invention also provide a computer-readable storage medium having at least one instruction, at least one program, a code set, or an instruction set stored therein, the at least one instruction, the at least one program, the code set, or the instruction set being loaded and executed by a processor to implement the artificial island micro-seismic monitoring method as described above.
Those of ordinary skill in the art will appreciate that all or part of the steps of the various methods of the above embodiments may be implemented by a program to instruct related hardware, the program may be stored in a computer readable storage medium including Read-Only Memory (ROM), random access Memory (Random Access Memory, RAM), programmable Read-Only Memory (Programmable Read-Only Memory, PROM), erasable programmable Read-Only Memory (Erasable Programmable Read Only Memory, EPROM), one-time programmable Read-Only Memory (One-time Programmable Read-OnlyMemory, OTPROM), electrically erasable programmable Read-Only Memory (EEPROM), compact disc Read-Only Memory (CD-ROM) or other optical disc Memory, magnetic disk Memory, tape Memory, or any other medium capable of being used for carrying or storing data that is readable by a computer.
Because the storage medium is a storage medium corresponding to the artificial island microseism monitoring method according to the embodiment of the present invention, and the principle of solving the problem of the storage medium is similar to that of the method, the implementation of the storage medium can refer to the implementation process of the embodiment of the method, and the repetition is omitted.
In some possible implementations, aspects of the methods of the embodiments of the present invention may also be implemented in the form of a program product comprising program code for causing a computer device to carry out the steps of the artificial island microseismic monitoring method according to the various exemplary embodiments of the present application as described herein above, when the program product is run on a computer device. Wherein executable computer program code or "code" for performing the various embodiments may be written in a high-level programming language such as C, C ++, c#, smalltalk, java, javaScript, visual Basic, structured query language (e.g., act-SQL), perl, or in a variety of other programming languages.
In conclusion, the method fully utilizes the advantages of good underwater adaptability, space continuous observation and high space sampling rate of the DAS system, and accurately identifies and positions microseism signals in the artificial island. The microseism signal positioning adopts a two-step walking strategy: firstly, a coarser initial velocity model and a microseism event initial position are established according to original data, and then the velocity model and the microseism event position are jointly optimized, so that a more accurate stratum velocity field and a stratum tiny breaking zone are obtained. The method can obtain stratum activity conditions of the artificial island in real time, accurately position the occurrence position of the underground fault, and has important significance for evaluating geological natural disasters of the island.
In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.
The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement the same, and are not intended to limit the scope of the present invention. All equivalent changes or modifications made in accordance with the essence of the present invention are intended to be included within the scope of the present invention.
Claims (10)
1. The artificial island micro-seismic monitoring method is characterized by comprising the following steps of:
distributed optical fiber acoustic wave sensing monitoring equipment is circumferentially distributed in island land and shallow water and deep water areas around the island land, an optical cable in the equipment is coupled with water sediment and sand matrixes, and the specific position of the optical cable is calculated through GPS and active source signals;
continuously observing the microseism signals in the stratum with meter-scale space precision; picking up microseism signals based on a long-short time window ratio method, picking up the relative arrival time of DAS (data acquisition system) earthquake signals by using a cross correlation method, and constructing a time difference matrix;
establishing a three-dimensional initial speed model of the artificial island by using a measuring means;
dividing a research area into coarse grids, and obtaining the initial position of the microseism signal by using a grid searching method;
the initial velocity model and the initial position of the microseism event are updated in a combined mode by adopting a simulated annealing method, and the optimal velocity model and the optimal microseism event position are obtained;
and (3) synthesizing DAS microseism signal acquisition, processing and inversion means, and determining the accurate position of the artificial island microseism.
2. The method for monitoring the micro-earthquake of the artificial island according to claim 1, wherein distributed optical fiber acoustic wave sensing monitoring equipment is circumferentially arranged on the island land and the shallow water and deep water areas around the island land, and an optical cable in the equipment is coupled with a water sediment and sand matrix, and the method comprises the following specific steps:
pouring the land cable in cement, wherein the land cable is buried in a deep trench of not less than fifty centimeters when no pouring condition is provided, and compacting soil after the land cable is buried;
digging a groove at the bottom of the water by a barge method in a shallow water environment, burying a sensitized submarine cable in the groove, and covering and compacting a filler;
in the deepwater environment, a sensitized submarine cable is directly paved by utilizing a gravity sedimentation method, a weight is tied at intervals of one hundred meters, and the sensitized submarine cable is sunk into the seabed along with the submarine cable.
3. The artificial island microseismic monitoring method according to claim 2, wherein the specific position of the optical cable is calculated through the GPS and the active source signals, and the specific steps comprise:
recording the specific spatial position of the optical cable through GPS dotting in the process of laying the land cable and the sea cable;
manually knocking a weight above the land optical cable, and recording DAS signals in the optical cable and GPS positions corresponding to the land hammering;
the movable air gun is adopted to emit signals in water, the relative position of an air gun source is recorded through a submarine cable, and the space layout path of each section of optical cable is obtained through one-to-one correspondence between the GPS position, the active source position and the DAS signal position.
4. The artificial island microseism monitoring method according to claim 1, wherein the continuous observation of the microseism signal in the stratum with the meter-scale space precision comprises the following specific steps:
the DAS demodulator is connected in series with land, shallow water and deep water sea cables, and emits laser light inside the demodulator and receives reflected laser light signals based onPrinciple analysis is carried out on strain caused by micro-earthquake outside the optical cable in the laser path; setting the optical cable monitoring strain gauge length to be 1 meter, and setting the time sampling rate to be 250Hz; microseismic signals were continuously monitored and recorded 24 hours a day.
5. The method for monitoring the micro-earthquake of the artificial island according to claim 1, wherein the method for constructing the time difference matrix comprises the following specific steps of:
and picking up the effective microseism event by using a long-short time window ratio method, wherein the long-short time window is an energy average value of a longer-time signal sampling length, and the short-time window is an energy average value of a shorter-time signal sampling length:
wherein S (N) is the signal amplitude obtained by DAS monitoring, N is the number of long-time window signal samples, M is the number of short-time window signal samples, N > M, ratio is the average energy Ratio of the short-time signal obtained by recording to the long-time signal, and when the Ratio is larger than a threshold value, the monitored signal can be judged to be caused by an earthquake event;
then picking up accurate relative arrival time of different optical fiber monitoring channels by using a cross-correlation method, constructing a time difference matrix, and expressing the formula of the cross-correlation method as follows:
wherein x is 1 And x 2 The seismic traces are monitored for different DASs,is a similarity coefficient;
and precisely obtaining similarity coefficients of the seismic events extracted by Ratio among different optical fiber channels by using a cross-correlation formula, and selecting a time difference with the maximum similarity coefficient of the seismic channels to form a time difference matrix.
6. The method for monitoring the micro-earthquake of the artificial island according to claim 1, wherein the method for establishing the three-dimensional initial speed model of the artificial island by using the measuring means comprises the following specific steps:
obtaining the speed of an artificial island rock and sediment sample by laboratory measurement, wherein the speed is used as a speed background; obtaining the speed of rock and sediment at a specific point location through in-situ measurement, and taking the speed as regional stratum speed constraint; by combining the data, the three-dimensional speed field of the artificial island in the research area is established through a geophysical method, and the geophysical method comprises well logging and seismic data inversion.
7. The artificial island microseism monitoring method according to claim 1, wherein the research area is divided into coarse grids, and the initial positions of microseism signals are obtained by using a grid search method, and the method comprises the following specific steps:
dividing a research area into three-dimensional rectangular grids according to the obtained uniformity degree of the three-dimensional speed model, wherein the central point of each grid represents a possible seismic source position;
calculating the travel time from each grid seismic source to a DAS optical cable by using a ray tracing method, and establishing an arrival time difference matrix of each seismic source in optical cable signals based on a cross correlation method;
performing difference between the recorded optical cable arrival time difference matrix and the real observed arrival time difference matrix to form a double difference matrix; the seismic source corresponding to the double difference matrix with the smallest mode is the position of the micro-seismic signal.
8. The method for monitoring the micro-earthquake of the artificial island according to claim 1, wherein the method for jointly updating the initial velocity model and the initial position of the micro-earthquake event by adopting a simulated annealing method to obtain the optimal velocity model and the optimal position of the micro-earthquake event comprises the following specific steps:
setting a higher initial temperature of a simulated annealing method, taking microseism signals obtained by optical cable observation to a time difference matrix as constraint data, taking a three-dimensional initial velocity model and a microseism initial position as initial conditions, and updating the velocity model and the microseism event position at the temperature;
after a certain iteration number is reached, the temperature of a simulated annealing method is reduced, the combination of the time difference calculated by forward modeling of the velocity model and the microseism position in the last temperature and the real time difference is used as an initial condition, and the new temperature is updated in an iterative mode again;
gradually reducing the temperature of the simulated annealing method, stopping iteration when the obtained position change range of the microseism event is smaller than 2 meters, wherein the speed model is the optimal speed model, and the inversion position is the final microseism event position.
9. An electronic device comprising a processor and a memory, wherein the memory stores at least one instruction, at least one program, code set, or instruction set, the at least one instruction, the at least one program, the code set, or instruction set being loaded and executed by the processor to implement the artificial island microseismic monitoring method according to any one of claims 1 to 8.
10. A computer readable storage medium having stored therein at least one instruction, at least one program, code set, or instruction set, loaded and executed by a processor to implement the artificial island microseismic monitoring method according to any one of claims 1 to 8.
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