Method and System for Real-Time Calculating a Microseismic Focal Mechanism Based on Deep Learning

Patent metadata

Field	Value
Publication number	US-2024230942-A9
Application number	US-202318199531-A
Country	US
Kind code	A9
Filing date	May 19, 2023
Priority date	Oct 25, 2022
Publication date	Jul 11, 2024
Grant date	—

Abstract

A method and system for real-time calculating a microseismic focal mechanism based on deep learning is provided, which belongs to the technical field of microseismic monitoring. The method includes: creating a training dataset, the training data including simulated DAS microseismic strain data and a focal mechanism corresponding to the simulated DAS microseismic strain data; training a focal mechanism calculation model by using the training dataset, with the simulated DAS microseismic strain data as an input and the focal mechanism corresponding to the simulated DAS microseismic strain data as a target output, so as to obtain a trained focal mechanism calculation model; collecting DAS microseismic strain data by a surface and downhole DAS acquisition system; performing preprocess operations such as removing abnormally large values on the DAS microseismic strain data; inputting the preprocessed DAS microseismic strain data into a trained focal mechanism calculation model to obtain a focal mechanism.

First claim

1 . A method for real-time calculating a microseismic focal mechanism based on deep learning, comprising steps:
building a training dataset comprising a plurality of training data, the training data comprising simulated Distributed Acoustic Sensing (DAS) microseismic strain data and a focal mechanism corresponding to the simulated DAS microseismic strain data, and parameters of the focal mechanism comprising a rake angle, a strike angle and a dip angle; training a focal mechanism calculation model by using the training dataset, with the simulated DAS microseismic strain data as an input and the focal mechanism corresponding to the simulated DAS microseismic strain data as a target output, so as to obtain a trained focal mechanism calculation model, wherein the focal mechanism calculation model is a neural network model, and the focal mechanism calculation model comprises four convolution blocks and two fully-connected blocks which are connected in sequence, the four convolution blocks each comprise a convolution layer, an activation layer, a maximum pooling layer and a Dropout layer connected in sequence, the activation layer adopts a ReLU activation function, and a 2D convolution layer is adopted; collecting DAS microseismic strain data by a ground and downhole DAS acquisition system, the DAS microseismic strain data comprising P-wave information and/or S-wave information recorded in a plurality of channels; preprocessing the DAS microseismic strain data to obtain preprocessed DAS microseismic strain data, the preprocessing comprising removing abnormal values from data recorded in each channel of the DAS microseismic strain data; inputting the preprocessed DAS microseismic strain data into the trained focal mechanism calculation model to obtain a focal mechanism for revealing a generation mechanism of microseism and stress change of underground reservoirs, and optimizing hydraulic fracturing with the focal mechanism; wherein after the step of building a training dataset comprising a plurality of training data, the method further comprises: randomly selecting a plurality of the simulated DAS microseismic strain data in the training dataset; setting data of a plurality of random channels in the selected simulated DAS microseismic strain data to null, to obtain simulated DAS microseismic strain data with abnormal channels; wherein the step of building a training dataset comprising a plurality of training data comprises: determining a plurality of simulated focal mechanisms within value ranges of various parameters of the focal mechanism; generating simulated DAS microseismic strain data corresponding to each simulated focal mechanism; deeming each simulated DAS microseismic strain data and corresponding simulated focal mechanism as a training datum to obtain a training dataset, wherein value ranges of various parameters of the focal mechanism are: 0°<rake angle<180°, 0°<strike angle<360°, 0°<dip angle<90°; wherein the simulated focal mechanisms conform to Gaussian distribution centered on an accurate focal mechanism, and an angular resolution is 1°, the calculation formula for the Gaussian distribution is as follows:

M
⁡
(
rake
)

=

(

rake
-

r
⁢
0

)

2

2
⁢

σ
2
2

M
⁡
(
strike
)

=

(

strike
-

s
⁢
0

)

2

2
⁢

σ
2
2

M
⁡
(
dip
)

=

(

dip
-

d
⁢
0

)

2

2
⁢

σ
2
2

where rake, strike and dip are values of various parameters of the simulated focal mechanisms, respectively, r0 is an accurate rake angle, σ is a standard deviation of the Gaussian distribution, s0 is an accurate strike angle, and d0 is an accurate dip angle.

2 . (canceled)

3 . (canceled)

4 . The method according to 1 , wherein after the step of generating simulated DAS microseismic strain data corresponding to each simulated focal mechanism according to the simulated focal mechanism, and before the step of deeming each simulated DAS microseismic strain data and corresponding simulated focal mechanism as a training datum to obtain a training dataset, the method further comprises:
adding background noise to a plurality of the simulated DAS microseismic strain data, the background noise being background noise during real monitoring.

5 . (canceled)

6 . A system for real-time calculating a microseismic focal mechanism based on deep learning, comprising:
a processor; and a memory having program instructions stored, wherein when the processor executes the program instructions stored on the memory, the processor is configured to: build a training dataset comprising a plurality of training data, the training data comprising simulated DAS microseismic strain data and a focal mechanism corresponding to the simulated DAS microseismic strain data, and parameters of the focal mechanism comprising a rake angle, a strike angle and a dip angle; train a focal mechanism calculation model by using the training dataset, with the simulated DAS microseismic strain data as an input, and the focal mechanism corresponding to the simulated DAS microseismic strain data as a target output, so as to obtain a trained focal mechanism calculation model, wherein the focal mechanism calculation model is a neural network model, and the focal mechanism calculation model comprises four convolution blocks and two fully-connected blocks which are connected in sequence, the four convolution blocks each comprise a convolution layer, an activation layer, a maximum pooling layer and a Dropout layer connected in sequence, the activation layer adopts a ReLU activation funct

Assignees

• Inst Geology & Geophysics Cas

Inventors

• Wu Shaojiang
• Wang Yibo
• Zheng Yikang
• Yao Yi

Classifications

• G01V1/46 Primary

  Data acquisition · CPC title

• G06N3/0464

  Convolutional networks [CNN, ConvNet] · CPC title

• G06N3/082

  modifying the architecture, e.g. adding, deleting or silencing nodes or connections · CPC title

• G06N3/048

  Activation functions · CPC title

• G01V1/42

  using generators in one well and receivers elsewhere or vice versa (G01V1/52 takes precedence) · CPC title