Machine learning-based two-step impedance inversion method and apparatus using seismic data
Techniques for a machine learning-based two-step impedance inversion method using seismic data are disclosed. In some embodiments of the disclosed technology, an impedance inversion method includes generating a domain adaptation model configured to predict, based on source data associated with a source area that includes a well, a P-impedance value of a target area that does not include a well, and generating, using the P-impedance value generated by the domain adaptation model, a P-impedance low frequency model configured to predict a final P-impedance value of the target area by performing an inversion. In this way, it is possible to accurately predict P-impedance value of an area where a well does not exist.
1 . A machine learning-based two-step impedance inversion method for identifying a presence of subsurface gas or oil reservoirs in a target area that does not include a well using seismic data, comprising:
directing seismic energy into the target area and detecting reflected seismic waves;
generating a domain adaptation model based on a source data associated with a source area that includes a well and the detected reflected seismic waves from the target area, and predicting a P-impedance value of the target area;
generating, using the P-impedance value generated by the domain adaptation model, a P-impedance low frequency model configured to predict a final P-impedance value of the target area by performing an inversion, the generating the P-impedance low frequency model comprising performing a preprocessing operation by generating the P-impedance low frequency model using the P-impedance value, the preprocessing operation comprising:
performing a smoothing operation by obtaining a smoothed P-impedance value by smoothing the P-impedance value; and
performing a filtering operation by obtaining the P-impedance low frequency model by applying a filter to the smoothed P-impedance value; and
displaying a prediction result for the presence of the subsurface gas or oil to a user.
2 . The impedance inversion method of claim 1 , wherein generating the domain adaptation model comprises:
extracting: feature information from seismic data of the source data associated with the source area; and feature information from seismic data of target data associated with the target area;
generating a first loss function value that decreases upon a decrease in an accuracy of determination in response to determining whether the feature information is associated with the source area or the target area;
generating a second loss function value representing a difference between a label of the feature information extracted from the source data and a label of the source data associated with well log data by predicting the label of the feature information extracted from the source data using a label prediction algorithm;
retraining a feature extraction algorithm to decrease a sum of the first loss function value and the second loss function value until the sum of the first loss function value and the second loss function value reaches a predetermined minimum value; and
predicting a label corresponding to the seismic data of the target data using the label prediction algorithm.
3 . The impedance inversion method of claim 1 , wherein generating the P-impedance low frequency model further comprises:
performing an inversion operation by predicting the final P-impedance value using the P-impedance low frequency model and the seismic data of the target data.
4 . The impedance inversion method of claim 3 ,
wherein the preprocessing operation further comprises:
performing an extension operation by obtaining a smoothed S-impedance value using the smoothed P-impedance value,
wherein the filtering operation further includes obtaining an S-impedance low frequency model by applying a filter to the smoothed S-impedance value, and
wherein the inversion operation includes predicting the final P-impedance value of the target area and a final S-impedance value of the target area by performing a simultaneous inversion on the P-impedance value and an S-impedance value using the P-impedance low frequency model, the S-impedance low frequency model and the seismic data of the target data.
5 . The impedance inversion method of claim 4 ,
wherein the extension operation further includes obtaining a smoothed density value using the smoothed P-impedance value,
wherein the filtering operation further includes obtaining a density low frequency model by applying a filter to the smoothed density value, and
wherein the inversion operation includes predicting the final P-impedance value of the target area, the final S-impedance value of the target area, and a final density value of the target area by performing a simultaneous inversion on the P-impedance value, the S-impedance value, and density value using the P-impedance low frequency model, the S-impedance low frequency model, the density low frequency model and the seismic data of the target data.
6 . The impedance inversion method of claim 4 , wherein the extension operation includes converting the smoothed P-impedance value into the smoothed S-impedance value using a relational expression derived from a relationship between a P-impedance value and an S-impedance value included in well log data of the source data.
7 . The impedance inversion method of claim 5 , wherein the extension operation includes converting the smoothed P-impedance value into the smoothed density value using a relational expression derived from a relationship between a P-impedance value and a density value included in well log data of the source data.
8 . A machine learning-based two-step impedance inversion apparatus configured to identify a presence of subsurface gas or oil reservoirs in a target area that does not include a well using seismic data, comprising:
a processor;
a storage unit communicatively connected to the processor, the storage unit being configured to store:
program codes operating in the processor,
data defining reflected seismic waves resulting from directing seismic energy in the target area, and
source data associated with a source area that includes a well
the program codes comprising:
a training module configured to generate a domain adaptation model for predicting a P-impedance value of a target area that does not include a well by using source data obtained from a source area that includes a well and target data obtained from the target area;
a preprocessing module configured to generate a P-impedance low frequency model by using the P-impedance value generated by the domain adaptation model, the preprocessing module being further configured to:
obtain a smoothed P-impedance value by smoothing the P-impedance value; and
obtain a P-impedance low frequency model by applying a filter to the smoothed P-impedance value; and
an inversion module configured to generate a final P-impedance value by performing an inversion using the P-impedance low frequency model and the target data; and
an input/output interface configured to display a prediction result for the presence of the subsurface gas or oil to a user.
9 . The impedance inversion apparatus of claim 8 , wherein the training module is configured to:
extract feature information from seismic data of the source data and feature information from seismic data of the target data, using a feature extraction algorithm;
determine, using a domain classification algorithm, whether the feature information is associated with the source area or the target area;
generate a first loss function value that decreases upon a decrease in an accuracy of determination using the domain classification algorithm;
predict, using a label prediction algorithm, a label of the feature information extracted from the seismic data of the source data;
generate a second loss function value that decreases upon an increase in the accuracy of prediction;
retrain the feature extraction algorithm to decrease a sum of the first loss function value and the second loss function value;
stop training the domain adaptation model upon a determination that the sum of the first loss function value and the second loss function value reaches a predetermined minimum value; and
predict a label corresponding to the seismic data of the target data using the label prediction algorithm.
10 . The impedance inversion apparatus of claim 8 , wherein:
the preprocessing module is further configured to: obtain a smoothed S-impedance value using the smoothed P-impedance value; and obtain an S-impedance low frequency model by applying a filter to the smoothed S-impedance value; and
the inversion module is configured to predict the final P-impedance value and a final S-impedance value by performing a simultaneous inversion on the P-impedance value and an S-impedance value using the P-impedance low frequency model, the S-impedance low frequency model and the seismic data of the target data.
11 . The impedance inversion apparatus of claim 10 , wherein:
the preprocessing module is further configured to: obtain a smoothed density value using the smoothed P-impedance value; and obtain a density low frequency model by applying a filter to the smoothed density value; and
the inversion module is configured to predict the final P-impedance value, the final S-impedance value and a final density value by performing a simultaneous inversion on the P-impedance value, the S-impedance value and a density value using the P-impedance low frequency model, the S-impedance low frequency model, the density low frequency model and the seismic data of the target data.
12 . The impedance inversion apparatus of claim 10 , wherein the preprocessing module is configured to convert the smoothed P-impedance value into the smoothed S-impedance value using a relational expression derived from a relationship between a P-impedance value and an S-impedance value included in well log data of the source data.
13 . The impedance inversion apparatus of claim 11 , wherein the preprocessing module is configured to convert the smoothed P-impedance value into the smoothed density value using a relational expression derived from a relationship between a P-impedance value and a density value included in well log data of the source data.