Monitoring the changes of rock properties in a micritic limestone upon injection of a CO2‐rich fluid

Structural geological models are widely used to represent relevant geological interfaces and property distributions in the subsurface. Considering the inherent uncertainty of these models, the non-uniqueness of geophysical inverse problems, and the growing availability of data, there is a need for methods that integrate different types of data consistently and consider the uncertainties quantitatively. Probabilistic inference provides a suitable tool for this purpose. Using a Bayesian framework, geological modeling can be considered as an integral part of the inversion and thereby naturally constrain geophysical inversion procedures. This integration prevents geologically unrealistic results and provides the opportunity to include geological and geophysical information in the inversion. This information can be from different sources and is added to the framework through likelihood functions. We applied this methodology to the structurally complex Kevitsa deposit in Finland. We started with an interpretation-based 3D geological model and defined the uncertainties in our geological model through probability density functions. Airborne magnetic data and geological interpretations of borehole data were used to define geophysical and geological likelihoods, respectively. The geophysical data were linked to the uncertain structural parameters through the rock properties. The result of the inverse problem was an ensemble of realized models. These structural models and their uncertainties are visualized using information entropy, which allows for quantitative analysis. Our results show that with our methodology, we can use well-defined likelihood functions to add meaningful information to our initial model without requiring a computationally-heavy full grid inversion, discrepancies between model and data are spotted more easily, and the complementary strength of different types of data can be integrated into one framework.

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Near-surface real-time seismic imaging using parsimonious interferometry

Scientific Reports ◽

10.1038/s41598-021-86531-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Sherif M. Hanafy ◽

Hussein Hoteit ◽

Jing Li ◽

Gerard T. Schuster

Keyword(s):

Fluid Flow ◽

Real Time ◽

Temporal Resolution ◽

Seismic Imaging ◽

Time Lapse ◽

Rock Properties ◽

Recording Time ◽

Near Surface ◽

Arrival Times ◽

Order Of Magnitude

AbstractResults are presented for real-time seismic imaging of subsurface fluid flow by parsimonious refraction and surface-wave interferometry. Each subsurface velocity image inverted from time-lapse seismic data only requires several minutes of recording time, which is less than the time-scale of the fluid-induced changes in the rock properties. In this sense this is real-time imaging. The images are P-velocity tomograms inverted from the first-arrival times and the S-velocity tomograms inverted from dispersion curves. Compared to conventional seismic imaging, parsimonious interferometry reduces the recording time and increases the temporal resolution of time-lapse seismic images by more than an order-of-magnitude. In our seismic experiment, we recorded 90 sparse data sets over 4.5 h while injecting 12-tons of water into a sand dune. Results show that the percolation of water is mostly along layered boundaries down to a depth of a few meters, which is consistent with our 3D computational fluid flow simulations and laboratory experiments. The significance of parsimonious interferometry is that it provides more than an order-of-magnitude increase of temporal resolution in time-lapse seismic imaging. We believe that real-time seismic imaging will have important applications for non-destructive characterization in environmental, biomedical, and subsurface imaging.

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A New Technique To Estimate Vertical Variability of Rock Properties for Reservoir Rock Evaluation

10.2118/24724-ms ◽

1992 ◽

Author(s):

Bijon Sharma

Keyword(s):

Reservoir Rock ◽

New Technique ◽

Rock Properties ◽

A New Technique ◽

Vertical Variability

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Comparison between electrical resistivity tomography and tunnel seismic prediction 303 methods for detecting the water zone ahead of the tunnel face: A case study

Open Geosciences ◽

10.1515/geo-2020-0193 ◽

2020 ◽

Vol 12 (1) ◽

pp. 1094-1104

Author(s):

Nima Dastanboo ◽

Xiao-Qing Li ◽

Hamed Gharibdoost

Keyword(s):

Electrical Resistivity ◽

Electrical Resistivity Tomography ◽

Geological Structure ◽

Rock Properties ◽

Electrical Tomography ◽

Tunnel Face ◽

Resistivity Tomography ◽

Geological Conditions ◽

Seismic Prediction

AbstractIn deep tunnels with hydro-geological conditions, it is paramount to investigate the geological structure of the region before excavating a tunnel; otherwise, unanticipated accidents may cause serious damage and delay the project. The purpose of this study is to investigate the geological properties ahead of a tunnel face using electrical resistivity tomography (ERT) and tunnel seismic prediction (TSP) methods. During construction of the Nosoud Tunnel located in western Iran, ERT and TSP 303 methods were employed to predict geological conditions ahead of the tunnel face. In this article, the results of applying these methods are discussed. In this case, we have compared the results of the ERT method with those of the TSP 303 method. This work utilizes seismic methods and electrical tomography as two geophysical techniques are able to detect rock properties ahead of a tunnel face. This study shows that although the results of these two methods are in good agreement with each other, the results of TSP 303 are more accurate and higher quality. Also, we believe that using another geophysical method, in addition to TSP 303, could be helpful in making decisions in support of excavation, especially in complicated geological conditions.

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Rock Location and Property Analysis of Lunar Regolith at Chang’E-4 Landing Site Based on Local Correlation and Semblance Analysis

Remote Sensing ◽

10.3390/rs13010048 ◽

2020 ◽

Vol 13 (1) ◽

pp. 48

Author(s):

Hanjie Song ◽

Chao Li ◽

Jinhai Zhang ◽

Xing Wu ◽

Yang Liu ◽

...

Keyword(s):

Electromagnetic Waves ◽

Lunar Regolith ◽

Landing Site ◽

Rock Properties ◽

The Moon ◽

Local Correlation ◽

Near Surface ◽

Property Analysis ◽

Stratigraphic Division ◽

Formation And Evolution

The Lunar Penetrating Radar (LPR) onboard the Yutu-2 rover from China’s Chang’E-4 (CE-4) mission is used to probe the subsurface structure and the near-surface stratigraphic structure of the lunar regolith on the farside of the Moon. Structural analysis of regolith could provide abundant information on the formation and evolution of the Moon, in which the rock location and property analysis are the key procedures during the interpretation of LPR data. The subsurface velocity of electromagnetic waves is a vital parameter for stratigraphic division, rock location estimates, and calculating the rock properties in the interpretation of LPR data. In this paper, we propose a procedure that combines the regolith rock extraction technique based on local correlation between the two sets of LPR high-frequency channel data and the common offset semblance analysis to determine the velocity from LPR diffraction hyperbola. We consider the heterogeneity of the regolith and derive the relative permittivity distribution based on the rock extraction and semblance analysis. The numerical simulation results show that the procedure is able to obtain the high-precision position and properties of the rock. Furthermore, we apply this procedure to CE-4 LPR data and obtain preferable estimations of the rock locations and the properties of the lunar subsurface regolith.

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