Geophysical characterization of a small pre-Alpine catchment

Vignoli, Giulio; Cassiani, Giorgio; Rossi, Matteo; Deiana, Rita; Boaga, Jacopo; Fabbri, Paolo

doi:10.1016/j.jappgeo.2012.01.007

Cited by 22 publications

(11 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In fact, ground roll contains valuable information about the share velocity distribution in the subsurface and is generally characterized by high amplitude. Recently high-resolution shallow techniques based on surface waves have been developed and tested successfully for hydrogeological investigations (Vignoli et al, 2012(Vignoli et al, , 2016. A possible limitation of techniques based on surface waves concerns the availability of low-frequency sources: in presence of slow sediments, low frequencies are required to reach the desired depths, but generating them is very demanding and potentially detrimental to the seismic vibrator.…”

Section: Discussionmentioning

confidence: 99%

Multiple-point statistical simulation for hydrogeological models: 3-D training image development and conditioning strategies

Høyer

Vignoli

Hansen

et al. 2017

Hydrol. Earth Syst. Sci.

Self Cite

View full text Add to dashboard Cite

Abstract. Most studies on the application of geostatistical simulations based on multiple-point statistics (MPS) to hydrogeological modelling focus on relatively fine-scale models and concentrate on the estimation of facies-level structural uncertainty. Much less attention is paid to the use of input data and optimal construction of training images. For instance, even though the training image should capture a set of spatial geological characteristics to guide the simulations, the majority of the research still relies on 2-D or quasi-3-D training images. In the present study, we demonstrate a novel strategy for 3-D MPS modelling characterized by (i) realistic 3-D training images and (ii) an effective workflow for incorporating a diverse group of geological and geophysical data sets. The study covers an area of 2810 km 2 in the southern part of Denmark. MPS simulations are performed on a subset of the geological succession (the lower to middle Miocene sediments) which is characterized by relatively uniform structures and dominated by sand and clay. The simulated domain is large and each of the geostatistical realizations contains approximately 45 million voxels with size 100 m × 100 m × 5 m. Data used for the modelling include water well logs, high-resolution seismic data, and a previously published 3-D geological model. We apply a series of different strategies for the simulations based on data quality, and develop a novel method to effectively create observed spatial trends. The training image is constructed as a relatively small 3-D voxel model covering an area of 90 km 2 . We use an iterative training image development strategy and find that even slight modifications in the training image create significant changes in simulations. Thus, this study shows how to include both the geological environment and the type and quality of input information in order to achieve optimal results from MPS modelling. We present a practical workflow to build the training image and effectively handle different types of input information to perform large-scale geostatistical modelling.

show abstract

Section: Discussionmentioning

confidence: 99%

Multiple-point statistical simulation for hydrogeological models: 3-D training image development and conditioning strategies

Høyer

Vignoli

Hansen

et al. 2017

Hydrol. Earth Syst. Sci.

Self Cite

View full text Add to dashboard Cite

show abstract

“…Recently high-resolution shallow techniques based on surface waves have been developed and tested successfully for hydrogeological investigations (Vignoli et al, 2012(Vignoli et al, , 2016. A possible limitation of techniques based on surface waves concerns the availability of low-frequency sources: in presence of slow sediments, low frequencies are required to reach the desired depths, but generating them is very demanding and potentially detrimental to the seismic vibrator.…”

Section: Discussionmentioning

confidence: 99%

Reply to Reviewer #1

Vignoli¹

2017

Self Cite

View full text Add to dashboard Cite

Most studies on the application of geostatistical simulations based on multiple-point statistics (MPS) to hydrogeological modelling focus on relatively fine-scale models and concentrate on the estimation of facies-level structural uncertainty. Much less attention is paid to the use of input data and optimal construction of training images. For instance, even though the training image should capture a set of spatial geological characteristics to guide the simulations, the majority of the research still relies on 2-D or quasi-3-D training images. In the present study, we demonstrate a novel strategy for 3-D MPS modelling characterized by (i) realistic 3-D training images and (ii) an effective workflow for incorporating a diverse group of geological and geophysical data sets. The study covers an area of 2810 km 2 in the southern part of Denmark. MPS simulations are performed on a subset of the geological succession (the lower to middle Miocene sediments) which is characterized by relatively uniform structures and dominated by sand and clay. The simulated domain is large and each of the geostatistical realizations contains approximately 45 million voxels with size 100 m × 100 m × 5 m. Data used for the modelling include water well logs, high-resolution seismic data, and a previously published 3-D geological model. We apply a series of different strategies for the simulations based on data quality, and develop a novel method to effectively create observed spatial trends. The training image is constructed as a relatively small 3-D voxel model covering an area of 90 km 2 . We use an iterative training image development strategy and find that even slight modifications in the training image create significant changes in simulations. Thus, this study shows how to include both the geological environment and the type and quality of input information in order to achieve optimal results from MPS modelling. We present a practical workflow to build the training image and effectively handle different types of input information to perform large-scale geostatistical modelling.

show abstract

“…CC BY 4.0 License. complex geologic systems (e.g., Dzikunoo et al 2018;Rapiti et al, 2018;Jørgensen et al, 2015;Vignoli et al, 2017;Høyer et al 2017;Vignoli et al, 2012). In this regard, the diverse kinds of data used in this study consist of: i) AEM data (namely, GEOTEM B-field), ii) borehole lithological and geophysical logs, and iii) ground-based Electrical Resistivity Tomography (ERT).…”

Section: Data and Modelling Requirementsmentioning

confidence: 99%

New regional stratigraphic insights from a 3D geological model of the Nasia Sub-basin, Ghana, developed for hydrogeological purposes and based on reprocessed B-field data, originally collected for mineral exploration

Dzikunoo¹,

Vignoli²,

Jørgensen³

et al. 2019

Preprint

Self Cite

View full text Add to dashboard Cite

Abstract. Re-processing of regional-scale airborne electromagnetic data is used in building a 3D geological model of the Nasia Sub-Basin, Northern Ghana. The resulting 3D geological model consistently integrates all the pieces of information brought by the electromagnetic data, lithologic logs, ground-based geophysical surveys and the prior geological knowledge of the terrain based on previous research. The geo-modelling process is aimed at defining the lithostratigraphy of the area, chiefly to improve the stratigraphic definition of the area as well as for hydrogeological purposes. The airborne electromagnetic measurements, consisting of GEOTEM B-field data, were originally collected for mineral exploration purposes. Thus, those B-field data had to be (re)processed and properly inverted as the original survey and data handling were designed for the detection of potential mineral targets and not for detailed geological mapping. These new geophysical inversion results, compared with the original Conductivity Depth Images, provided a significantly different picture of the subsurface. The new geophysical model led to new interpretations of the geological settings and to the construction of a comprehensive 3D geomodel of the basin. In this respect, the evidences of a hitherto unexposed paleovalley could be inferred from the airborne data. The stratigraphic position of these paleovalleys suggests a distinctly different glaciation history from the Marinoan events, commonly associated with the Kodjari formation of the Voltaian sedimentary basin. Indeed, their presence may be correlated to mountain glaciation within the Sturtian period though no unequivocal glaciogenic strata have yet been identified. This pre-Marinoan glaciation is recorded in rocks of the Wassangara group of the Taoudeni basin. The combination of the Marinoan and, possibly, Sturtian glaciation episodes, both of the Cryogenian period, can be an indication of a Neoproterozoic Snowball Earth. Hence, the occurrence of those geological features, do not only have an important socio-economic consequences – as the paleovalleys can act as reservoirs for groundwater – but, also from a scientific point of view, could be extremely relevant – as their presence would require a revision of the present stratigraphy of the area.

show abstract

Geophysical characterization of a small pre-Alpine catchment

Cited by 22 publications

References 30 publications

Multiple-point statistical simulation for hydrogeological models: 3-D training image development and conditioning strategies

Multiple-point statistical simulation for hydrogeological models: 3-D training image development and conditioning strategies

Reply to Reviewer #1

New regional stratigraphic insights from a 3D geological model of the Nasia Sub-basin, Ghana, developed for hydrogeological purposes and based on reprocessed B-field data, originally collected for mineral exploration

Contact Info

Product

Resources

About