scholarly journals Construction of a regional-scale 3D geological model from geologically constrained potential field inversion

2010 ◽  
Vol 2010 (1) ◽  
pp. 1-4
Author(s):  
Robert J. Musgrave ◽  
Stephen Dick
Keyword(s):  
Potential Field ◽  
Regional Scale ◽  
Geological Model ◽  
3D Geological Model ◽  
Field Inversion

scholarly journals 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

Solid Earth ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 349-361 ◽  
Author(s):  
Elikplim Abla Dzikunoo ◽  
Giulio Vignoli ◽  
Flemming Jørgensen ◽  
Sandow Mark Yidana ◽  
Bruce Banoeng-Yakubo
Keyword(s):  
Field Data ◽  
Mineral Exploration ◽  
Regional Scale ◽  
Geological Mapping ◽  
Northern Ghana ◽  
Geological Model ◽  
Electromagnetic Data ◽  
3D Geological Model ◽  
Geophysical Surveys ◽  
Airborne Electromagnetic

Abstract. Reprocessing of regional-scale airborne electromagnetic data is used to build a 3D geological model of the Nasia sub-basin, northern Ghana. The resulting 3D geological model consistently integrates all the prior pieces of information brought by electromagnetic data, lithologic logs, ground-based geophysical surveys, and geological knowledge of the terrain. The geo-modeling process is aimed at defining the lithostratigraphy of the area, chiefly to improve the stratigraphic definition of the area, and 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 geo-model of the basin. In this respect, the evidence of a hitherto unexposed system of paleovalleys could be inferred from the airborne data. The stratigraphic position of these paleovalleys suggests a distinctly different glaciation history from the known Marinoan events, commonly associated with the Kodjari formation of the Voltaian sedimentary basin. Indeed, the presence of the paleovalleys within the Panabako may be correlated with mountain glaciation within the Sturtian age, though no unequivocal glaciogenic strata have yet been identified. Pre-Marinoan glaciation is recorded in rocks of the Wassangara group of the Taoudéni 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 not only has important socioeconomic consequences – as the paleovalleys can act as reservoirs for groundwater – but also from a scientific point of view, they could be extremely relevant as their presence would require a revision of the present stratigraphy of the area.

Geothermal exploration of Paleozoic formations in Central Alberta

2013 ◽  
Vol 50 (5) ◽  
pp. 519-534 ◽  
Author(s):  
Simon Weides ◽  
Inga Moeck ◽  
Jacek Majorowicz ◽  
Dan Palombi ◽  
Matthias Grobe
Keyword(s):  
Regional Scale ◽  
Three Dimensional ◽  
Geothermal Gradient ◽  
Rock Properties ◽  
Geological Model ◽  
Field Development ◽  
Geothermal Reservoirs ◽  
Geostatistical Methods ◽  
3D Geological Model ◽  
Alberta Basin

This study explores the distribution of Paleozoic formations in the Central Alberta Basin and investigates rock properties with regard to their usability as geothermal reservoirs. The study area of this regional-scale investigation is about 160 km × 200 km in size and located around Edmonton where the basin depth ranges between 1.8 and 3.5 km. A three-dimensional (3D) geological model was developed based on stratigraphic tops from about 7000 wells from the database of the Alberta Geological Survey (AGS). Spatial distribution and thickness of deep formations were established in the 3D geological model. Porosity and permeability of four Devonian carbonate formations — Cooking Lake, Leduc, and Nisku formations, and Wabamun Group — were investigated using data from more than 50 000 core analyses. Average porosity of the Devonian strata in the study area ranges from 4.5% (Nisku) to 8.7% (Wabamun), average permeability is between 3.5 × 10−15 m2 (Wabamun) and 26 × 10−15 m2 (Leduc). The distribution of both parameters was analyzed using geostatistical methods. Based on an average geothermal gradient and the geometry of formations from the 3D modeling study, an estimation of formation temperatures for the Paleozoic formations is presented. Temperature in the Cambrian Basal Sandstone Unit ranges from 62 °C in the shallower northeast (1.8 km) to 122 °C in the deeper southwest (3.5 km); temperature in the Devonian strata ranges from 22 to 87 °C. With these new results, potential geothermal reservoirs can be delineated in the Alberta Basin around Edmonton, enabling future detailed exploration and field development.

scholarly journals 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

2019 ◽  
Author(s):  
Elikplim Abla Dzikunoo ◽  
Giulio Vignoli ◽  
Flemming Jørgensen ◽  
Sandow Mark Yidana ◽  
Bruce Banoeng-Yakubo
Keyword(s):  
Field Data ◽  
Mineral Exploration ◽  
Regional Scale ◽  
Geological Mapping ◽  
Northern Ghana ◽  
Geological Model ◽  
Electromagnetic Data ◽  
3D Geological Model ◽  
Geophysical Surveys ◽  
Airborne Electromagnetic

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.

scholarly journals Study on 3D Geological Model of Highway Tunnels Modeling Method

2010 ◽  
Vol 02 (01) ◽  
pp. 6-10
Author(s):  
Kun ZHENG ◽  
Fang ZHOU ◽  
Pei LIU ◽  
Peng KAN
Keyword(s):  
Modeling Method ◽  
Geological Model ◽  
3D Geological Model

scholarly journals Towards a national 3D geological model of Denmark

2016 ◽  
Vol 35 ◽  
pp. 27-30
Author(s):  
Peter B.E. Sandersen ◽  
Thomas Vangkilde-Pedersen ◽  
Flemming Jørgensen ◽  
Richard Thomsen ◽  
Jørgen Tulstrup ◽  
...  
Keyword(s):  
Subsurface Layer ◽  
Geological Model ◽  
Technical Standards ◽  
Near Surface ◽  
Subsurface Geology ◽  
3D Geological Model ◽  
Combining Data ◽  
National Model ◽  
Surface Geology ◽  
2D To 3D

As part of its strategy, the Geological Survey of Denmark and Greenland (GEUS) is to develop a national, digital 3D geological model of Denmark that can act as a publicly accessible database representing the current, overall interpretation of the subsurface geology. A national model should be under constant development, focusing on meeting the current demands from society. The constant improvements in computer capacity and software capabilities have led to a growing demand for advanced geological models and 3D maps that meet the current technical standards (Berg et al. 2011). As a consequence, the users expect solutions to still more complicated and sophisticated problems related to the subsurface. GEUS has a long tradition of making 2D maps of subsurface layer boundaries and near-surface geology (Fredericia & Gravesen 2014), but in the change from 2D to 3D and when combining data in new ways, new geological knowledge is gained and new challenges of both technical and organisational character will arise. The purpose of this paper is to present the strategy for the national 3D geological model of Denmark and the planned activities for the years ahead. The paper will also reflect on some of the challenges related to making and maintaining a nationwide 3D model. Initially, the model will only include the Danish onshore areas, with the Danish offshore areas and Greenland to be added later using a similar general setup.

Current and future limits to automated 3D geological model construction

2021 ◽  
Author(s):  
Mark Jessell
Keyword(s):  
Structural Information ◽  
Mineral Exploration ◽  
Structural Data ◽  
Model Construction ◽  
Research Centre ◽  
Geological Model ◽  
Cooperative Research ◽  
Geological Modelling ◽  
3D Geological Model ◽  
Secondary Information

<p>In geological settings characterised by folded and faulted strata, and where good field data exist, we have been able to automate a large part of the 3D modelling process directly from the raw geological database (maps, bedding orientations and drillhole data). The automation is based upon the deconstruction of the geological maps and databases into positional, gradient and spatial and temporal topology information, and the combination of deconstructed data into augmented inputs for 3D geological modelling systems, notably LoopStructural and GemPy.</p><p>When we try to apply this approach to more complex terranes, such as greenstone belts, we come across two types of problem:</p><ul><li>1) Insufficient structural data, since the more complexly deformed the geology, the more we need to rely on secondary structural information, such as fold axial traces and vergence to ‘solve’ the structures. Unfortunately these types of data are not always stored in national geological databases. One approach to overcoming this is to analyse the simpler (i.e. bedding) data to try and estimate the secondary information automatically.</li> </ul><p> </p><ul><li>2) The available information is unsuited to the logic of the modelling system. Most modern modelling platforms assume the knowledge of a chronostratigraphic hierarchy, however, especially in more complexly deformed regions, a lithostratigraphy may be all that is available. Again a pre-processing of the map and stratigraphic information may be possible to overcome this problem.</li> </ul><p>This presentation will highlight the progress that has been made, as well as the road-blocks to universal automated 3D geological model construction.</p><p> </p><p>We acknowledge the support of the MinEx CRC and the Loop: Enabling Stochastic 3D Geological Modelling (LP170100985) consortia. The work has been supported by the Mineral Exploration Cooperative Research Centre whose activities are funded by the Australian Government's Cooperative Research Centre Programme. This is MinEx CRC Document 2020/xxx.</p><p> </p>

Insights on fault reactivation during the 2019, Mw4.9 Le Teil earthquake in southeastern France, from a joint 3D geology and InSAR study

2021 ◽  
Author(s):  
Léo Marconato ◽  
Philippe-Hervé Leloup ◽  
Cécile Lasserre ◽  
Séverine Caritg ◽  
Romain Jolivet ◽  
...  
Keyword(s):  
Time Series ◽  
Surface Displacement ◽  
Fault Reactivation ◽  
Least Square ◽  
Shallow Depth ◽  
Slip Distribution ◽  
Fault System ◽  
Geological Model ◽  
Coseismic Slip ◽  
3D Geological Model

<div> <div> <div> <p>The 2019, M<sub>w</sub>4.9 Le Teil earthquake occurred in southeastern France, causing important damage in a slow deforming region. Field based, remote sensing and seismological studies following the event revealed its very shallow depth, a rupture length of ~5 km with surface rupture evidences and a thrusting mechanism. We further investigate this earthquake by combining geological field mapping and 3D geology, InSAR time series analysis and coseismic slip inversion.</p> <p>From structural, stratigraphic and geological data collected around the epicenter, we first produce a 3D geological model over a 70 km<sup>2</sup> and 3 km deep zone surrounding the 2019 rupture, using the GeoModeller software. This model includes the geometry of the main faults and geological layers, and especially a geometry for La Rouvière Fault, an Oligocene normal fault likely reactivated during the earthquake.</p> <p>We also generate a time series of the surface displacement by InSAR, based on Sentinel-1 data ranging from early January 2019 to late January 2020, using the NSBAS processing chain. The spatio-temporal patterns of the surface displacement for this limited time span show neither clear pre-seismic signal nor significant postseismic slip. We extract from the InSAR time series the coseismic displacement pattern, and in particular the along-strike slip distribution that shows spatial variations. The maximum relative displacement along the Line-Of-Sight is up to ~16 cm and is located in the southwestern part of the rupture.</p> <p>We then invert for the slip distribution on the fault from the InSAR coseismic surface displacement field. We use a non-negative least square approach based on the CSI software and the fault surface trace defined in the 3D geological model, exploring the range of plausible fault dip values. Best-fitting dips range between 55° and 60°. Such values are slightly lower than those measured on La Rouvière Fault planes in the field. Our model confirms the reactivation of La Rouvière fault, with reverse slip at very shallow depth and two main slip patches reaching 30 cm and 24 cm of slip at 400-500m depth. We finally discuss how the 3D fault geometry and geological configuration could have impacted the slip distribution and propagation during the earthquake.</p> <p>This study is a step to better quantify strain accumulation and assess the seismic hazard associated with other similar faults along the Cévennes fault system, in a densely populated area hosting several nuclear plants.</p> </div> </div> </div>

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