Geost (United States)

The overarching upgrade project at a coal dumping facility in North Vancouver, BC, consisted of a new railcar dumper pit vault with an outfeed conveyor to increase coal handling capacity at the facility. The site is located 200 m (656 ft) from the Burrard Inlet with groundwater table close to grade and coarse sands and gravels, presenting high risk for both groundwater and soil ingress. An active rail yard immediately adjacent to the site was to remain operational throughout the project's construction. Support of excavation for the multi-level coal dumper vault involved an internally braced three-cell cofferdam with pipe-pipe and pipe-sheet combi pile walls, connected to a four-cell trench that accommodated the dumper vault's outfeed conveyor tunnel. The center cell of the main dumper pit vault was designed for a maximum excavation depth of 27 m (89 ft), hydrostatic pressures starting 3 m (10 ft) below grade, and surcharge pressures from six adjacent rail lines. Three levels of bracing were used with spans of up to 10.5 m (34 ft) to facilitate the buildout of the permanent structure without cold joints. An unreinforced tremie base plug with tie-down anchors created basal stability against hydraulic uplift. This paper will highlight the challenging design requirements and the detailed construction sequencing that was required for successful installation of the support of excavation system. In addition to complicated geotechnical conditions and constraints due to the geometry of the permanent structure, environmental and health and safety requirements were a driving factor of this project. Construction for the deep excavation was to occur in a live coal handling facility with confined spaces, several contractors, and sensitive waterways. The project was an exceptional example of innovative design and illustrates the potential of a job when coordination and collaboration between the construction team, design team, and owners is prioritized. Support of excavation for the railcar dumper pit vault and outfeed conveyor tunnel was accomplished with a design-build approach.

Summary Geosto Oy has developed the NOVEL-EM electromagnetic surveying method for the detection and monitoring of contaminated mining water. It has been used at several mine sites in Finland and abroad. NOVEL-EM method is comprised of instrumentation, field, processing, and modelling procedures which aim to achieve high accuracy and repeatable data and the results of water chemistry changes in the surface or groundwater layer within a depth range of 0–10 m. This presentation depicts the baseline setting from one mine site, one monitoring line time-lapse result, and an example of how the water electrolyte content have evolved along the exemplified monitoring line. It has been verified that detected anomalies are related to changes in water chemistry, and the monitoring line network has been expanded over the course of the years.

Summary Under the pressure of climate change, reduced precipitation, including snowfall, which makes a major contribution to groundwater recharge, inevitably leads to lower water levels in both alluvial and crystalline basement aquifers. The ground water available is actually getting deeper and deeper. What technical approaches are available to support integrated management of groundwater resources? This paper illustrates the use of a nodal electrical resistivity tomography (ERT) system in Italy aiming for helping the setting of potential zones for drilling. The survey covers an area of about 95 hectares for maximizing the exploration depth down to about 425 meters from ground level. Together with geological knowledge of the area, newly collected measurements, make it possible to highlight mineralogical/textural, geological-structural variations and tectonic discontinuities in terms of subsurface electrical resistivity. The area is characterized by the outcrop of predominantly Tertiary (pre-Orogenetic) and only minimally Quaternary (post-Orogenetic) rocks.The complex geology and the poor access forced the scientist to choose a unconventional method based on the FullWaver system and ErtLab Studio software. The ERT and induced polarization survey results gave enough evidences to the stake holders for selecting three potential zones.

<p>The Castelluccio basin in the central Apennines (Italy) is a ~20-km<sup>2</sup>-wide intramontane Quaternary depression located in the hangingwall of the NW-trending and SW-dipping Vettore-Bove normal fault system (VBFS). This system is responsible for the 2016-2017 seismic sequence, culminated with the 30 October 2016 Mw 6.5 Norcia earthquake that caused widespread surface faulting affecting also the northern part of the Castelluccio basin. Available borehole and geophysical data are not enough to constrain the basin structure, infill architecture and their relations with the long-term activity of the VBFS. Therefore, we carried out an extensive 3D survey using the innovative Fullwaver (FW) technology, conceived to perform deep electrical resistivity tomography (DERT). We aimed at: a) mapping the geometry of the pre-Quaternary limestone basement and the basin infill thickness down to a depth of ~1 km; b) mapping the subsurface structure of known faults and their extent underneath the alluvial cover; c) mapping possible blind faults splays.</p><p>The 3D survey covered a 23 km<sup>2 </sup>area and it was designed with the aim to map the region as regularly as possible, taking into account the rugged topography and logistic issues. We used a series of independent 2-channels receivers connected each to three grounded steel electrodes, 200 m spaced, to record the electrical field generated by a five kilowatt current regulated Time Domain Induced Polarization transmitter. Data were modelled with ViewLab software via a regularized inversion with smoothness constraints to cope with the expected subsurface strong resistivity changes, and to obtain a robust 3D resistivity model.</p><p>The FW technology allowed us to constrain the geometry of the basin. The infill material is imaged as a wide, N-trending moderately resistive (< 300 Ωm) to conductive  (< 100 Ωm) region, likely made of silty sands and gravels, deepening down to 500 m b.g.l. in the southern sector, suggesting the occurrence of two main depocenters. All over the basin, we identify paired high-resistivity (> 500-1000 Ωm) and low-resistivity (< 400 Ωm) belts related to the limestone basement and to the basin infill, respectively. They display NNE and NNW dominant trends. We interpret the sharp boundaries of NNE-trending belts as related to early extensional faults promoting the basin inception. The NNW-trending belts suggest the occurrence of faults that locally cross-cut the previous ones, and that we interpret as splays of the VBFS buried under the basin sedimentary cover. The recognition of different systems of extensional faults is coherent with results of high-resolution seismic profiling carried out recently in the basin. A high-resolution 2D transect with 15 m-spaced electrodes across the 2016 surface ruptures shows details of the active VBFS splay down to 300 m depth. Moreover, in the eastern sector of the survey area, low-resistivity round-shaped anomalies in the Mesozoic substratum hints for deep Miocene compressional structures. Therefore, our DERT imaging suggests a complex tectonics in the subsurface of the Norcia earthquake fault. In particular, the currently active NNW-trending faults seem to overprint a pre-existing structural framework, promoting fault segmentation at different spatial scales</p>

Summary In this contribution we propose a joined migration of a GPR datum, where essentially two migration algorithms are applied on the same datum and then the two results are combined in order to provide a better focused image. We have applied this idea on real data gathered from a previous commitment assigned to the company Geostudi Astier. For sake of space, we will show the procedure applied on a single Bscan, but we have applied it to several GPR data within this case history. The proposed joined migration can be useful when there are horizontal variations of the propagation velocity of the electromagnetic wave from point to point within the GPR measurement line. In such a situation, a single value might be optimal for part of the buried target, whereas another value might be better suited for other targets. A joined migration mitigated this problem allowing to choose more values for the migration result and combining them so to focus at best all the targets.

Summary Regional seismic studies performed for the first time on Taymyr in the 21st century allowed to fundamentally change the existing ideas about the geological structure of the Taymyr folded area and adjacent territories of the West Siberian, North Karsky and Khatanga-Vilyuisky sedimentation basins. Until recently, the main information on the geological structure of Mountain Taymyr was based mainly on the geological surveys data. The Taymyr folded-thrust region is subdivided into three different large structural-tectonic zones: North-Central and South-Taymyr, separated by the Main Taimyr and Pyasino-Faddeyevsky deep faults - thrusts. These three zones differ in the tectonic structure, the material composition of the sections of the strata forming them, and the development history. At the same time, the South-Taymyr zone remained the least studied, since for the most part it was overlapped by Mesozoic-Cenozoic sediments (West-Taymyr and South-Taymyr Mesozoic monoclises).

Summary Currently, the key task of the country's oil and gas complex is the creation of new major hydrocarbon production and processing centers. Gydan, the Taimyr Peninsula and the shelf of Russian Arctic in the Russian Federation define the main directions of exploration in the XXI century. The main prospects for further development of the Russian oil and gas production complex are connected with these territories.

Summary Industrial oil production in the Republic of Bashkortostan has been underway for more than 80 years. Over the years, more than 200 oil, oil and gas and gas fields have been discovered, most of which are in the late stage of operation and are characterized by high water-cut. To maintain the current production volume, it is necessary to conduct a complex of geological exploration and replenish the reserves through involvement new oilfields and deposits in development. Experience shows that modern 3D seismic exploration, carried out in the marginal parts of large oilfields, allows in some cases to specialize the identified prospective features, expand the reservoir limits of known structures and confidently single out new prospects. Among such features there are erosionkarst cuts, which are developed in the upper parts of large reef structures.

Summary In connection with the resumption of geological exploration in the north of Krasnoyarsk region at the beginning of the XXI century the study of prospects, opportunities for reproduction and development of raw materials in the region remains actual. Tanamsky arch is one of those perspective objects in the north-east of Western Siberia, this arch is located within Tanamsk oil and gas bearing area (OGBA) of the Ust-Enisei oil and gas region (OGR) of the West Siberian oil and gas province (OGP). The main increase in hydrocarbon resources of explored area is associated with the underdeveloped deposits of the Tanamsky Arch, which are referred to the inversion ring structures. Besides, oil and gas prospects are connected to anticlinal traps on the shelf of the Neocomian clinoforms and the insufficiently explored Jurassic complex.