scholarly journals Indications of sandstone-type uranium mineralization from 3D seismic data: a case study of the Qiharigetu deposit, Erenhot Basin, China

2021 ◽  
Vol 11 (3) ◽  
pp. 1069-1080
Author(s):  
Qubo Wu ◽  
Yucheng Huang
Keyword(s):  
Coalbed Methane ◽  
Seismic Inversion ◽  
Uranium Mineralization ◽  
Seismic Survey ◽  
3D Seismic ◽  
Sand Content ◽  
Geological Features ◽  
Sand Body ◽  
Geophysical Techniques ◽  
Target Layer

AbstractThe primary exploration objective of Qiharigetu Sandstone-type Uranium (SU) deposit in the Erenhot Basin of China is to understand the stratigraphy, lithology and fault distribution of the target layer. Various geophysical techniques including gravity, magnetic, electromagnetic and 2D seismic have been proved not very effective due to its shallow depth of burial and small geophysical differences between layers. A specific 3D seismic survey of the Qiharigetu SU deposit has been carried out, and the inferred geological features of the uranium mineralization could provide important references for subsequent drilling programs. It is deduced that the target layer in the central part of the study area has a local "depression" through 3D seismic imaging and interpretation, which is conducive to river runoff and formation of sand body, as the sand body is a necessary precondition for mineralization. There are faults (5–50 m in throw) striking north–south for around 2 km, and it is an important ore-controlling factor, which could provide channels for the rise of reducing agents (such as gas, H2S, and coalbed methane) at depth as they can promote the redox reaction for mineralization. The 3D seismic inversion is used to estimate the impedance, lithology, sand content and porosity of the target layer. With the help of drilling verification, it is found that the area with sand content over 75% and porosity over 10% is favorable for the SU deposit. Compared with other geophysical techniques, 3D seismic method is able to provide high-resolution images for unraveling SU mineralization and thereby reduce the drilling risk of the SU deposit.

Porosity estimation and characterization of a geothermal carbonate reservoir in the South German Molasse Basin based on seismic inversion and attribute analysis

2021 ◽  
Author(s):  
Sonja Wadas ◽  
Hartwig von Hartmann
Keyword(s):  
Structural Information ◽  
Hanging Wall ◽  
Seismic Inversion ◽  
Middle Part ◽  
Seismic Survey ◽  
Molasse Basin ◽  
3D Seismic ◽  
Reservoir Properties ◽  
Attribute Analysis ◽  
Geothermal Potential

<p>The Molasse Basin is one of the most promising areas for deep geothermal exploration in Germany and a very ambitious project in this region is to power the entire district heating system of the city of Munich with renewable energies by 2040; a major part of this will consist of geothermal energy. As part of a joint project (financed by the German Federal Ministry For Economic Affairs And Energy; FKZ 0324332B) the Leibniz Institute for Applied Geophysics (LIAG) works together with the Munich City Utilities (Stadtwerke München), to improve reservoir characterization and sustainable reservoir exploration within the German Molasse Basin. The target horizon for hydrothermal exploration is the aquifer in the Upper Jurassic carbonates. A major problem is the strong heterogeneity of the carbonates. Compared to quantity and quality of the structural data of the reservoir, the database of reservoir properties such as density, porosity and permeability, which describe the geothermal potential, is insufficient. Therefore, it is necessary to generate such data in order to improve the value of the structural information. A 3D seismic survey cannot only provide structural information, but also important reservoir properties such as elastic parameters and seismic attributes. One of the most important attributes is the acoustic impedance, which can be determined with a seismic inversion and used to estimate a porosity volume.</p><p>The data basis for this study was the 170km² GRAME-3D seismic survey measured in Munich, a structural geological model, and drilling and logging data from the geothermal site “Schäftlarnstraße”.</p><p>The inversion results show low impedance values at the top of the reservoir, but also at the middle part. Spatially, the intermediate block of the Munich fault shows low values but also the eastern part of the hanging wall block and the western part of the footwall block. Based on a well correlation a relationship between acoustic impedance and porosity could be determined and a 3D porosity volume was calculated. In the upper part but also in the middle part of the reservoir areas with increased porosity (>10%) are shown, which might indicate a high geothermal potential.</p><p>For a better classification, an attribute analysis was performed. The intermediate block and the eastern part of the hanging wall block show strongly fractured rocks. In contrast, there are hardly any conspicuous features in the western part of the footwall block, although high porosities are also expected here. This suggests that the presence of faults is not the only factor favoring high porosities in carbonates. More likely is a combination with karstification processes, which is why even areas that do not show enhanced tectonic deformation have high porosities.</p>

Preconditioning point-source/point-receiver high-density 3D seismic data for lacustrine shale characterization in a loess mountain area

2017 ◽  
Vol 5 (2) ◽  
pp. SF177-SF188 ◽  
Author(s):  
Wei Wang ◽  
Xiangzeng Wang ◽  
Hongliu Zeng ◽  
Quansheng Liang
Keyword(s):  
Data Quality ◽  
Seismic Data ◽  
Ordos Basin ◽  
Seismic Inversion ◽  
High Density ◽  
Seismic Survey ◽  
3D Seismic ◽  
Noise Characteristics ◽  
Lacustrine Shale ◽  
3D Seismic Data

In the study area, southeast of Ordos Basin in China, thick lacustrine shale/mudstone strata have been developed in the Triassic Yanchang Formation. Aiming to study these source/reservoir rocks, a 3D full-azimuth, high-density seismic survey was acquired. However, the surface in this region is covered by a thick loess layer, leading to seismic challenges such as complicated interferences and serious absorption of high frequencies. Despite a specially targeted seismic processing workflow, the prestack Kirchhoff time-migrated seismic data were still contaminated by severe noise, hindering seismic inversion and geologic interpretation. By taking account of the particular data quality and noise characteristics, we have developed a cascade workflow including three major methods to condition the poststack 3D seismic data. First, we removed the sticky coherent noise by a local pseudo [Formula: see text]-[Formula: see text]-[Formula: see text] Cadzow filtering. Then, we diminished the random noise by a structure-oriented filtering. Finally, we extended the frequency bandwidth with a spectral-balancing method based on the continuous wavelet transform. The data quality was improved after each of these steps through the proposed workflow. Compared with the original data, the conditioned final data show improved interpretability of the shale targets through geometric attribute analysis and depositional interpretation.

A review of some amplitude-based seismic geometric attributes and their applications

2021 ◽  
pp. 1-52
Author(s):  
Sumit Verma ◽  
Satinder Chopra ◽  
Thang Ha ◽  
Fangyu Li
Keyword(s):  
Cross Correlation ◽  
East Coast ◽  
Seismic Attributes ◽  
Seismic Survey ◽  
Mean Square ◽  
3D Seismic ◽  
Root Mean Square Amplitude ◽  
Geological Features ◽  
Shape Changes ◽  
Transfer Zone

Seismic interpreters frequently use seismic geometric attributes such as coherence, dip, curvature, and aberrancy for defining geological features, including faults, channels, angular unconformities, etc. Some of the commonly used coherence attributes, e. g. cross-correlation or energy ratio similarity are sensitive to only waveform shape changes, whereas the dip, curvature, aberrancy attributes are based on changes in reflector dips. There is another category of seismic attributes, which includes attributes that are sensitive to amplitude values. Root mean square amplitude is one of the better-known amplitude-based attributes, whereas coherent energy, Sobel-filter similarity, normalized amplitude gradients, and amplitude curvature are amongst lesser-known amplitude-based attributes. We compute not-so-common amplitude-based attributes on the Penobscot seismic survey from the Nova Scotia continental shelf consisting of the east coast of Canada, to bring out their interpretative value. We analyze seismic attributes at the level of the top of the Wyandot Formation that exhibits different geological features, including a synthetic transfer zone with two primary faults and several secondary faults, polygonal faults associated with differential compaction, as well as fixtures related to basement related faults. The application of the amplitude-based seismic attributes defines such features accurately. We take these applications forward by describing a situation where some geological features do not display any bending of reflectors, but only exhibit changes in amplitude. One of such examples is the Cretaceous Cree Sand channels, present in the same 3D seismic survey used for the previous applications. We compute amplitude curvature attributes and identify the channels, whereas these channels are not visible on the structural curvature display. In both the applications, we observe that appropriate corendering not-so-common amplitude based seismic attributes leads to convincing displays, that can be of immense aid in seismic interpretation and help define the different subsurface features with more clarity.

Seismic inversion of single sensor land 3D seismic survey: Kuwait, Magwa field, Wara reservoir

2006 ◽  
Author(s):  
Osman Al‐Khaled ◽  
Yousef Al‐Zuabi ◽  
Mafizar Rahaman ◽  
Jarrah Al‐Jenai ◽  
Thekriat Hussain
Keyword(s):  
Seismic Inversion ◽  
Seismic Survey ◽  
3D Seismic ◽  
Single Sensor

Optimization Of A 3D Seismic Survey Onshore Abu Dhabi - From Field Tests To Final Design

2000 ◽  
Author(s):  
Abu Baker Al Jeelani ◽  
Samer Marmash ◽  
Abdul Salam Bin Ishaq ◽  
Ahmed Al-Shaikh ◽  
Eric Kleiss ◽  
...  
Keyword(s):  
Field Tests ◽  
Seismic Survey ◽  
Abu Dhabi ◽  
3D Seismic ◽  
Final Design

Exploring for stratigraphic traps in the Patchawarra Formation, Cooper Basin: an integrated seismic methodology

2018 ◽  
Vol 58 (2) ◽  
pp. 779
Author(s):  
Alexandra Bennett
Keyword(s):  
Complex Geometry ◽  
Imaging Techniques ◽  
South Australia ◽  
Seismic Interpretation ◽  
Seismic Survey ◽  
3D Seismic ◽  
Seismic Resolution ◽  
Seismic Reflectivity ◽  
Seismic Area ◽  
Cooper Basin

The Patchawarra Formation is characterised by Permian aged fluvial sediments. The conventional hydrocarbon play lies within fluvial sandstones, attributed to point bar deposits and splays, that are typically overlain by floodbank deposits of shales, mudstones and coals. The nature of the deposition of these sands has resulted in the discovery of stratigraphic traps across the Western Flank of the Cooper Basin, South Australia. Various seismic techniques are being used to search for and identify these traps. High seismic reflectivity of the coals with the low reflectivity of the relatively thin sands, often below seismic resolution, masks a reservoir response. These factors, combined with complex geometry of these reservoirs, prove a difficult play to image and interpret. Standard seismic interpretation has proven challenging when attempting to map fluvial sands. Active project examples within a 196 km2 3D seismic survey detail an evolving seismic interpretation methodology, which is being used to improve the delineation of potential stratigraphic traps. This involves an integration of seismic processing, package mapping, seismic attributes and imaging techniques. The integrated seismic interpretation methodology has proven to be a successful approach in the discovery of stratigraphic and structural-stratigraphic combination traps in parts of the Cooper Basin and is being used to extend the play northwards into the 3D seismic area discussed.

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