scholarly journals Characterization of heterogeneous near-surface materials by joint 2D inversion of dc resistivity and seismic data

2003 ◽  
Vol 30 (13) ◽  
Author(s):  
Luis A. Gallardo ◽  
Max A. Meju
Solid Earth ◽  
2016 ◽  
Vol 7 (3) ◽  
pp. 943-958 ◽  
Author(s):  
Xènia Ogaya ◽  
Juan Alcalde ◽  
Ignacio Marzán ◽  
Juanjo Ledo ◽  
Pilar Queralt ◽  
...  

Abstract. Hontomín (N of Spain) hosts the first Spanish CO2 storage pilot plant. The subsurface characterization of the site included the acquisition of a 3-D seismic reflection and a circumscribed 3-D magnetotelluric (MT) survey. This paper addresses the combination of the seismic and MT results, together with the available well-log data, in order to achieve a better characterization of the Hontomín subsurface. We compare the structural model obtained from the interpretation of the seismic data with the geoelectrical model resulting from the MT data. The models correlate well in the surroundings of the CO2 injection area with the major structural differences observed related to the presence of faults. The combination of the two methods allowed a more detailed characterization of the faults, defining their geometry, and fluid flow characteristics, which are key for the risk assessment of the storage site. Moreover, we use the well-log data of the existing wells to derive resistivity–velocity relationships for the subsurface and compute a 3-D velocity model of the site using the 3-D resistivity model as a reference. The derived velocity model is compared to both the predicted and logged velocity in the injection and monitoring wells, for an overall assessment of the computed resistivity–velocity relationships. The major differences observed are explained by the different resolution of the compared geophysical methods. Finally, the derived velocity model for the near surface is compared with the velocity model used for the static corrections in the seismic data. The results allowed extracting information about the characteristics of the shallow unconsolidated sediments, suggesting possible clay and water content variations. The good correlation of the velocity models derived from the resistivity–velocity relationships and the well-log data demonstrate the potential of the combination of the two methods for characterizing the subsurface, in terms of its physical properties (velocity, resistivity) and structural/reservoir characteristics. This work explores the compatibility of the seismic and magnetotelluric methods across scales highlighting the importance of joint interpretation in near surface and reservoir characterization.


2021 ◽  
Author(s):  
Bjarne Almqvist ◽  
Maria Ask ◽  
Linus Brander ◽  
Stefan Buske ◽  
Christoph Büttner ◽  
...  

<p>Increasing the effectiveness of exploration for mineral resources is vital to meet future societal, economic and environmental challenges. Effective exploration drilling for mineral resources is an area where industrial innovation plays an important role. Measurements-while-drilling, data acquisition and next generation logging sondes represent three important areas that need development in the mineral exploration sector. Despite this need, there is a lack of test beds that allow to test novel drilling equipment. This limits the development and implementation of equipment with technology that has been proven, but does not yet fulfil the requirements of a product on the commercial market. Although a variety of test sites exist throughout Europe, they are constrained to existing infrastructure, which limits users to pre-existing conditions that may not fit their purpose or need. The I-EDDA-TC provides a unique environment for the development of drilling, and related, equipment used for exploration of mineral resources.</p><p>The regional geology around the test center site is dominated by Svecokarelian age granitoid intrusive and acid volcanic rocks (rhyolites) that strike east-west and dip sub-vertical. During 2019 and 2020, two boreholes were drilled at the test center site, as part of an EIT Raw Materials upscaling project. The first borehole is a fully cored 970 m deep borehole drilled with diamond bit (HQ dimension). The second borehole was drilled in the late summer of 2020, and is a 200 m deep percussion-drilled borehole with ~220 mm diameter. Here we present a preliminary synthesis of results from a geophysical survey, borehole logging and geological logging of drill core.</p><p>In summer 2019 a comprehensive geophysical surveying program was performed at the site, including 3D high resolution seismic, 2D deeper seismic with a large vibrator source, a series of high-resolution resistivity profiles and magnetic profiles. The 3D seismic data provided detailed velocity information in the near-surface at the site, allowing interpretation of depths to the groundwater table and bedrock in 3D. Data gained from two downhole logging campaigns provides a robust base for the detailed differentiation and characterization of the formations. A first look on the data shows well defined correlations amongst the various geophysical downhole parameters. Geological logging focused both on material properties (e.g. mineralogy, grain-size, texture, alteration and mineralization) and rock mass (joints and RQD). Magnetic susceptibility and ultrasonic pulse velocity were measured at regular intervals along the full core length, and 66 specimens were prepared and analysed with respect to porosity, density, abrasivity, major chemical elements, indirect tensile strength and uniaxial compressive strength. The integrated analysis of core data, surface and borehole seismic data, and the continuous logging profiles allows for the 3-dimensional characterization of the underground below the test center platform, as well as provides reference data for assessment of work conducted at the site (e.g. development of geophysical instruments, testing of drillabilaty and wear on drill bits). Our results will be open access published so that data can be compared to drilling and instruments test of commercial and academic parties utilizing this testing facility in future.</p>


Author(s):  
Julia T. Luck ◽  
C. W. Boggs ◽  
S. J. Pennycook

The use of cross-sectional Transmission Electron Microscopy (TEM) has become invaluable for the characterization of the near-surface regions of semiconductors following ion-implantation and/or transient thermal processing. A fast and reliable technique is required which produces a large thin region while preserving the original sample surface. New analytical techniques, particularly the direct imaging of dopant distributions, also require good thickness uniformity. Two methods of ion milling are commonly used, and are compared below. The older method involves milling with a single gun from each side in turn, whereas a newer method uses two guns to mill from both sides simultaneously.


Geophysics ◽  
2006 ◽  
Vol 71 (5) ◽  
pp. U67-U76 ◽  
Author(s):  
Robert J. Ferguson

The possibility of improving regularization/datuming of seismic data is investigated by treating wavefield extrapolation as an inversion problem. Weighted, damped least squares is then used to produce the regularized/datumed wavefield. Regularization/datuming is extremely costly because of computing the Hessian, so an efficient approximation is introduced. Approximation is achieved by computing a limited number of diagonals in the operators involved. Real and synthetic data examples demonstrate the utility of this approach. For synthetic data, regularization/datuming is demonstrated for large extrapolation distances using a highly irregular recording array. Without approximation, regularization/datuming returns a regularized wavefield with reduced operator artifacts when compared to a nonregularizing method such as generalized phase shift plus interpolation (PSPI). Approximate regularization/datuming returns a regularized wavefield for approximately two orders of magnitude less in cost; but it is dip limited, though in a controllable way, compared to the full method. The Foothills structural data set, a freely available data set from the Rocky Mountains of Canada, demonstrates application to real data. The data have highly irregular sampling along the shot coordinate, and they suffer from significant near-surface effects. Approximate regularization/datuming returns common receiver data that are superior in appearance compared to conventional datuming.


2013 ◽  
Vol 32 (3) ◽  
pp. 308-314
Author(s):  
Phil Sirles ◽  
Jacob Sheehan ◽  
Nicole Pendrigh
Keyword(s):  

2013 ◽  
Vol 664 ◽  
pp. 94-98
Author(s):  
Guang De Zhang

Following deepened exploration and development in Shengli exploration area, seismic data requirements are also getting higher and higher. However, in recent years the difference of Xiaoqing river on both sides have made us know that the importance of this problem. In view of the above, this task is aimed at quaternary shallow of old river course within Xiaoqing River. Our analysis of lithology and sedimentary characteristics are using static cone penetration test and rock core exploration method, and we want to reappear near surface deposition of old river course within Xiaoqing River. The research is close combined with the exploration demand and theoretical study, so it has important theoretical and practical significance.


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