Artem Kashubin

A footprint of rainfall on land seismic data repeatability at the CO2 storage pilot site, Ketzin, Germany

Two vintages of land time-lapse seismic data were acquired in 2005 and in 2009 at the Ketzin CO2 storage site in Germany. The datasets showed some differences in frequency content, signal-to-noise ...

Crustal structure of the Middle Urals based on seismic reflection data

Abstract EUROPROBE-related seismic reflection surveys in the Middle Urals, Russia (latitude 56-62°) since 1993 have led to an increased understanding of the crustal structure and tectonic evolution of this region. A 400 km long profile now extends from the foreland basin in the west well into the West Siberian Basin in the east. Bivergent structures characterize the upper crust of the Uralide orogen, whereas the middle and lower crust generally contain gently west-dipping reflections. A crustal root is imaged down to almost 60 km beneath the exposed Urals. Below the foreland and the West Siberian Basin the lower crustal reflectivity is pronounced and the Moho lies at a depth of 40-45 km. Below the foreland on the recently acquired Serebrianka-Beriozovka profile, two sets of late arriving (20-25 s) reflections are present. One set reflects from a zone in the mantle at about 60-70 km depth that strikes ENE and dips about 45° to the SSE. The other set may represent imbricated lower crust. Major events during the Palaeozoic tectonic evolution of the Middle Urals were: continental and oceanic rifting (Late Cambrian to Early Ordovician); development of a passive continental margin (Mid-Ordovician to Mid-Carboniferous); intra-oceanic subduction below the Tagil arc (Silurian to Devonian); east-dipping subduction of the Baltica plate (Silurian to Early Devonian); possible subduction reversal with formation of the Alapaevsk island arc and the Krasnoturjinsk-Petrokamensk active continental margin (Devonian to Early Carboniferous); active building of a mountain belt and intrusion of collision-related granitic plutons (Carboniferous to Permian).

La estructura sísmica de la corteza de la Zona de Ossa Morena y su interpretación geológica

El experimento de sismica de reflexion profunda IBERSEIS ha proporcionado una imagen de la corteza del Orogeno Varisco en el sudoeste de Iberia. Este articulo se centra en la descripcion de la corteza de la Zona de Ossa Morena (OMZ), que esta claramente dividida en una corteza superior, con reflectividad de buzamiento al NE, y una corteza inferior de pobre reflectividad. Las estructuras geologicas cartografiadas en superficie se correlacionan bien con la reflectividad de la corteza superior, y en la imagen sismica se ven enraizar en la corteza media. Esta esta constituida por un cuerpo muy reflectivo, interpretado como una gran intrusion de rocas basicas. La imagen de las suturas que limitan la OMZ muestra el caracter fuertemente transpresivo de la colision orogenica varisca registrada en el sudoeste de Iberia. La Moho actual es plana y, en consecuencia, no se observa la raiz del orogeno.

The relationship of soil-moisture saturation and time-lapse static shifts-An example from the Ketzin pilot site

Changes in the near surface are a major problem for land time-lapse seismic projects. Three seismic surveys at the Ketzin pilot site for CO2 storage in Germany demonstrated the importance of removing the variations in the shallow subsurface by applying spatially variable, relative time shifts to the different vintages prior to 4D interpretation. The main reason for these time shifts is a change in seismic velocities in the ground layer above the water table due to different soil-moisture saturation at the times of acquisition. We compared the variation in precipitation, groundwater level and trace-to-trace time shifts between the baseline and two monitor surveys and revealed that delays in reflected energy are in a qualitative sense, proportional to the moisture content in the soil.

4D Result Enhancement with Crosscorrelation-based Time-lapse Static Correction at Ketzin, Germany

A method for correction of time-lapse differences (TLD) in the statics of seismic data from repeated surveys is presented. Such static differences are typically caused by changes in the near-surface velocities between the acquisition repeats and have a deteriorating impact on the time-lapse image. Trace-to-trace time shifts are determined from the pre-stack data sets using cross-correlations. These time shifts are decomposed in a surface-consistent manner, which is providing a static correction that is capable of aligning the repeat data to the baseline data. The approach is demonstrated on a 4D seismic data set from the Ketzin CO2 pilot storage site, Germany, and is compared with results of an initial processing that was based on individual refraction static corrections. It is shown that the proposed TLD static correction reduces 4D noise more effectively than refraction static corrections while being significantly less labor intensive.

Tomographic modeling and petrophysical measurements for locating weakness zones in bedrock, Kiruna, Sweden

The Kiirunavaara iron ore in northern Sweden has been mined since 1898. Originally mined from an open pit, extraction of the ore today continues underground with the “sublevel caving” method. In this method the ore between sublevels is broken above and the overlying waste rock caves into the void created as the ore is extracted [1]. The overall mining progresses downwards while the caving progresses upwards, eventually reaching the surface and causing large-scale deformation. This surface deformation has an obvious negative impact on the surrounding infrastructure of the town of Kiruna, which is partly located above the mine and lies less than 1 km from where the east-dipping orebody was originally outcropping. This proximity to a residential area makes it absolutely necessary for the mining company to acquire as much knowledge as possible about the current near-surface geology and potential future deformation patterns.