Calin Cosma

• PhD
• Owner at Vibrometric

"Advanced Seismic Imaging Solutions for Hardrock Site Evaluation and Characterisation Across Scales", published in the August 2024 issue of First Break, highlights decades of innovation and relentless pursuit of excellence in geophysics. Our work benefits geophysicists and engineers involved in hardrock exploration, be it for nuclear waste disposal...

Reflection seismic surveys are relevant to the detailed characterisation of crystalline bedrock. Relatively small-scale features, even single fractures, can demonstrably be detected. Integrated analysis and modelling of geological, hydrogeological and geophysical data is instrumental in the interpretation of reflection seismic data. This requires t...

In this study, we explored the capability of coda wave interferometry (CWI) for monitoring CO2 storage by estimating the seismic velocity changes caused by CO2 injection. Given that the CWI method is highly efficient, the primary aim of this study was to provide a quick detection tool for the long-term monitoring of CO2 storage safety. In particula...

Retrofitting existing dams for the installation of modern monitoring instrumentation requires confidence in one’s knowledge of the dam’s internal structures. In 2010, the operator of the Mactaquac Generating Station wished to install a fibre optic distributed temperature sensing (DTS) cable as close as possible to the sub-vertical contact between t...

Seismic reflection methods have been used for the exploration of mineral resources for several decades. However, despite their unmatched spatial resolution and depth penetration, they only have played a minor role in mineral discoveries so far. Instead, mining and exploration companies have traditionally focused more on the use of potential field, el...

We present an overview of the seismic exploration initiatives at the Outokumpu ore district in Eastern Finland, with new results from the COGITO-MIN active-passive seismic survey in 2016. Through this example from Outokumpu, we aim to demonstrate the possibilities of different types of seismic data, including new emerging, cost-effective methodolog...

This work presents a high-resolution seismic imaging study of a target sulphide mineralization located in the Kylylahti polymetallic mine, Eastern Finland. For this purpose, in-mine VSP measurements were carried out, using two different technologies: a conventional three-component VSP and a fibre-optic Distributed Acoustic Sensing (DAS) system. The...

We conducted VSP measurements in the Kylylahti underground mine in eastern Finland to delineate a massive sulphide polymetallic depost. For this purpose, we applied two different technologies: a conventional VSP using three-component geophones, and a fibre-optic Distributed Acoustic Sensinc (DAS) cable. This is the first time, DAS technology was t...

The focus of this study is reflection seismic imaging of a massive sulfide deposit in the Kylylahti Cu-Au-Zn mine in eastern Finland. The geological environment in the target area is dominated by high-velocity rocks which have been severely folded resulting in a complicated assemblage of various near-vertical structures. In order to image those, we...

The collaborative COGITO-MIN project between six partners from Finland and Poland aims to develop cost-effective, novel, geophysical deep mineral exploration techniques, with particular emphasis on seismic imaging. The three-year-long project was launched in January 2016, with the data acquisition stage ending in late September 2016. The purpose of...

Figure caption: Top left: Crustal-scale FIRE3 and high-resolution seismic reflection profiles OKU1-OKU3, V1-V8 and E1 previously acquired in the Outokumpu area (Kukkonen et al. 2012) shown on the geological map (Bedrock of Finland –DigiKP). Bottom left: Geological cross-section A-A´ from Peltonen et al. (2008) across the Kylylahti deposit. Right: S...

Geophysical Research Abstracts Vol. 13, EGU2011-9687, 2011 EGU General Assembly 2011

RD&D activities for structure characterization ahead and around tunnels are ongoing, with focus on the safety assessment for engineering and mining applications. With hard rock nuclear waste repositories, brittle deformation zones and large fractures are considered to pose a potential risk for the mechanical integrity of the spent fuel disposal can...

Posiva and SKB conduct RD&D activities for the safety assessment and to test disposal techniques in real deep-seated conditions. Brittle deformation zones and large fractures are considered to pose a potential risk for the mechanical integrity of the spent fuel disposal canisters. These are to be avoided in positioning of the deposition holes that...

At the CO 2 storage pilot site near the town of Ketzin (35 km west of Berlin, Germany) the sandstone reservoir at 630 m–650 m depth is thin and heterogeneous. The time-lapse analysis of zero-offset VSP measurements shows that CO 2 -induced amplitude changes can be observed on near-well corridor stacks. Further, we investigate whether CO 2 -induced...

ONKALO is the underground rock characterisation built for the final disposal of spent nuclear fuel at Olkiluoto, Finland. Geology, geophysics, hydro-geology, geochemistry and rock mechanics contribute to bedrock studies conducted during repository construction to ensure the suitability of the bedrock for the final disposal. A high-resolution 3D ref...

As part of the seismic monitoring at the Ketzin CO2 storage site, time-lapse VSP data were acquired. The purpose of the VSP experiment was to complement 3D surface seismic data with higher spatial resolution in close vicinity to the injection well. More than 45 kt of CO2 were injected between the baseline and repeat VSP surveys. For each VSP survey...

The Millennium uranium deposit is located within the Athabasca Basin, in northern Saskatchewan, Canada. The deposit is hosted within moderately dipping Paleoproterozoic gneisses that are unconformably overlain by more than 500 m of flat lying, porous Paleoproterozoic to late Mesoproterozoic Athabasca Group sandstones. The deposit is associated with...

The Ketzin pilot site is the first European on-shore CO2 storage project site. Injection started in June 2008 and until the latest repeat survey in February 2011 around 45,000 t of CO2 had been injected into a saline aquifer at approximately 630 m depth. Seismic monitoring methods that have been applied at the Ketzin site comprise baseline and repe...

Three-dimensional seismic reflection measurements have been used to assist mine planning at the Millennium uranium deposit, Canada. The deposit is located within the crystalline basement, separated from the overlying Athabasca Basin sediments by an unconformity potentially associated with significant fluid flow. The primary objective of the similar...

In April 2004, a research pilot project in the German town of Ketzin started as the first onshore CO2 storage project in Europe. Injection started in June 2008 and until the latest repeat survey in February 2011 around 45 kilotons of CO2 had been injected into a saline aquifer at approximately 630 m depth. Different seismic methods, such as time-la...

Geological storage of CO2 is one means of mitigating the effects of continued burning of fossil fuels for power generation. An important component in the storage concept is the monitoring of the CO2 distribution at depth. Seismic methods can play a significant role in this monitoring, in particular cross-well methods are of interest due to their hi...

Ketzin is an European pilot site for onshore CO2 storage in a saline aquifer. Injection started in summer 2008 and to date, more than 37.000 tons of CO2 have been injected into the Stuttgart Formation at approximately 650 m depth. A wide range of monitoring methods are being applied at Ketzin, among which are active seismic observations at various...

The CO2SINK project has been the first onshore European CO2 injection experiment. CO2 is being injected at the project site near the town of Ketzin. The seismic characterization of CO2 storage at Ketzin consisted of several investigation and monitoring el

Monitoring of CO 2 underground is a rather new application of seismic analysis. An integrative concept is presented from the Ketzin site where a comprehensive seismic monitoring program is ongoing Initial developments at Ketzin were done within the CO 2 SINK project, while now work continues in a series of new projects. Seismic monitoring comprises...

The Ketzin project provides an experimental pilot test site for the geological storage of CO2. Seismic monitoring of the Ketzin site comprises 2D and 3D time-lapse experiments with baseline experiments in 2005. The first repeat 2D survey was acquired in 2009 after 22kt of CO2 had been injected into the Stuttgart Formation at approximately 630m dept...

Two high-resolution multi-offset vertical seismic profile (VSP) surveys were carried out in a permafrost mound near Umiujaq in northern Quebec, Canada, while performing seismic cone penetration tests (SCPT) to study the cryostratigraphy and assess the body waves velocities and the dynamic properties of warm permafrost. Penetrometer-mounted triaxial...

Structural and lithological delineation is seen as an emerging mining application of seismic imaging. The general benefits expected from applying delineation techniques include: reduced economic risk, shorter project timelines, and more accurate resource evaluations. The structural aspect has been documented relatively well in the past decade and c...

The Millennium uranium deposit is located within the Athabasca Basin of Saskatchewan, Canada. The deposit, situated in metapelitic basement rocks, is controlled by multiple sub-vertical faults, and crossfaults and is overlain by ~500 m of intensely altered, porous Manitou Falls group sandstones. The rock quality directly surrounding the deposit is...

The borehole seismic monitoring in the in situ laboratory for saline aquifer CO2 storage (Ketzin, Germany) comprises crosswell tomography, offset-VSP, walkaway-VSP, and single level 3D-VSP. Timelapse measurements of the crosshole tomography indicated a decreased P-wave velocity of the rock units affected by CO2 injection, the walkaway-VSP observed...

Baseline moving source profiling data were acquired in borehole Ketzin 202/2007 along seven lines at the Ketzin CO2 injection site in 2007. The data were recorded on eight three-component receivers spaced 10 m apart over a depth interval of 470-540 m. The main objective of the moving source profile survey was to generate high-resolution seismic ima...

Restricted resolution imposes limits on the detection of subsurface geologic features using surface seismic data. Despite great improvements in acquisition and processing techniques in recent years, seismic data still suffer from limited resolution. Detailed subsurface information on the geologic conditions at depth cannot always be attained from c...

Seismic and Radar investigations performed in 2009 at Olkiluoto in a niche excavated on the side of the ONKALO access tunnel. The objectives have been to confirm the existence of the EDZ at Olkiluoto, to evaluate its extent and to determine its physical characteristics. Three crosshole and one singlehole seismic sections have been measured before a...

The Excavation Damage Zone in crystalline bedrock was mapped under controlled conditions. The work was carried out in drill and blasting excavated Investigation Niché at depth level-350 m along access tunnel to ONKALO underground characterization facility, Olkiluoto. The work belongs to geological disposal project of spent nuclear fuel in Finland,...

ONKALO is the underground rock characterisation built for the final disposal of spent nuclear fuel at Olkiluoto, Finland. Geology, geophysics, hydro-geology, geochemistry and rock mechanics contribute to bedrock studies conducted during repository construction to ensure the suitability of the bedrock for the final disposal. A high-resolution reflec...

Pseudo-3D surface seismic data (baseline and repeat) were acquired in conjunction with CO2 injection at the Ketzin site. Similar processing steps were used for the baseline and repeat data sets. After processing, stacked profiles from both data sets were compared. No large differences were found on Line 6, and good quality data of line6 starts abou...

Seismic and Radar investigations performed in 2009 at Olkiluoto in a niche excavated on the side of the ONKALO access tunnel. The objectives have been to confirm the existence of the EDZ at Olkiluoto, to evaluate its extent and to determine its physical characteristics. Three crosshole and one singlehole seismic sections have been measured before a...

The common characteristic of the seismic methods involving downhole measurements is the difficulty of designing surveys able to image the subsurface space evenly. Migration schemes for these layouts are sensitive to reconstruction artifacts. The defining property of the image point (IP) transform is its ability to accumulate amplitudes of curved re...

The CO2SINK project began in April 2004 with a focus on geological CO2 storage in a saline aquifer near the town of Ketzin, west of Berlin. The injection started on June 30th, 2008, and as of October 25th 2009, 23,936 tons of CO2 have been injected into the underground. In order to monitor the CO2 injection, time-lapse cross-well seismic measuremen...

The main objectives of the survey presented here were to image, cost effectively, long vertical faults, nearly perpendicular to the tunnel, to image long, gently dipping fractures at the side and/or below the tunnel and to draw refraction velocity profiles along the tunnel wall. New aspects covered New, cost effective, combination of reflection & r...

The ONKALO tunnel is the underground rock characterisation facility being built for rock characterisation for the final disposal of spent nuclear fuel at Olkiluoto, in Finland. The bedrock is studied, during the construction phase, by geology, geophysics, hydro-geology and geochemistry and rock mechanics. The research is meant to help ensure the su...

Monitoring of CO2 underground is a rather new application of seismic analysis. A comprehensive seismic monitoring program is ongoing within the CO2SINK project. It comprises baseline and repeat observations at different scales in time and space: surface 3D and multi-line 2D, VSP (Vertical Seismic Profiling), MSP (Moving Source Profiling) and cross-...

The CO2SINK project at the German town of Ketzin (near Berlin), is aimed at a pilot storage of CO2, and at developing and testing efficient integrated monitoring procedures (physical, chemical, and biological observations) for assessing the processes triggered within the reservoir by a long term injection operation. In particular, geophysical metho...

A 3D seismic survey was acquired at the CO2SINK project site over the Ketzin anticline in the fall of 2005. Main objectives of the survey were (1) to verify earlier geological interpretations of the structure based on vintage 2D seismic and borehole data, (2) to provide, if possible, an understanding of the structural geometry for flow pathways wit...

The CO2SINK project at the German town of Ketzin (near Berlin), is aimed at a pilot storage of CO2, and at developing and testing efficient integrated monitoring procedures (physical, chemical, and biological observations) for assessing the processes triggered within the reservoir by a long term injection operation. In particular, geophysical metho...

In 2004 three seismic surface sources (VIBSIST, accelerated weight drop and MiniVib) were tested in a pilot study at the Ketzin test site, Germany, a study site for geological storage of CO2 (EU project CO2SINK). The main objectives of this pilot study were to 1) evaluate the response of the Ketzin site to reflection seismics, especially at the pla...

Main objectives Verify continuity of the main seismic responsive features to 1 km depth and attain sufficient confidence in the geologic model of the Olkiluoto site, to support the plans for the construction of the final disposal repository for nuclear waste in Finland. New aspects covered First high resolution 3D seismic survey in Finland. Correla...

Over the past five years, the use of seismic reflection methods for mineral exploration has increased significantly. Although, the overall industry knowledge is still based on very few surveys and each new survey can be considered unique. There is no pre‐established quick recipe when it comes to using seismic reflection methods in the search for th...

Storage of CO2 in saline aquifers is, perhaps, the most promising and relevant sequestration option for Europe. Saline aquifers are ubiquitous and their storage capacity exceeds that of depleted oil and gas fields. The CO2SINK project, officially started in April 2004, is aimed at developing an "in-situ laboratory" for CO2 storage to fill the gap b...

The CO 2 SINK project, a carbon dioxide storage and monitoring project, has been in operation in the Ketzin area, Germany since 2004. Goals are to investigate the techniques and understand the processes related to geological storage of CO 2 in a saline aquifer. A key element of the project is comprehensive monitoring and the development of verifica...

A 3D 25-fold seismic survey with a bin size of 12 by 12 m and about 12 km(2) of subsurface coverage was acquired in 2005 near a former natural gas storage site west of Berlin, as part of the five-year EU funded CO2SINK project. Main objectives of the seismic survey were to verify earlier geologic interpretations of structure based on vintage 2D sei...

Extensive geophysical data and imaging have been used to produce and refine a 3D geological model of the Olkiluoto site, in Finland. An underground research facility, ONKALO, is being built at Olkiluoto for detailed characterization of the planned nuclear waste repository host rock. The bedrock consists of multiphase deformed and fractured high-gra...

High resolution reflection seismic methods have proven to be useful tools for locating fracture zones in crystalline rock. Siting of potential high-level nuclear waste repositories is a particularly important application of these methods. By using small explosive sources (15-75 grams), high resolution images of the sub-surface have been obtained in...

The characterization of a deep-rock nuclear waste repository site requires an understanding of the structural geometry of the rockmass over a range of scales, from fractures identified in boreholes, to lower resolution, but wider coverage surface geological and geophysical data. Where complex fracture networks exist the inclusion of interpretations...

This case study was undertaken for a low-porosity fractured carbonate reservoir with a complex fracture network resulting from several phases of tectonic activity. The integration of the image log and seismic-derived interpretations was problematic due to the complexity of the image log signature and the variable quality of the surface seismic data...

The main objectives of the survey were to detect-directly or indirectly-uranium ore and to contribute to the understanding of the structural ore controls. Investigations from boreholes were aimed at imaging vertical and steeply dipping structures directly related to the uranium mineralization. Summary The McArthur River mine has become a testing gr...

A project for geological disposal of spent nuclear fuel deep into Finnish bedrock has been run now since 1988 in Eurajoki Olkiluoto, western Finland (Anttila et al. 1999, Enescu et al. 2004). The related research and development tasks are carried out by Posiva Ltd. A multiphase characterization with geological, hydrological, geophysical and hydroch...

Since April 2004, preparatory work prior to CO2 injection has been conducted in the CO2SINK Project, the European Union's first research and development activity on the in-situ testing of geological storage of CO2 near the town of Ketzin, Germany. Carbon dioxide will be injected into a saline aquifer of the Triassic Stuttgart Formation in an anticl...

We conducted seismic cone-penetration tests (SCPT) and tomographic imaging in a permafrost mound in northern Quebec, Canada, to study the cryostratigraphy and assess the seismic properties of permafrost at temperatures near 0°C. A swept impact source generating both P- and S-waves and penetrometer-mounted three-component accelerometers were used to...

A project for geological disposal of spent nuclear fuel deep into Finnish bedrock has been run now since 1988 in Eurajoki Olkiluoto, western Finland (Anttila et al. 1999, Enescu et al. 2004). The related research and development tasks are carried out by Posiva Ltd. A multiphase characterization with geological, hydrological, geophysical and hydroch...

Finsch mine is engaged in a resource estimation project. A critical requirement for accurate resource estimation is the determination of morphology and volume of the kimberlite pipe. Geostatistical simulation studies indicated that a total of 70 borehole pierce points would be required to estimate the volume of the Block 5 kimberlite with a 15% var...

The Finnish Site Investigation Programme for the Final Disposal of Spent Nuclear Fuel started over two decades ago. The Eurajoki-Olkiluoto was selected for building the planned repository. Based on the large number of surveys performed and the ample direct and indirect verifications, the multi-azimuth multi-offset VSP is considered an effective met...

Over the studied area of a fractured carbonate reservoir few faults or fracture zones were interpretable with confidence from the surface seismic data due to the variable quality of these data. From earlier experience, [4], it was considered that VSP data may produce information on faulting and/or fracturing that may otherwise be difficult to deter...

Geological characterization aimed initially to select the site for final disposal from a series of candidate sites, and later to support the positioning and design of the repository facilities. Airborne and ground level geophysical mapping and soundings, geological mapping, core logging, detailed geophysical logging and surface and borehole reflect...

Three pairs of diamond drillholes were surveyed at Voisey' Bay, Labrador, Canada, in the Eastern Deeps deposit. The surveys were carried out in NQ diameter drillholes, which were approximately 800-850 m in length. The holes were nearly vertical and hole-to-hole distances ranged from 45 m to 80 m. The p-wave velocity tomography surveys were designed...

Crosshole tomography is emerging as the most common geophysical technique for mapping sulphide distribution between drillholes. This paper describes the crosshole seismic investigations carried out in the Eastern Deeps deposit at Voisey's Bay, Labrador, Canada, in October and November, 1999. The Eastern Deeps deposit consists of troctolite-hosted d...

VSP has lately extensively been used for mapping fractures and fracture zones with various hardrock applications. Fracture zones in hardrock display weak seismic contrast and reflected wavefields are easier identified by increased coherency along time-depth paths corresponding to possibly real reflection events than by amplitude standout. With the...

The optimization of field development requires an understanding of the structural geometry of the reservoir over a range of scales. Where complex fracture networks exist the integration of VSP data with image logs and surface data leads to a more robust understanding of the reservoir. This study utilized specialist reprocessing of VSP data that wer...

The resolution of a seismic survey is directly related to the energy and frequency bandwidth generated by the signal source. The high-resolution requirement can be fulfilled if the signal energy is b uilt up in time, rather than being emitted as a short burst /4/, /8/. This article will describe the state -of-the-art development of seismic sources...

The diversity of the applications of high-resolution seismics requires investigations in the range of hundreds of meters to be performed in very diverse conditions. We found the Swept Impact Seismic Technique (SIST) to be a viable solution for high-resolution surveys in hard rocks. SIST combines the Vibroseis swept-frequency and the Mini-Sosie mult...

VSP surveys have been carried out at several potential nuclear waste disposal sites in Finland since the mid 1980s. To date, more than 200 three-component profiles have been measured. The main purpose of the surveys was to detect fracture zones in the crystalline bedrock and to determine their positions. Most seismic events could be linked to zones...

In 1986, the Swedish Nuclear Fuel and Waste Management Co. (SKB) decided to build an underground research laboratory, the Äspö Hard Rock Laboratory (HRL). The Äspö HRL offers the possibility to test and demonstrate a full site investigation sequence. As part of this work, various seismic techniques were tested and demonstrated, from the kilometer t...

Borehole seismic imaging surveys have been undertaken over a range ofdifferent scales at the Aspo Hard Rock Laboratory (HRL) to address a number of different objectives. In this paper two of those objectives, that encompass the end members of the range of scales are presented and discussed.

The paper reviews the seismic data processing techniques based on a version of the Radon transform, developed for characterizing non-planar and spatially limited structures of arbitrary orientations in crystalline rock. The examples are taken from the VSP surveys carried out in Borehole KR6, at the Olkiluoto site in SW Finland, as a part of the Sit...

As a part of the site investigation programme for the final disposal of spent nuclear fuel, conducted by Teollisuuden Voima Oy (TVO), VSP-surveys have been carried out at several sites in Finland starting in 1987.

In 1993 the Industrial Power Company - TVO, from Finland, manifested interest in the use of high frequency seismics, as a means to characterize the rock in the immediate vicinity of nuclear waste disposal facilities.

Summary The purpose of the method is to map velocities of P- and S-waves, elastic moduli and attenuation coefficients in the region between two boreholes. The results can also be used to determinein situ mechanical properties of the rockmass and to locate cracks, fractured zones and ore bodies. The seismic excitor is basically a hammer driven by a...