Intergrated Well‐Log, VSP, and Surface Seismic Analysis of Near‐Surface Glacial Sediments: Red Lodge, Montana

2011 ◽  
Author(s):  
Jingqiu Huang ◽  
Robert Stewart ◽  
Joe Wong ◽  
Carlos Montana
Keyword(s):  
Seismic Analysis ◽  
Well Log ◽  
Near Surface ◽  
Glacial Sediments

Near-surface glaciotectonic structures in the sediments of an overdeepened glacial valley revealed by a shallow 3D seismic survey

2021 ◽  
Author(s):  
David Tanner ◽  
Hermann Buness ◽  
Thomas Burschil
Keyword(s):  
Seismic Reflection ◽  
P Wave ◽  
Seismic Survey ◽  
Small Scale ◽  
Academic Press ◽  
Near Surface ◽  
Glacial Sediments ◽  
Area Source ◽  
Terminal Moraine ◽  
Rhine Valley

<p>Glaciotectonic structures commonly include thrusting and folding, often as multiphase deformation. Here we present the results of a small-scale 3-D P-wave seismic reflection survey of glacial sediments within an overdeepened glacial valley in which we recognise unusual folding structures in front of push-moraine. The study area is in the Tannwald Basin, in southern Germany, about 50 km north of Lake Constance, where the basin is part of the glacial overdeepened Rhine Valley. The basin was excavated out of Tertiary Molasse sediments during the Hosskirchian stage, and infilled by 200 m of Hosskirchian and Rissian glacioclastics (Dietmanns Fm.). After an unconformity in the Rissian, a ca. 7 m-thick till (matrix-supported diamicton) was deposited, followed by up to 30 m of Rissian/Würmian coarse gravels and minor diamictons (Illmensee Fm.). The terminal moraine of the last Würmian glaciation overlies these deposits to the SW, not 200 m away.</p><p>We conducted a 3-D, 120 x 120 m², P-wave seismic reflection survey around a prospective borehole site in the study area. Source/receiver points and lines were spaced at 3 m and 9 m, respectively. A 10 s sweep of 20-200 Hz was excited by a small electrodynamic, wheelbarrow-borne vibrator twice at every of the 1004 realized shot positions. We recognised that the top layer of coarse gravel above the till is folded, but not in the conventional buckling sense, rather as cuspate-lobate folding. The fold axes are parallel to the terminal moraine front. The wavelength of the folding varies between 40 and 80 m, and the thickness of the folded layer is on average about 20 m. Cuspate-lobate folding is typical for deformation of layers of differing mechanical competence (after Ramsay and Huber 1987; µ<sub>1</sub>/µ<sub>2</sub> less than 10), so this tell us something about the relative competence (or stiffness) of the till layer compared to the coarse clastics above. We also detected small thrust faults that are also parallel to the push-moraine, but these have very little offset and most of the deformation was achieved by folding.</p><p>Ramsay, J.G. and Huber, M. I. (1987): The techniques of modern structural geology, vol. 2: Folds and fractures: Academic Press, London, 700 pp.</p>

scholarly journals Geochemistry and related studies of Clyde Estuary sediments

2017 ◽  
Vol 108 (2-3) ◽  
pp. 269-288 ◽  
Author(s):  
David G. Jones ◽  
Christopher H. Vane ◽  
Solveigh Lass-Evans ◽  
Simon Chenery ◽  
Bob Lister ◽  
...  
Keyword(s):  
Seismic Data ◽  
Surface Sediments ◽  
Sidescan Sonar ◽  
Near Surface ◽  
Glacial Sediments ◽  
Shallow Seismic ◽  
Limited Success ◽  
Shallow Layer ◽  
Quaternary History ◽  
Different Sources

ABSTRACTGeochemical and related studies have been made of near-surface sediments from the River Clyde estuary and adjoining areas, extending from Glasgow to the N, and W as far as the Holy Loch on the W coast of Scotland, UK. Multibeam echosounder, sidescan sonar and shallow seismic data, taken with core information, indicate that a shallow layer of modern sediment, often less than a metre thick, rests on earlier glacial and post-glacial sediments. The offshore Quaternary history can be aligned with onshore sequences, with the recognition of buried drumlins, settlement of muds from quieter water, probably behind an ice dam, and later tidal delta deposits. The geochemistry of contaminants within the cores also indicates shallow contaminated sediments, often resting on pristine pre-industrial deposits at depths less than 1m. The distribution of different contaminants with depth in the sediment, such as Pb (and Pb isotopes), organics and radionuclides, allow chronologies of contamination from different sources to be suggested. Dating was also attempted using microfossils, radiocarbon and 210Pb, but with limited success. Some of the spatial distribution of contaminants in the surface sediments can be related to grain-size variations. Contaminants are highest, both in absolute terms and in enrichment relative to the natural background, in the urban and inner estuary and in the Holy Loch, reflecting the concentration of industrial activity.

scholarly journals Uncertainty based multi-step seismic analysis for near-surface imaging

2019 ◽  
Vol 11 (1) ◽  
pp. 727-737 ◽  
Author(s):  
Artur Marciniak ◽  
Iwona Stan-Kłeczek ◽  
Adam Idziak ◽  
Mariusz Majdański
Keyword(s):  
Seismic Imaging ◽  
Seismic Analysis ◽  
Data Uncertainty ◽  
Near Surface ◽  
Seismic Surveys ◽  
Recorded Data ◽  
Single Method ◽  
Multi Method Approach ◽  
Tomographic Analysis ◽  
Processing Steps

Abstract Near-surface seismic surveys are often designed for surface wave and seismic tomographic analysis. In recent years, seismic imaging methods have been more frequently used at this scale. Recognition of near-surface structures using a single method is insufficient because of the ambiguity of the inversion problem. As a solution, the authors propose a multi-step approach, where several different seismic methods are used in a particular order, to achieve an optimal model. A multi-method approach allows utilisation of a whole spectrum of recorded data, even the elements that are treated as background noise in other techniques. In classical processing approach, information about data uncertainty is often omitted or used in the simplest way for the single method only. This work presents an updated approach to uncertainty analysis by transferring estimated uncertainty between processing steps. By assuming that every consecutively applied method is more certain, the authors were able to obtain accurate velocity fields for seismic imaging, as the main information received from the previous steps. Based on information from multiple methods, a seismic stack in the depth domain was created as a final result, with an estimate of uncertainty.

A seismic analysis of Black Creek and Wabumun salt collapse features, western Canadian sedimentary basin

Geophysics ◽  
1991 ◽  
Vol 56 (5) ◽  
pp. 618-627 ◽  
Author(s):  
N. L. Anderson ◽  
R. J. Brown
Keyword(s):  
Seismic Data ◽  
Seismic Analysis ◽  
High Amplitude ◽  
Well Log ◽  
Areal Extent ◽  
Distribution Maps ◽  
Salt Distribution ◽  
Lateral Variations ◽  
Reservoir Facies

Two Devonian salts of western Canada, those of the Black Creek member (Upper Elk Point subgroup) in northwest Alberta and those of the Wabamun group in southeastern Alberta, were widely distributed and uniformly deposited within their respective basins. Both of these salts are interbedded within predominantly carbonate sequences and both have been extensively leached. They are now preserved as discontinuous remnants of variable thickness and areal extent. These salt remnants and their associated collapse features are often associated with structural or stratigraphic traps. Structural traps typically form where reservoir facies are closed across remnant salts, stratigraphic traps often develop where reservoir facies were either preferentially deposited and/or preserved in salt collapse lows. As a result of these relationships between dissolution and hydrocarbon entrapment, the distribution (areal extent and thickness) of these salt remnants is of significant interest to the explorationist. Both the Black Creek and Wabamun salts have relatively abrupt contacts with the encasing higher velocity, higher density carbonates. Where these salts are sufficiently thick, their top and base typically generate high amplitude reflections, and lateral variations in the salt isopach can be directly determined from the seismic data. Relative salt thicknesses can also be indirectly estimated through analyses of lateral variations in the thicknesses of the encompassing carbonates, time structural drape and velocity pullup. Such seismic information about the thickness and the extent of these salts should be used together with well log control to generate subsurface distribution maps. These maps will facilitate both the delineation of prospective structural and stratigraphic play fairways and the determination of the timing of salt dissolution. In addition, an appreciation of regional salt distribution will decrease the likelihood that remnant salts will be misinterpreted as either reefs and/or faulted structures.

scholarly journals Joint interpretation of magnetotelluric, seismic, and well-log data in Hontomín (Spain)

Solid Earth ◽  
2016 ◽  
Vol 7 (3) ◽  
pp. 943-958 ◽  
Author(s):  
Xènia Ogaya ◽  
Juan Alcalde ◽  
Ignacio Marzán ◽  
Juanjo Ledo ◽  
Pilar Queralt ◽  
...  
Keyword(s):  
Seismic Data ◽  
Velocity Model ◽  
Unconsolidated Sediments ◽  
Well Log ◽  
Storage Site ◽  
Near Surface ◽  
Log Data ◽  
Velocity Models ◽  
Joint Interpretation

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.

Multiphysics characterization of reservoir prospects in the Hoop area of the Barents Sea

2018 ◽  
Vol 6 (3) ◽  
pp. SG1-SG17 ◽  
Author(s):  
Pedro Alvarez ◽  
Fanny Marcy ◽  
Mark Vrijlandt ◽  
Øyvind Skinnemoen ◽  
Lucy MacGregor ◽  
...  
Keyword(s):  
Barents Sea ◽  
Seismic Analysis ◽  
Rock Physics ◽  
High Resistivity ◽  
Well Log ◽  
The Barents Sea ◽  
Geophysical Measurement ◽  
Very High

The inherent nonuniqueness of geophysical analysis can mean that interpretations based only on a single geophysical measurement can be ambiguous or uncertain. We have developed a case study from the Hoop area of the Barents Sea, in which prestack seismic, well-log, and controlled-source electromagnetic (CSEM) data were integrated within a rock-physics framework to provide a more robust assessment of the prospectivity of the area than could be obtained by seismic analysis alone. In this example, although quantitative seismic interpretation identified potentially hydrocarbon-bearing sands, the saturation was uncertain. In this area and at shallow depths, the main focus is on (very) high oil saturations. Adding the CSEM data in this setting allows us to distinguish between high saturations ([Formula: see text]) and low and medium saturations ([Formula: see text]): It is clear that saturations similar to those observed at the nearby Wisting well ([Formula: see text]) are not present in this area. However, because of limitations on the sensitivity of the CSEM data in this high-resistivity environment, it is not possible to distinguish between low and medium saturations. This remains an uncertainty in the analysis. Based on the resulting downgrade of the main prospect Maya and the limited additional high-risk prospectivity at other stratigraphic levels, the partnership agreed to surrender the license.

Shallow 3-D seismic reflection surveying: Data acquisition and preliminary processing strategies

Geophysics ◽  
1998 ◽  
Vol 63 (4) ◽  
pp. 1434-1450 ◽  
Author(s):  
Frank Büker ◽  
Alan G. Green ◽  
Heinrich Horstmeyer
Keyword(s):  
Data Acquisition ◽  
Seismic Reflection ◽  
Full Range ◽  
Depth Range ◽  
Data Set ◽  
Processing Scheme ◽  
Seismic Reflection Data ◽  
Near Surface ◽  
Glacial Sediments ◽  
Reflection Data

A comprehensive strategy of 3-D seismic reflection data acquisition and processing has been used in a study of glacial sediments deposited within a Swiss mountain valley. Seismic data generated by a downhole shotgun source were recorded with single 30-Hz geophones distributed at 3 m × 3 m intervals across a 357 m × 432 m area. For most common‐midpoint (CMP) bins, traces covering a full range of azimuths and source‐receiver distances of ∼2 to ∼125 m were recorded. A common processing scheme was applied to the entire data set and to various subsets designed to simulate data volumes collected with lower density source and receiver patterns. Comparisons of seismic sections extracted from the processed 3-D subsets demonstrated that high‐fold (>40) and densely spaced (CMP bin sizes ⩽ 3 m × 3 m) data with relatively large numbers (>6) of traces recorded at short (<20 m) source‐receiver offsets were essential for obtaining clear images of the shallowest (<100 ms) reflecting horizons. Reflections rich in frequencies >100 Hz at traveltimes of ∼20 to ∼170 ms provided a vertical resolution of 3 to 6 m over a depth range of ∼15 to ∼150 m. The shallowest prominent reflection at 20 to 35 ms (∼15 to 27 m depth) originated from the boundary between a near‐surface sequence of clays/silts and an underlying unit of heterogeneous sands/gravels.

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