Northwestern Williston Basin case histories with 3-D seismic data

Geophysics ◽  
1991 ◽  
Vol 56 (11) ◽  
pp. 1849-1874
Author(s):  
D. L. Connelly ◽  
B. J. Ferris ◽  
L. D. Trembly
Keyword(s):  
Signal To Noise Ratio ◽  
Three Dimensional ◽  
Cost Effective ◽  
Field Studies ◽  
Careful Analysis ◽  
Williston Basin ◽  
Event Correlation ◽  
Near Surface ◽  
Single Fold ◽  
Exploration Area

Two Northwestern Williston Basin field studies illustrate the cost‐effective geological and three‐dimensional seismic methods used to explore for structurally controlled oil reservoirs in the Tule Creek area of northeast Montana. These examples present the geologic and seismic characteristics of a Mississippian Charles C zone pool at Northwest Poplar field and a Devonian Nisku accumulation at Long Creek West field. A classic, upward‐shoaling, nearshore marine carbonate sequence characterizes the reservoir and associated strata in both fields. The Charles C zone pool of Northwest Poplar field is a subtle, tectonically‐controlled accumulation which remained undiscovered and downdip from the large, nearby, well‐known East Poplar field until 1983. Long Creek West field exhibits the subtle character of small closed structures produced by multistage evaporite solution. Three‐dimensional (3-D) seismic techniques best detect such fields of low vertical relief and small areal extent. The significant acquisition costs of multifold, 3-D seismic surveys led us to design, acquire, process, and interpret single‐fold 3-D surveys to disclose these subtle, small structures. Augmented conventional 48-channel vibroseis crews collected the 3-D data. Near‐surface glacial till deposits in the area created residual statics and normal‐moveout problems on the single‐fold data. These processing problems were handled by constraining the statics and normal‐moveout velocity solutions with plausible geologic conditions: the near‐flat attitude of the reflecting beds, and the inferred horizontal simplicity of the earth velocity field. Our geologically constrained processing methods included: single‐event correlation picking, single‐fold, surface‐consistent statics, and velocity interpolation on flattened events. In addition, spatially oriented six‐fold stacking increases the signal‐to‐noise ratio in areas where poor signal quality exists. In the case of Northwest Poplar field, geologic studies and subsequent interpretations involving isochron mapping techniques showed that the absence of Mississippian evaporites and paleostructural thinning produce disruption of evaporite events and interval thinning near the evaporites, respectively. Long Creek West field exhibited the interval thickening below, and the interval thinning above the trap formed by two‐stage evaporite solution. Careful analysis of geologic conditions coupled with single‐fold 3-D methods makes it possible to economically explore for small undiscovered structural traps in a mature exploration area.

scholarly journals Modern Geodetic Measurement Techniques in Gravimetric Studies on the Example of Gypsum Karst in the Siesławice Region

2018 ◽  
Vol 35 ◽  
pp. 03002 ◽  
Author(s):  
Sławomir Porzucek ◽  
Monika Łój ◽  
Karolina Matwij ◽  
Wojciech Matwij
Keyword(s):  
Laser Scanning ◽  
Measurement Techniques ◽  
Three Dimensional ◽  
Digital Terrain Model ◽  
Field Studies ◽  
Surface Zone ◽  
Three Dimensional Model ◽  
Geodetic Measurement ◽  
Near Surface ◽  
Gypsum Karst

In the region of Siesławice (near Busko-Zdrój, Poland) there are unique phenomena of gypsum karst. Atmospheric factors caused numerous gypsum outcrops, canals and underground voids. The article presents the possibility of using non-invasive gravimetric surveys supplemented with geodetic measurements to illustrate karst changes occurring around the void. The use of modern geodetic measurement techniques including terrestrial and airborne laser scanning enables to generate a digital terrain model and a three-dimensional model of voids. Gravimetric field studies allowed to map the anomalies of the gravitational field of the near-surface zone. Geodetic measurement results have made it possible to accurately determine the terrain correction that supplemented the gravimetric anomaly information. Geophysical interpretation indicate the presence of weathered rocks in the near surface zone and fractures and loosened zones located surround the karst cave.

Observational Test for Wave Propagation Effects in Local Earthquake Seismograms

1990 ◽  
Vol 61 (2) ◽  
pp. 109-116 ◽  
Author(s):  
David E. Williams ◽  
Charles A. Langston
Keyword(s):  
Thin Layer ◽  
Three Dimensional ◽  
Strong Motion ◽  
Careful Analysis ◽  
Corner Frequency ◽  
Vector Particle ◽  
Low Velocity ◽  
Waveform Data ◽  
Near Surface ◽  
Source Models

Abstract Strong motion data for aftershocks of the 1982 Miramichi earthquake are analyzed to determine site effects on recorded waveforms. Although aftershocks vary in source mechanism, the complicated vector particle motion of P and S arrivals are often coherent between events recorded at the same station. This suggests that near-surface receiver structure has a significant effect on the recorded waveforms. Resonance features dominate the wavetrains with P reverberations existing on the vertical components and S reverberations prominent on the radial components indicating near vertical incidence. These reverberations take the form of peaks in the amplitude spectra which may complicate corner frequency interpretation. As an example, a corner frequency shift, fc(S) < fc(P), is evident and is attributed to structure induced effects. Synthetic seismograms computed using the propagator matrix method indicate that a thin low velocity layer of unconsolidated glacial till located directly beneath the receivers is responsible for most waveform effects. Attenuation effects in the thin layer are included in the computation of the synthetics in order to help match amplitude ratios. The geometry of the till-bedrock interface is interpreted as being three dimensional due to high tangential P amplitudes and anomalous particle motions. The observed waveforms are believed to consist mainly of direct waves, reverberations within the thin layer, and scattered arrivals resulting from the nonplanar interface. A careful analysis of three component waveform data in earthquake aftershock data sets such as this one considered here may be useful in determining local site conditions independent of assumed source models.

Delineating hydrothermal stockwork copper deposits using controlled-source and radio-magnetotelluric methods: A case study from northeast Iran

Geophysics ◽  
2009 ◽  
Vol 74 (5) ◽  
pp. B167-B181 ◽  
Author(s):  
Mehrdad Bastani ◽  
Alireza Malehmir ◽  
Nazli Ismail ◽  
Laust B. Pedersen ◽  
Farhang Hedjazi
Keyword(s):  
Signal To Noise Ratio ◽  
Three Dimensional ◽  
Near Surface ◽  
2D Inversion ◽  
Controlled Source ◽  
Copper Mineralization ◽  
Radio Transmitters ◽  
Ground Magnetic ◽  
2D Resistivity

Radio- and controlled-source-tensor magnetotelluric (RMT and CSTMT) methods are used to target hydrothermal veins of copper mineralization. The data were acquired along six east-west- and three north-south-trending profiles, covering an area of about [Formula: see text]. The tensor RMT data were collected in the [Formula: see text] frequency band. A double horizontal magnetic dipole transmitter in the [Formula: see text] frequency range allowed us to constrain the deeper parts of the resistivity models better. To obtain optimum field parameters, ground magnetic profiling was conducted prior to the RMT and CSTMT surveys. Although the study area (in Iran) is remote, a number of radio transmitters with acceptable signal-to-noise ratio were utilized. The 2D inversion of RMT data led to unstable resistivity models with large datamisfits. Thus, the RMT data were used to complement and analyze the near-surface resistivity anomalies observed in the 2D CSTMT models. Analyses of strike and dimensionality from the CSTMT data suggests that the low-resistivity structures are mainly three dimensional; therefore, 2D inversion of determinant data is chosen. Independent 2D inversion models of the determinant CSTMT data along crossing profiles are in good agreement. Known copper mineralization is imaged well in the CSTMT models. The thinning of the conductive overburden correlates very well with magnetic highs, indicating the bedrock is resistive and magnetic. In this sense, the magnetic and electromagnetic fields complement each other. Analysis of the 2D resistivity models indicates the volcanic rock deepens at the center of the study area. This zone is associated with a magnetic low and therefore is recommended for detailed exploration work.

Estimation of near‐surface elastic parameters using multicomponent seismic data

Geophysics ◽  
1993 ◽  
Vol 58 (7) ◽  
pp. 1017-1029 ◽  
Author(s):  
E. Z. Ata ◽  
D. Corrigan ◽  
G. A. McMechan ◽  
J. E. Gaiser
Keyword(s):  
Field Data ◽  
Signal To Noise Ratio ◽  
Surface Effects ◽  
Test Site ◽  
Compressional Wave ◽  
Elastic Parameters ◽  
Surface Source ◽  
Near Surface ◽  
Multicomponent Seismic ◽  
Single Fold

In multicomponent seismic reflection surveys, surface and near‐surface effects can severely deteriorate the quality of reflection data. Such effects are more pronounced on shear‐wave than on compressional‐wave profiles. Amplitude anomalies, statics, and strong coherent source‐generated noise (i.e., surface waves) are often associated with inhomogeneous, poorly compacted near‐surface sediments of the weathering layer. The magnitude of such effects increases when sources and receivers are deployed at or near the surface in proximity to such inhomogeneities. Near‐surface effects can be investigated with respect to their depth of occurrence by burying seismic sources and/or receivers at various depths below the inhomogeneous weathering layer. In this context, an experiment was conducted to collect multicomponent seismic field data on a borehole‐controlled test site in east Texas. Data were recorded on three‐component surface and buried receivers using a full‐vector wavefield surface source. Although the geology appears simple, results of modeling one or two components of the field data with synthetics yields nonunique estimates of elastic parameters. Effects of anisotropy and heterogeneities are better identified and estimated with full‐wavefield surface and buried receiver observations. Single fold data from buried receivers yield reflection events with higher signal‐to‐noise ratio than 30‐fold CDP surface data previously acquired in the same area.

A vibroseis reflection seismic survey at the Buchans Mine in central Newfoundland

Geophysics ◽  
1993 ◽  
Vol 58 (1) ◽  
pp. 154-166 ◽  
Author(s):  
Carl Spencer ◽  
Geoffrey Thurlow ◽  
James Wright ◽  
Don White ◽  
Peter Carroll ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Cost Effective ◽  
Massive Sulfide ◽  
Careful Analysis ◽  
Fault Zones ◽  
Geophysical Data ◽  
Seismic Survey ◽  
Signal To Noise ◽  
Reflection Seismic ◽  
Seismic Sections

We present results from the first major vibroseis seismic reflection survey at a mine site in North America. It is demonstrated that conventional high‐stack fold reflection seismic techniques can image fault structures associated with volcanogenic massive sulfide bodies, despite the fact that these structures are locally steeply dipping and produce records with low signal‐to‐noise ratios. The new lines were recorded at the locations of two earlier experimental explosive surveys that failed to image many strong reflectors. The principal reasons for the success of the vibroseis experiment were the proper choice of sweep frequencies for maximum signal‐to‐noise ratio, the use of high‐stack fold, and the careful analysis of velocities and statics during processing. A comparison of the new seismic sections with borehole and other geophysical data indicates that the origin of reflections at Buchans can be attributed to various mechanisms including contrasts in lithologies and rock competence and intrusion of diabase sills into pre‐existing fault zones. The best reflections emanate from shallow‐dipping brittle‐ductile thrust fault zones characterized by fault gouge within broader fractured zones. The two seismic lines presented have proven to be a useful and cost‐effective supplement to existing borehole and geophysical data and have provided enough new information on the nature of thrust faulting at the mine to significantly influence current exploration plans.

Cryomicroscopy of crotoxin complex crystals at 400 KV

1989 ◽  
Vol 47 ◽  
pp. 826-827
Author(s):  
Jaap Brink ◽  
Wah Chiu
Keyword(s):  
Signal To Noise Ratio ◽  
3D Structure ◽  
Three Dimensional ◽  
Carbon Films ◽  
Depth Of Field ◽  
Basic Subunit ◽  
Ewald Sphere ◽  
Diffraction Patterns ◽  
Complex Crystals ◽  
Acidic Subunit

The crotoxin complex is a potent neurotoxin composed of a basic subunit (Mr = 12,000) and an acidic subunit (M = 10,000). The basic subunit possesses phospholipase activity whereas the acidic subunit shows no enzymatic activity at all. The complex's toxocity is expressed both pre- and post-synaptically. The crotoxin complex forms thin crystals suitable for electron crystallography. The crystals diffract up to 0.16 nm in the microscope, whereas images show reflections out to 0.39 nm2. Ultimate goal in this study is to obtain a three-dimensional (3D-) structure map of the protein around 0.3 nm resolution. Use of 100 keV electrons in this is limited; the unit cell's height c of 25.6 nm causes problems associated with multiple scattering, radiation damage, limited depth of field and a more pronounced Ewald sphere curvature. In general, they lead to projections of the unit cell, which at the desired resolution, cannot be interpreted following the weak-phase approximation. Circumventing this problem is possible through the use of 400 keV electrons. Although the overall contrast is lowered due to a smaller scattering cross-section, the signal-to-noise ratio of especially higher order reflections will improve due to a smaller contribution of inelastic scattering. We report here our preliminary results demonstrating the feasability of the data collection procedure at 400 kV.Crystals of crotoxin complex were prepared on carbon-covered holey-carbon films, quench frozen in liquid ethane, inserted into a Gatan 626 holder, transferred into a JEOL 4000EX electron microscope equipped with a pair of anticontaminators operating at −184°C and examined under low-dose conditions. Selected area electron diffraction patterns (EDP's) and images of the crystals were recorded at 400 kV and −167°C with dose levels of 5 and 9.5 electrons/Å, respectively.

EXPERIMENTAL INVESTIGATION OF FLOW RESPONSE TO STATIONARY DISTURBANCE IN ROTATING-DISK FLOW

2019 ◽  
Vol XVI (2) ◽  
pp. 13-22
Author(s):  
Muhammad Ehtisham Siddiqui
Keyword(s):  
Boundary Layer ◽  
Boundary Layer Flow ◽  
Three Dimensional ◽  
Rotating Disk ◽  
Careful Analysis ◽  
Laboratory Frame ◽  
Transition To Turbulence ◽  
Turbulent Regime ◽  
Mean Velocity ◽  
Layer Flow

Three-dimensional boundary-layer flow is well known for its abrupt and sharp transition from laminar to turbulent regime. The presented study is a first attempt to achieve the target of delaying the natural transition to turbulence. The behaviour of two different shaped and sized stationary disturbances (in the laboratory frame) on the rotating-disk boundary layer flow is investigated. These disturbances are placed at dimensionless radial location (Rf = 340) which lies within the convectively unstable zone over a rotating-disk. Mean velocity profiles were measured using constant-temperature hot-wire anemometry. By careful analysis of experimental data, the instability of these disturbance wakes and its estimated orientation within the boundary-layer were investigated.

Fracture-Tolerant and Shear-Resistant Interlayers for Mitigation of Reflective Cracking

2019 ◽  
Vol 2673 (10) ◽  
pp. 35-46
Author(s):  
Cristian Cocconcelli ◽  
Bongsuk Park ◽  
Jian Zou ◽  
George Lopp ◽  
Reynaldo Roque
Keyword(s):  
Asphalt Pavement ◽  
Aggregate Size ◽  
Cost Effective ◽  
Design Guidelines ◽  
Reflective Cracking ◽  
Rubber Membrane ◽  
Near Surface ◽  
Field Evidence ◽  
Cracking Performance ◽  
Interface Cracking

Reflective cracking is frequently reported as the most common distress affecting resurfaced pavements. An asphalt rubber membrane interlayer (ARMI) approach has been traditionally used in Florida to mitigate reflective cracking. However, recent field evidence has raised doubts about the effectiveness of the ARMI when placed near the surface, indicating questionable benefits to reflective cracking and increased instability rutting potential. The main purpose of this research was to develop guidelines for an effective alternative to the ARMI for mitigation of near-surface reflective cracking in overlays on asphalt pavement. Fourteen interlayer mixtures, covering three aggregate types widely used in Florida, and two nominal maximum aggregate sizes (NMAS) were designed according to key characteristics identified for mitigation of reflective cracking, that is, sufficient gradation coarseness and high asphalt content. The dominant aggregate size range—interstitial component (DASR-IC) model was used for the design of all mixture gradations. A composite specimen interface cracking (CSIC) test was employed to evaluate reflective cracking performance of interlayer systems. In addition, asphalt pavement analyzer (APA) tests were performed to determine whether the interlayer mixtures had sufficient rutting resistance. The results indicated that interlayer mixtures designed with lower compaction effort, reduced design air voids, and coarser gradation led to more cost-effective fracture-tolerant and shear-resistant (FTSR) interlayers. Therefore, preliminary design guidelines including minimum effective film thickness and maximum DASR porosity requirements were proposed for 9.5-mm NMAS (35 µm and 50%) and 4.75-mm NMAS FTSR mixtures (20 µm and 60%) to mitigate near-surface reflective cracking.

Thermomechanical Coupling of a Hyper-viscoelastic Truck Tire and a Pavement Layer and its Impact on Three-dimensional Contact Stresses

2021 ◽  
pp. 036119812110171
Author(s):  
Angeli Jayme ◽  
Imad L. Al-Qadi
Keyword(s):  
Contact Stress ◽  
Contact Area ◽  
Three Dimensional ◽  
Interaction Model ◽  
Rolling Resistance ◽  
Contact Stresses ◽  
Thermomechanical Coupling ◽  
Temperature Profiles ◽  
Near Surface ◽  
Truck Tire

A thermomechanical coupling between a hyper-viscoelastic tire and a representative pavement layer was conducted to assess the effect of various temperature profiles on the mechanical behavior of a rolling truck tire. The two deformable bodies, namely the tire and pavement layer, were subjected to steady-state-uniform and non-uniform temperature profiles to identify the significance of considering temperature as a variable in contact-stress prediction. A myriad of ambient, internal air, and pavement-surface conditions were simulated, along with combinations of applied tire load, tire-inflation pressure, and traveling speed. Analogous to winter, the low temperature profiles induced a smaller tire-pavement contact area that resulted in stress localization. On the other hand, under high temperature conditions during the summer, higher tire deformation resulted in lower contact-stress magnitudes owing to an increase in the tire-pavement contact area. In both conditions, vertical and longitudinal contact stresses are impacted, while transverse contact stresses are relatively less affected. This behavior, however, may change under a non-free-rolling condition, such as braking, accelerating, and cornering. By incorporating temperature into the tire-pavement interaction model, changes in the magnitude and distribution of the three-dimensional contact stresses were manifested. This would have a direct implication on the rolling resistance and near-surface behavior of flexible pavements.

scholarly journals Frequency-diverse multimode millimetre-wave constant-ϵr lens-loaded cavity

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
M. A. B. Abbasi ◽  
V. F. Fusco ◽  
O. Yurduseven ◽  
T. Fromenteze
Keyword(s):  
Signal To Noise Ratio ◽  
Cost Effective ◽  
Doa Estimation ◽  
Frequency Diversity ◽  
Millimetre Wave ◽  
Single Lens ◽  
Dielectric Lens ◽  
Diversity Principle ◽  
First Time ◽  
Multi Mode

AbstractThis paper presents a physical frequency-diverse multimode lens-loaded cavity, designed and used for the purpose of the direction of arrival (DoA) estimation in millimetre-wave frequency bands for 5G and beyond. The multi-mode mechanism is realized using an electrically-large cavity, generating spatio-temporally incoherent radiation masks leveraging the frequency-diversity principle. It has been shown for the first time that by placing a spherical constant dielectric lens (constant-ϵr) in front of the radiating aperture of the cavity, the spatial incoherence of the radiation modes can be enhanced. The lens-loaded cavity requires only a single lens and output port, making the hardware development much simpler and cost-effective compared to conventional DoA estimators where multiple antennas and receivers are classically required. Using the lens-loaded architecture, an increase of up to 6 dB is achieved in the peak gain of the synthesized quasi-random sampling bases from the frequency-diverse cavity. Despite the fact that the practical frequency-diverse cavity uses a limited subset of quasi-orthogonal modes below the upper bound limit of the number of theoretical modes, it is shown that the proposed lens-loaded cavity is capable of accurate DoA estimation. This is achieved thanks to the sufficient orthogonality of the leveraged modes and to the presence of the spherical constant-ϵr lens which increases the signal-to-noise ratio (SNR) of the received signal. Experimental results are shown to verify the proposed approach.

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