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Collaborating Authors
Search Seismic Surveying: Acknowledgements
...irlin, R. L, Farmer, S.L., and Bahorich, M.S., 1998, 3-D seismic attributes using a semblance-based Acknowledgements: coherency algorithm: Geophysics, 63, 1150-1165. We thank the US Department of Energy and Output Ex...roject. The effect of prestack depth migration on 3-D seismic attributes: Geophysics, 64, 1553-1561.Acknowledgements Figure 1a: Inline with no smoothing. Figure 2a: Inline with smoothing. Figure 1b: Time slice wit...
Summary Multitrace seismic attributes including coherence, dip/azimuth, amplitude gradients, and spectral decomposition provide a means of rapidly extracting structural, stratigraphic, and tuning features from high quality 3-D seismic data. Unfortunately, given cost and time constraints our 3-D seismic images often suffer from inaccurate velocity/depth models giving rise to defocused, somewhat smeared images. Likewise variability in seismic survey fold and source-receiver azimuth within cdp bins, as well as inadequate geophone array suppression of backscattered surface waves can give rise to acquisition footprint which is often exacerbated by these modern edge detection attributes.
- Geophysics > Seismic Surveying > Seismic Processing (1.00)
- Geophysics > Seismic Surveying > Seismic Interpretation (1.00)
- Geophysics > Seismic Surveying > Surface Seismic Acquisition > Land Seismic Acquisition (0.55)
...ments and advice from a selection of eminent contributors to this field, and they are listed in the acknowledgements. I have also included a few references on various aspects of this important problem. A more complet...
...flections using the Radon transform, Geophysics, 57, cost and processing objectives. 3, p.386-395. ACKNOWLEDGEMENTS Hadidi, M., Johnston, D., and Levin, S., 1995, Removal of surface related diffracted multiples, EAE...
These methods exploit some difference between multiple and The basic model in seismic processing assumes that reflection primary. This difference may only become apparent in a data consists of primaries only. If multiples are not particular domain, hence the reason for so many transformations removed they can be misinterpreted as, or interfere with, employed in these techniques.
...urvey, and the other is a stack of the Teapot Dome 3D land survey (a publicly available survey, see acknowledgements for more information). For the marine dataset case, Figure 2 shows a CMP gather with NMO applied fr...
...s method has in reducing velocity picking time, and in turn, processing cost for a seismic project. Acknowledgements The author would like to thank Warren Ross, Eric Foley, and the rest of the team at Shearwater Open...
ABSTRACT Velocity auto-picking can reduce time spent on processing large volumes of seismic data and increase the number of CMP gathers that are picked in a project. Many velocity auto-pickers have been developed but few, if any, have utilized the power of unsupervised machine learning. Machine learning is an emerging technology for the solution of difficult problems. A new technique using seismic attributes in conjunction with an unsupervised machine learning clustering algorithm has been developed. The results on both marine and land datasets have shown that this method could potentially reduce the time spent on manual-picking, thus driving down the cost of processing a dataset. Presentation Date: Wednesday, September 27, 2017 Start Time: 8:55 AM Location: 371A Presentation Type: ORAL
- Geophysics > Seismic Surveying > Seismic Processing (0.95)
- Geophysics > Seismic Surveying > Seismic Modeling > Velocity Modeling (0.71)
Hybrid Ray Tracer And Amplitude Calculation With Finite Difference, Graph Theory And Ray Bending
Hu, Chaoshun (Jackson School of Geosciences, The University of Texas at Austin) | McIntosh, Kirk (Jackson School of Geosciences, The University of Texas at Austin) | van Avendonk, Harm (Jackson School of Geosciences, The University of Texas at Austin) | Stoffa, Paul (Jackson School of Geosciences, The University of Texas at Austin)
...1988, Finite-difference calculation of equation. traveltimes: Bull. Seis. Soc. Am., 78, 2062-2076. Acknowledgements Conclusions The author ...acknowledgements to the support of TAIGER Our example verifies the accuracy and efficiency of our project. Special t...
ABSTRACT We proposed a new hybrid ray tracer to calculate the traveltime and ray geometrical spreading using finite difference, graph theory and ray bending. It utilizes the finite difference method to compute the traveltime in an arbitrary medium to avoid the shadow zone, the graph theory based on the traveltime result to find the zigzag raypath efficiently and the pseudo ray bending method to improve the zigzag raypath and get a smooth and accurate ray path. We also proposed a new ray geometrical spreading equation. Using this equation, we can calculate ray amplitude based on the Laplacian of the traveltime calculated by the finite difference and high accurate ray bending.
A Comparison of Inversion Results For Two Full-waveform Methods That Utilize the Lowest Frequencies In Dual-sensor Recordings
Kelly, Steve (Petroleum Geo-Services) | Ramos-Martรญnez, Jaime J. (Petroleum Geo-Services) | Tsimelzon, Boris (Petroleum Geo-Services) | Crawley, Sean (Petroleum Geo-Services)
...offset of 8 km. In addition, inversion based on impedance yields velocity models with significantly Acknowledgements lower wavenumber content than those based solely on reflectivity. 2010 SEG SEG Denver 2010 Annual...
...A comparison inversion results for two full-waveform methods that utilize dual-sensor recordings Acknowledgements We thank Dave Carlson, Alejandro Valenciano, Nizar Chemingui, Seongbok Lee, Dan Whitmore and Li Jia...
INTRODUCTION Summary In this abstract, we test the capability of full-waveform inversion to exploit the lowest frequencies available from dual-sensor, single-streamer recordings. Two different, time-domain methods are tested. The first method follows the โconventionalโ approach of iteratively updating interval velocity by using the gradient obtained from back-projected residuals between modelled and recorded data. The second method constructs perturbations in impedance from the gradient, which is then used to update the velocity. These methods are tested on 2-D and 3-D, synthetic data, using a wavelet with realistic bandwidth. They are also applied to field data for one cable from a dual-sensor field survey. Both this inversion and the synthetic inversion study indicate that features ~ 0.5 km can be accurately recovered at depths of a few kilometres using maximum offsets of only 8 km. The goal of full-waveform inversion (FWI) is to refine a preliminary velocity model that is typically computed using ray or beam tomography. Spectacular improvements in resolution have been reported using both acoustic and elastic inversion formulations, when the target (gas) is relatively shallow and the data is recorded at the ocean bottom (Sirgue et al., 2009; Brossier et al., 2009). These improvements have been shown to both advance interpretation of the reservoir and significantly improve the quality of migrated images (Sirgue et al., 2009). However, in the case of towed-streamer marine acquisition, the benefit of waveform inversion is still being explored. Models obtained by ray tomography are generally sufficient to โflattenโ gathers and provide an adequate model for depth migration, provided that the scale sizes of all velocity variations conform to the assumptions of ray theory. Departures from these assumptions include velocity perturbations of a few hundred meters per second with scale sizes of roughly 1 km or less. Features larger than a few hundred meters can significantly alter the โmoveoutโ of CDP gathers, even for the low frequency ranges normally employed in FWI. The determination of features in this size range thus represents an opportunity for FWI to materially improve the quality of depth migration for towed-streamer acquisition. Unfortunately, it can be very difficult for FWI to resolve features larger than a few hundred meters, particularly for maximum offsets of a few kilometers and deep targets. As discussed by Carlson et al. (2007), dual-sensor, single-cable acquisition allows a deeper recording depth, which yields both improved S/N and improved low-frequency content. Our research has thus focused on developing strategies that exploit these low frequencies during FWI in order to augment ray tomography and improve stacking quality during depth migration. Theory and method We have investigated two different implementations of the method originally proposed by Tarantola (1984). Both methods employ the two-way, acoustic wave equation in the time domain. The first implementation disregards the time derivatives in the imaging principle, in order to enhance low-wavenumber recovery (Kelly et al., 2009). Since the velocity and density are extracted from gradient images that represent perturbations in reflectivity, we refer to this approach as the โreflectivity-basedโ method.
- Geophysics > Seismic Surveying > Seismic Processing > Seismic Migration (1.00)
- Geophysics > Seismic Surveying > Seismic Modeling > Velocity Modeling > Seismic Inversion (0.91)
Chasing the Upper Jurassic Alpine-type Reservoir: Recent Exploration Success In the National Petroleum Reserve, Alaska
Wilson, Gregory C. (ConocoPhillips Alaska, Inc.) | Veldhuis, Jerry H. (ConocoPhillips Alaska, Inc.) | Keskula, Erik (ConocoPhillips Alaska, Inc.) | Bannan, David (ConocoPhillips Alaska, Inc.) | Hebertson, Gregory F. (Anadarko Petroleum Corporation)
...ed to be a catalyst for lease offerings and an invigorated exploration program on the North Slope. Acknowledgements The authors gratefully acknowledge ConocoPhillips and Anadarko Petroleum Corporation and the Alaska... management for permission to publish the data in this paper. Special acknowledgements also to ConocoPhillips seismic acquisition and processing specialists Jim Darnall, Ronald Darnell, ...
ABSTRACT Alaska's North Slope has seen a resurgence of exploration activity following the discovery of the 429 MMBO Alpine Field (Jurassic Kingak Formation) in 1994 and resumption of leasing in the adjacent National Petroleum Reserve - Alaska (NPR-A) in 1999. ConocoPhillips and Anadarko Petroleum Corporation, the Alpine Field co-owners, have recently been the most active explorers in the NPR-A. Together they have announced oil or gas and condensate in eight wells that have penetrated Upper Jurassic reservoirs, including four flow tests. Much of the exploration success is a result of highresolution 3D seismic and the recognition of reservoir facies directly from that data, with an accompanying understanding of ancestral topography at the time of transgression. Sandstone reservoirs were locally deposited during transgression of an incised surface with as much as 200 feet of erosional relief. Traps are exclusively stratigraphic. Most of the reservoir facies in the discoveries appear to have been deposited in normal marine shoreface settings in areas of modest accommodation flanking erosional topography. Reservoir in the two Lookout wells is interpreted to have developed in a deep but relatively narrow incision. Reworking of proximal parts of the sandy siltstone substrate almost certainly provided some of the quartzose framework grains for the glauconitic reservoirs.
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.58)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock (0.36)
- North America > United States > Alaska > North Slope Basin > Western North Slope > Colville River Field > Alpine Field > Kingak Formation (0.99)
- North America > United States > Alaska > North Slope Basin > Prudhoe Bay Field (0.99)
- North America > United States > Alaska > North Slope Basin > Kuparuk River Field (0.99)
- (2 more...)
...seismometer (S/N 19614713) was chosen from among the three seismometers made Method available (see Acknowledgements). The 7.4GB SEG-Y file contained a total of 314,241 traces. These were The unit of a first-break pi...
...elft Method Non-Centrality Parameter - the difference between inlying and outlying population means Acknowledgements Thanks to James Thompson and Etienne Marc of FairfieldNodal who provided and arranged for permissio...
Summary Wide-azimuth, far-offset, refracted first breaks are too often eschewed as an alternative, redundant, inexpensive ocean-bottom seismic (OBS) positioning technology. I document their viability despite adverse bathymetry and anisotropy Introduction There are many ways to position Ocean Bottom Seismic (OBS) receivers. Dedicated, high-frequency, positioning acoustics are probably the most common way ... and the most expensive in time and equipment. Seismic airgun water-arrival, first break positioning lines are also possible. Extra time is required, but no extra equipment. Unfortunately, the first-break observable is much cruder than the dedicated acoustic observable and first-break picking delays are difficult to calibrate. Therefore, direct water-arrival first breaks are not the same as dedicated acoustics. A third technique is to use wide-azimuth, faroffset production seismic data. This is the cheapest way since no positioning lines are required. Vastly more data are available than in water-arrival first break positioning, so the statistics of large numbers make up for the coarse quality of the first-break observation. Because data are observed at all azimuths and offsets, picking delays are easily calibrated. Far-offset seismic data arrive through the water and also through one or more faster refractors. Therefore, refracted first breaks are subject to geological velocity gradients that must be calibrated. Is this the reason that refracted first-break OBS positioning has lost popularity since the 1990s? At the time of writing this paper FairfieldNodal were conducting a multi-client Ocean Bottom Node (OBN) survey in about 2200 meter depth in Walker Ridge in the Gulf of Mexico. OBNs in this survey have more than 300,000 source events in 12-second records. These copious data can be divided into multiple, mutually-exclusive, amply-populated zones (rings) to investigate the repeatability of a wide-azimuth, far-offset, first-break positioning algorithm that calibrates the velocity gradient in the refractors. This paper reports on that investigation.
- Geophysics > Time-Lapse Surveying > Time-Lapse Seismic Surveying (1.00)
- Geophysics > Seismic Surveying > Surface Seismic Acquisition > Marine Seismic Acquisition (1.00)
...rification of the general stability was run by means of PHASE2 ( Rocscience Inc.) code (Figure 12). ACKNOWLEDGEMENTS Slope stability was verified for more water level in the basin (empty, 520m, 548m and 560m a.s.l.),... for wet Our acknowledgements to ENEL (Electric Power and dry conditions of the rock-mass and taking also into Enterprise) for th...
ABSTRACT The Vagli arc-gravity dam (95.50m in high), in the Northern Apennines (Italy), was built in the early '50s of the last century. Its basin contains about 34Mm3 and is one of the largest hydroelectric basins in the peninsular, Italy. Early after the water in-filling, a large landslide developed on a slope of the basin. That resulted in a restriction, with the water level authorized only up 2/3 of the basin capacity. Recently, due to the increase of the petroleum costs and energy demand, a joint research program Universities-ENEL was established to overcome that restriction by verifying the real state of stability of that slope. The first step of the research was a detailed field geological, geostructural and geomechanical survey finalized to define the geological setting and the geomechanical model of the whole slope: the results showing a sub-horizontal setting of thin to thick bedded limestone and limestone with marls, with a thick debris cover. Seismic survey evidenced that near the surface rock-mass appear to be loosened for about a few tens of a meter. Critical analysis of the data from the monitoring performed in the last thirty years outlined movements in the order of about a few mm/y, which is in the range of a natural slope-dynamic. Critical field analysis and document reconstruction of the historical landslide points in favor of a large debris collapse due to the cut of a new road above the full-water-level. A decision was made to perform a full stability analysis of the whole slope according to the most recent geomechanical methods. The slope was analyzed by using a self-developed GIS tool suitable to apply the SMR and the Critical Equilibrium methods to each TIN-grid of the slope: it resulted into a generally stable but raveling slope, thus justifying the thick debris cover. The slope stability was also verified by means of numerical models, namely PHASE2 (ยฉ Rocscience Inc.): the slope resulted to be generically stable, but debris cover and loosened rock-mass appear to have a Stability Factor close to 1.3 in the slope segment between 500m and 600m above sea level. Here, some criticalities could grow up in the event of strong rainfall with water saturation of the slope or of a large earthquake. 1 INTRODUCTION The Vagli arc-gravity dam is 95.50m in height and was built in the early '50s of the XX century in the Edron creek Valley,Tuscany(Italy). Its basin contains about 34Mm3 and is one of the largest hydroelectric basins in the peninsularItaly. A first dam, 65.50m high, was built during theII World War(1941โ1946)and wasenlarged intheyear1952โ1953uptotheheightof95.50m. The Vagli Basin allowed a yearly electric power production of about 120GWh. Because the new basin top water level (560m a.s.l) resulted higher than the existing road, a new road was cut in the slope above (180m a.s.l) the top water level.
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Structural Geology > Tectonics > Plate Tectonics > Earthquake (0.90)
- Geology > Rock Type > Sedimentary Rock > Carbonate Rock (0.58)
...es Patent and SeisPAD . Number 5,545,858. . Results from a field test in California are presented. Acknowledgements Field Tests Thanks to Messers. Doty and Crawford for their great technical insight and contributio...
Conclusions In 1952 Doty and Crawford invented a Frequency Seismic information provided by each type of Modulated source - Vibroseis. It has proven a reliable sensor/receiver or geophone exhibits different technique. A new system has been developed which characteristics of amplitude and frequency. These impulse incorporates Frequency Modulated/Demodulated Receivers characteristics reveal information that characterize phase utilizing Interferometric techniques.
...nhancements thereof have been found to be very useful in delineating this boundary offshore Gabon. Acknowledgements Data source I wish to express my appreciation to Schlumberger for permitting me to show these data...
Summary The sedimentary basin found offshore Gabon is part of the West African salt basin; a prolific hydrocarbon province stretching along the west African coast from southern Angola to Equatorial Guinea. The formation of the West African salt basin, together with its Brazilian parallel is intimately linked with the early Cretaceous opening of the southern Atlantic Ocean. Gravity and magnetic data are a powerful and costeffective tool to define the tectonic framework of this rifted margin as well as to provide clues to the early Cretaceous syn-rift architecture. Introduction Gravity and magnetic data complement seismic data. Reflection seismic data (especially 2D data) images the shallower sediments effectively, but the presence of substantial salt associated with prolific oil provinces found offshore West Africa and Brazil reduces the sub-salt resolution of conventional reflection seismic data. An integrated gravity, magnetic and seismic interpretation will reduce ambiguities and result in an improved geological understanding.
- Geology > Sedimentary Basin (1.00)
- Geology > Structural Geology > Tectonics > Extensional Tectonics (0.40)
- Geophysics > Seismic Surveying (1.00)
- Geophysics > Magnetic Surveying (1.00)