Interpretive advantages of 90°-phase wavelets: Part 2 — Seismic applications

Geophysics ◽  
2005 ◽  
Vol 70 (3) ◽  
pp. C17-C24 ◽  
Author(s):  
Hongliu Zeng ◽  
Milo M. Backus
Keyword(s):  
Seismic Data ◽  
High Frequency ◽  
Seismic Modeling ◽  
Permian Basin ◽  
Seismic Amplitude ◽  
Depositional Systems ◽  
Phase Data ◽  
Dual Polarity ◽  
Gulf Of Mexico Basin ◽  
Zero Phase

We examine field seismic data to test the benefits of 90°-phase wavelets in thin-bed interpretation that are predicted by seismic modeling in part 1 of this paper. In an interbedded sandstone-shale Miocene succession in the Gulf of Mexico basin, a 90°-phase shift of nearly zero-phase seismic data significantly improves lithologic and stratigraphic interpretation. A match between seismic and acoustic impedance (AI) profiles results in a better tie between seismic amplitude traces and lithology-indicative logs. Better geometric imaging of AI units that does not use dual-polarity seismic events results in easier and more accurate reservoir delineation. Less amplitude distortion and the stratigraphy-independent nature of thin-bed interference significantly improves stratigraphic resolution and seismic stratigraphic profiling. For a Ricker-like wavelet having small side lobes, stratigraphic resolution of 90°-phase data is considerably higher than that of zero-phase data. In this specific case, stratigraphic resolution of 90°-phase data is λ/4 (λ = wavelength), compared with λ/2 for its zero-phase counterpart. Stratal slices made from 90°-phase data show geomorphologic patterns of depositional systems with less noise and fewer interference fingerprints. A Permian Basin field provides a real-world example of porous zones in thin, high-frequency carbonate sequences that are better visualized with 90°-phase seismic data than with zero-phase data.

Interpretive advantages of 90°-phase wavelets: Part 1 — Modeling

Geophysics ◽  
2005 ◽  
Vol 70 (3) ◽  
pp. C7-C15 ◽  
Author(s):  
Hongliu Zeng ◽  
Milo M. Backus
Keyword(s):  
Seismic Data ◽  
High Frequency ◽  
Thick Layer ◽  
Amplitude Data ◽  
Frequency Components ◽  
Wireline Logs ◽  
Phase Data ◽  
Dual Polarity ◽  
Seismic Models ◽  
Zero Phase

We discuss, in a two-part article, the benefits of 90°-phase wavelets in stratigraphic and lithologic interpretation of seismically thin beds. In Part 1, seismic models of Ricker wavelets with selected phases are constructed to assess interpretability of composite waveforms in increasingly complex geologic settings. Although superior for single surface and thick-layer interpretation, zero-phase seismic data are not optimal for interpreting beds thinner than a wavelength because their antisymmetric thin-bed responses tie to the reflectivity series rather than to impedance logs. Nonsymmetrical wavelets (e.g., minimum-phase wavelets) are generally not recommended for interpretation because their asymmetric composite waveforms have large side lobes. Integrated zero-phase traces are also less desirable because they lose high-frequency components in the integration process. However, the application of 90°-phase data consistently improves seismic interpretability. The unique symmetry of 90°-phase thin-bed response eliminates the dual polarity of thin-bed responses, resulting in better imagery of thin-bed geometry, impedance profiles, lithology, and stratigraphy. Less amplitude distortion and less stratigraphy-independent, thin-bed interference lead to more accurate acoustic impedance estimation from amplitude data and a better tie of seismic traces to lithology-indicative wireline logs. Field data applications are presented in part 2 of this article.

Modeling dolomitized carbonate‐ramp reservoirs: A case study of the Seminole San Andres unit—Part II, Seismic modeling, reservoir geostatistics, and reservoir simulation

Geophysics ◽  
1998 ◽  
Vol 63 (6) ◽  
pp. 1876-1884 ◽  
Author(s):  
Fred P. Wang ◽  
Jiachun Dai ◽  
Charles Kerans
Keyword(s):  
Reservoir Simulation ◽  
Seismic Data ◽  
High Frequency ◽  
Block Size ◽  
Synthetic Seismograms ◽  
Carbonate Ramp ◽  
High Porosity ◽  
Seismic Modeling ◽  
Rock Fabric ◽  
Seismic Resolution

In part I of this paper, we discussed the rock‐fabric/petrophysical classes for dolomitized carbonate‐ramp rocks, the effects of rock fabric and pore type on petrophysical properties, petrophysical models for analyzing wireline logs, the critical scales for defining geologic framework, and 3-D geologic modeling. Part II focuses on geophysical and engineering characterizations, including seismic modeling, reservoir geostatistics, stochastic modeling, and reservoir simulation. Synthetic seismograms of 30 to 200 Hz were generated to study the level of seismic resolution required to capture the high‐frequency geologic features in dolomitized carbonate‐ramp reservoirs. At frequencies <70 Hz, neither the high‐frequency cycles nor the rock‐fabric units can be identified in seismic data because the tuning thickness of seismic data is much greater than the average thickness of high‐frequency cycles of 6 m. At frequencies >100 Hz, major high‐porosity and dense mudstone units can be better differentiated, while the rock‐fabric units within high‐frequency cycles can be captured at frequencies higher than 200 Hz. Seismic inversion was performed on the 30- to 200-Hz synthetic seismograms to investigate the level of seismic resolution required to recover the high‐resolution inverted impedance logs. When seismic data were noise free, wavelets were known and sampling rates were high; deconvolution techniques yielded perfect inversion results. When the seismic data were noisy, the inverted reflectivity profiles were poor and complicated by numerous high‐frequency spikes, which can be significantly removed using the moving averaging techniques. When wavelets were not known, the predictive deconvolution gave satisfactory inversion results. These results suggest that interwell information required for reservoir characterization can be recovered from low‐frequency seismic data by inversion. Outcrop data were collected to investigate effects of sampling interval and scale‐up of block size on geostatistical parameters. Semivariogram analysis of outcrop data showed that the sill of log permeability decreases and the correlation length increases with an increase of horizontal block size. Permeability models were generated using conventional linear interpolation, stochastic realizations without stratigraphic constraints, and stochastic realizations with stratigraphic constraints. The stratigraphic feature of upward‐shoaling sequences can be modeled in stochastic realizations constrained by the high‐frequency cycles and rock‐fabric flow units. Simulations of a fine‐scale Lawyer Canyon outcrop model were used to study the factors affecting waterflooding performance. Simulation results show that waterflooding performance depends strongly on the geometry and stacking pattern of the rock‐fabric units and on the location of production and injection wells.

Permian Basin seismic data reprocessing: A case study

2017 ◽  
Author(s):  
Yan Yan ◽  
Xianhuai Zhu ◽  
Junru Jiao ◽  
Pan Deng ◽  
Bin Yang ◽  
...  
Keyword(s):  
Seismic Data ◽  
Permian Basin

scholarly journals Seismic modeling of two depositional systems

1994 ◽  
Vol 37 (5) ◽  
Author(s):  
G. Brancolini ◽  
G. Casula ◽  
C. De Cillia ◽  
A. Manzella ◽  
A. Polonia ◽  
...  
Keyword(s):  
Flood Plain ◽  
Alluvial Plain ◽  
Elastic Plane ◽  
Seismic Modeling ◽  
Accurate Analysis ◽  
2D Modeling ◽  
Fluid Content ◽  
Wave Velocities ◽  
Full Wave ◽  
Depositional Systems

Two ideal lithologic sections representing a tidal bar system and a fluvial complex were drawn in order to run seismic modeling programs developed by OGS on behalf of the European Community. The simulations allowed an accurate analysis of the seismic expressions of the two sections. The tidal bar system is formed by a number of sandstone lenses interlayered with siltstone and mudstone deposits. These lenses meet together on an erosion surface, while they thin and vanish in the other direction. The fluvial complex is fonned by a limestone basement overlain by coarse alluvial plain sediments which in turn are transgressed by finer flood plain sediments, including sandstone lenses stacking towards the top in a meandering belt. These lithofacies associations represent potential multi-pool reservoirs in which the mudstone layers constitute the plugs. As a function of the granulometric and depositional features of each lithological unit, together with fluid content, wave velocities and densities were evaluated. A 2D modeling for elastic plane wave propagation in these hypothesized geologic sections was run on a Cray supercomputer. The numerical scheme is based on solving the full wave equation by pseudospectral methods.

A 108km2 Compressive Sensing Processing Trial

2021 ◽  
Author(s):  
Dustin Blymyer ◽  
Klaas Koster ◽  
Graeme Warren
Keyword(s):  
Compressive Sensing ◽  
Surface Waves ◽  
Seismic Data ◽  
High Frequency ◽  
Quality Data ◽  
Low Velocity ◽  
Conventional Design ◽  
Seismic Acquisition ◽  
Similar Cost ◽  
Station Density

Abstract Summary Compressive sensing (CS) of seismic data is a new style of seismic acquisition whereby the data are recorded on a pseudorandom grid rather than along densely sampled lines in a conventional design. A CS design with a similar station density will generally yield better quality data at a similar cost compared to a conventional design, whereas a CS design with a lower station density will reduce costs while retaining quality. Previous authors (Mosher, 2014) have shown good results from CS surveys using proprietary methods for the design and processing. In this paper we show results obtained using commercially available services based on published algorithms (Lopez, 2016). This is a necessary requirement for adoption of CS by our industry. This report documents the results of a 108km2 CS acquisition and processing trial. The acquisition and processing were specifically designed to establish whether CS can be used for suppression of backscattered, low velocity, high frequency surface waves. We demonstrate that CS data can be reconstructed by a commercial contractor and that the suppression of backscattered surface waves is improved by using CS receiver gathers reconstructed to a dense shot grid. We also show that CS acquisition is a reliable alternative to conventional acquisition from which high-quality subsurface images can be formed.

Analysis of Gravity-Flow Depositional Systems From 3-D Seismic Data: Neogene Deposits of the Niger Delta Slope

1999 ◽  
pp. 3-20
Author(s):  
John M. Armentrout ◽  
Katherine A. Kanschat ◽  
Kristian E. Meisling ◽  
Jerome J. Tsakma ◽  
Lisa Antrim ◽  
...  
Keyword(s):  
Seismic Data ◽  
Niger Delta ◽  
Gravity Flow ◽  
Depositional Systems ◽  
Delta Slope
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