scholarly journals Tomographic inversion of reflection seismic amplitude data for velocity variation

1995 ◽  
Vol 123 (2) ◽  
pp. 355-372 ◽  
Author(s):  
Yanghua Wang ◽  
Gregory A. Houseman
Keyword(s):  
Velocity Variation ◽  
Tomographic Inversion ◽  
Reflection Seismic ◽  
Seismic Amplitude ◽  
Amplitude Data

Estimating tilted fracture weaknesses from azimuthal differences in seismic amplitude data

Geophysics ◽  
2020 ◽  
Vol 85 (3) ◽  
pp. R135-R146
Author(s):  
Huaizhen Chen ◽  
Tiansheng Chen ◽  
Kristopher A. Innanen
Keyword(s):  
Reflection Coefficient ◽  
Tilt Angle ◽  
Seismic Data ◽  
Fractured Reservoirs ◽  
Transverse Isotropy ◽  
Elastic Response ◽  
Moderate Degree ◽  
Fractured Reservoir ◽  
Seismic Amplitude ◽  
Amplitude Data

Tilted transverse isotropy (TTI) provides a useful model for the elastic response of a medium containing aligned fractures with a symmetry axis oriented obliquely in the vertical and horizontal coordinate directions. Robust methods for determining the TTI properties of a medium from seismic observations to characterize fractures are sought. Azimuthal differencing of seismic amplitude data produces quantities that are particularly sensitive to TTI properties. Based on the linear slip fracture model, we express the TTI stiffness matrix in terms of the normal and tangential fracture weaknesses. Perturbing stiffness parameters to simulate an interface separating an isotropic medium and a TTI medium, we derive a linearized P-to-P reflection coefficient expression in which the influence of tilt angle and fracture weaknesses separately emerge. We formulate a Bayesian inversion approach in which amplitude differences between seismic data along two azimuths, interpreted in terms of the reflection coefficient approximation, are used to determine fracture weaknesses and tilt angle. Tests with simulated data confirm that the unknown parameter vector involving fracture weakness and tilted fracture weaknesses is stably estimated from seismic data containing a moderate degree of additive Gaussian noise. The inversion approach is applied to a field surface seismic data acquired over a fractured reservoir; from it, interpretable tilted fracture weaknesses, consistent with expected reservoir geology, are obtained. We determine that our inversion approach and the established inversion workflow can produce the properties of systems of tilted fractures stably using azimuthal seismic amplitude differences, which may add important information for characterization of fractured reservoirs.

Seismic attributes and structural interpretation—it takes two to tango...

2012 ◽  
Vol 52 (1) ◽  
pp. 437 ◽  
Author(s):  
Guillaume Backé ◽  
Ernest Swierczek ◽  
Justin MacDonald ◽  
Adam Bailey ◽  
David Tassone ◽  
...  
Keyword(s):  
Structural Information ◽  
Median Filter ◽  
Seismic Attributes ◽  
3D Seismic ◽  
Seismic Amplitude ◽  
The North ◽  
Amplitude Data ◽  
Fracture Models ◽  
Processing Techniques

In this paper, different 3D seismic attributes calculated to improve the accuracy and robustness of structural interpretations in several energy-rich Australian basins are compared. Detailed and precise fault and fracture maps are crucial not only for initial petroleum play assessment, but also for fault seal analysis and reservoir integrity studies. Robust fault and fracture models are also needed to improve the design of reservoir simulation programs and to manage the long-term containment of gas in geological formations. Different attributes (including coherency, dip-steered similarity, dip-steered median filter, dip-steered variance, apparent dip, and dip-steered most-positive and most-negative curvatures) from an array of 3D seismic datasets to better image structural fabrics, such as normal and different fractures patterns, in the North Perth, Cooper, Ceduna, Otway and Gippsland basins have been calculated. The results provide a remarkable improvement in the quality and precision of structural maps using this multi-attribute mapping workflow by comparison with more conventional maps produced, solely using seismic amplitude data. The key to the successful application of multi-attribute structural analysis, however, remains with the ability of the interpreter to identify meaningful structural information from a large volume of data. Thus, the structural expertise of the interpreter remains as the cornerstone to making geological sense of the various seismic processing techniques available.

Implications of the Fresnel-zone texture for seismic amplitude interpretation

Geophysics ◽  
2012 ◽  
Vol 77 (4) ◽  
pp. O35-O44 ◽  
Author(s):  
Dengliang Gao
Keyword(s):  
Spectral Decomposition ◽  
Frequency Tuning ◽  
Fresnel Zone ◽  
Single Point ◽  
Rock Properties ◽  
Reflection Seismic ◽  
Seismic Amplitude ◽  
Convolution Algorithm ◽  
Convolution Model ◽  
Textural Anisotropy

The 3D reflection seismic response is associated with a zone (the Fresnel zone), rather than with a single point used in the idealized 1D convolution model. Unlike a point of incidence, the Fresnel zone is complicated by its textural characters that are defined by the dip and azimuth of microreflectors in the zone. The Fresnel-zone texture makes seismic amplitude interpretation more complicated than previously documented. A conceptual model suggests that seismic amplitude variations with offset (AVO), azimuth (AVAz), and frequency (spectral decomposition) were physically related to textural roughness, textural anisotropy, and textural scale of the Fresnel zone, respectively. Textural roughness is defined by the dip deviation of microreflectors and contributes to the AVO intercept and gradient. Textural anisotropy is defined by the degree of the preferred orientation of the microreflectors and directly affects the AVAz signature. Textural scale is defined by the spacing of the microreflectors and controls the selective frequency tuning in spectral decomposition data. The Fresnel-zone texture gives rise to amplitude variations that can not be accurately modeled by using a 1D reflectivity-wavelet convolution algorithm, and thus poses challenges to the reliability of many previous predictions of rock properties and thickness from amplitude. The AVO, AVAz, and spectral decomposition data should be used to characterize Fresnel-zone texture for predicting depositional facies, deformational fabrics, and hydraulic properties in the subsurface.

Amplitude map analysis using forward modeling in sandstone and carbonate reservoirs

Geophysics ◽  
1993 ◽  
Vol 58 (10) ◽  
pp. 1428-1441 ◽  
Author(s):  
Dennis B. Neff
Keyword(s):  
Tuning Curve ◽  
Forward Modeling ◽  
Carbonate Reservoirs ◽  
Model Type ◽  
Seismic Amplitude ◽  
Modeling Process ◽  
Fluid Saturation ◽  
Amplitude Data ◽  
Map Analysis ◽  
Amplitude Versus

The extent to which seismic amplitude maps can contribute to the analysis of hydrocarbon reservoirs was investigated for clastic and carbonate reservoirs worldwide. By using a petrophysical‐based, forward modeling process called incremental pay thickness (IPT) modeling, five lithology types were quantitatively analyzed for the interplay of seismic amplitude versus lithology, porosity, hydrocarbon pore fluid saturation, bedding geometries, and reservoir thickness. The studies identified three common tuning curve shapes (concave, convex, and bilinear) that were primarily dependent upon the lithology model type and the average net porosity therein. While the reliability of pay and porosity predictions from amplitude maps varied for each model type, all analyses showed a limited thickness range for which amplitude data could successfully predict net porosity thickness or hydrocarbon pore volume. The investigation showed that systematic forward modeling is required before amplitude maps can be properly interpreted.

Techniques and best practices in multiattribute display

2015 ◽  
Vol 3 (1) ◽  
pp. B1-B23 ◽  
Author(s):  
Kurt J. Marfurt
Keyword(s):  
Central Basin ◽  
Seismic Amplitude ◽  
West Texas ◽  
3D Data ◽  
Amplitude Data ◽  
Data Volume ◽  
Similar Images ◽  
True Color ◽  
Central Basin Platform ◽  
Display Technique

All color monitors display images by mixing red, green, and blue (RGB) components. These RGB components can be defined mathematically in terms of hue, lightness, and saturation (HLS) components. A fourth alpha-blending (also called opacity) component provides a means to corender multiple images. Most, but not all, modern commercial interpretation workstation software vendors provide multiattribute display tools using an opacity model. A smaller subset of vendors provide tools to interactively display two or three attributes using HLS, CMY, and RGB color models. I evaluated a technique (or trick) to simulate the HLS color model using monochromatic color bars and only opacity. This same trick only approximates true color blending of RGB or CMY components. There are three basic objectives in choosing which attributes to display together. The first objective is to understand the correlation of one attribute to another, and most commonly, of a given attribute to the original seismic amplitude data. The second objective is to visualize the confidence or relevance of a given attribute by modulating it with a second attribute. The third objective is to provide a more integrated image of the seismic data volume by choosing attributes that are mathematically independent but correlated through the underlying geology. I developed the interpretation value of the HLS display technique on a 3D data volume acquired over the Central Basin Platform of west Texas exhibiting faults, fractures, folds, channels, pinch outs, and karst features. To be a useful “technique,” I need to demonstrate these workflows within a specific package. Although I implemented the workflow in Petrel 2014, similar images can be generated using any software with flexible opacity capabilities. I also developed a short list of attribute combinations that are particularly amenable to corendering in HLS.

Resolving subtle stratigraphic features using spectral ridges and phase residues

2013 ◽  
Vol 1 (1) ◽  
pp. SA93-SA108 ◽  
Author(s):  
Oswaldo Davogustto ◽  
Marcílio Castro de Matos ◽  
Carlos Cabarcas ◽  
Toan Dao ◽  
Kurt J. Marfurt
Keyword(s):  
Seismic Data ◽  
Thin Layers ◽  
Earth Model ◽  
Well Log ◽  
Anadarko Basin ◽  
Seismic Amplitude ◽  
West Texas ◽  
Amplitude Data ◽  
Using Data ◽  
Extract Information

Seismic interpretation is dependent on the quality and resolution of seismic data. Unfortunately, seismic amplitude data are often insufficient for detailed sequence stratigraphy interpretation. We reviewed a method to derive high-resolution seismic attributes based upon complex continuous wavelet transform pseudodeconvolution (PD) and phase-residue techniques. The PD method is based upon an assumption of a blocky earth model that allowed us to increase the frequency content of seismic data that, for our data, better matched the well log control. The phase-residue technique allowed us to extract information not only from thin layers but also from interference patterns such as unconformities from the seismic amplitude data. Using data from a West Texas carbonate environment, we found out how PD can be used not only to improve the seismic well ties but also to provide sharper sequence terminations. Using data from an Anadarko Basin clastic environment, we discovered how phase residues delineate incised valleys seen on the well logs that are difficult to see on vertical slices through the original seismic amplitude.

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