TESSERAL 2-D

Short Description

Tesseral 2-D is the first commercially available PC-based full-wave modeling software package. You can easily simulate different seismic observation systems and build digital models of complex seismic-geological cross-sections. The Tesseral scheme calculates wave propagation in heterogeneous media faster and more precisely than ever before.

Tesseral 2-D uses an economic and reliable computation method, which is based on the finite-difference technique. This makes it possible to model very complex geological media - including a combination of solids and liquids - in a comparatively short time. In addition, during the development of the Tesseral scheme a multitude of computation problems inherent in wave equation numerical solutions were eliminated, and calculation flaws were considerably reduced.

Tesseral 2-D was designed for interactive analysis and verification of depth-velocity models. Integration with conventional seismic data processing and interpretation is straightforward. Model construction can be facilitated with the supplied data sets of rock physical properties that include correlations, lithology patterns, and a library of typical geological situations.

The main Possibilities, which are unique to the TESSERAL 2-D Package v.5.0.

1. Besides the creation of the conventional thick-layer models, the TESSERAL 2-D package offers the convenient possibilities of modeling the wave-field under conditions of thinly-bedded models, which are input with the help of the acoustic and density well log data for complex media.
(In absence of such well log data, the velocity model is formulated as a no homogenous, anisotropic layer model with velocity/density boundaries of arbitrary shape).
This allows monitoring the changes of signal shape, AVO curves, effective velocities, etc., which are caused by the thin-bed layers. The thin-layers, which, under the real-world range of seismic frequencies, leads to the phenomenon of quasianisotropy, can be augmented in Tesseral by the superimposition of several distinct systems of fractures, which brings the media to the orthorhombic or monoclinal system of assymetry. All of the layers in the quasianisotropic package can, in their turn, be anisotropic, with inclined axis of symmetry of anisotropy. Such packages exert a significant influence not only upon the velocities or the dynamic wave characteristics, but also lead to geometrical distortion of the discontinuities, positioned beneath these packages on the migrated seismic sections. This is conveniently analyzed with Tesseral, in particular by generating synthetic P- and S-wave VSP data for vertical and inclined wells.

For estimating such distortions, the package TESSERAL 2-D contains programs for pre-stack depth migration, allowing to obtain migrated sections both with and without the anisotropy correction. In many cases, the differences between such migrated sections are practically impossible to predict in advance.

2. It is possible to obtain undistorted migrated sections under conditions of abrupt lateral velocity changes, anisotropic thin-bed packages, scattering boundaries and formations, rugged relief of the recording surface, low velocity zones; for reflected and refracted waves, arising from the velocity gradient of the section, etc.

This is made possible by the functionality of migration with the Kirchhoff energy operator, contained in the package. There is a possibility of migration of the real data using the energy operator, computed inside the package.

3. A suite of post-stack and pre-stack time migration programs allows to evaluate the benefit of the more time-intensive depth migrations upon the quality of the final product, and thereby to formulate an economically justifiable processing flow for the actual field data. This is equally applicable to the other processing tools contained in the package, which can be used to process not only synthetic, but also real field data in SEG-Y or SDS-PC formats.

4. Special tools, developed in the package, allow estimating the distortions of the AVO curves, caused by the contacts of various thin-bed, anisotropic packages, complicated by the effects of inelastic absorption, boundary curvature, etc. It is also possible to estimate the influence of the overburden upon the AVO effect, measured at surface.

5. Special means of displaying the intermediate time slices of the wave-field during the computation process (animation of the wave-field propagation process) allow one to easily interpret complex wave-fields, and also to use the package for educational purposes.

A commercial version of the TESSERAL 2-D package has already been successfully used by geophysical organizations in the C.I.S., North America, Europe, China, Japan, and also at several universities in Europe and North America.

The track record has shown, that the TESSERAL 2-D package is a very useful tool for the geophysicist at all stages of work: from the planning of the data acquisition, to the modeling of delicate wave effects during the search for the oil and gas traps, using, in particular, the possibility of exploring the complex, thinly-bedded, and anisotropic media, the AVO-effect, etc.

With the assistance of the program you can model seismic gathers and sections

• For models of practically any type of complexity, including those with large lateral velocity changes, reflectors with arbitrary shapes, block-structured geology, complex ray path reflections such as from vertical borders, etc.

• In complex superficial conditions including those with dissected topography, large weathering variations, traps, permafrost, etc., demanding a correct account of the travel time characteristics and behavior of the surface waves, ghost waves, refractions etc.

• In conditions of thin-layered models originated from acoustic and density logging data.

• For transversely anisotropic medium, complicated by step dipping structure systems with inclined axis of symmetry, leads to a most complex 2D-type of monoclinic system of symmetry.

• For porous fluid-saturated media within the limits of Gassman's model

You can also obtain:

• AVO-curves in anisotropic porous fluid-saturated, absorbing thin-layered conditions of the media.
• AVO-curves for layers of irregular shapes upon changing vertical and lateral physical properties.
• Estimation of AVO-curves distortion due to near-surface heterogeneity.
• Estimation of absorbing properties of the thin-layered medium by modeling VSP gathers using acoustic logging data and then matching them with real VSP data.

The software package also include:

• Depth migration software system, including post-stack and pre-stack depth Kirchhoff migrations with vector wave equation Green's function calculation:

     * Adjustment of Migration operator on data properties.
     * Correction for Thin-layering.
     * Correction for anisotropy and topography.
     * Imaging of vertical boundaries.

• Time migration software system, including post-stack and pre-stack Kirchhoff migrations, DMO correction, CDP Velocity Analysis, etc.

•  VSP Migration

The package gives the opportunity to analyze wave field "Snapshots" and direct energy wave field used for complex wave fields' interpretation and training purposes.