Seismic horizon

C SEISMIC HORIZON - CADNA-OWIE 1. MOUNT ANNA SANDSTONE MEMfifeR FORMATION... 

Fig. 19. Seismic traverse along line B-B (see Fig. 21) illustrating the major seismic horizons and the high-amplitude zone caused by major calcite cementation in the Lower Namur Sandstone, Gidgealpa Field. Note the lateral variation in seismic character of the high-amplitude zone caused by variable carbonate cementation. Horizons C, top Cadna-Owie Formation P, top Permian (Toolachee Formation).

Automated Structural Interpretation Through Classification of Seismic Horizons... 

Classification tools are widely used in both 3D and 4D reservoir characterization, for example in mapping 3D structures, lithological properties and production effects [8]. In this work we extend the area of application of the classification methodology into automated interpretation of seismic horizons... 

A 3D seismic volume is represented by a cube S = S x,y,z) containing seismic amplitudes at each voxel position x,y,z), where x and y are positions in the two horizontal directions, measured in distance, and 2 is the position in the vertical dimension, measured in depth or two-way travel-time. The column S xq, yo, z) at position (xq, yo) is denoted a seismic trace. A seismic horizon is a piecewise continuous surface in 3D, consisting of positions 2 = g x, y) within the seismic volume. Throughout this work, seismic horizon segments are used as primitives for structural interpretation. Horizon interpretations are often placed on minimum, maximum or zero crossing events in the seismic cube, and are defined as piecewise continuous surfaces in 3D falling along these types of events. Minimum and maximum events in a seismic cube are commonly referred to as seismic extrema, and are chosen as the basis for the automated horizon interpretation presented in this paper. A set of seismic extrema can be described as a contour surface... 

The shape of the seismic signal along a specific seismic horizon is assumed to inhabit similar characteristics laterally. This results in similar values of the attributes along the extrema surface representing the horizon. Classification... 

Fig. 7. The figure compares an existing seismic horizon interpretation (left) with the corresponding interpretation obtained using extrema classification (center). White regions are fault zones void of horizon interpretation. The absolute value of the difference between the two interpretations (right) is mainly within 0.5 sample.

Fig. 8. A seismic horizon extracted using extrema classification is marked (dashed line) on a vertical cross section through the seismic cube.

Classification of seismic horizons, denoted extrema classification, has been described, and has proved valuable for mapping automatically seismic horizons in structurally complex regions. Furthermore, a new procedure for automatic fault displacement estimation across pre-interpreted fault surfaces is designed with the extrema classification as the core methodology. The performance of the extrema classification method has been illustrated through a set of real data examples. 

The main assumption of the presented methodology is that seismic horizons inhabit lateral similarities in seismic wave form. Similarities in signal wave form along horizons are revealed through classification of a set of wave form attributes, enabling grouping of horizon segments. This assumption... 

H.G. Borgos, T. Skov, and L. Spnneland (2004) Automated structural interpretation through classification of seismic horizons. This volume. 

There are different ways to measure the pull-down from seismic signals. One method is to cross-correlate the seismic signals between the seismic surveys, using only the signals from below the injected CO2 [2]. Also, direct interpretations of seismic horizons below the CO2 can be compared, as indicated in Figure 1. These two methods give the integrated time-delay, caused by total volume of injected CO. ... 

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