The following abstract
has been submitted to the SEG for a talk at the 2009 convention. If
accepted, you can hear the whole talk/presentation there:

Using Horizon Binning and
2D

Summary

Horizon Binning and
2D

Introduction

After identifying an amplitude, AVO or other attribute anomaly, it is normal
to ask the question, “Does it fit structure?” Many anomalies can be
judged to “fit structure,” by inspection. In other cases, the fit might
be more tenuous, more debatable or simple corrupted by noise. In the less
straight-forward cases, it is helpful to have a set of tools to make simple
reproducible measurements.

The purpose of both Horizon
Binning and 2D

Horizon Binning calculation

Horizon Binning is a
method of accumulating statistics as a function of structure, either time or
depth (the “Z” value). This is a horizon based calculation that requires
a fully interpreted horizon that contains both Z values and an extracted
horizon based attribute. Typical horizon based attributes might be the
maximum instantaneous amplitude near the picked event, RMS over a short window
or simply maximum negative trough amplitude. In the area of an anomaly of
interest, an enclosing polygon must be selected that encompasses both the
anomaly and a corresponding down-dip water-leg region. A sequence of bins
is constructed that covers the Z-range of the data. Within each Z-bin,
corresponding attribute values are collected. For each bin, the mean and
standard deviation are computed and then graphed (see Figure 1). In the
graph of Figure 1, down-structure is to the right (increasing Z). The
transition from the water-leg to the hydrocarbon-leg is seen as a step
function, in this example plot.

2D

2D GrAZ is a method of
determining whether changes in the derived horizon attribute change abruptly in
the up-dip direction, at a specific Z value and, hopefully, due to a fluid
contact. To make this determination, the gradients of both the
interpreted Z values and of the extracted attributes are computed in 2D.
This produces 2 gradient vectors at each horizon grid location. A dot
product is formed using both vectors. The dot product can be put through a
Horizon Binning process to make a graph like the one seen in Figure 2, or can
be mapped directly, as shown in the example of Figure 3.

2D

Figure 2: In an 2D |

Figure 3: A 2D |

Water-leg and
size of the polygon area

Both Horizon Binning
and 2D

Conclusions

Horizon Binning and
2D

Acknowledgements

The author would
like to thank OpenSpirit Corporation for permission to use the data analyzed in
Figure 3.