Petro-Ed

presents

THE CONSEQUENCES OF ACQUISITION AND
PROCESSING ON SEISMIC DATA INTERPRETATION

Duration: 2 days

Designed for: This course will present an integrated approach to acquisition and processing and will be of great interest and benefit to all geophysicists whatever their area of specialization or experience. The course will also be of benefit to geologists who have a good understanding of seismic field acquisition and processing methods.

Seismic signal amplitude is a fundamental parameter in the modern seismic process. Essentially the visible parameter, it is also potentially the most misleading. Seismic amplitude is the platform for all mapping, both structural and stratigraphic. However, amplitude is often misinterpreted when the effects of acquisition and processing are not recognised or corrected.

Traditional approaches to acquisition and processing involve numerous routine assumptions. These assumptions are critical to the interpretation process and it is essential that their implications and consequences are examined if pitfalls are to be avoided. It follows that some sense of why seismic might fail, or, why we might presume that it is correct, is also necessary.

The traditional acquisition approaches focus on noise reduction with the use of arrays. These are not perfect in that they also filter the signal. Traditional processing has a dual role, namely, eliminate the residual noise and repair the signal. It is too late, the damage is already done.

The ideas of Anstey (1987) led to a better understanding of acquisition. He advocated "Designing on the signal" and was followed by Ongkiehong (1988) who demonstrated that controlled spatial aliasing of the noise resulted in improved signal to noise enhancement in f-k space. This produced better pre-stack data with immediate benefits for velocity, statics, deconvolution and AVO purposes.

These approaches were limited to 2D data sets and were pushed aside with the surge of seismic 3D activity. Vermeer who had earlier advocated 2D symmetrical sampling (1990) demonstrated in 1998 that 3D symmetrical sampling was practical with the Cross Spread gather, paving the way for the application of f-k-k filters in 3D volumes for enhanced signal to noise in the pre-stack domain.