Schlumberger

Survey Matching

Types of matching used in time-lapse 4D processing

The degree to which matching is required generally depends upon how well the acquisition has been repeated from one survey to the next. Variability within or between datasets should, where possible, be compensated by appropriate processing algorithms, rather than by survey matching.

Deterministic matching

Determinisitic matching is often used to normalize the wavelet for surveys that used different acquisition configuration. A common reference wavelet is defined, and filters created that match the farfield signatures of each survey to the reference. This can be performed in an angular-dependent fashion, if required.

Global matching

Uses a single statistically-computed matching operator to cause one survey to better match another in amplitude, phase, and timing. The operator may be frequency invariant or vary with frequency.

Low frequency specific matching

Schlumberger low-frequency specific matching addresses the issue of residual bubble energy generated by the source array. Applied as a frequency-variant global or local operator, the process matches one survey to another over the bandwidth affected by the residual bubble. All other frequencies are left untouched, minimizing the chances of affecting the time-lapse signal.

Signal-only matching

Standard matching algorithms assume that the datasets to be matched have consistent signal-to-noise ratio. Where this is not the case, the matching operation will not correctly normalize the datasets. We have implemented signal-only global matching and signal-only constrained cross-equalization algorithms to help overcome this problem

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