# Mapping irregularly spaced data

Series Geophysical References Series Problems in Exploration Seismology and their Solutions Lloyd P. Geldart and Robert E. Sheriff 10 367 - 414 http://dx.doi.org/10.1190/1.9781560801733 ISBN 9781560801153 SEG Online Store

## Problem 10.9a

Figure 10.9a is the result of map-migrating Figure 10.9b, which shows the lines of seismic control marked by diagonal dashes. The map shows a high on a north plunging, anticlinal nose. What additional program would you recommend to check weaknesses in the interpretation before recommending a well to test for hydrocarbon accumulation?

### Background

In map migration, observed traveltimes to a reflector are mapped along seismic lines and contoured. The contoured surface is then gridded into bins, each bin is migrated, and the result is contoured to yield the migrated map. Migration is discussed further in problem 9.27 (see also Sheriff and Geldart, 1995, section 9.12 for more details).

### Solution

Figure 10.9b shows that there is relatively little control on the structure except on the east flank, so appreciable additional seismic work is required before a well location can be selected.

Most of the seismic lines in Figure 10.9a, except for those on the east flank apparently show little structural dip, so the structural picture must be inferred from jump correlations between seismic lines. Jump correlation is highly suspect as faults or dip can also explain the situation even if the correlations are reliable.

In particular, there is little evidence of south dip except that inferred from correlation between disconnected seismic lines. Consequently, a N25${\displaystyle ^{\circ }}$E line connecting the two mapped high closures is called for and it should extend far enough north to confirm north dip as well as south dip. There is little control directly over the central high, and the absence of mapped faults in this region may be a consequence of this poor control. At least one east-west line across the high is required. Based on the results of these two lines, additional lines will probably be required.