Understanding through Seeing - The role of Seismic in an Integrated Study of a Mature Nigerian Field

M. Hartung

The impact of integration of both data and disciplines is presented in the case of an Nigerian field, with particular emphasis on the central role of seismic data:

A pre-requisite for any seismic interpretation is a reliable well-to-seismic tie. Due to log data availability and quality, this match was only achieved by generating synthetic seismograms based on acoustic impedance models.

The seismic time interpretation was guided by the geological framework following sequence stratigraphical principles. Depth conversion and evaluation of volumetric uncertainties were based on all data. The resulting STOIIP estimates have been compared to the volumes derived independently from production data. it then became possible to explain apparent mismatches seen in some reservoirs by modifying the best-estimate volumes within the uncertainties and by comparison with analogue reservoirs

Channel-like amplitude features encountered in shallow reservoirs helped to explain variable production performance and consequently to identify appraisal and development opportunities. Some of the deeper, shoreface sands seem to behave in a more tank-like manner. This is not only confirmed by recent RST-logs, but also by seismic flatspots. The flatspots are conformable to structure and reflect the remaining oil distribution.

These results highlight the value of continuous integration of data and disciplines to the petroleum engineering study.

AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California