Traditionally interpretation of geological structures from seismic data in 2D and 3D have been validated through structural balancing techniques as a final stage, if at all. Structural modeling at this stage leads to inefficient iterations or to structural inconsistencies passing through to volume and reservoir models. This paper outlines a new technique for structurally validating geological models evolved from seismic data as an integral part of the interpretation process, drawing examples from an area of active exploration offshore Cabinda, Africa.

The technique involves combining the use of standard seismic interpretation and structural modeling software. The first stage in the process is to interpret the structural framework of the faults. The faults are picked in the interpretation software and their 3D relationships are examined in the modeling software. If any problems in the interpretation are highlighted the picks are re-examined in the interpretation software.

Once a satisfactory fault network has been produced the stratigraphic horizons can be interpreted. The markers are picked on a fault block by fault block basis. As each horizon fault block interpretation is completed, the surfaces are validated in the modeling software. The techniques available for validation include both kinematic (move-on-fault) and non-kinematic (jigsaw fitting) types of restoration.

Using examples from offshore Cabinda we will show how this methodology has helped in imaging strike-slip faults, extensional faults and their associated tip structures, branch lines, splays and transfer faults together with the footwall and hangingwall deformation related to these features. In addition we will highlight how this method, when applied correctly, can help in imaging structures in areas where the seismic data quality is poor.

The technique produces an improved structural model within the timeframe of a standard project and hence reduces technical risk.

AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas