‘Salt Window’ Prediction: A New Frontier Technology Applied in Gabon Albian Carbonate Exploration

Abstract

‘Salt window’ forms when salt completely removed by viscous flow and dissolution. It’s the key for the pre-salt HC migrated to post-salt carbonate in South Gabon basin. The failure wells indicate that 50 m thin salt can prevent pre-salt HC migration, but cannot be picked on seismic profile because of the resolution. Considering no more study about how to identify ‘salt window’, the prediction for ‘salt window’ would be a great challenge for the post-salt carbonate prospect evaluation.

Based on RTM seismic volume, the study start from the interpretation of thin salt according to the reflection characters and identify potential ‘salt welds’. Then the comparing between forward modeling and seismic profile define different amplitude and frequency characters for top salt reflection. A new AFR attribute is designed to indicate the thin salt variance below seismic resolution within the potential ‘salt welds’, and helped to pick ‘salt windows’ inside. Finally, based on Petrel 3D structure model, the study find out migration faults which connect the ‘salt window’ and carbonate reservoir, that helps us better understanding for the petroleum pattern and evaluation for post-salt carbonate prospect.