SEISMIC RESPONSE AND PROPERTIES OF NON-STRATABOUND DOLOSTONE RESERVOIRS: SCENARIO EVALUATION
J.G. Solum, K. Lauriks, A. Bistacchi, F. Storti, F. Balsamo, R. Swennen, M. Mozafari, C. Tueckmantel, C. Taberner, 2017. "SEISMIC RESPONSE AND PROPERTIES OF NON-STRATABOUND DOLOSTONE RESERVOIRS: SCENARIO EVALUATION", Characterization and Modeling of Carbonates–Mountjoy Symposium 1, Alex J. Macneil, Jeff Lonnee, Rachel Wood
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The aim of this study is to evaluate what seismic attributes are best able to highlight porous non-stratabound dolostone geobodies set in low porosity limestone. For this purpose three dolostone geobody volume scenarios were defined using outcrop based three-dimensional models to define the range of dimensions of dolostone geobodies and their association with particular fault populations. Three porosity scenarios were created using a global compilation to assign porosities to three lithologies: host limestone, bulk dolostone geobodies, and dolostone geobodies adjacent to faults. The combination of porosity and geobody volume scenarios yielded nine non-stratabound dolostone geobody scenarios. These include models in which the properties of near-fault dolostones were enhanced or degraded relative to the bulk dolostone geobody values. This allows for the effects of processes such as overdolomitization or dissolution to be implicitly explored, since those processes can degrade or enhance near-fault properties such as porosity, although in all scenarios dolostone porosities are greater than host limestone porosity.
Density and compressional velocity (Vp) were assigned to the scenarios based on a global compilation of the density, porosity, and Vp in limestones and dolostones to allow for the calculation of acoustic impedance volumes that are representative of the range of values that could exist at depth. Synthetic seismic cubes and a suite of 14 seismic attributes were generated for each of the nine dolostone scenarios. Each attribute response was evaluated for its potential to highlight porous non-stratabound dolostone geobodies. Attributes that are most sensitive to lateral changes in acoustic properties rank the highest in the evaluation, followed by amplitude attributes, followed in turn by frequency attributes. Continuity attributes rank poorly in this example because fault offset is relatively small and is obscured by dolomitization.