Subsalt Depth Seismic Imaging and Structural Interpretation in Dumre Area, Albania.

Abstract : The challenge of seismic exploration in fold and thrust belt settings is to optimize the depth seismic images of the deep structural objectives beneath a complex overburden that may show strong horizontal and vertical velocity variations. In such areas, the seismic image is frequently of poor quality and the depth models of deep layers is often false due to the perturbed propagation of seismic energy through the deforming lens of the overlying layers. A range of seismic processing tools, including post-stack and pre-stack depth migrations, are appropriate to predict the accurate geometry of deep target structures and to improve the building of a depth structural model. A strong combination of geological reasoning and depth seismic imaging processing can improve the understanding of the deep geological structures by reducing the uncertainties in depth geometrical and velocity model estimation. We propose an interpretative and iterative approach to the post stack depth migration method to guide the interpreter in the development of a reliable subsurface model. We have applied this approach during an exploration study in the Dumre area, located in the Ionian Basin (Albania) which is a complex fold and thrust belt. The main objectives of this study were to understand the failure of a former exploration well and to propose a new location for the potential closure of the carbonate structure. This subsalt imaging study aims at illustrating the improvements obtained by application of this integrated seismic imaging method especially in the evaluation of a subthrust prospect in a tectonically complex belt setting.