A transpressional model for deformation patterns in northern part of dezful Embayment's oil fields in Zagros (Iran), using geo-information technologies

Abstract

The Dezful Embayment Zone (DEZ) is a discrete structural unit hosting predominant oil fields in the Zagros Mountains. The northern part of the DEZ has been studied using Geo-information Techniques (GiT) to ascertain the role of surface and subsurface deformation patterns forming traps for oil fields in the region. The surface structures and outcropped rock types were studied using remote sensing techniques and detailed field investigations. Also, the subsurface studies are consist of: a) preparation of iso-potential surface maps from underground contour (UGC) maps and their 3D-sketches; b) preparation of 3D-perspectives from field surveying data and 2D seismic studies; c) the compilation of three cross sections; and d) compilation of a basement and aeromagnetic maps. The results of the subsurface and surface investigations revealed that activity along subsurface NW-SE orientated thrust faults caused to folding of sedimentary cover as fault related folding and then, the accumulation of hydrocarbons were taken placed in these structures in DEZ. Movement along these faults resulted in the forming of a network of braided pattern of elliptical shaped anticlinal oilfields with structural blocks at different depths. Thus, the thrust faults controlled the position, elliptical form and elevation of anticlines in the northern part of the DEZ. Finally, a complex consecutive transpressiontranstensional model, due to a shear regime, is proposed for the deformation pattern in the region. Whereas, the structural pattern of the southern part of the DEZ is a simple discrete folding and coeval thrusts which forming anticlinal oil traps at similar depths.