Analysis of fold and fault-related fracture systems development using image logs at Asmari Formation in the Rag Sefid Anticline, SW Iran

Abstract

Image logs of 13 wells in the Rag Sefid Anticline show two systems of fractures developed under two deformation phase in the Dezful Embayment. This deformation phases are folding resulted from Zagros NE contraction and reactivation of the basement fault rotated the fold axial trace within the Hendijan-Izeh fault zone. Folding phase comprises four sets of fractures, which include axial and cross axial sets that trend parallel and perpendicular to the fold axial trace, respectively and two oblique sets that trend at moderate angles to the axial trace in the eastern part of the fold. Reactivation of the Hendijan-Izeh Fault has caused the restraining bend and dextral shear zone in the western part of the Rag Sefid Anticline. This dextral shear has produced three fracture sets which include two sets of Riedel shear fractures and an extensional set. The mean shortening directions measured from the fold and fault related fracture systems in the eastern and western parts of Rag Sefid Anticline are N022±2° and N064±1°, respectively. The measured NNE and ENE shortening orientations in the well sites is consistent with maximum horizontal stress orientations derived from earthquake focal mechanism solutions.