Fracture Characterisation and Basement Reservoir Potential of Phra Wihan Formation in Southern Part of Uttaradit Province, Northern Thailand

Abstract

This research describes the characterization of fractures in the Mesozoic sandstones Phra Wihan Formation exposed at the southern part of Uttaradit province, Northern Thailand. Fracture characterization of outcrop analog is important to determine potential of subsurface reservoir. The methodology using field study and petrography analysis to determine the relationship of fractures and other structures such as bedding plane and fold geometry. In addition, microstructure analysis can be analoged to the potential of reservoir. The Phra Wihan Formation composed of thick quartz arenite sandstone laminated with mudstones. The structural architectures in study area are remarked by two open fracture sets with orthogonal relationship dominated in the fold limb. The first Set I, subdivided into Set Ia and Set Ib, developed in WNW-ESE direction perpendicular to the fold axial plane and parallel to the major compression stress. The second Set II, subdivided into Set IIa and Set IIb, developed in NNE-SSW direction parallel to the fold axial plane. These fractures imply to be associated with folding stage related to WNW-ESE compression stress during India-Eurasia collision.