The study aimed to combine the different available data to understand the subsurface system and the characteristic of reservoirs in Asala Field to represent the vertical and lateral heterogeneity at the well, multi-well and field scale, which could be used as a tool for reservoir management. Seismic interpretation was conducted on the seismic sections that concerned the study area to make a detailed structural interpretation to determine the structural geometry of the horizons. Petro-physical well log analysis of the reservoir rock of Lower and Middle zones of Abu Roash "G" member has been done and mapped. The estimated volume of original hydrocarbon in place of Lower and Middle zones of Abu Roash "G" member has been calculated.