Correlation of the reservoir characteristics from the well-logging data and core measurements in QASR field, north Western Desert, Egypt

Abstract

Petrophysical well-logging data and core measurements were integrated in order to assess the Lower Safa reservoir characteristics of the QASR gas field, northern part of the Western Desert, Egypt. The study mainly depends on the relation between the core and log data of the hydrocarbon-bearing reservoir Jurassic (Lower Safa) using four productive wells QASR-3, QASR-5, QASR-6, and QASR-12; the linear regression is then used to establish a respective relationship between core and log data to estimate some of the reservoir parameters such as permeability (K), porosity (Φ), shale volume (Sh), clay content (Vcl), and fluid saturation (Sf), which are variables that determine reservoir quality. Average permeability values of the reservoir was found to be above 100 md, while porosity values ranged between 10 and 15%, reflecting well-sorted coarse grained sandstone reservoirs with minimal cementation, indicating very excellent reservoir quality. Low water saturation (10–30%) in the Lower Safa reservoir of the QASR wells indicated that the proportion of void spaces occupied by water is low, thus, showing high hydrocarbon saturation. Quantitative porosity fulfillment using regression equations revealed significant similarity in the porosity values obtained from petrophysical well logs and core data. Plots on scatter diagrams using porosity values derived from both core and log data of the Lower Safa reservoir reflecting good linear relationships. Plots of values of water saturation derived from core analysis and that from petrophysical log for the Lower Safa reservoir also showed linear trends. Porosity against permeability plots represents a linear relationship between both variables in Lower Safa reservoir, indicating that Lower Safa reservoir are permeable and have pores that are strongly communicated. The petrophysical properties of the Lower Safa reservoir in the QASR field are sufficient to permit hydrocarbon production.