Characterization of the Permo-Triassic upper Khuff reservoir, central Saudi Arabia: An integrated core plugs, petro-fabrics and mercury injection analysis

Abstract

The present work aims to characterize the reservoir properties of the upper Khuff Formation using integrated core plugs, petro-fabrics and Mercury injection analyses. A thirty four rock samples are picked up from the exposure of the upper Khuff Formation (Khuff A Member) at Al-Qassim province. These samples are subjected to a verity of laboratory measurements including core plugs, thin sections and mercury injection as matched with well log and crude oil analyses. Good porosity and permeability ranges (4–18% and 5–20 mD) are indicated, especially at the lower part with a uni-modal pore size distribution. The lithology is mainly dolomitic with minor limestone. Some fractures, cemented pores and dissolution process are indicated at the middle and upper parts of the section, respectively. Autopore-based mercury injection is performed to determine the volume of intrusion, touristy, pore size distribution and diameter. Total intrusion volumes of 0.352, 0.137 and 0.036 ml, threshold pressures of 127.44, 146.04 and 216.00 psi and tortuosities of 40.01, 75.19 and 60.26 are indicated for the analyzed samples, respectively. The results of the logging analyses are matched with the laboratory ones. Good hydrocarbons content is recognized in the middle part of the section. The analysis of crude oil sample indicates medium oil with high carbon content of 81.29 wt% and average specific gravity of 0.886 gm/cc. In conclusion, this integrated study indicates that the lower part of the Khuff A Member attains the best reservoir properties among the studied section.