Petrographic charcaterization of microporosity in the organic-rich carbonate Hanifa Formation, Jafurah Basin, Saudi Arabia

Abstract

A comprehensive petrographic characterization has been conducted on the microporosity of the organic-rich carbonate Hanifa Formation in Jafurah Basin, Saudi Arabia. Hanfia Formation composed of organic-rich muddy limestone with more than 90 % carbonate minerals content. Based on XRD analysis, the investigated samples are consisting of calcite (87 wt.%), anhydrite (9 wt.%) and less than 1 wt.% of quartz, illite, pyrite and dolomite. Total organic carbon reaches up to 5.46 wt. % and yielding Kerogen (S2) 5.09 mg/g rock, while the free hydrocarbon content (S1) is 5.36 mg/g rock. The kerogen type is type II and the thermal maturity index is 1.28. Based on the hosting element, microporosity in Hanifa Fm. can be categorized into three groups: framework, solid bitumen and intraparticle pores. A key observation of this study is that pore types in Hanifa Formation vary between framework which accounts for 25% of the measured pore areas while the intraparticle porosity only contribute with about 15 %. The organic- hosted porosity is significantly contribute to the porosity of Hanifa Formation with up to 60 % of the measured pore areas. Note: This paper was accepted into the Technical Program but was not presented at IMAGE 2022 in Houston, Texas.