CARBONATE PORE SYSTEMS VARIABILITY IN SHALLOW MARINE UPPERMOST JUBAILA FM: ARAB-D RESERVOIR ANALOGUE IN SAUDI ARABIA

In research areas there are 3 depositional facies: Stromatoporoid wackestone-packstone (SWP), Dolomitic wackestone (DW), and Dolomitic mudstone (DM). Three types of diagenesis occurred which consist of: dolomitization, dissolution, and burial. Five of pore systems was recognized: Intercrystal non-fabric preserved (BC-nfp), Intercrystal fabric preserved (BC-fp), Intraparticle (WP), Fracture (FR), and Tight. Diagenesis play an important role in altering the depositional texture, pore systems control reservoir quality instead of lithology. Similar lithology will have different pore systems resulted in different reservoir quality. Therefore, diagenesis defines reservoir quality (RQ): Intercrystal non-fabric preserved (BC-nfp): Mostly in dolomitic mudstone (DM) - Dissolution created pore system which increase porosity and permeability (RRT-1). Intercrystal fabric preserved (BC-fp), interparticle: Experienced dissolution in different degree in SWP and DW - pore systems slightly increase porosity and permeability even though not significantly (RRT-2). Tight/minimum dissolution, fracture: Does not created of pore space but it tighten the rocks and reduce porosity and permeability (RRT-3).