Geomechanical assessment of the Lower Turonian AR-F limestone Member, Abu Gharadig Field, Egypt: Implications for unconventional resource development

This study evaluates the unconventional reservoir geomechanical characteristics of the Lower Turonian Abu Roash-F (AR-F) carbonates from the Abu Gharadig field, onshore Egypt, which has not been attempted before. The interval dominantly consists of planktic foraminifera and micrite matrix. The AR-F marine carbonate is organic-rich (0.59-3.57 wt% total organic carbon), thermally mature (435-441? T-max) and falls within the oil generation window. The studied interval is very tight with up to 2.6% porosity and 0.0016-0.0033 mD permeability with the wireline log-based brittleness index ranging between 0.39-0.72 which indicates a less brittle to brittle nature. AR-F exhibits a hydrostatic pore pressure gradient with minimum horizontal stress (S-hmin) varying between 0.66-0.76 PSI/ft. Safe wellbore trajectory analysis was performed for deviated and horizontal wells to infer the mud pressure gradients required to avoid wellbore instabilities. Based on the inferred in-stress magnitudes and considering an NNE regional maximum horizontal stress orientation, none of the fractures are found to be critically stressed at present day. To produce from the AR-F, hydraulic fracturing is necessary, and we infer a minimum pore pressure increment threshold of 1390 PSI by fluid injection to reactivate the vertical fractures parallel to regional minimum horizontal stress azimuth.

Automated summary

This study evaluates the geomechanical characteristics of the unconventional reservoir of AR-F carbonates in the Abu Gharadig field in Egypt. The study found that the reservoir has low porosity and permeability, indicating its tight nature. Hydraulic fracturing is necessary for production from this reservoir.