Identification of Poor Hydrocarbon Chargeability in Initially Pressured Reservoir Using Initial Water Saturation, Formation Tester Mobility, and Movable Hydrocarbon, Basal Alam El Bueib 3A Reservoir, AEB-3C Field, Western Desert, Egypt

Abstract The integration of initial water saturation (Swi) with movable hydrocarbon (Smo) can demonstrate the charging capacity of a reservoir under initial pressure regardless of the hydrocarbon fluid gradient. In an initially pressured reservoir with oil gradient, high initial calculated water saturation, good mobility, and low calculated movable hydrocarbon (Smo), in which the study integrates these reservoir characteristics, the risk of running casing or encountering a well test with 100% water cut can be mitigated. The AEB-3C field was discovered in August 2010 by El Hamra Oil Company (EHO) with the drilling of AEB-3C-1X well to be the first commercial oil discovery in the field through production testing at about 500 BOPD of 23.3°API from the AEB-3A sands reservoir. The Basal AEB-3A (B.AEB-3A) reservoir comprises three distinct sand bodies was formed in a depositional setting characterized by lower intertidal-subtidal conditions and distributary mouth sand bars. The environmental setting allows for penetrating various sand bars under initial conditions within the same field. In Well AEB-3C-6, the third sand body within the B.AEB-3A reservoir exhibits a fluid gradient of 0.39 psi/ft, alongside an average mobility of 30 mD/CP (millidarcies per centipoise). Initial water saturation (Sw) was determined using the Archie Equation and used in establishing a water saturation (Sw) height function to describe the difference in initial water saturation (Swi) by porosity band, assuming a clean sandstone reservoir concluded from Cation Exchange Capacity (CEC). The reservoir yielded an average Sw of 60%. The movable hydrocarbon, however, was interpreted conservatively, consistently remaining below 5% and far from the expected value. The primary challenge involved casing installation and reservoir testing. This paper aims to illustrate the integration between Swi and Smo concerning initial reservoir pressure in comparison to the producing wells, while also addressing associated risks and results.