https://doi.org/10.36719/2663-4619/112/162-166
Azer Ahmadov
Azerbaijan State Oil and Industry University
Master student
https://orcid.org/0009-0002-4100-393X
azerehmedov2002@gmail.com
Optimization of Low-Salinity Water Injection For Enhanced Oil Recovery
in Naturally Fractured Dolomite Reservoirs With Anhydrite
Abstract
Enhanced oil recovery in carbonate reservoirs, particularly in naturally fractured formations, is challenging due to the influence of spontaneous imbibition. Low salinity water injection is a promising technique; however, its effectiveness depends on rock mineralogy, water salinity, and complex chemical interactions. Therefore, its application in carbonate reservoirs and the underlying mechanisms are not yet fully understood. This study aims to experimentally evaluate the efficiency of low salinity water injection in fractured dolomite reservoirs containing anhydrite and lacking clay. Spontaneous and forced imbibition tests were conducted at 75°C with varying salinity levels to determine the optimal salinity for oil recovery. The results indicated that decreasing salinity enhances oil production. To predict large-scale applications, a refined dimensionless-time correlation was employed. To better understand the mechanisms, mineral dissolution, pH increase, and wettability alteration were examined.
Wettability alteration was identified as the primary mechanism for improved oil recovery, while mineral dissolution further enhanced the process. Additionally, an increase in pH contributed to further enhancement of oil recovery with low salinity water.
Keywords: self-induced imbibition, alkalinity rise, dolomite reservoir with natural fractures, reduced salinity, mineral breakdown, wettability modification