Mechanisms and experimental research of ion-matched waterflooding to enhance oil recovery in carbonate reservoirs: A case of Cretaceous limestone reservoirs in Halfaya Oilfield, Middle East

PENG Yingfeng,LI Yiqiang,ZHU Guangya,PAN Deng,XU Shanzhi,WANG Xiuyu

Table 1 Classification of mechanisms of ion-matched waterflooding for EOR.

Result Primary mechanisms (direct impact) Secondary mechanisms (impact by affecting primary mechanism) Working approaches Research methods Oil recovery improved Improving wettability; mineral/ chemical particle/microemulsion movement; oil-water IFT drop/flow characteristics changing; rock surface/pore structure improvement; physical properties improving I: exchange of multiple ions (1) decrease salinity (or IS) (2) change the con- centration of PDIs Core flow experiments, oil/water IFT test, XRD, nuclear magnetic resonance (NMR), zeta potential test, contact angle test, chromatographic analysis II: corrosion deepening III: dissolution/recrystallization of slightly soluble or in-soluble salts IV: micro dispersion of oil and water, IFT changes