Crude Oil/Brine/Rock Factors Influencing Chalk Wettability
T. Puntervold, S. Strand and I.D. Piñerez Torrijos
Event name: 80th EAGE Conference and Exhibition 2018
Session: Modified Salinity Waterflooding in Chalk Reservoirs (Dedicated Session)
Publication date: 11 June 2018
Info: Extended abstract, PDF ( 390.11Kb )
Price: € 20
Smart Water EOR is based on wettability alteration from mixed wettability to a more water-wet case, generating capillary forces and improving the microscopic sweep efficiency. The Smart Water EOR potential for a reservoir is dependent on the initial wetting state, and the EOR potential increases with decreasing water wetness. Outcrop Stevns Klint chalk cores with reproducible properties were used in parametric studies. The influence of crude oil components, formation water composition and rock impurities on the core wettability was investigated. Spontaneous imbibition tests reflected the initial wetting of the cores prepared in different ways. The core wettability is dependent on the acidic components in the crude oil. Higher acid number lowered the water wetness. Ion composition and salinity of the formation water also affected the initial wetting. Deionized water decreased water wetness the most, promoting adsorption of crude oil components onto chalk. Cores containing initial sulphate from impurities, behaved more water-wet than cores without sulphate. Sulphate prevented adsorption of polar crude oil components onto chalk. Chalk wettability is influenced by all phases present in the reservoir; rock, crude oil and formation water. The chemical properties of all phases present must be considered when performing laboratory work, and evaluating reservoir wettability.