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Low Salinity Waterflooding in Sandstone Reservoir Containing Enriched Potassium Ion Concentration
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 79th EAGE Conference and Exhibition 2017, Jun 2017, Volume 2017, p.1 - 5
Abstract
Low salinity waterflooding has been intensively studied all over the world. Several oil recovery mechanisms have been suggested and most studies emphasize on effects from injected water. Nevertheless, effects from formation water have not been noticed much but it should be thoroughly studied since it plays important role in controlling oil-brine-surface equilibrium. Not very often that formation brine is enriched in potassium ion. Due to smaller size of hydrated molecule, formation brine with high potassium ion could cause adsorbed oil layer to adhere onto sandstone surface with higher strength compared to usual formation water with high amount of sodium ion. Coreflood test shows the results that, formation water with low portion of potassium ion responds to LSWF differently, depending on amount of calcium and magnesium ions, whereas high potassium ion one does not show variation in oil recovery factor by LSWF. High potassium ion in formation brine is therefore not desirable for LSWF. Nevertheless, positive results by means of LSWF can be observed. Mixing of high potassium ion formation water with seawater can slightly improve oil recovery as monovalent ion in injected brine important for MIE mechanism is increased while total ionic strength of injected brine is still low.