000			02518nab a2200217 4500
005			20260520002031.0
008			260224s2011 xxu
245	0	0	_aEffect of crude oil ageing on low salinity and low salinity surfactant flooding
260			_a _b _cagos. 2011
270			_a03/04/2012 ; 03/04/2012
300			_a8 p. ; 220 - 227
520			_aTranscripción del resumen del autor. Injection of brine with lower salinity than the connate brine has proven to give a moderate increase in oil recovery in sandstones. Recent research has shown that this process will significantly benefit from introducing surfactant optimised for low salinity environment. The mechanisms underlying increased recovery by low salinity brine injection are not yet fully understood. However, research to date suggests that they are related to complex crude oil/brine/rock interactions. With this in mind, the present paper investigates primarily how the extent of oil recovery from Berea sandstones subjected to long term exposure of crude oil is influenced by (1) low salinity water injection and (2) combined process low salinity water injection with surfactant flooding. Core displacement tests were conducted on four Berea cores (30 cm), two in a natural state and two that had been subject to extensive crude oil ageing at high temperature. Results obtained from different flooding steps are discussed in terms of oil recovery and effluent properties including turbidity, pH- and ion analysis (Na+, Mg2+, Ca2+). The results effectively illustrate that oil recoveries from the aged cores are higher during both low salinity water injection and low salinity water injection combined with surfactant flooding. An assessment of how tertiary oil recovery in aged and unaged cores varies with surfactant concentration is also presented. Effluent ion analysis from low salinity water floods showed that Mg2+ ions were strongly retained in the aged core while Ca2+ ions were being produced from both aged and unaged cores. The latter was attributed mainly to calcite dissolution. Results obtained from pressure profiles, effluent ion analysis and turbidity tests suggest higher production and elution of fine particles from the unaged core.
581			_a2
773	0		_tJournal of Petroleum Science & Engineering _g78
942			_cARTICULO
100	1		_aAlagic, Edin _952304
100	1		_aSpildo, Kristine _952305
100	1		_aSkauge, Arne _952306
100	1		_aSolbakken, Jonas _952307
999			_c186973 _d186973