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Enhance Microscopic Sweep Efficiency by Smart Water in Tight and Very Tight Oil Reservoirs Part II
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, IOR 2017 - 19th European Symposium on Improved Oil Recovery, Apr 2017, Volume 2017, p.1 - 19
Abstract
Improvement of oil recovery in smart water injection schemes has been shown to be affected by wettability alteration. This process reduces residual oil saturation, which in turn affects the microscopic sweep efficiency and leads to subsequent enhancement of overall waterflood performance ( Willhite, 1986 ). Tight oil reservoirs are often associated with high clay content and significant cation exchange capacity (CEC) values ( Breeuwsma et al., 1986 ). CEC directly influences smart waterflood behavior as it controls ion exchangeability between the solid and aqueous phases, which in turn, regulates the double layer thickness and the wettability of the system ( Nasralla and Nasr-El-Din, 2014 ).
This paper is an extended study from Kadeethum et al. (2017a) in which only one static realization was analyzed. This practice may lead to a bias and unreliable result because we did not include the uncertainties into the system. Therefore, statistical analysis is used to reveal the smart waterflooding’s true potential. Furthermore, an “estimated effect” method is utilized to identify heterogeneity and CEC value effect. Smart waterflooding outperforms conventional waterflooding in both tight and very tight oil reservoirs in terms of oil recovery. Moreover, smart waterflooding also significantly decelerates the water cut (WCUT) trend by subduing the water relative permeability.