Modeling Ion Exchange and Wettability Alteration during Low Saline Water Flooding in Sandstone Reservoirs

Аннотация

The behavior of ion interactions during low © 2025 Original content from this work may be used under the terms of the creative commons attributes 4.0 License. saline water flooding in sandstone reservoirs plays a crucial role in enhanced oil recovery (EOR) processes. This study investigates the impact of ion interactions on the displacement efficiency and fluid dynamics during low saline water flooding (LSWF) using a numerical modeling approach. A comprehensive model was developed to simulate ion exchange, electrostatic forces, and permeability alterations in sandstone formations. Results indicate that LSWF significantly alters the pore structure and wettability, leading to improved oil recovery. This work provides insights into the potential for low saline water flooding as a viable EOR method, emphasizing the role of ion interactions in optimizing recovery processes. Keywords: Low saline water flooding, ion interactions, ion exchange, sandstone reservoirs, enhanced oil recovery, numerical simulation, wettability alteration, electrostatic forces, relative permeability, capillary pressure, reservoir modeling, ionic composition, oil displacement, fluid dynamics, reservoir engineering. Introduction: Enhanced oil recovery (EOR) techniques are widely employed to maximize hydrocarbon production from mature and underperforming reservoirs. Low saline water flooding (LSWF), a subset of water-based EOR methods, has gained attention for its potential to improve recovery in sandstone reservoirs. The American Journal of Engineering and Technology 1 https://www.theamericanjournals.com/index.php/tajet The process involves injecting water with lower salinity LSWF is the alteration of the wettability of the rock than the native formation water, which can induce surface. In many sandstone reservoirs, the rock surface changes in reservoir rock properties and fluid behavior. tends to be oil-wet or mixed-wet, which means that One of the key mechanisms behind LSWF is the water has a poor ability to displace the oil from the pore alteration of ion interactions at the rock-fluid interface, spaces. By injecting low saline water, ions in the brine affecting wettability, capillary forces, and relative exchange with ions on the rock surface, particularly permeability. calcium (Ca²⁺) and sodium (Na⁺), causing a shift in wettability towards a more water-wet condition. This Sandstone reservoirs are typically composed of a wettability alteration is believed to facilitate more mixture of quartz and other minerals that are sensitive efficient oil displacement during the water injection to the ionic composition of the injected water. Ion process. exchange reactions between the brine and rock surface can lead to changes in pore structure, thereby The interaction between the injected brine and the rock influencing the effectiveness of water flooding. While surface is heavily influenced by the electrostatic forces experimental studies have provided valuable insights, at the interface. When low saline water is injected, the there is a need for a more detailed understanding of the reduction in ionic strength weakens the electrostatic ion interactions through advanced numerical double layer that forms at the rock-fluid interface, which approaches. This study aims to assess the role of ion in turn modifies the capillary pressure and relative interactions during LSWF in sandstone reservoirs using a permeability. The ions in the brine interact with the numerical modeling framework. mineral surfaces of the rock, causing ion exchange reactions that alter the surface charge density and Enhanced oil recovery (EOR) techniques are critical in structure of the porous media. For example, divalent improving oil recovery from mature reservoirs that have ions such as Ca²⁺ tend to replace monovalent ions like already undergone primary and secondary recovery Na⁺, which can lead to changes in surface chemistry, methods. Among various EOR techniques, water swelling of clays, and changes in the pore network. flooding is one of the most widely employed, with its efficiency being highly dependent on factors such as the The challenge, however, is to predict and quantify these water chemistry, injection rates, and reservoir ion interactions and their impact on the overall properties. While conventional water flooding uses displacement process. While laboratory experiments formation water or brines with high salinity, a relatively have provided valuable insights into the ion exchange newer approach known as low saline water flooding processes, there is still a lack of a comprehensive (LSWF) has gained attention in recent years for its understanding of how these interactions play out in real potential to increase recovery efficiency in sandstone reservoir conditions. Moreover, sandstone reservoirs reservoirs. are not homogeneous, and their mineralogical composition, pore structure, and initial brine In traditional water flooding, the injected water composition can vary s