Application of Low-Salinity Waterflooding in Carbonate Cores: A Geochemical Modeling Study

Abstract

Waterflooding is the most widely applied improved oil recovery technique. Recently, there has been growing interest in the chemistry and ionic composition of the injected water. Low-salinity waterflooding (LSWF) is a relatively recent enhanced oil recovery technique that has the ability to alter the crude oil/brine/rock interactions and improve oil recovery in both clastics and carbonates. In this paper, the increase in the recovery factor during LSWF was modeled based on the exchange of divalent cations (Ca2+ and Mg2+) between the aqueous phase and the carbonate rock surface. Numerical simulations were performed using laboratory coreflood data, and oil recovery and pressure drop from experimental works were successfully history matched. The ion exchange equivalent fractions, effluent ions concentrations, changes in mineral moles, and pH have also been examined. Besides, an investigation of multi-component ionic exchange as a mechanism responsible for wettability alteration during LSWF in heterogeneous low-permeability carbonate cores is presented. The results show that wettability alteration is responsible for the increase in oil recovery during LSWF, as reflected by the shift in the crossover points of the relative permeability curves. A sensitivity study done on many key parameters (e.g., timing of LSWF injection, injection rate and temperature) and the mechanistic modeling method revealed that they all have huge effects on the process.

Effects of MgO, γ-Al2O3, and TiO2 Nanoparticles at Low Concentrations on Interfacial Tension (IFT), Rock Wettability, and Oil Recovery by Spontaneous Imbibition in the Process of Smart Nanofluid Injection into Carbonate Reservoirs

“…According to available sources, at least 50% of the primary oil is trapped in oil reservoirs after initial production and thus is not produced for various reasons. 1 The water injection method in secondary and tertiary recovery operations shows improved performance. 2 In the chemically improved water injection, dissolved components are engineered and managed to achieve the best performance in the presence of reservoir fluid and rock.…”

“…According to available sources, at least 50% of the primary oil is trapped in oil reservoirs after initial production and thus is not produced for various reasons . The water injection method in secondary and tertiary recovery operations shows improved performance .…”

Impact of Physical Heterogeneity and Transport Conditions on Effective Reaction Rates in Dissolution

“…Reactive transport in porous media is commonly encountered in contaminant hydrology (MacQuarrie and Sudicky 1990), reactive flow in batteries and fuel cells (Gayon Lombardo et al 2019), nuclear waste disposal (Kenney et al 2017), oil recovery (Egbe et al 2021), carbon storage (Metz et al 2010), and chemical reactor engineering (Fogler 1987). In some applications, such as well stimulation by acidization, reaction is required, while in others, such as in dissolution-induced compromised well integrity, reaction is detrimental.…”

Enhancing surfactant desorption through low salinity water post-flush during Enhanced Oil Recovery

“…Sheng reviewed that approximately 17 mechanisms pertaining to solely LSWF, among which fine migration, mineral dissolution, Multicomponent Ion Exchange (MIE), and wettability alteration stood as prominent [22]. Extensive works [23][24][25][26] presented comprehensive results regarding the effects of ion types on the effectiveness of LSWF. They found that SO 4 2À is the most dominant in driving rock to less oil wetness.…”