Coupled Geochemical-Based Modeling of Low Salinity Waterflooding

Abstract

Low salinity waterflooding is an emerging EOR technique in which the salinity of the injected water is substantially reduced to improve oil recovery over conventional higher salinity waterflooding. Although there are many low salinity experimental results reported in the literature, publications on modeling this process are rare. While there remains some debate about the mechanisms of LoSal®1 EOR, the geochemical reactions that control the wetting of crude oil on the rock are likely to be central to a detailed description of the process. Since no comprehensive geochemical-based modeling has been applied in this area, it was decided to couple a state-of-the-art geochemical package, IPhreeqc, developed by the United States Geological Survey (USGS) with UTCOMP, the compositional reservoir simulator developed by The University of Texas at Austin. A step-by-step algorithm is presented for integrating IPhreeqc with UTCOMP. Through this coupling, we are able to simulate homogeneous and heterogeneous (mineral dissolution/precipitation), irreversible, and ion-exchange reactions under non-isothermal, non-isobaric and both local-equilibrium (away from the wellbore) and kinetic (near wellbore) conditions. Consistent with the literature, there are significant effects of water-soluble hydrocarbon components (e.g., CO2, CH4, and acidic/basic components of the crude) on buffering the aqueous pH and more generally, on the crude oil, brine, and rock reactions. Thermodynamic constrains are used to explicitly include the effect of these water-soluble hydrocarbon components. Hence, this combines the geochemical power of IPhreeqc with the important aspects of hydrocarbon flow and compositional effects to produce a robust, flexible, and accurate integrated tool capable of including the reactions needed to mechanistically model low salinity waterflooding. Different geochemical-based approaches to modeling wettability change in sandstones (e.g., interpolation based on total ionic strength and Multicomponent Ion Exchange through surface complexation of the organometallic components) were implemented in UTCOMP-IPhreeqc and the integrated tool is then used to match and interpret a low salinity experiment published by Kozaki (2012) and the field trial done by BP at the Endicott field.

A Digital Twin for Unconventional Reservoirs: A Multiscale Modeling and Algorithm to Investigate Complex Mechanisms

“…IPHREEQC is also a state-of-art geochemical engine, and UTCHEM-IPHREEQC is an accurate, robust, and flexible tool that enables to model low salinity waterflooding and many other enhanced oil recovery techniques with respect to geochemistry. Later, another threedimensional equation-of-state-based compositional simulator, also developed by the University of Texas at Austin, UTCOMP, is coupled with IPHREEQC and the effect of hydrocarbon components soluble in the aqueous phase on the pH buffering and other related reactions in the oil/brine/rock system [35].…”

A Review of Lattice-Boltzmann Models Coupled with Geochemical Modeling Applied for Simulation of Advanced Waterflooding and Enhanced Oil Recovery Processes

“…Researchers from academia and the oil and gas industry proposed various names to refer to this process, for example, advanced Ion Management by ExxonMobil, Modified Salinity Flooding, and Engineered Waterflood . The underlying mechanisms for LSWF are not fully understood, and there is no universally applicable mechanism attributable to both sandstone and carbonate rocks.…”

Modelling Low-Salinity Water Flooding as a Tertiary Oil Recovery Technique

“…Low-salinity water flooding most recently has been considered as more than just a water flooding technique (secondary recovery); it has been considered to be an improved oil recovery technique due to the chemical reactions that take place when water having a reduced ionic content (reduced salinity) is used for water flooding [2]. Due to its simplicity and low application costs, the procedure has gained many interests in the oil industry [3].…”