Detailed Modeling of the Alkali/Surfactant/Polymer (ASP) Process by Coupling a Multipurpose Reservoir Simulator to the Chemistry Package PHREEQC

Abstract

Summary Accurate modeling of an ASP flood requires detailed representation of geochemistry and, if natural acids are present, the saponification process. Geochemistry and saponification affect the propagation of the injected chemicals and the amount of generated natural soaps. These in turn determine the chemical phase behavior and, hence, the effectiveness of the ASP process. In this paper, it is shown that by coupling a multipurpose reservoir simulator (MPRS) with PHREEQC (Parkhurst and Appelo 1999; Charlton and Parkhurst 2008), a robust and flexible tool is developed to model ASP floods. PHREEQC is used as the chemical-reaction engine, which determines the equilibrium state of the chemical processes modeled. The MPRS models the impact of the chemicals on the flow properties, solves the flow equations, and transports the chemicals. The validity of the approach is confirmed by benchmarking the results with the ASP module of the UTCHEM simulator (Delshad et al. 2000). Moreover, ASP corefloods have been matched with the new tool. The functionality of the model also has been tested on a 2D sector model. The advantages of using PHREEQC as the chemical engine include its rich database of chemical species and its flexibility in changing the chemical processes to be modeled. Therefore, the coupling procedure presented in this paper can also be extended to other chemical enhanced-oil-recovery (EOR) methods.

Mechanistic Modeling of Low-Salinity Waterflooding Through Coupling a Geochemical Package With a Compositional Reservoir Simulator

“…CO 2 dissolves in the aqueous phase, especially at high reservoir pressure, and carbonic acid is formed. Acidic/basic components are integral to the wettability of the reservoir (Buckley 1994) and likewise involved in the underlying mechanisms behind the low-salinity waterflooding (Austad et al 2010;Farooq et al 2011;RezaeiDoust et al 2011). Moreover, acidic/basic components of the crude oil can also exchange between the hydrocarbon and aqueous phases (Havre et al 2003;Austad et al 2010;RezaeiDoust et al 2011).…”

“…It is widely believed that low-salinity waterflooding changes wettability through geochemical reactions (Lager et al 2008a;Austad et al 2010;Pu et al 2010;Farooq et al 2011;Nasralla and Nasr-El-Din 2011;RezaeiDoust et al 2011;Fjelde et al 2012;Brady and Krumhansl 2012;Dang et al 2013;Emadi and Sohrabi 2013). Hence, mechanistic modeling of this process is possible only by modeling geochemical reactions.…”

Improving Reactive Transport Modelling Predictivity for ASP Flooding Simulations

“…Farajzadeh et al (2012) applied this methodology for the mechanistic modeling of ASP processes. However, the geochemical databases from the PHREEQC release have not been specifically calibrated with the experimental data under typical ASP flooding reservoir conditions (most of the released databases from PHREEQC are for surface or shallow hydrogeological systems).…”

A Robust Geochemical Simulator to Model Improved Oil Recovery Methods

“…PHREEQC (Parkhurst and Appelo, 1999), a generalized geochemical reactive solver supported by United States Geological Survey (USGS) since 1980, is able to provide friendly junction to simulators from different disciplines and has been used to couple to several reservoir simulators. For example, MoReS, an in-house simulator of Shell Global, coupled to PHREEQC and successfully modelled the ASP flooding in reservoirs containing oil acid (Farajzadeh et al, 2012;Wei, 2012;Karpan et al, 2011). Kazemi Nia Korrani et al (2013 also coupled UTCOMP and UTCHEM to IPhreeqc (Interactive Phreeqc), and succeeded in modelling low salinity water flooding, ASP flooding, and formation damage, etc.…”