Wag Process Design – An Updated Review

Abstract

The design and implementation of water-alternating-gas (WAG) process in an improved and cost-effective way are still under process. Due to the complexities involved in implementing the process and the lack of information regarding fluid and reservoir properties, the water-alternating-gas process has not yet been as successful as initially expected. This situation can be overcome by better understanding the fluid distribution and flow behavior within the reservoir. The ultimate purpose can be achieved with improved knowledge on wettability and its influence on fluid distribution, capillary pressure, relative permeability, and other design parameters. This paper gives an insight on the WAG process design and the recently developed correlations which are helpful in incorporating the effects of wettability variations on fluid dynamics within the reservoir.

The effect of designing parameter of WAG injection on enhancement of CO2 trapping in heterogeneous formations: A numerical study

“…The method applies alternating slugs of CO 2 and water injection. Dissolution of the injected gas in oil reduces hydrocarbon viscosity and increases recovery, while water injection is used to control the CO 2 front stability, reduce gas mobility ratio, enhance imbibition process, increase sweep efficiency during gas flooding, and prevent CO 2 channeling . The purpose of optimization, in the context of EOR, is to reduce the total amount of injected gas needed to produce hydrocarbon.…”

Comparative Analysis of Relative Permeability Models with Reference to Extreme Saturation Limit and Its Influence on Reservoir Performance Prediction

“…The developed state-of-the-art K r Estimator has been effectively used for relative permeability data generation and brief comparative analysis at micro-scale (Zahoor 2011). In this paper, the study is further extended and a number of relative permeability models which are based on formation type and displacement systems, i.e.…”

“…FIGURE 1. Effect of wetability on relative permeability permeability (Kr) versus water saturation (Sw) curves (Zahoor et al 2011) Figure 1 shows that the wetting phase has lesser relative permeability as compared to the non-wetting phase, because the wetting phase occupies the smaller pores while the non-wetting phase occupies the larger pores. The analogous situation exists in case of using different relative permeability models.…”

“…The number of parameters can hinder the fluid flow and a displacement of one fluid by another in a reservoir. Such parameters involve wettability as of prime importance (Ahmed 2000;Zahoor & Derahman 2013;Zahoor et al 2011). Wettability, in turn also affects the relative permeability of displacing and displaced fluids, as shown in Figure 1.…”

“…These models vary in sensitivity with respect to variations in minimum saturation and degree of sorting (Brooks & Corey 1966;Corey 1954). Different studies (Ahmed 2000;Honarpour et al 1986;Li 2010;Naar & Henderson 1961) are available in the literature to describe relative permeability curve behavior by using these correlations and recently an in-depth sensitivity analysis of Brooks and Corey model (Brooks & Corey 1966) and Pirson correlation (Pirson 1958) was studied and analyzed by Zahoor in 2011 (Zahoor 2011), using the in-house developed software, namely; Kr Estimator. In this paper, the study is further extended and broadened by including more relative permeability models, which are used for generating relative permeability data, based on the information, such as type of fluids present in the reservoir, formation type, undergoing displacement processes and saturation variations.…”