Page 119 - Hybrid Enhanced Oil Recovery Using Smart Waterflooding

CHAPTER 5

Hybrid CO EOR Using Low-Salinity and
2
Smart Waterflood

ABSTRACT commercial CO 2 EOR projects. The CO 2 EOR can be
The CO 2 injection is the widely used enhanced oil applied with various designs (Jarrell, Fox, Stein, &
recovery (EOR) method because of economics and Webb, 2002): (1) continuous CO 2 gas injection
(CGI), (2) continuous CO 2 injection followed with
recovery efficiency. Although miscible/immiscible CO 2
injections mainly enhance the displacement efficiency water, (3) conventional water-alternating gas (WAG)
employing a number of advantages, the CO 2 injection followed with water, (4) tapered WAG, and (5) WAG
has an inherent unfavorable mobility ratio because of followed gas. Using the water, the CO 2 EOR can
low-viscous CO 2 gas. To support the EOR potential of improve the sweep efficiency as well as displacement
CO 2 injection, auxiliary water injection is developed efficiency. Recently, the usage of low-salinity water or
to cooperate in CO 2 injection. The coapplication of smart water rather than conventional water into the
water and CO 2 injections enhances displacement CO 2 EOR has been proposed to introduce the synergy.
efficiency as well as sweep efficiency improving The applications of hybrid low salinityeaugmented
the mobility ratio. Recently, the use of low-salinity CO 2 EOR (LS-CO 2 EOR) are discussed in this chapter.
water rather than conventional high-salinity water in Before the discussion of recent investigations of the
coinjections of water and CO 2 is proposed as low LS-CO 2 EOR, the important aspects of CO 2 injection
salinityeaugmented CO 2 EOR (LS-CO 2 EOR). This are firstly summarized to help the understanding of
LS-CO 2 EOR. The detailed description of CO 2 flood
chapter reviews the studies of CO 2 EOR, mainly CO 2
water-alternating gas and carbonated water injection, will be found in the references (Jarrell et al., 2002;
to investigate the effect of salinity on the mechanisms Stalkup, 1983).
of CO 2 EOR process. Laboratory and numerical simula-
tion studies of LS-CO 2 EOR are discussed to evaluate MINIMUM MISCIBLE PRESSURE
whether the additional displacement efficiency employ-
ing the mechanism of low-salinity waterflood or other Although there are other solvents, the CO 2 is a good
effects can be introduced. solvent for miscible process. The CO 2 generally forms
a phase, which has comparable density of a liquid
and low viscosity, in a high pressure condition. More
The understanding of CO 2 EOR has been investigated, importantly, the CO 2 relatively has a low minimum
and some researchers have reported the experimental miscible pressure (MMP), which is defined as mini-
works of carbonated water recovery as early as 1951 mum pressure to achieve a miscibility, compared with
(Martin, 1951). The first patent of CO 2 EOR technology the methane and nitrogen. The miscible process can
was granted by the Atlantic Refinery Company in 1952 be effective for a reservoir system, which has a higher
(Whorton, Brownscombe, & Dyes, 1952). In 1964, the pressure than MMP. Because the CO 2 generally results
field test of CO 2 EOR was developed in the Mead in a lower MMP compared with the other solvents,
Strawn Field and the test was designed with carbonated the CO 2 injection can be used to enhance the miscible
water injection following CO 2 slug (Holm, apos, & oil recovery process in a wide range of oil reservoirs.
Brien, 1971; Holm, 1987). The CO 2 EOR produces
more oil by 53%e82% over the best performance of
waterflood. Following the success of pilot test, the first MISCIBLE/IMMISCIBLE PROCESSES
commercial CO 2 EOR project was deployed in SACROC The solvent EOR process can be either a miscible or an
(Scurry Area Canyon Reef Operators Committee) Unit immiscible displacement depending on the miscibility
of the Kelly-Snyder Field in Scurry County, West Texas condition. The miscibility between two fluids, i.e.,
(Langston, Hoadley, & Young, 1988). The successful displacing and displaced fluids, can be achieved by
field project leads to a number of applications of first-contact miscibility or multiple-contact miscibility.

Hybrid Enhanced Oil Recovery using Smart Waterflooding. https://doi.org/10.1016/B978-0-12-816776-2.00005-2
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