Page 96 - Enhanced Oil Recovery in Shale and Tight Reservoirs

Huff-n-puff injection in shale gas condensate reservoirs 83

From the above discussion of the problem, one easy way is to increase
the pressure near the wellbore or in the reservoir above the dew point
pressure by gas and/or water flooding (Hernandez et al., 1999). Surfactants
may be injected to reduce interfacial tension or alter wettability so that
residual liquid oil saturation is reduced (Kumar et al., 2006; Ahmadi et al.,
2011; Ganjdanesh et al. (2015). Solvents may be injected to mitigate the
impact of liquid blockage (Al-Anazi et al., 2005; Sayed and
Al-Munstasheri, 2014). These methods have been proposed for conven-
tional reservoirs. This chapter proposes huff-n-puff gas injection in shale
and tight reservoirs to mitigate the liquid condensate blocking. The method
is compared with solvent injection and surfactant treatment.

4.2 Experimental setup
Fig. 4.3 is a general experimental setup for flooding and huff-n-puff.
During the huff (injection) period, a single-phase gas condensate is injected
from Accumulator 2 into the two ends of core through Valves C, A, and B.
During the puff period, the valve G for Accumulator 2 and Valve F for
Accumulator 1 are closed, the valve E for the back-pressure regulator is
open, and Valves A, B, C, and H are open. The flowback fluid is stored
in Accumulator 3. The core is placed inside a CT scanner. The average

Figure 4.3 A general experimental setup for flooding and huff-n-puff.