Page 16 - Enhanced Oil Recovery in Shale and Tight Reservoirs

6 Enhanced Oil Recovery in Shale and Tight Reservoirs

Figure 1.3 U.S. crude oil and dry natural gas production, Reference case (EIA, 2018b).

Produced fluids may be reinjected into reservoirs in some situations.
Thus, the fluids are recycled. Such cyclic injection can be performed in
both flooding mode and huff-n-puff mode. However, in the petroleum
literature, cyclic injection, more often, refers to huff-n-puff injection.

1.3 Shale and tight resources
According to EIA, the future oil and gas production increases come
from tight reservoirs, as shown in Fig. 1.3. The oil and gas production
from tight resources is more than the total from other sources. It is similar
in China.

1.4 Current production technologies

Current production technologies from shale and tight reservoirs are
primary depletion using hydraulically fractures horizontal wells. In terms
of enhanced oil recovery methods, Orozco et al. (2018) stated: “Up to
now, most of the industry efforts for enhancing oil recovery from shales
have been devoted to H&P gas injection.” The Society of Petroleum Engi-
neers had a forum on EOR in unconventional reservoirs in San Antonio,
Texas, November 5e10, 2017. The huff-n-puff method of gas injection
was discussed in the whole week of the forum. At the end of the form, it
was asked: “Is there any other EOR methods feasible for shale and tight
reservoirs?” Of course, potential EOR methods have been proposed.
EOR methods and related topics are discussed in the rest of this book.