Page 15 - Enhanced Oil Recovery in Shale and Tight Reservoirs

Introduction to shale and tight reservoirs 5

much more publicly known, which is horizontal well drilling and fracturing.
In the Chinese literature, there is a word “volume fracturing” if literally
translated. It actually means massive fracturing which results in a large stim-
ulated reservoir volume (SRV) (Qi, 2015).

1.2.3 Injection modes
A fluid, either water or gas, could be injected into reservoirs through a
flooding mode or in a huff-n-puff (huff and puff) mode. For the flooding
mode, a fluid is injected through a dedicated well and oil and gas are
produced from a separate well or wells (see Fig. 1.1). For the huff-n-puff
mode, after a fluid is injected through a well, in situ fluids (oil, gas and water)
and a fraction of the injected fluid are produced from the same well
(see Fig. 1.2). For the huff-n-puff mode, there is a period the well is
shut-in in some situations. This period is called soaking time. The process
of injecting-soaking-producing is repeated.

Figure 1.1 Schematic of flooding.

Gas Soaking Produced
Injection Period Fluids

Figure 1.2 Schematic of huff-n-puff.