Page 358 - Enhanced Oil Recovery in Shale and Tight Reservoirs

Forced imbibition 331

11.7 Experimental study of forced imbibition
Tu and Sheng (2019) did some experiments of forced imbibition. The
experimental setup was a modified Amott cell, a high-pressure accumulator,
and a Quizix pump (Fig. 11.19). A traditional Amott cell is commonly used
for the experiments on spontaneous imbibition. However, the Amott cell
cannot stand pressure, probably higher than 5 psig. During surfactant injec-
tion in a real reservoir, the injection pressure will be higher than the pressure
inside matrix. In other words, the imbibition is forced imbibition during a
huff or soaking period. To reflect this reality, the Amott cell was modified
as shown in Fig. 11.19. The bottom cap with a communication port
balances the pressures inside and outside the cell. By submerging the whole
Amott cell into the upper portion of the accumulator filled with designated
fluid, any target pressures can be simply achieved by injecting water through
the Quizix pump into the bottom portion of the accumulator. The balanced
pressure in the top space of the accumulator can be recorded from the
pressure gauge. The advantage of such apparatus is that the pressurized imbi-
bition occurs inside the cell and any oil coming out the core can be viewed
at the cell neck with graduated scales.
A total of eight cycles of pressurized huff (including soaking) and puff
tests were performed for each core sample listed in Table 11.11. Each test

Figure 11.19 Modified high-pressure Amott apparatus.