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CHAPTER ELEVEN

Forced imbibition

Abstract
This chapter discusses the imbibition by pressure gradient that is sometimes called
forced imbibition. Forced imbibition occurs in ﬂooding and soaking. Numerical simu-
lation approach is used to analyze the performance of forced imbibition in fractured
shale and tight rocks. The effects of permeability and porosity, wettability alteration,
interfacial tension, capillary pressure, and pressure gradients on fractured shale and
tight rock system are investigated. At the end, experimental results are discussed,
and ﬁeld tests of surfactant EOR are presented.

Keywords: Forced imbibition; Fractured reservoirs; IFT; Pressure gradient; Surfactant EOR;
Wettability alteration.

11.1 Introduction
In terms of EOR methods, water injection has not been studied as
extensively as gas injection, probably because the former may not be as
effective as the latter (Sheng and Chen, 2014; Yu and Sheng, 2017). To
improve water injection performance, many efforts have been made to
add surfactants or chemicals. Once water is injected, water may imbibe
into rocks through capillarity or by pressure. The capillary imbibition is
called spontaneous imbibition which was discussed in Chapter 10. The
imbibition by pressure gradient is sometimes called forced imbibition which
is discussed in this chapter. Forced imbibition occurs in ﬂooding and soak-
ing. Numerical simulation approach is used to analyze the performance of
forced imbibition in fractured shale and tight rocks. The effects of perme-
ability and porosity, wettability alteration, interfacial tension, capillary
pressure, and pressure gradients on fractured shale and tight rock system
are investigated. At the end, experimental results are discussed, and ﬁeld tests
of surfactant EOR are presented.

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