Page 9 - Hybrid Enhanced Oil Recovery Using Smart Waterflooding

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CHAPTER 1

History of Low-Salinity and

Smart Waterﬂood

ABSTRACT LABORATORY EXPERIMENTS
Historically, the signiﬁcant investigations regarding the This section focuses on explaining experimental observa-
reservoir wettability develop the technology of low- tions in sandstone and carbonate rocks. The description
salinity and smart waterﬂood. Because of the different of carbonate rocks follows that of sandstone.
conditions and the difﬁcult consistency of experiments,
many laboratories show a variety of responses of the Sandstone
low-salinity waterﬂood (LSWF). Especially, the totally Extensive studies of waterﬂood have interested in the
different conditions between the sandstone and carbon- effects of salinity on oil recovery from sandstones and
ate rocks hardly draw the universal and consistent developed the LSWF to improve oil production.
results of LSWF in sandstone and carbonate reservoirs. Bernard (1967) ﬂooded freshwater and brines into
In addition, the increasing oil recovery from LSWF synthetic and natural water-sensitive cores containing
experiments hardly guarantees the successful ﬁeld clays and investigated the relative effectiveness of
deployments of LSWF. Despite the various observations salinity on oil recovery. The study assumed that the
and uncertainty, extensive research studies have clearly fresh brine causes the clay hydration, which contributes
observed the enhanced oil production of LSWF in to the oil production of freshwater injection. The clay
some conditions and agreed the potential of LSWF bearing synthetic and natural cores are subjects to the
as enhanced oil recovery technology. Therefore, this experimental study. The synthetic cores have 2% mont-
chapter reviews the important laboratory and ﬁeld morillonite, which has extremely high surface activity,
studies, up to date, to summarize the evidences and swelling potential, and exchange capacity. The natural
experimental conditions of LSWF. cores are provided from Berea sandstone and outcrop
near Wyoming. The Berea sandstone core has relatively
More than 50 years ago, the observations of the salinity less clay concentration of 0.1%, but it exhibits high
effect on waterﬂood recovery initiate to investigate the water sensitivity. Another core from Wyoming has
potential of low-salinity waterﬂood (LSWF) in sand- expandable clays of 1.2%. The brines are made by
stone. In addition, the unexpected higher oil recovery controlling NaCl concentration (0.1%, 0.5%, 10%,
of seawater injection in the carbonate ﬁeld leads and 15%). While the brines and freshwater are ﬂooded
to the investigations of ionic composition on the wetta- into the cores and oil recovery, residual oil saturation
bility of carbonates and triggers the research studies of and pressure gradient are measured. The experiments
LSWF or smart waterﬂood in carbonates. Up to date, observe that the injection of freshwater results in less
the many researchers and industries have explored residual oil saturation as well as higher pressure
and developed the novel technologies of LSWF or smart gradient compared with the injection of brines
waterﬂood, which are known as LoSal, SmartWater, (Fig. 1.1). The study proposed the two mechanisms to
Desinger Waterﬂood, and Advanced Ion Management explain the observations. Further experiments of
(AIM). Hereafter, the terminology of LSWF is used constant injection rate or constant differential pressure
as a representative. This chapter illustrates the history are carried out to demonstrate the suggested mecha-
of LSWF and describes the important observations of nisms and validated the previous observations of
experiments and ﬁeld applications in sandstone and increasing oil recovery and pressure drop. In the
carbonate rocks, respectively. experiments, the freshwater injection at constant rate

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