Alkali and Hybrid-Alkali Flooding as a Tertiary Oil Recovery Mode: Prospects and Challenges

Abstract

Discovery of new oil being in declining trend and demand being on the rise, EOR technologies has to play a bigger role in the future to meet the energy demand and economics. This paper presents a comprehensive review of EOR technologies related to alkaline flooding and its hybrids. Alkaline flooding is one of the chemical enhanced oil recovery techniques in which high pH alkaline chemicals are injected to the reservoir for recovering the residual oil. It is among the oldest EOR techniques and its history started way back in the early 20 th century. The history of alkaline flooding, mechanisms by which it recovers oil, different process variations, the effectiveness and costs of different alkalis, problems associated with alkaline flooding and its application in carbonates are briefly reviewed in this paper. This paper also focuses on the reviews of the application of various hybrid floods developed along with alkali and their advantages, limitations both in clastic and carbonate reservoirs. The technical solutions to some of these challenges will be discussed.

Investigation into the Oil Recovery Process Using an Organic Alkali–Amino Acid-Based Surfactant System

“…The wettability alteration capabilities of inorganic alkalis such as NaOH and Na 2 CO 3 are well established in the literature via laboratory experiments and field applications. 11,69 Studies on the wettability alteration capability of organic alkalis are, however, limited in the literature. 15 Bai et al 23 compared the wettability alteration capability of organic alkalis (monoisopropanolamine and monoethanolamine) to that of brine.…”

“…These combinatory flooding techniques have been proven by laboratory experiments, pilot tests, and field-scale applications to offer better additional recovery than their unitary flooding process. ,,, Alkali and polymer floodings are combined to mobilize the residual oil with alkali, while the polymer maintains a stable displacement front. ,, The alkali reacts with the acidic content of the crude oil (saponifiable component) to generate an in situ surfactant (soap), which can reduce interfacial tension (IFT) . The injected alkali is also expected to act as a sacrificial agent to reduce polymer adsorption .…”

“…Mobility control is also achieved through emulsification. Alkali also reduces surfactant adsorption. ,, The ternary combination of alkali, surfactant, and polymer is widely considered the most promising among all chemical EOR processes. This is due to the integration of all of the synergies upon combining these three chemical agents. ,,, …”

“…2,3,9,10 Alkali and polymer floodings are combined to mobilize the residual oil with alkali, while the polymer maintains a stable displacement front. 2,11,12 The alkali reacts with the acidic content of the crude oil (saponifiable component) to generate an in situ surfactant (soap), which can reduce interfacial tension (IFT). 3 The injected alkali is also expected to act as a sacrificial agent to reduce polymer adsorption.…”

“…This is due to the integration of all of the synergies upon combining these three chemical agents. 2,11,13,14 Though these combinatory flooding processes offer added advantages and yield more recovery, their application still has associated limitations mainly due to the individual chemical agents used. 15 The conventionally used alkalis are inorganic alkalis such as NaOH and Na 2 CO 3 .…”