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

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.