Enhanced Oil Recovery Techniques (EOR) and Their Efficacy

With the depletion of easily recoverable oil reserves, the global oil industry faces the challenge of maximizing extraction from existing reservoirs.

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Abstract

Enhanced Oil Recovery (EOR) has emerged as a pivotal set of techniques to increase the amount of crude oil that can be extracted from oil fields beyond what is achievable using primary and secondary recovery methods. This article explores the various EOR techniques, their mechanisms, effectiveness, technological advances, and associated challenges, providing a comprehensive understanding of their role in modern petroleum engineering.

1. Introduction

Petroleum extraction traditionally occurs in three phases: primary, secondary, and tertiary (or enhanced) recovery. Primary recovery uses the natural pressure of the reservoir or simple pumping methods to extract oil, typically recovering only 5–15% of the original oil in place (OOIP). Secondary recovery techniques, such as water flooding and gas injection, can improve recovery to around 30–50% of OOIP. However, a significant portion of oil remains trapped due to capillary forces, reservoir heterogeneity, and viscosity issues.

Enhanced Oil Recovery (EOR), also known as tertiary recovery, aims to extract an additional 10–30% of OOIP through advanced techniques. EOR encompasses a range of methods involving thermal, chemical, and gas injection processes that alter reservoir conditions to mobilize trapped oil. These techniques are increasingly important for extending the life of mature fields and improving energy security.

2. Classification of EOR Techniques

EOR methods are broadly classified into three major categories:

2.1 Thermal EOR

Thermal methods involve the application of heat to reduce the viscosity of heavy crude oil, making it easier to extract.

a) Steam Injection

•Steam Flooding: Continuous injection of steam into the reservoir to heat and displace oil.