ISSN 1996-1073 www.mdpi.com/journal/energies Review
Enhanced Oil Recovery: An Update Review
Vladimir Alvarado 1,* and Eduardo Manrique 2
Department of Chemical and Petroleum Engineering, University of Wyoming, Department 3295, 1000 E. University Ave, Laramie, WY, USA TIORCO (NALCO & STEPAN Company), 2452 Trenton Way, Suite M, Denver, CO 80231, USA; E-Mail: firstname.lastname@example.org
* Author to whom correspondence should be addressed; E-Mail: email@example.com; Tel.: +1-307-766-6464; Fax: +1-307-766-6777. Received: 27 June 2010 / Accepted: 10 August 2010 / Published: 27 August 2010
Abstract: With the decline in oil discoveries during the last decades it is believed that EOR technologies will play a key role to meet the energy demand in years to come. This paper presents a comprehensive review of EOR status and opportunities to increase final recovery factors in reservoirs ranging from extra heavy oil to gas condensate. Specifically, the paper discusses EOR status and opportunities organized by reservoir lithology (sandstone and carbonates formations and turbiditic reservoirs to a lesser extent) and offshore and onshore fields. Risk and rewards of EOR methods including growing trends in recent years such as CO2 injection, high pressure air injection (HPAI) and chemical flooding are addressed including a brief overview of CO2-EOR project economics. Keywords: enhanced oil recovery; EOR; reservoir lithology; CO2; steam injection; air injection; chemical flooding
1. EOR Status Most of the current world oil production comes from mature fields. Increasing oil recovery from the aging resources is a major concern for oil companies and authorities. In addition, the rate of replacement of the produced reserves by new discoveries has been declining steadily in the last decades. Therefore, the increase of the recovery factors from mature fields under primary and secondary production will be critical to meet the growing energy demand in the coming years.
Energies 2010, 3
Improved Oil Recovery (IOR) methods encompass Enhanced Oil Recovery (EOR) methods as well as new drilling and well technologies, intelligent reservoir management and control, advanced reservoir monitoring techniques and the application of different enhancements of primary and secondary recovery processes. However, the present paper presents a comprehensive review of EOR status and opportunities to increase oil recoveries and final recovery factors in reservoirs ranging from extra heavy oil to gas condensate. It is well known that EOR projects have been strongly influenced by economics and crude oil prices. The initiation of EOR projects depends on the preparedness and willingness of investors to manage EOR risk and economic exposure and the availability of more attractive investment options. In the U.S., chemical and thermal EOR projects have been in constant decline from mid 1980’s to 2005 (Figure 1). It is important to indicate that statistics on EOR activity is often masked because it goes unreported. In this article, all statistics and reports are based on available data from published articles, conference proceedings and other references. EOR gas injection project statistics remained constant since mid 1908’s and exhibited a growing trend since year 2000, especially with the increase of CO2 projects. Indeed, since 2002 EOR gas injection projects outnumber thermal projects for the first time in the last three decades. However, thermal projects have shown a slightly increase since 2004 due to the increase of High Pressure Air Injection (HPAI) projects in light oil reservoirs. Chemical EOR methods still have not captured the interest of oil companies with only two projects reported in 2008 [1–5,7–18]. However, there is an increase in EOR chemical projects in the U.S. and abroad that have not been documented in the literature for different reasons that will be...