Once again, the NPC expects too much from enhanced oil recovery
(Note: Commentaries do not necessarily represent ASPO-USA's positions; they are personal statements and observations by informed commentators.)
In their 400+ page report “Facing the Hard Truths About Energy” (July 2007), the National Petroleum Council (NPC) projects that enhanced oil recovery (EOR) will contribute an enormous increment of total global supply of petroleum liquids. By any reasonable analysis, NPC’s projection of EOR production rates is unachievable.
EOR is the extraction of additional oil from fully developed fields, using a variety of methods beyond conventional waterflooding or gas injection, to maintain reservoir pressure. One major category of EOR is thermal recovery (typically steam injection) to recover heavy, viscous oil. Another major category is injection of carbon dioxide or nitrogen at miscible pressures to recover light oil in fields with special reservoir properties.
NPC’s graph on page 7 of the Executive Summary1 shows that worldwide EOR production would grow from 4.7 million b/d in 2007 to 20 million b/d in 2030. The graph also shows that total petroleum liquids production grows by 30 million b/d over the same time span. Thus EOR would account for half of the expected growth of liquids supply. Exploration potential and unconventional oil production account for the remainder.
NPC has a long history of expressing high hopes for EOR. They neatly summarize their earlier overly optimistic expectations for EOR in the U.S.
The NPC studied EOR in 1976 and 1984, and raised great expectations for domestic EOR activity (projecting 3 million and 2 million barrels per day, respectively). These expectations have not been met. Peak domestic EOR production occurred in 1992 at 761,000 barrels per day. Current activity is 680,000 barrels per day. In the interim, many technologies have been tried, but most failed. Two successes are CO2-miscible floods and steam (cyclic, steam-assisted gravity drainage [SAGD], and steam flood). 2,3
Nevertheless, NPC expresses faith that an array of new and improved technologies will bring more oil to the surface from old oil fields. For CO2 injection alone, NPC sees eventual recovery of 89 billion barrels (equivalent to about seven or eight Prudhoe Bay fields). However, NPC does not say how long such recovery would take. (At one million barrels per day, recovery of 89 billion barrels would take 244 years.)
Let’s compare NPC’s EOR projections for 2030 with the history of actual U.S. EOR. We will see that EOR must grow much faster and over a longer period than ever before if NPC’s projections are to become reality. The graph shown here summarizes 26 years of EOR production in the U.S.4
As NPC mentioned, the figure shows that domestic EOR production peaked in 1992. Other major features of the figure are:
- Chemically enhanced waterfloods evidently were the failures that NPC mentioned. EOR surveys show that hundreds of projects were attempted over 30 years, but only negligible oil was ever recovered.
- Thermal recovery (typically steam injection) dominated EOR early on, reaching a peak of 480,000 b/d in 1986, but fell to near 300,000 b/d by 2006.
- Gas injection under miscible pressures gained steadily over the years, finally exceeding thermal EOR in 2006 by producing 348,000 b/d.
EOR data from projects around the world are also readily available in the biennial surveys published by the Oil & Gas Journal. Countries with production from qualified EOR projects are: Canada, Venezuela, Columbia, Trinidad, China, Indonesia, India, and Turkey. Mexico’s massive nitrogen injection system for the Cantarell field is not a qualified EOR project because the system merely maintains reservoir pressure for secondary recovery.
The 2006 survey shows that EOR production from all projects in the world total 1.8 million b/d. This is a far cry from the nearly 5 million b/d that NPC shows as current production. It also means that worldwide EOR would have to balloon by a factor of 11 from 2006 to 2030 in order to achieve NPC’s projection.
By contrast, domestic EOR production grew by a factor of 2.3 during 1980 – 1992, but then slipped by almost 15% during 1992 – 2006. Domestic EOR projects appear to be vulnerable to the same principles of depletion as are primary and secondary recovery projects. In typical EOR projects, old wells are rehabilitated (perhaps converted to injection status), and new wells are drilled. New injection systems are constructed.
Because primary and secondary reserves have been largely exhausted, production rates from individual EOR wells are low, usually a small fraction of the rate of a flowing well that taps a previously undrilled reservoir. Production rates are typically highest during the early stages of an EOR project, and gradually taper off as oil saturation decreases in the reservoir. Eventually, any EOR project will run its course as production declines (and consequently, also revenue) until operating expenses match revenue. The project then reaches its economic limit, and is subsequently terminated.
In order for EOR production to grow, new projects would have to come on stream faster than declining production from older EOR projects. Thus, the industry was able to increase domestic EOR production until 1992. Thereafter, terminations and declining production from older projects apparently exceeded production from new projects, leading to the decline of domestic EOR production.
Again, by any reasonable analysis, NPC’s projection of EOR production rates is unachievable. Because the industry developed EOR technologies on U.S. oil resources since the 1960s, the history of domestic EOR serves as a leading indicator for EOR trends on a global scale. While we should expect some gains in the years ahead, all indicators point to a gradual increase, but nothing near NPC’s projected 11-fold increase.
An aspect of EOR that is seldom discussed is that recovery processes target oil fields with highly specific properties of reservoir rock and fluids. In brief, EOR processes are not universally applicable. With long years of research and field trials, the industry has developed two categories of EOR success.
- Thermal methods in highly permeable reservoirs containing heavy viscous oil
- Carbon dioxide or nitrogen injection at miscible pressures in reservoirs with poor permeability
The vast population of oil fields with light oil and good permeability generally have not responded to EOR efforts. Such narrow application does not bode well for NPC’s vision of 20 million b/d.
Future Commentaries here will trace the history of how the industry developed EOR technologies, where certain processes have succeeded, and where they have failed. We will see that the vast majority of EOR production comes from the two groups of fields with narrow ranges of reservoir properties described above. As a result, domestic EOR production is tightly clustered geographically: Kern County California and West Texas. In 2006 Kern County supplied 86.5% of thermal EOR in the U.S. while West Texas supplied 54.1% of miscible gas EOR.
Tom Standing began his career as a chemical engineer in refinery operations and later shifted to work as an engineer for the San Francisco water system. He is self-taught in the sciences of petroleum production, geology and geochemistry.
1. See Exaggerated Oil Recovery (ASPO-USA, July 19, 2007) to see the NPC's graph.
2. National Petroleum Council, “Facing the Hard Truths About Energy,” Chapter 3 (Technology) p. 22, July 2007.
3. Recent domestic EOR production is slightly lower. According to biennial EOR reports compiled by the Oil & Gas Journal, domestic EOR production (barrels per day) in 2002, 2004, and 2006 was 669,000, 663,400, and 649,300, respectively.
4. Oil & Gas Journal, biennial EOR surveys, published in April of even-numbered years.