Unconventional Petroleum Resources and “Hubbert’s Peak”

Long-term predictions of world petroleum supply are generally risky at best. Such predictions are often in error since they do not account for new discoveries, volatile political climates, and the wide variation in oil prices over time.

There is one prediction that (until recently) was considered to be an accurate forecast of oil supply in the United States and in the World. In 1956, M. King Hubbert, a geophysicist with Shell Oil, predicted petroleum production in an oil-producing region would follow a bell-shaped curve. Following a point of maximum production, there would be a decline in oil production. This phenomenon has been known as “Hubbert’s peak”. For the United States, Hubbert predicted that peak conventional oil production would occur in the 1965-1970 interval, and it did apparently occur in 1971. In 2005, U.S. imports accounted for about 60% of consumption. Hubbert’s prediction of a peak in global oil production was to occur early in the 21st century – at about the present time.

However, today it seems that Hubbert’s predictions may have been pessimistic. As shown in Chopra et al. (2010 SEG book entitled “Heavy oils: Reservoir characterization and production monitoring”) world oil production continues to increase – lagging slightly behind consumption. Some experts are also predicting that the United States may become energy independent in oil and gas in the next 10 years through conservation and increased production. What has changed?

The answer lies in unconventional resources – including heavy oil, tight gas and tight oil. During Hubbert’s time, these unconventional resources were not anticipated to be major contributors to world oil production.

In heavy oil and bitumen production, Canada has immense reserves – in excess of a trillion barrels with 300 billion barrels believed to be recoverable. Venezuela may be the only country with comparable reserves in heavy oil. Alberta has been a leader in pioneering enhanced heavy oil recovery, both in mining and in the use of in-situ recovery methods such as steam-assisted gravity drainage (SAGD), and cold heavy oil production with sand (CHOPS). This March issue of the CSEG RECORDER includes a paper by Kelly and Lawton on seismic monitoring of a SAGD project in Northern Alberta. There is also a contribution by Lines and Alam on methods that can aid in modeling of seismic data, well logs (synthetic sonic logs), and the modeling of core samples. Their examples are from a CHOPS field in Saskatchewan. A paper by Wikel and Kendall describes a 4D-3C seismic monitoring of heavy oil recovery by an in-situ recovery method known as Toe to Heel Air Injection (THAI).

These are important projects since heavy oil now constitutes more than 50% of Canadian production and will likely continue to increase in the future. In addition to the technical challenges of production, there continue to be environmental and economic challenges for heavy oil.

In North America, we also now see the production of oil and gas from formations whose permeability was once considered impermeable or “tight”. The production of tight gas and tight oil has recently revolutionized the American petroleum production picture. These plays are also important in Western Canadian oil production as outlined in a paper in this issue by Solano, Clarkson, Krause, Aquino and Wiseman.

Technology has improved our ability to characterize unconventional reservoirs.

In this issue, Leiceaga, Norton, LeCalvez and Henery predict capacity in individual fields using seismically derived parameters.

The optimum placement of wells in unconventional reservoirs using rock physics is described by Marco Perez.

In summary, it seems that Hubbert’s predictions were very good for that period of history where conventional petroleum resources were produced. However, all has changed with the advent of unconventional petroleum resources. This issue covers some of these exciting developments.