What's new in production

 Vol. 232 No. 11

Only fairly recently have bituminous sands been counted as petroleum reserves. That’s ironic, because this thick, black, sticky goo was probably the first form of petroleum that mankind found to be generally useful. There is clear evidence that Paleolithic people used bitumen over 40,000 years ago. A natural waterproofing agent, bitumen was gathered and heated, then slathered on boats and buildings to make them watertight. Early Egyptians found the stuff to be particularly helpful in preserving the bodies of their deceased relatives. The word “mummy” is derived from the Persian word for bitumen.

While “pure” seeps of bitumen are known to exist, most often it is found in association with sand. As we know, bituminous sands are called “oil sands” by those who like them and “tar sands” by those who don’t. Bitumen isn’t tar and it isn’t oil, though it can be upgraded into crude oil. These deposits occur in such vast quantities that, given the economics and the price of oil, they are irresistible.

Heavy business. By far the most significant bitumen deposits are found in the Western hemisphere, in Venezuela and Canada. The Orinoco belt of Venezuela contains some 513 billion bbl of producible reserves, according to the US Geological Survey. This is usually called “very heavy oil” rather than bitumen because it is somewhat easier to refine.

Even this vast resource is dwarfed by Canadian deposits. These amount to some 1.75 trillion bbl of “technically recoverable” hydrocarbons found principally in the Athabasca-Wabiskaw, Cold Lake and Peace River deposits of Alberta, comprising 54,000 sq mi. The Canadian government estimates that about 10% of the bitumen is commercially recoverable.

Over 50% of Canada’s oil production is upgraded bitumen (synthetic crude), and this share will only increase as conventional discoveries level off and new technologies (and higher prices) make bitumen more commercially attractive. In-situ production methods are well-known and have been discussed in this magazine: cold flow using progressing-cavity pumps, which is cheap but practical only where the oil is warm and fluid enough to flow, or three-stage “huff-and-puff” production with repeating cycles of injection, soaking (to absorb heat) and production; and, in recent years, steam-assisted gravity drainage (SAGD), a two-well method using injected steam and solvents to move the viscous crude or bitumen to a lower well for recovery by pumps.

Still, up to 20% of Canada’s bituminous sands are close enough to the surface to be recoverable by shovel. This is the most efficient method and the most brutal. Overburden (also known as “the land”) is removed, and the sands are surface-mined and hauled away in trucks. Besides the impact on the land surface, which to date has affected about 212 sq mi in the Athabasca region, the process of separating bitumen from sand is very water-intensive. About 2–4 bbl of hot water is required to separate 1 bbl of bitumen, and another half a barrel is used in upgrading the bitumen to syncrude.

Contaminated water, containing various acids, salts, heavy metals, other chemicals and residual bitumen, eventually ends up in tailing ponds to settle, a process that can take many years (though there have been recent advances in accelerating tailings settlement). Every year there are many bird deaths, despite vigorous efforts to keep them from landing in the water.

Dry idea. Any extraction method that utilizes less water would provide obvious benefits. One of the most intriguing ideas, still in the experimental stage, uses no water at all to extract the oil, and only a tiny amount in the entire process.

Liquid solvents, whether water, petroleum ethers or alcohols, are molecular liquids. A whole other class of solvents is the ionic fluids, consisting mostly of ions and ion pairs. These ionic liquids or “liquid salts” are generally defined as salts that are liquid at or near ambient temperatures without evaporating or decomposing.

Earlier this year, a team of scientists from Pennsylvania State University announced an experimental method of extracting hydrocarbons from sand using an ionic fluid based on 1-alkyl-3-methylimidazolium cations. The fluid has several properties that make it suitable to remove oil from sand. It is positively charged, exhibits high thermal and chemical stability, and has almost no vapor pressure. The extraction process, developed by polymer science professor Paul Painter and his team, operates at room temperature and claims to remove 100% of the bitumen without producing any wastewater. Bituminous sand, ionic fluid and a small amount of organic solvent are mixed, quickly separating into distinct layers with clean sand at the bottom. The recovered bitumen is very pure. A small amount of water is used to remove the remaining ionic fluid from the sand and clay, but both the fluid and the water are completely recyclable.

“We started at the test-tube level, but now we’ve gone to a benchtop unit where we can separate kilogram quantities of bitumen from tar sands, and it seems to be working,” Painter told a Business News Network reporter. “The process is very simple, so scaling should not be a problem. It’s just that we’ve got to overcome things like the cost of the ionic liquid and develop other types of separation methods.”

Another potential use of the technique is beach cleanup. The Penn State group processed a sample of beach sand contaminated by the Macondo spill and reported that the sand was left clean enough to be returned directly to the beach.

A lot of promising technologies have come and gone. But with the US importing a million barrels a day from Canada, much of that syncrude, and with controversies growing ever more choleric, producers are looking seriously at ideas that hold the potential to make bitumen production cleaner. There’s a lot more at stake than whether your canoe leaks. 

henry.terrell@gulfpub.com