About the blog: What Things Are Made Of


The United States relies on imports for dozens of commodities in everyday use. Often enough, that reliance is 100%. In this book I aim to provide awareness of the hidden geology and mineralogy behind common things, and to develop an appreciation for the global resource distribution that underpins our society. While concerns about oil import reliance are in the news every day, our needs for other minerals are comparable and are typically unknown even to technologically aware Americans.

Thursday, December 13, 2012

The price of lead

by Richard I. Gibson

from Wikipedia Commons (public domain)
It will come as no surprise: the basic driver of the price of lead is automobile sales in China. Lead's price had been stable for quite a few years at about 20 cents a pound; but in 2004 it doubled to 40¢ then to 60¢ in 2005. World economy made it volatile in '08-'09 but it peaked at about $1.50 in 2007-2008. It has remained volatile since but floating around $1.00 per pound, still driven mostly by the lead-acid battery business and by China's 25%-a-year increase in auto sales (at least from 2006-10 with a small dip for the global recession in 2009).

In the US in 2011 86% of lead went to lead-acid batteries. China produces about half the world's lead but is still a net importer. U.S. production amounts to less than 8% of world total, but the US is a net exporter. Mine production totaled about 345,000 metric tons of lead in 2011, worth about $918,000,000. The vast majority of U.S. lead production comes from Missouri and the Red Dog Mine in Alaska. Consumption of lead in the United States runs to about 1,500,000 metric tons a year, five times the mine production; the apparent shortfall is made up from recycling which accounts for 83% of U.S. lead consumption.

As a consequence of the high price of lead, a friend of mine can make a good profit by making 4-ounce lead sinkers for high-end fishing expeditions.
Historical Lead Prices - Lead Price History Chart
from InfoMine.com

Wednesday, December 5, 2012

Oil shale is not shale oil

by Richard I. Gibson

Jargon confuses, and confusing jargon confuses more of us. Oil shale is a rock, a solid rock, that contains some solid organic material called bitumen. It is not liquid. One does not simply drill a well into oil shale and produce oil. It’s more like a mining proposition, like the tar sands in Alberta, only more so—although there are ways of heating it up below the ground, converting that solid bitumen into something that can come up a drill pipe.

There are some oil shales that are oil source rocks, and then there are some other shales that may be even better source rocks, while most people would not call them oil shales. Source rock has enough organic material in it, and has had the proper geologic history, that nature has done the converting, maturing the organic material into actual liquid oil which may (if you are lucky) then migrate into some kind of trap, where explorers may find and produce it.

Some of the best oil shale in the U.S. is in the Piceance Creek Basin of northwestern Colorado. Much of the oil shale there formed in a large, long-lived lake that occupied the area especially during Eocene time, about 50 million years ago. Some estimates suggest more than a trillion barrels of oil in the solid bitumen of these rocks. The problem is you can’t turn it into liquid oil without a lot of heat—a lot of energy, and a lot of dollars. Oil shale in the U.S. is not an economic proposition at current prices. I’ve seen some things that say sustained prices around $85-$100 per barrel could make oil shale economic, but the other stumbling block is huge up-front costs to build the processing plants. Don’t hold your breath for oil shale as some panacea any time soon.

Gravity map, Railroad Valley Nevada
Shale as source rock is another matter. Here, nature does the work. A good example is the marine Chainman Shale of Nevada, laid down during Mississippian time around 330,000,000 years ago. There are places where this rock is up to 8% total organic carbon—really remarkable, given that good source rocks may be 1% or 2%, and some of the best source rocks in Saudi Arabia are typically 5% total organic carbon. The Chainman Shale is not generally a target for exploration, but as a source rock it is critical to the complex oil systems in Nevada. Nevada? Yep. One two-well field, Grant Canyon, produced around 6,000 barrels a day for quite a few years in the 1980s, the best onshore wells in the conterminous United States. That’s an astounding number when you realize that the U.S. average is 10 barrels per day per well. (Note that there are at least some possible reservoir targets in the Chainman, thin sand beds, but none have been proven and the Chainman is probably a source rock, not a reservoir.)

“Shale oil” is the phrase often applied to unconventional oil production, and the Bakken formation of North Dakota is the best example. It’s much less “unconventional” than real oil shale, because in shale oil, the oil is liquid. It’s just trapped in rocks that are very tight—meaning they have possibly abundant but often tiny pores to contain the oil, and their permeability, the ability of the oil to flow through the rock, is limited. So the way we try to exploit such deposits is not a simple vertical punch into the oil-bearing zone; you’d get precious little that way. Horizontal drilling is the common approach: drill down some 9,000 feet, make a right turn, then navigate your drill string through a 140-foot-thick zone that has oil—for another 9,000 feet. Fracture it to make the porosity better. That’s all expensive, but very doable, and that has turned North Dakota into one of the leading oil producing states in the U.S. in only a few years. Even so, the average North Dakota well only produces around 90 or so barrels per day.

So “oil shale,” or shale source rock, or “shale oil” – they are all really different!