[Dr. Scott W. Tinker] The traditional way to find oil was to look for large reservoirs, but in fact, oil is not found in a big tank. It's found in rocks that look like this, with billions of tiny connected pores. We drill a straight well pressure from the overlying layers squeezes the oil up the drill string to the surface. But many of these reservoirs have been found, so we're looking for new ways to find oil in rocks like this. The oil here migrated from the source rock here, which we know was once organic mud. This rock, too, contains tiny pores, but they're so microscopic the producers had no way to get the oil out economically. With horizontal drilling and fracturing directly in this layer, we're producing oil from so-called unconventional reservoirs directly from the source rock. And there are other new sources of oil like oil shale, which looks like this. The organics here- dead plankton- have transformed into kerogen, the precursor to oil, and we can heat this to convert it to oil. And there's also heavy oil or oil sands. This stuff won't flow. You may have heard about it in Canada, where it's near the surface it can be mined and then heated, and the oil is released. Most are deeper, though, and are recovered with a cleaner process that heats it underground by pumping in steam and then pumping out oil and water. These processes have environmental concerns: they use a lot of water, and they need a lot of heat. That usually comes from natural gas and their emissions from burning it. In terms of CO2, these processes emit 5 to 20% more than conventional oil. They're also significantly more expensive. When oil prices are high enough, companies can afford to produce this unconventional oil.