NEW YORK (AP) — Here's a look at some key energy terms and technologies.
HORIZONTAL DRILLING: Companies used to drill wells straight down into the earth to tap pools of oil and gas that had formed over millions of years. Now they can drill down and then change the angle to follow thin layers of source rock, reaching more oil and gas with each well.
SOURCE ROCK: Wide, thin layers of sedimentary rock, like frosting in the middle of a layer cake, that are interspersed with oil and gas. In the past, drillers had to look for places where oil and gas had seeped out of this rock and into large pools that were easy to tap. Now drillers can extract oil and gas directly from source rock, opening up vast new resources.
FRACKING: The colloquial name for hydraulic fracturing. This is the practice of injecting water, sand and chemicals into source rock to crack it and create escape routes for oil and gas. Its increased use has raised concerns that the chemicals used could seep into groundwater, either through faulty wells or if it is not disposed of properly.
DOWN-HOLE SENSORS: Engineers have developed increasingly sophisticated sensors that follow drill bits and measure physical characteristics of the rocks and fluids underground. The information can be sent via fiber optic cable to engineers at the surface.
REMOTE DRILLING: Using computers, engineers can direct drill bits from command centers thousands of miles away. This reduces drilling costs.
WALKING RIGS: In the past, when rigs were finished drilling a well, they had to be disassembled and trucked to the next location, a process that took several days. Now some rigs can "walk" hundreds of feet on hydraulic shoes to the next drilling spot. This reduces drilling costs.