Not available at the moment <a href=" http://www.hearthandmade.co.uk/nexium-esomeprazole-obat-apa.pdf ">nexium false positive drug test</a> A key factor behind the development of new resources is the relatively high global price for oil. Extracting oil from "unconventional" sources such as "tight" rocks like shale costs more than from traditional reservoirs - and requires far more energy - so only becomes viable at certain price levels.