Unconventional resources are those that have been bypassed by conventional oil and gas recovery technologies for decades, because they were not considered economically feasible to produce. The improvements in geophysical and geochemical exploration, and drilling and completion technologies since the early 1990s have opened up vast new resources in the United States both onshore and offshore. Some unconventional resources are in hostile or challenging environments such as the Arctic tundra or deep water. Others are in regions of the U.S. that have not previously experienced extensive oil and gas development and thus lack infrastructure, and community and political support. This book is the only comprehensive treatment of these resources, covered in-depth by one of the most well-respected engineers in oil and gas today.