An oil well is defined as producing less than 6,000 cubic feet of natural gas for each barrel of oil produced in a year. Vertical wells include directionally drilled wells and wells with an unknown drilled method. Oil wells drilled horizontally through hydrocarbon-bearing formations are often among the most prolific oil wells in the United States. Although modern horizontal drilling achieved commercial success in the 1980s, drilling techniques have improved, and in recent years, horizontal drilling has become more common. Geologic formations are almost always much greater in horizontal extent than they are in vertical thickness. For this reason, more oil-bearing rock is exposed for production in horizontal drilling than in vertical drilling. Horizontal wells are often completed in combination with hydraulic fracturing to maximize production along the exposed rock formation. In 2015 nearly 77% of the most prolific U.S. […]