Crude oil is organic matter (mostly plant life, even though it’s common and fun for people to refer to it as dinosaurs, most of the biomatter was flora) that decayed. Then sediment was deposited over the material via geological accumulation, layers and layers of sediment, thousands of feet’s worth exerted pressure on this matter due to weight. 
This pressure causes chemical chains in the hydrocarbons to change and form properties that store incredible amounts of energy, which can be released when burned. In addition to the energy stored, it also contains compounds that contain vast amounts of nitrogen, which can be used in fertilizer as well as other organic compounds.

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Reported as rig counts, the figures from Baker Hughes show investors may be responding to improved market conditions by spending more on exploration and production. There's a long lag time between when rig counts would translate to actual production, though U.S. output is already above 9 million barrels per day.