Extensive drilling was done in the Canadian Arctic during the 1970s and 1980s by such companies as Panarctic Oils Ltd., Petro Canada and Dome Petroleum. After 176 wells were drilled at a cost of billions of dollars, a modest of oil were found. None of the finds were big enough to pay for the multibillion-dollar production and transportation schemes required to bring the oil out, so all the wells which had been drilled were plugged and abandoned. In addition, after the Deepwater Horizon explosion in the Gulf of Mexico in 2010, new rules were introduced which discouraged companies from drilling in the Canadian Arctic offshore.