Nabors Alaska Drilling and its predecessor companies drilled the discovery well and confirmation wells on the Prudhoe Bay field. The company has been a leading North Slope contractor since 1963. It holds many of the drilling records in Alaska and was one of the pioneers in horizontal drilling, which was initially applied full-scale on the North Slope. The company is a subsidiary of Nabors Industries, which owns and operates nearly 600 land drilling and 970 land workover and well servicing rigs throughout the world. Offshore, Nabors operates more than 40 platforms, 17 jack-ups and three barge rigs in the domestic and international markets. It also markets 30 marine transportation and support vessels, primarily in the Gulf of Mexico. Nabors Alaska Drilling is located in Anchorage, Alaska.