Valaris Limited (previously ENSCO-Rowan plc) is an offshore drilling contractor headquartered in Houston, Texas, and incorporated in Bermuda.

[1] In 1975, after the 1973 oil crisis, John R. Blocker bought Choya Energy, a six-rig contract drilling company based in Alice, Texas, and renamed the company Blocker Energy.

[3] In 1981 and early 1982, the company borrowed heavily to expand its fleet to 54 rigs.

[4] However, in late 1982, the price of oil plunged and, to avoid bankruptcy, Blocker Energy restructured, giving 64% of the company to its banks in exchange for $240 million in debt forgiveness.

[12] In October 2017, the company acquired Atwood Oceanics for $860 million and became the largest owner of jackup fleets worldwide.