Nexen, formerly known as Canadian Occidental Petroleum Ltd., is an international oil and gas company with headquarters in Calgary, Alberta. Along with petroleum resources, the company has a chemicals division. The company has offices in Canada, the US, South America, Africa, Asia and the Middle East. It has three core businesses: Conventional Oil and Gas, Synthetic Crude Oil and Chemicals. In its Oil and Gas segment, the Company explores for, develops and produces crude oil, natural gas and related products around the world. Its core operations are onshore in Yemen and Canada, and offshore in the United States Gulf of Mexico and Australia.