Penn West Petroleum Ltd. (Penn West) is an exploration and production company. The Company operates in the segment of exploring for, developing and holding interests in oil and natural gas properties, and related production infrastructure in the Western Canada Sedimentary Basin directly and through investments in securities of subsidiaries holding such interests. Penn West owns the petroleum and natural gas assets or over 100% of the equity, directly or indirectly, of the entities that carry on the remainder of the oil and natural gas business of Penn West, except for an unincorporated joint arrangement (the Peace River Oil Partnership). Penn West's subsidiaries hold approximately 55% interest in the Peace River Oil Partnership. Penn West operates under the trade names of Penn West and Penn West Exploration. Based in Calgary, Alberta, Penn West operates a portfolio of opportunities with a position in light oil in Canada on a land base encompassing approximately four million acres.