Horizon Oil Limited is an upstream oil and gas company. The principal activities of the Company is petroleum production, development, and exploration. It operates in three segments. Under China development segment, it is involved in developing and producing crude oil from the Block 22/12 - WZ6-12, WZ12-8W and WZ12-8E oil field developments and in the exploration and evaluation of hydrocarbons within Block 22/12. Under New Zealand development segment, it is involved in developing and producing crude oil from the Maari/Manaia oil field development. Under Australia development segment, it is involved in developing and producing oil and gas from the Mereenie OL4 and OL5 oil and gas fields. The Block 22/12 oil development comprises nine hydrocarbon pools across three different Production Licenses. It lies 35 kilometers (kms) southwest of Weizhou Island, China, in 30m water depth. The Maari oil field is a producing oil field. It lies 80 km off the south Taranaki coast in 100 m water depth.