During the Tenth Five-Year Plan(2001-2005)

the reserves of Tahe oilfield reached 1.638772 billion tons of oil equivalent

in which the proved reserves is 522.2601 million tons of oil equivalent.The boundary of the Ordavician reservoirs in Tahe oilfield expands steadily with its target strata and exploration areas also increasing.The main achievements in oil and gas exploration can be boiled down to the following 'three breakthroughs': ①the exploration of the Ordovician in new regions in Tahe oilfield is realized by basing on identification of the main controlling factors of development and distribution pattern of the Ordovician paleokarst reservoirs;②the exploration of new clasitic rock sequences is actualized

enlarging the exploration area in Tahe oil field;and ③the exploration of new types of traps is achieved with attainment of commercial oil and gas flow in non-anticlinal traps.Meanwhile

great achievements are also made in exploration concepts: ①estaclishment of the theory of hydrocarbon accumulation in fractured-vuggy paleokarst reservoir lays the foundations for the finding of oversize Tahe oilfield

②discovery of the middle Caledonian karst provides a scientific basis for the southward expansion of Tahe oilfield

③development of theory of multiple hydrocarbon accumulation effectively guides the exploration of clastic rocks

and ④the concept of 'frontal uplift and the slope controlling hydrocarbon accumulation'guides the exploration in the southern margin of Tianshan and contributes to the discovery of a number of new traps

putting a cornerstone for the sustainable development of SINOPEC Northwest Petroleum Branch Company.