Abstract: In order to improve the reservoir development effect of Triassic Yanchang formation in Changqing oil-field and enhance the producing to proven reserves ratio,based on the corresponding oil field development experiences at home and abroad, the authors have, through much investigation and practices, discovered a new method of improving the single-well production and developing the ultra-low permeability oilfield effectively,namely the water-drive development method of advance water injection, injectionfirst, then recovery, to compensate the formation energy properly and to crease the formation pressure,thus maintaining a relatively high formation energy and strong productivity of the oil wells in a long period, and minimizing the production decline. Meanwhile, this method can prevent the physical property of the crude from turning bad, ensure the open conduit of oil flow channel, expand the sweep volume of injected water effectively and eventually maximize the development economic benefit of the ultra-low permeability reservoirs in . Triassic Yanchang formation in Changqing oilfield.

Key words: Ordos basin, Triassic, low permeability pools, development test