Generally, the reservoirs with permeability lower than 50× 10-3µm2 is called low permeable oil field. Ansai oil field in which the average permeabihty is about 1.29× 10-3µm2 is classified as ultra-low permeable oil field. Despite many low permeable reservoirs were discovered in early days, they haven’t been effectively produced due to the complicated production technology and low profit. However, with the development of petroleum industry, the technologies of developing low permeable reservoirs have been improved, particularly, the progress of fracturing and water injection, the production of low permeable reservoirs has been rapidly developed. This paper aims to overview the reservoir, fracturing and water injection, describe the key methods used in production of Ansai ultra-low permeable reservoirs, including the results of water injection.

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