Abstract: Enhance Oil Recovery (EOR)is one of the permanent top-ics in research on Oil/gas reservoir development. Because of low oil price, the demand for chemical drive is keeping decreasing and for gas drives increasing. The reservoirs in East China oil fields are non-marine deposits with Serious heterogeneity and high viscosity crudes, Water Cut increases very fast, recovery by water drive is relatively low, only 33%.The reserve discov-
ered recently is difficult to produce because of low permeability of the reservoirs and high viscosity of the crudes, streathening gas injection for enhanced oil recovery has become an urgent strategy in on shore petroleum industry development. China launched the evaluation in the second time on tertiary recovery potential in 1998.By statistics, the geological reserve suitable
for gas injection(CO2) miscible flooding is over 10.57×108 tons. By combination of foreign experience and the analysis and evaluation on China’s tertiary recovery potential, it is recog-nized that the oil fields in east china oil- bearing provinces should streathen non-gas drive and the oil field in west china should be hydrocarbon drive dominant. The key to gas drive is
gas resource, the discovery of CO2resource should be placed at-tention to, and the technology to generate N2and CO2, inject and sperate N2should be probed. The development of compres-sion facility-home made, pilot tests of gas drive and dry gas recycle for gas condensate reservoir with rich condensates should be speeded up.

Key words: Enhanced oil recovery, Gas Injection, Misci-ble flooding