Abstract: It is difficult for complicated small fault block oil reservoir unit by many faults to commercial}cale operation by water injec-lion because of communication difference among wells, boundary seal, producing energy finite, producing energy falling soon dur-ing exploitation. It may be a kind of powerful method with CO₂ huff and puff forced production to this kind of reservoir. Thus ai-
ming at these complicated small fault block oil reservoir charac-teristic of geology and exploitation, on a basis of phase state analyses to the actual fluid of the oil well ,By carrying out CO₂ swell-ing experiment, drive mechanism of CO₂ huff and puff is confirmed. And by CO₂huff and puff' long core drive experiment,oil increasing production degree and time phase are confirmed.
Under that foundation geologic model and numerical simulation model of single well CO₂ huff and puff are established aiming at actual small fault block oil reservoir. After carrying out fitting to producing history before gas injection, sensitivity analyses are carried out of operation parameters during CO₂huff and puff forced production,it has been stress reviewed the influence of in-jection occasion and cycle injection rate to effect of increasing production of small fault block oil reservoir unit, saturation and pressure distributing of different injection occasion are analyzed.Thereby effective and optimal operation parameters of small fault block cell oil reservoir single well CO₂ huff' and puff forced pm duction are derived, and systemic indoor integrative evaluation method is supplied for project design of small fault block cell oil
reservoir single oil well CO₂ huff and puff.

Key words: small fault block oilreseivoir, CO₂ huff and puff, long core drive experiment, numerical simulation, injec-tion occasion