Li Q.,Petrochina |
Li Q.,High Sulfur Gas Reservoir Engineering Research Institute |
Zhong B.,Petrochina |
Zhong B.,High Sulfur Gas Reservoir Engineering Research Institute |
And 6 more authors.
Natural Gas Industry | Year: 2015
There are two main development modes for gas condensate reservoirs at present: depletion and gas injection. However, for the latter mode, little research was found on the reasonable gas injection time, that is, when should be the best time to commence gas injection. If it's being too early, the volume of the injected gas will be too much to afford economically; if being too late, severe condensed oil contamination will be resulted and both gas productivity and ratio of gas recovery will be highly lowered down. In view of this, a real core was selected from a condensate gas well and the proper gas injection time was studied by use of long-core displacement experiments. On this basis, a geological model was established to study the issue by numerical simulation and response surface method. The following findings were obtained. As for rich condensate gas reservoirs, the optimal injection time is when the reservoir pressure is reduced to be about the dew pressure. This will prevent a larger volume of condensate oil from precipitating, avoiding a significant decrease of gas well productivity and gas recovery ratio. As for lean condensate gas reservoirs, the reasonable injection time is when the reservoir pressure is lower than the dew pressure but higher than the maximum condensate dropout pressure. This can not only obtain a higher condensate recovery, but achieve a greater economic efficiency. It is also concluded that the earlier the gas is injected, the better the development efficiency will be, but a high economic benefit will be uncertain as a result. ©, 2015, Natural Gas Industry Journal Agency. All right reserved.