Recovery of oil from an oil reservoir by miscible displacement

摘要

Oil from an oil reservoir and subsequently from several oil reservoirs is recovered by injecting, in a first stage, a displacement agent in a gaseous state into the oil reservoir. Afterwards, in a second stage, there is withdrawn 90% of the displacement agent from the oil reservoir together with water through the wells. In a third stage there is injected into a second oil reservoir this withdrawn displacement agent, after water separation and drying and compression of the agent. As in the aforementioned stages 1-3 there is withdrawn from the second oil reservoir 90% from the displacement agent left in this oil reservoir which may be injected into the third oil reservoir, etc. The entire (overall) amount of the displacement agent used is half of the amount used according to previously known processes. At the end one recovers the used displacement agent. Initially one may even use a mixture of displacement agent with impurities that are purged by the injection process itself in the first oil reservoir.