HUFF AND PUFF PROCESS UTILIZING NITROGEN GAS

摘要

A cyclic or "huff and puff" enhanced oil recovery process utilizes purified nitrogen gas as the injection gas. The purified nitrogen gas is preferably generated near the well site by the use of a membrane separator. The resulting purified nitrogen gas comprises at least about 90% by volume nitrogen with the remaining gas mixture fraction being primarily oxygen. The producing well is shut in. The gas mixture is injected down through the well into the formation. The well is then shut in allowing the gas mixture to soak into the formation for a predetermined period of time of at least 7 days and in some cases as much as 180 days or more. Then the well is placed on production and additional hydrocarbons are produced back from the same well into which the nitrogen gas was injected.