The concept of using the nitrogen from an air separation plant for enhanced hydrocarbon recovery and the oxygen for sulphur production is reviewed. An area within the Province of Alberta 1st identified where the potential exists for using both nitrogen and oxygen from an air separation plant.
For oxygen-based sulphur recovery, both the classic oxygen enrichment process and the 1987 Kirkpatrick award winning COPE ™ process are reviewed. The limitations of the classic oxygen enrichment process to ach1eve high levels of oxygen enrichment for rich acid gas feeds are described. It is shown how the COPE process overcomes these limitations.
Nitrogen injection and rejection costs are presented For the case in which nitrogen is the primary economic driving force for a project to recover hydrocarbons. For this case, the economic benefits of using the oxygen vent in existing or grass roots sulphur recovery plants is presented.
Oxygen costs are presented for sulphur recovery plants where the use of oxygen is the primary economic driving force For a project to recover sulphur In this case, it is shown that the nitrogen vent can be upgraded at a low incremental cost for use in hydrocarbon recovery.
North America contains vast reserves of conventional crude oil, heavy oil, oil sands, and natural gas containing sulphur in the form of hydrogen sulfide. In order to produce these reserves economically, industry is constantly investigating the application of new methods to enhance production.
One relatively new development in the recovery of conventional crude oil, reported by Chemical Week1 in 1977, was the use of cryogenically produced pure nitrogen instead of methane or inert gas (generated by burning natural gas) for enhanced oil recovery. In July of 1978, Wilson2 presented extensive work comparing the process and economic factors associated with the production of an inert gas for injection into a reservoir. The work of Donohoe and Buchanan3, published in October 1978, gives cost information for cryogenically produced nitrogen and also installed cost information for nitrogen rejection plants. The rejection cost information is important in any application where nitrogen is injected because the injected nitrogen will eventually "break through" and must be rejected from the produced gas to make a pipeline quality sales gas.
While there is a wealth of information on the application of nitrogen injection and rejection in the literature, most of the papers deal with lab studies4,5,6, computer simulations7, reservoir engineering8,9,10,11,12, or technology related to the rejection of nitrogen from produced gas13,14. Rice and Van de Graaf15 presented a comprehensive paper which describes Exxon's integrated nitrogen injection and rejection project at the Jay-Little Escambia Creek Field near the Florida and Alabama border.
The use of nitrogen for enhanced oil recovery has grown since the late 1970's and has been applied primarily in the "lower 43" United States. In their June 1985 paper, Clancy et al.16 provide a list of 33 reservoirs which have used, or are using, nitrogen injection technology, and mention the use of a nitrogen rejection plant at the Willesden Green Field, which is located in Alberta.
