An Evaluation Of The Feasibility Of Carbon Dioxide Flooding In Alberta Available to Purchase

Enhanced oil recovery by gas injection has been practiced by the oil industry for years. In immiscible recovery projects, the injected fluid maintains reservoir pressures and drives the oil towards producing wells. In miscible projects, the injected fluid and oil dissolve in one another, reducing the residual oil saturation which results in improved oil recovery.

The Petroleum Recovery Institute has focused attention on CO₂ as one of the fluids available as an injection agent in enhanced oil recovery processes. Use of the immiscible CO₂ process has been investigated in a Southeastern Alberta reservoir (1), while in Texas a full-scale commercial application has been in operation for several years (2). In addition, several other large CO₂ injection projects are being initiated in the U. S.

The Alberta department of Energy and Natural Resources commissioned Saturn Engineering Ltd. to undertake a study of the supply of CO₂ potentially available in Alberta and the cost of processing, compressing and transporting it to applicable oil reservoirs which are suitable for miscible flood recovery projects. The desired quantity of CO₂ may range upwards to 200 MMSCFD for full scale projects and for pilot scale field tests would be in the 10–20 MMSCFD range. The Pembina Cardium reservoir is considered a possibility for CO₂ flooding, hence Drayton Valley was chosen as the delivery point for the CO₂. The required quality of CO₂ for this study was assumed at 98 plus per cent, the remainder being mainly N₂ or H₂, depending on source.

This paper summarizes the results of our study of the cost of CO₂ extracted from various sources facilities. The CO₂ is used in the food and beverage industry, welding, oil well treating etc. Locally these plants are in the 1–2 MMSCFD range.

In some remote areas of the world, CO₂ is extracted from flue gas which is the product of combustion of natural gas. They commonly use monoethanolamine as the extraction solvent, followed by the steps listed above.

Prior to World War II, CO₂ was commonly recovered from coal or oil combustion flue gas (4). The standard facility consisted of water and limestone scrubbers to cool the flue gas and remove dust and sulphur compounds. CO₂ extraction using an alkali carbonate solvent in an absorption tower at atmospheric pressure followed by hot stripping to recover CO₂. Further processing consisted of water washing, permanganate treating, dehydration and compression.

1. Extractions of CO₂ from flue gas Extraction of CO₂ from flue gas is difficult and costly not only because the source gas is at atmospheric pressure but also due to the presence of sulphur oxides, nitrogen oxides, oxygen and ash. Preliminary investigations eliminated cryogenic separation, dry bed absorption or membrane type processing for CO₂ extraction because of very high energy requirements and/or lack of proven commercial experience. Conventional solvent treating was pursued in further detail. Physical solvents were ruled out because of the high cost of compressing the total flue gas upstream of the treater. Of the chemical solvents, the choices was narrowed to monoethanolamine (MEA) as most suited for this application.