CO2 injection for enhanced oil recovery in Bakken tight oil reservoirs

CO2 injection into tertiary oil reservoirs has been widely accepted as an effective technique for enhanced oil recovery (EOR), and has been used by the oil industry for over 40 years. Concerns over greenhouse gas emissions are leading to the investigation and realisation of its potential as a carbon storage method in recent years. With the right reservoir conditions, injection of CO2 into oil reservoirs can result in incremental oil recovery and permanent storage of CO2 in geological formation. The majority of previous and current CO2 EOR projects use low cost CO2 sources and have good economic returns in terms of high gas utilisation efficiencies (167-227 sm3 CO2 /STB oil). The potential of CO2 storage combining EOR is high; approximately 60% injected CO2 can be retained in the reservoir at the CO2 breakthrough if reinjection is not considered. It has been accepted that there is little major technical challenges for CO2 EOR projects, but there are economic constrictions if high cost anthropogenic CO2 (such as from power plant) is used for EOR and storage operations. In this chapter, a general review is given on the CO2 EOR and storage potentials, field screening and economic analysis. A case study for CO2 EOR application in a North Sea field is also presented.

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CO2 Eor and Storage in Oil Reservoir

Carbon dioxide (CO2) is the main compound identified as affecting the stability of the Earth’s climate A significant reduction in the volume of greenhouse gas emissions to the atmosphere is a key mechanism for mitigating climate change Geological storage of CO2, or the injection and long-term stabilization of large volumes of CO2 in the subsurface in saline aquifers, in existing hydrocarbon reservoirs or in unmineable coal seams, is one of the more technologically advanced options available A number of studies have been carried out and are reported here They are aimed at understanding the safety, physical and chemical behaviour and long-term fate of CO2 when stored in geological formations Until efficient, alternative energy options can be developed, geological storage of CO2, the subject of this volume, provides a mechanism to reduce carbon emissions significantly whilst continuing to meet the global demand for energy

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Geological storage of carbon dioxide

Advances in improved/enhanced oil recovery technologies for tight and shale reservoirs

Experimental study on water-rock interactions during CO2 flooding in the Tensleep Formation, Wyoming, USA

CO/sub 2/ can enhance the recovery of oil from porous rock by (1) solution gas drive, (2) swelling oil and reducing its viscosity, and (3) miscible effects. The most efficient use of carbon dioxide as an oil recovery agent is obtained at flooding pressures where miscible type displacement is achieved.The extraction of hydrocarbons (C/sub 3/ to C/sub 30/) from the crude oil in place by CO/sub 2/ at these pressures promotes a displacement efficiency which approaches 100%. This high displacement efficiency can be obtained at flooding temperatures below 200/sup 0/F and pressures below 3,000 psi with any crude oil containing appreciable hydrocarbons in the gasoline-light gas-oil range. Also, the process is applicable to waterflooded reservoirs which have been depleted of their gas and LPG components. The presence of methane in the injected CO/sub 2/ or in the reservoir oil reduces the overall recovery efficiency of the displacement process. A simple correlation is presented to determine the optimum displacement pressure for CO/sub 2/ floods.

V.A. Josendal

Papers

Mechanisms of Oil Displacement By Carbon Dioxide

Mechanisms of oil displacement by carbon dioxide