As the major fields which have been the mainstay of global production mature there is a need to apply new technology and recovery techniques to extend field life and maximize economic recovery. As a result, there is growing interest in EOR. For the light oil reservoirs in the Middle East this leads to consideration of two main technology groups: miscible gas injection and chemical flooding. However the relatively high reservoir temperatures and salinity and the shortage of low cost hydrocarbon gas in many countries has so far restricted the application of EOR. The two main technology groups require different solutions to create commercial EOR systems suitable for application in the region and this paper maps out the key barriers and how they may be overcome.
For gas injection, while there are significant differences in the subsurface conditions compared to many existing projects, the key issue is the availability of miscible gas at an acceptable price for EOR. Many countries are hydrocarbon gas short, and those with the capacity to export have access to high prices through LNG or GtL value chains. The focus for gas injection is therefore the use of CO2, which is relatively abundant in anthropogenic emissions, but generally expensive to capture. Value chains linking industrial sources of CO2 to appropriate field targets are expected to be the key enabler of CO2 EOR, initially from niche sources. Robust technical and non-technical integration across the capture-transport-injection chain is required, to ensure that the potentially competing operational requirements for capture and EOR usage are reconciled, and that commercial and regulatory considerations are addressed. Existing and emerging CO2 capture options will be described and illustrated with experience from the development of CO2 value chains for projects such as Boundary Dam, Quest and Peterhead.
For chemical injection the principal challenge to overcome is the impact of the harsh reservoir conditions due to temperature and high salinity, compounded with the impact of carbonate lithology in many of the major reservoirs in the region. The development of enhanced waterflood techniques in which the TDS and ionic composition of the injected water is manipulated may give incremental benefits in itself, and also create more amenable conditions for follow-up chemical flooding. The challenge of effective sweep with modified brines, given the viscosity and density differences relative to formation brine, requires careful assessment. New polymers and surfactants are expanding the technical window of opportunity, currently chemical EOR in these environments is still commercially challenged.
EOR technology to allow cost effective recovery of remaining oil saturations after waterflooding will eventually have large scale application in the region. Both technology groups have the potential to deliver this prize, but by following different development thrusts, focusing on the surface capture issues for CO2 and the subsurface issues for chemical flooding. In the coming decade technology development and piloting in the field will show the likely scale of future application of the different EOR technologies. An integrated system approach to miscible gas and chemical EOR highlights the key technology challenges and provides a roadmap to develop commercial EOR systems.