Post SAGD In-Situ Combustion: Potentials and Challenges
- Seyed Javad Paitakhti Oskouei (University of Calgary) | Robert Gordon Moore (U. of Calgary) | Brij B. Maini (U. of Calgary) | Sudarshan A. Mehta (U. of Calgary)
- Document ID
- Society of Petroleum Engineers
- SPE Heavy Oil Conference Canada, 12-14 June, Calgary, Alberta, Canada
- Publication Date
- Document Type
- Conference Paper
- 2012. Society of Petroleum Engineers
- 1.2.3 Rock properties, 4.1.5 Processing Equipment, 5.3.9 Steam Assisted Gravity Drainage, 5.7.2 Recovery Factors, 6.5.2 Water use, produced water discharge and disposal, 5.2.1 Phase Behavior and PVT Measurements, 5.4.6 Thermal Methods, 5.1.1 Exploration, Development, Structural Geology, 1.10.1 Drill string components and drilling tools (tubulars, jars, subs, stabilisers, reamers, etc), 5.4 Enhanced Recovery, 2.4.3 Sand/Solids Control, 5.8.5 Oil Sand, Oil Shale, Bitumen, 5.5.2 Core Analysis, 5.3.4 Reduction of Residual Oil Saturation, 4.3.3 Aspaltenes, 4.2.3 Materials and Corrosion, 4.1.2 Separation and Treating, 4.3.4 Scale
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In Situ Combustion, ISC, is a process with strong potential to compliment Steam Assisted Gravity Drainage by extending the economic life of the SAGD pattern and hence improving the ultimate recovery. Implementing In-Situ Combustion, as a follow-up process to SAGD can improve recovery from the pattern by displacing residual oil from the steam chamber and more importantly by recovering oil from the wedge zones. Theoretically the temperature and residual oil saturation within the SAGD chamber are high enough to initiate and sustain the combustion process by switching from steam to air injection; however laboratory investigations of the hybrid process have shown that the in situ combustion behavior within the steam zone has some special features which must be considered.
Injection of air into the SAGD injection well is the desired option from an economic view point, however laboratory tests showed that the combustion zone tended to be more stable when air was injected at a location higher up in the chamber. This behavior relates to the fact that the combustion reactions were primarily occurring within the vapor phase, hence gravity plays a dominant role controlling the distribution of air flux within the chamber as well as the drainage of oil and water out of the combustion zone. Laboratory tests also confirmed the importance of promoting air flux across the walls of the original steamed chamber.
Steam Assisted Gravity Drainage, SAGD, is an economically proven technology to recover bitumen from oil sands reservoirs. Although SAGD has had a successful history in Alberta, it has still a huge potential to be improved by combining with other recovery methods. Non-depleted wedge zones after SAGD process contain almost 30-40% of original oil in place within the pattern however they do not have enough gravity head to create oil flow into the production well at an economical rate.
Therefore, there is a huge potential for a complimentary recovery method to follow up the SAGD process and displace both residual oil within the mature SAGD steam chamber and the oil within the wedge zone. Although the complimentary method will be able to take the advantage of thermal energy retained within the pattern, it will be challenged by the modifications left behind by the initial recovery method in the reservoir properties. Primary recovery method, SAGD, will change reservoir properties as follows:
- Water saturation will be significantly changed especially within the steam chamber region due to steam condensate.
- Permeability will be modified within the matrix due to thermal effect of SAGD on the rock properties.
- Reservoir heterogeneity will be modified due to change in the shale layers properties.
- A layer with gas saturation may form beneath reservoir overburden.
|File Size||6 MB||Number of Pages||19|