Summary
In-Situ Combustion. In-situ combustion (ISC) is an enhanced
oil-recovery method. Enhanced oil recovery is broadly described as a group of
techniques used to extract crude oil from the subsurface by the injection of
substances not originally present in the reservoir with or without the
introduction of extraneous energy (Lake 1996). During ISC, a combustion front
is propagated through the reservoir by injected air. The heat generated results
in higher temperatures leading to a reduction in oil viscosity and an increase
of oil mobility. There are two types of ISC processes, dry and wet
combustion.
In the dry-combustion process, a large part of the heat generated is left
unused downstream of the combustion front in the burned-out region. During the
wet-injection process, water is co-injected with the air to recover some of the
heat remaining behind the combustion zone. ISC is a very complex process. From
a physical point of view, it is a problem coupling transport in porous media,
chemistry, and thermodynamics. It has been studied for several decades, and the
technique has been applied in the field since the 1950s. The complexity was not
well understood earlier by ISC operators. This resulted in a high rate of
project failures in the 1960s, and contributed to the misconception that ISC is
a problem-prone process with low probability of success. However, ISC is an
attractive oil-recovery process and capable of recovering a high percentage of
oil-in-place, if the process is designed correctly and implemented in the right
type of reservoir (Sarathi 1999).
This paper investigates the effect of water on the reaction kinetics of a
heavy oil by way of ramped temperature oxidation under various conditions.
Reactions. Earlier studies about reaction kinetic were conducted by
Bousaid and Ramey (1968), Weijdema (1968), Dabbous and Fulton (1974), and
Thomas et al. (1979). In these experiments, temperature of a sample of crude
oil and solid matrix was increased over time or kept constant. The produced gas
was analyzed to determine the concentrations of outlet gases, such as carbon
dioxide, carbon monoxide, and oxygen. This kind of studies shows two types of
oxidation reactions, the Low-Temperature Oxidation (LTO) and the
High-Temperature Oxidation (HTO) (Burger and Sahuquet 1973; Fassihi et al.
1984a; Mamora et al. 1993). In 1984, Fassihi et al. (1984b) presented an
analytical method to obtain kinetics parameters. His method requires several
assumptions.
© 2009. Society of Petroleum Engineers
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History
- Original manuscript received:
2 June 2008
- Revised manuscript received:
16 October 2008
- Manuscript approved:
17 October 2008
- Published online:
19 February 2009
- Version of record:
9 September 2009
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