Combination Effect of in-Situ Combustion and Exhaust Gases Recirculation on 1D Combustion Tube: Numerical Approach

ABSTRACT

Despite the widespread use of renewable and green energy, the demand for fossil fuels is also rising due to increasing global energy demand. Therefore, unconventional solutions, with safe environmental impacts, are being pursued to solve this problem. Instead of getting rid of the exhaust gases in the surroundings, one solution might be to inject them with the oxidizer into the oil reservoir, to initiate an in-situ combustion (ISC) process to enhance oil recovery. A numerical study of a 1-D combustion tube has been conducted and validated to simulate the in-situ combustion process using enriched air as the oxidizer. The effects of injecting exhaust gases with the oxidizer are studied. Different ratios of oxygen to nitrogen are used in the enriched air as well as different ratios of exhaust gases. If enriched air which is mostly oxygen, i.e. 95% O₂ +5%N₂, is used, it is found that replacing 10% of the enriched air with exhaust gases can increase the oil recovery factor (ORF) from 94.7% to 94.9% and replacing 20% can improve oil recovery to 95.1%. For another enriched air, 60% O₂ +30% N₂, it is found that replacing portions of the enriched air with exhaust gases will reduce the oil recovery factor. In all previous cases, it was found that replacing the proportions of enriched air with exhaust gases reduces the amount of fuel burned and increases hydrogen production.

KEYWORDS:

• In-situ combustion
• oil recovery factor
• exhaust gases

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary data

Supplemental data for this article can be accessed online at https://doi.org/10.1080/00102202.2023.2239480

Nomenclature and abbreviations

${\mathrm{C}}_s$	=	Total solid concentration
EG	=	Exhaust gases
EA	=	Enriched air
hj	=	The enthalpy of phase j
h*j	=	The enthalpy of phase j at injection or production
k	=	Permeability
kr	=	Relative permeability
ORF	=	Oil recovery factor
qhc	=	The heat loss source/sink term.
rik	=	The rate of kth reaction
Sj	=	The saturation of phase j and xij is mole fraction of component i in phase j.
T	=	Absolute temperature
U	=	The internal energies as a function of temperature and phase composition
Ur	=	Energy per rock volume
u	=	Velocity component
Vj	=	Velocity
wi	=	The well productivity index
${\mathrm{x}}_{ij}$	=	Mole fraction of component i in phase j
z	=	Gridblock thickness
$\rho$	=	Fluid phase density
λ	=	Thermal conductivity of the formation
π	=	Number of phases
${\theta }_j$	=	Mass production rate per unit volume
$\phi$	=	Porosity
${\mu }_j$	=	Viscosity of the fluid