(305c) Synthetic Cores for Measuring Carbon Monoxide Concentration During in Situ Combustion

Synthetic cores for measuring carbon monoxide
concentration during in situ combustion

Henry
Copete¹, Yurladys Cross¹, Hania Hernández¹, Juan Duque¹, Sergio
Lopera²,  Alejandro Molina^1,*

¹Universidad Nacional
de Colombia - Sede Medellín, Facultad de Minas, Bioprocesos
y Flujos reactivos

²Universidad
Nacional de Colombia ? Sede Medellín, Facultad de Minas, Yacimientos de
Hidrocarburos

^* Corresponding author: amolinao@unal.edu.co

A procedure for the preparation of
synthetic cores that guarantees mineralogy, porosity and permeability similar
to those of a reservoir where in situ combustion (ISC) takes place was
developed. The cores are packed in a reactor with optical access, designed for
operation at conditions up to 40 bar and 900 K and allow the measurement of
chemical species concentration with laser techniques through a grove in the
porous core.

ISC consists of injecting an
oxidizing gas (air or oxygen-enriched air) into the well and igniting the air/oil
mixture to generate heat and increase the temperature to decrease the viscosity
and facilitate the extraction of heavy crude oil. In the past 30 years research
on ISC has been very active^{1, 2}. Although there are different
theoretical and experimental studies that addressed the different phenomena
involved, there are still many unexplained concepts inherent to the complexity
of exothermic reactions, temperature-dependent chemical kinetics and heat and
mass transfer processes.^{3, 4}

The state of the art of chemical
mechanisms for ISC presents little detail of the species involved in the
process. A better understanding of the chemistry of the process may be obtained
with laser diagnostics, a non-intrusive technique that has been fundamental in
the understanding of the chemical processes involved during combustion process
such as engines or high pressure burners and that may be applied in the study
of heavy crude oil chemical reactions. This study describes the procedure for
the conformation of sand cores that can be used during laser characterization
of in situ combustion.

The synthetic core was formed from a
mixture of sands, clay and water by packing unconsolidated sands distributed in
different sizes (40 mesh, 60 mesh and 100 mesh), a lower proportion of clay
(325 mesh ) and water. The content of silica and kaolinite clay minerals was
maintained at 80% ? 85 % and 10% - 15 % (wt. %) respectively. Permeability and
porosity were reproduced with variations lower than 10% of the original
reservoir composition. The procedure guaranties an initial
average oil saturation as high as 80%.

Table 1. Composition of synthetic cores

The materials were weighed in a
precision balance, uniformly mixed and packed in a compression machine at
controlled pressures. The synthetic cores have a diameter of 38.1 mm and 100 mm
length. Grooves inside the core, formed during the construction process, allow
optical access for the detection of chemical species using laser diagnostic
techniques such as carbon monoxide measurement using Tunable Diode Laser
Absorption Spectroscopy (TDLAS).^{5, 6, 7, 8} Figure 1 illustrates the
TDLAS experimental setup for the quantitative measurement of the carbon
monoxide concentration in the ISC process.

Figure 1. Proposed TDLAS experimental
setup

REFERENCES

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Combustion Modeling. SPE Advanced Technology Series, 1(1):98?107, 1990.

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E. A Theoretical and Experimental Study of Combustion Tubes.
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