25th International Meeting on Organic Geochemistry IMOG 2011

P-007
High resolution measurement of tarmat in cores using laser
pyrolysis
Daniel Dessort, Philippe Lapointe, Dominique Duclerc, Robert Le-Van-Loi
Total S.A., Pau, France (corresponding author:daniel.dessort@total.com)
Tarmat is a dark brown to black, thick, semisolid to
viscous mixture of heavy hydrocarbons enriched in
asphaltenes that occurs naturally in reservoirs.
Tarmat cannot be produced and is a nuisance
because it impacts on OIP assessment, on reservoir
quality (porosity, permeability, wettability...), on
development plans when tarmat forms permeability
barrier and on the response of electric logs.
Thus the Prediction and the Modeling of the vertical
and horizontal distribution of Tar mats require high
resolution & quantitative analysis.
Conventional core- or log-based methods for solid
bitumen analysis are not always satisfactory (poor
resolution and/or not reliable data).
The LIPS (Laser Induced Pyrolysis System) is a new
instrument developed by TOTAL. It performs the
automatic acquisition of quantitative and high
resolution (centimetric or sub-centimetric) logs of
organic carbon on cores (Tar mats, source rocks, oil
shales, gas shales).
The LIPS consists in:
1. One mobile bench carrying the core,
2. One power laser providing a continuous infra-red
laser beam through an optical fiber,
3. One 3D movable head which guides the laser
beam and collects the material expelled from the
core during the laser shoot,
4. One or more detectors which can be used for
analyzing the material pyrolyzed and expelled
from the core during the laser shoot (mass
spectrometer, PID, FID, sulphur detector…)
5. An acquisition and data processing system.
Typically one data point can be acquired every
minute.
The LIPS data are calibrated using the Rock- Eval in
reservoir mode allowing the quantitative analysis of
solid bitumen (sum of S2b peak + refractory organic
carbon). Thus, the results can be expressed as %
bitumen in whole rock or in porosity, when the
porosity is known.
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