Foothill zones give up their secrets

2D and 3D seismic reflection data acquisition and processing methods are today helping to optimize imaging, previously a major obstacle to exploration of foothill zones.

François Roure Expert Structural Geology and Basins Architecture & Thermicity francois.roure@ifpen.fr

For the last twenty or so years, IFPEN has been developing petroleum system simulation tools in tectonically complex zones. 2D kinematic modeling tools (Thrustpack and Ceres) have been developed to simulate the gradual formation of a tectonic prism.

2D incorporation of hydrocarbon generation, expulsion and migration processes by Ceres is now helping us to understand the distribution of excess pressures and predict hydrocarbon charge on regional transects as complex as the Albanides (see figure). However, the inversion of organic matter maturity data (Tmax and Ro) is insufficient here, since it does not enable simultaneous resolution of uncertainties related to the thickness of eroded series and paleo-heat flux values. Several analytical methods can be used to reduce these uncertainties and, in particular, the use of paleo-thermo-barometers, such as fluid inclusions, with the co-existence of aqueous inclusions and hydrocarbon inclusions in the same diagenetic cement enabling the paleo-temperature and paleo-burial (paleo-pressure) of reference points to be obtained.

Although the complexity of their structures will limit the use of the 3D tools currently being developed, foothills zones are still under-explored and likely to provide new hydrocarbon reserves. They will thus represent a natural laboratory ideal for studying the hydrodynamic properties of faults and validating new reactive transport tools for a long time to come.

Ceres modeling of the Albanides, demonstrating partitioning of fluids within the various tectonic units. The size of the arrows is proportional to the migration speeds, which range from 0.04 to 4.5 m per million years (Vilasi et al., 2009).

Publications

• N. Vilasi, J. Malandain, L. Barrier, J.P. Callot, N. Guilhaumou, O. Lacombe, K. Muska, F. Roure and R. Swennen, Fromoutcrop and petrographic studies to basin-scale fluid flowmodeling: the use of the Albanian natural laboratory for carbonate reservoir characterization, Tectonophysics, 474 (1-2), 367-392. DOI: 10.1016/j.tecto. 2009.01.033

• F. Roure, P. Andriessen, J.P. Callot, H. Ferket, E. Gonzales, N. Guilhaumou, N. Hardebol, O. Lacombe, J. Malandain, P. Mougin, K. Muska, S. Ortuño, W. Sassi, R. Swennen and N. Vilasi, The use of paleo-thermo-barometers and coupled thermal, fluid flow and pore fluid pressure modelling for hydrocarbon and reservoir prediction in fold and thrust belts, In G.P. Goffey, J. Craig, T. Needham and R. Scott., eds., Hydrocarbons in contractional belts, Geological Society, London, Spec. Pub., 348, 87-114. DOI: 10.1144/SP348.6 (2010)

>> See also IFPEN Publications database