Francois Roure¹, SUBTRAP Team¹

(1) Institut Francais du Petrole, Rueil-Malmaison Cedex, France

ABSTRACT: Critical Parameters Controlling Reservoir Quality in Foreland Fold-and-Thrust Belts

A multidisciplinary methodology has been tested to trace the respective effects of sedimentation, compaction, pressure-solution and fluid-rock interactions in subthrust reservoirs.

The diagenetic evolution of numerous Q-sandstone and both platform and pelagic carbonate reservoirs has been (1) documented in reference productive thrust belts in both South and North America, Europe and Asia, based on core data and outcrop samples, and (2) directly compared with the tectonic agenda, using cross-cutting relationships with deformation features such as normal, reverse and strike-slip faults, hydraulic fractures, joints and stylolitic planes, but also with the magnetic fabric.

Burial and thermal evolution of these reservoirs has been simultaneously reconstructed using specific 1D and 2D basin modelling tools, calibrated against bottom hole temperatures (BHT), maturity data (Tmax, Ro) of the organic matter and trapping temperatures of diagenetic cements (FI), thus resulting in a good dating of the main diagenetic events.

In both sandstone and carbonate reservoirs, the foreland evolution and the balance between overpressure development, cementation and hydraulic fracturing appear to be the most critical episodes controlling reservoir quality before its hydrocarbon charge, whereas synkinematic deformation episodes such as folding and thrusting are likely to enhance the overall fracture permeabilities.

**This integrated approach was developed within a Research Consortium (SUBTRAP) involving earth scientists from IFP and university labs (KUL-Leuven, Cergy, Paris VI and Amsterdam), with the sponsorship of 17 companies.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado