Conceptual Geological Model About Hydrocarbon Flow Through Fractures in Siliciclastic Sequences of the Chicontepec Fm.

Abstract

Abstract

In heterogeneous reservoirs it is important to evaluate the variation of the physical properties of the rocks to reduce uncertainty in petroleum system modeling. Natural fractures are one of the factors involved in reservoir evaluation affecting the distribution of the physical properties (porosity, effective permeability, water saturation) of lithostratigraphic units. Natural fractures in siliciclastic reservoirs (SR) can enhance or inhibit production and stimulation processes and therefore is substantial to use qualitative and quantitative criteria in order to discriminate the structural systems involved in the hydrocarbon flow.

This work summarizes the results of the static characterization of fracture systems in SR analogues of the Chicontepec Fm. The structural analysis was performed on several scales of observation: micro-structural analysis of oriented thin sections, quantitative and qualitative description of faults and fractures in outcrops and boreholes, structural lineaments in topographic relief, and seismic-structural interpretation.

The structural characterization was performed both on the silicilastics sequences and the underlaying cretaceous rocks, in order to establish a genetic relationship between fracture systems with regional structures related to the Mexican Fold-Thrust Belt (MFTB) and the foreland basin.

Two predominant structural systems were defined in seismic and regional scales of which the one with higher density is NE-SW system (35° to 60°), followed by the NW-SE system (315°-330°). Fracture families where identified at metric and centimeter scales compatible with the regional systems. Characterizing outcrop scale structures and boreholes was extended to classify them according to their internal morphology, mineral content, geometric features and hydrocarbon flow evidence. These qualitative attributes allowed us statistically discriminate families of fractures that are important in the history of oil flow in the analogue.

Finally, a conceptual model about the relative temporal evolution of the micro-fracture systems and hydrocarbon flow for the SR analogue is presented and which, by its self-similarity attribute, was correlated with the fault systems that were characterized at regional and seismic scales to identify the dominant system for migration and storage of oil.

AAPG Datapages/Search and Discovery Article #90260 © 2016 AAPG/SEG International Conference & Exhibition, Cancun, Mexico, September 6-9, 2016