Fluid flow in the Sub Andean fold and thrust belt, Bolivia

Abstract

Understanding fluid flow in fold and thrust belts has the potential to offer enormous insight into hydrocarbon accumulations in regions dominated by such structurally complex settings. Thrusting episodes can be key in creating a complete petroleum system, aiding maturation through burial, developing trapping scenarios, creating pathways for flow though juxtaposition and acting as conduits for flow connecting source to reservoir. The ability to model thrust and fold belts is limited due to the complex nature of threedimensional modelling of thrusts. However recent advancements is structural modelling software have allowed the representation of a stratigraphical surface in two depth locations at a single surface location enabling better realisations of overlain strata in thrust zones.

This work simulates the migration of hydrocarbons through fold and thrust zones using new Earth Models of the southern Sub Andean in Bolivia, created from seismic interpretation and well data analysis, and develops a new modelling workflow using multiple geological modelling applications. The migration pathways have been simulated in three dimensions using invasion percolation hydrocarbon migration modelling techniques developed by the Basin Dynamics Research Group at Keele University. These techniques allow the investigation of the relationship of stratal flow properties across thrust blocks.

The methodology employed allowed the geological uncertainty of the prospect to be evaluated for hydrocarbon trapping potential, through repeatable simulations where the location point of hydrocarbon source could be controlled. The results of the modelling work provides an insight into the evolution, maturation and potential accumulation of fluids in the Bolivian case study, and has produced a predictive approach to analysing fluid flow and accumulation applicable to other hydrocarbon systems as well as application in other fields considering fluid migration pathways and accumulation.