Fracturing flow and reactive transport in carbonate and chalks hydrocarbon and hydrothermal reservoi

Publieke samenvatting / Public summary

Mechanic and flow properties of carbonate hydrocarbon (and geothermal) systems are often conditioned by networks of discontinuities such as bedding surfaces, fractures and stylolites. These form potential weaknesses and pathways for fluids. Present models do not predict accurately the characteristics of these networks in the subsurface resulting in unsatisfactory predictions of reservoir behaviour.

The goal of CARBFRAC is to develop models to predict the mechanic and flow behaviour of carbonate (chalk) reservoirs honouring their complex geologic structure. This results in better production strategies, opening of new exploration opportunities and decreasing risks during production (e.g. reservoir depletion and stimulation).

Korte omschrijving
CARBFRAC builds on the cooperation and knowledge developed in the 2F2S program and adopts a multidisciplinary approach integrating the analysis of outcropping analogs, numerical modelling and mechanic experiments. Combining analysis of outcropping analogs with numerical studies (XFEM) and mechanic experiments, we derive rules controlling the characteristics of discontinuity networks (fractures, stylolites and bedding surfaces) expected in carbonate (chalk) reservoirs. Following the characterization of its geometry (inclusive of faults), mechanics and state of stress, the geological rules controlling discontinuity networks are applied to a subsurface reservoir which forms the CARBFRAC natural laboratory. Using innovative modelling tools (Automatic Differentiation General Purpose Research Simulator - ADGPRS) which include fluid-rock interactions, we map the sensitivity of sweep patterns to fracture network uncertainties. Using XFEM and lattice modelling approaches backed-up by mechanic experiments and constrained by geological data, we then predict flow and mechanic response of the reservoir to pressure changes and stimulations (EGS in the geothermal jargon).

CARBFRAC will produce • Rules predicting the type and distribution of discontinuities developing during and after subsidence to maximum burial depth • Maps of sensitivity of production strategies to relevant geologic uncertainties • Rules governing the response of the faulted/fractured medium to reservoir depletion and stimulation. • Improved numerical codes for discontinuity interactions, flow behaviour and mechanic reactivation • Benchmark with commercial software packages.