Abstract
Flow modelling challenges in fractured reservoirs have led to the development of many simulation methods. It is often unclear which method should be employed. High-resolution discrete fracture and matrix (DFM) studies on small-scale representative models allow us to identify dominant physical processes influencing flow. We propose a workflow that utilizes DFM studies to characterize subsurface flow dynamics. The improved understanding facilitates the selection of an appropriate method for large-scale simulations. Validation of the workflow was performed via application on a gas reservoir represented using an embedded discrete fracture model, followed by the comparison of results obtained from hybrid and dual-porosity representations against fully explicit simulations. The comparisons ascertain that the high-resolution small-scale DFM studies lead to a more accurate upscaled model for full field simulations. Additionally, we find that hybrid implicit–explicit representations of fractures generally outperform pure continuum-based models.
Highlights
Fractured reservoirs are often encountered in the exploitation of geothermal energy, hydrocarbon extraction, management of groundwater resources and carbon sequestration (Berkowitz 2002; Bonnet et al 2001; Singhal and Gupta 2010; March et al 2018)
Various simulation methods exist for modelling flow in naturally fractured reservoirs
We suggested that discrete fracture and matrix (DFM) simulation studies can be used to reveal flow characteristics in naturally fractured reservoirs
Summary
Fractured reservoirs are often encountered in the exploitation of geothermal energy, hydrocarbon extraction, management of groundwater resources and carbon sequestration (Berkowitz 2002; Bonnet et al 2001; Singhal and Gupta 2010; March et al 2018). We hypothesize that our understanding of subsurface flow behaviour will benefit from simulation studies using small-scale DFM models representative of a naturally fractured reservoir; this information can facilitate the selection of upscaled models (e.g. SP, DP, SPEDFM or DP-EDFM) that are fit for large-scale fluid modelling. Small-scale DFM models can be used to study the flow behaviour of water at different production rates By performing these simulations, the proposed workflow allows us to observe the effect of different fracture scales on fluid flow, how fractures interact and how matrix–fracture fluid exchange occur. The proposed workflow allows us to observe the effect of different fracture scales on fluid flow, how fractures interact and how matrix–fracture fluid exchange occur These qualitative observations can be used to select and construct upscaled flow models that are fit for purpose.
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