Unconventional Production Forecast Needs Integration of Field Hydraulic Stimulation Data Through Fracture Model Calibration and Optimized Numerical Scheme

Abstract

Objectives/Scope Hydraulic fracturing is today a standard when developing unconventional reservoir plays. This is studied through different models, based on a great deal of characterization data gathering and analysis. Unfortunately, numerical limitations impose drastic simplifications (number of fractures, some data being ignored…) leading to simple fracture geometries, lacking observed complexity. This limits any design optimization expectation. Our objective is to show that calibration data used for simpler models, along microseismic measurements, can lead to more realistic hydraulic fracturing geometries. Results can be linked to a reservoir platform, forecasting production. The presented computationally efficient method, within which sensitivity is performed, highlights key parameters governing the stimulation process. This study shows that the tool used is tailored for practical scenario design and evaluation. Methods, Procedures, Process The method used to generate realistic fracture geometries implies information at all scales (seismic, log, cores…) as well as numerical tools able to handle geomechanics and fluid flow, over a great number of fractures (as required by the characterization). Thus all data is input into one 3D Representative Deformable Discrete Fracture Network (DDFN), simulating the hydraulic stimulation. Characterization is based on geostatistical concepts applied to both natural and hydraulically induced fractures, driven by geological and geomechanical data. The process is simulated using a one phase hydrodynamic model within the DDFN (specific discretization) under far stress conditions. Fractures behavior is governed by geomechanical laws, reversible and non-reversible, with an approximate proppant model. Various scenarios are tested according to either geomechanical uncertain parameters, or characterization ones. Observed in-situ Bottom Hole Pressure (BHP) and microseismic characteristics (shape, frequency…) are then history-matched. Results, Observations, Conclusions For each simulated scenario, quality of the history match is shown and discussed, stressing the representativity of the data involved. The method has shown to be computationally efficient and robust enough to support hundred thousands of fractures while at the same time being able to simulate simpler cases. Also, within the studied framework, ties with already existing reservoir platform are shown. Advantages of such an approach are highlighted including current limitations of classical reservoir models. Novel/Additive Information This work undergone at different scales demonstrate the new possibilities of computational robust algorithms, within an approach considering both geological settings and geomechanical properties. The model offers the possibility to integrate several scales to an adaptive discretization scheme.

The MINC proximity function for fractured reservoirs flow modeling with non-uniform block distribution

“…The MINC approach showed its ability to handle transient flow modeling from unconventional reservoirs while achieving considerable accuracy and reducing the CPU time compared to the reference solution (Farah et al (2015). The MINC method can simulate matrix-fracture interactions from unconventional reservoirs for different flow regimes (Delorme et al, 2016;Farah, 2016;Farah et al, 2015) and can be easily implemented in any Discrete Fracture Model (Farah et al, 2018).…”

“…To provide a reference solution, the matrix media is meshed into very fine grid cells and the fractures are explicitly discretized considering the two connected fractures. The matrix cells exchange with fracture nodes are estimated as described in Delorme et al (2016). It must be mentioned that our reference solution used in this work is reliable even if the fractures are not parallel to the grid axes.…”

“…Due to the large grid blocks used by dual-continuum models, such phenomena cannot be simulated. However, this problem could be accurately solved using the MINC method (see Delorme et al, 2016;Farah et al, 2018;Ricois et al, 2016). Recently, Farah and Delorme (2020) proposed a Unified Fracture Network Model (UFNM) for unconventional reservoirs modeling.…”

“…The MINC-PF implements a fully numerical method that accounts for irregularity faced in unconventional reservoirs. This work is the development of the concept proposed in Farah (2016) Ph.D. work, in Delorme et al (2016) and in Khvoenkova and Delorme (2011).…”

Modeling of transport processes through large-scale discrete fracture networks using conforming meshes and open-source software

“…During recent decades, modeling of transport processes in fractured porous media has received increasing attention from the geoscientist community because of its wide range of applications in geothermal energy (Aquilina et al, 1998), petroleum exploration and production (Bourbiaux, 2010), CO 2 geological storage and nuclear waste disposal (Grenier et al, 2005;Fourno et al, 2007). Fracture networks might consist of pre-existing natural or pressure-induced fractures in the case of hydraulic fracturing (Delorme et al, 2016).…”