Modelling of hydraulic fracturing process by coupled discrete element and fluid dynamic methods

Abstract

A three-dimensional model is presented and used to reproduce the laboratory hydraulic fracturing test performed on a thick-walled hollow cylinder limestone sample. This work aims to investigate the implications of the fluid flow on the behaviour of the micro structure of the rock sample, including the material strength, its elastic constants and the initialisation and propagation of fractures. The replication of the laboratory test conditions has been performed based on the coupled Discrete Element Method and Computational Fluid Dynamics scheme. The numerical results are in good agreement with the experimental data, both qualitatively and quantitatively. The developed model closely validates the overall behaviour of the laboratory sample, providing a realistic overview of the cracking propagation towards total collapse as well as complying with Lame's theory for thick walled cylinders. This research aims to provide some insight into designing an accurate DEM model of a fracturing rock that can be used to predict its geo-mechanical behaviour during Enhanced Oil Recovery (EOR) applications.

Recent Developments in Multiscale and Multiphase Modelling of the Hydraulic Fracturing Process

“…Numerous mathematical solutions have been applied to look, for example, into the critical mechanical parameters, such as the stress envelope, the porosity and permeability of the material and the effect of layering within the rock, or the way that these are influenced by the external mechanical load [42]. However, studies that employ modelling and simulation of rocks at the microscale [43][44][45] are fewer and their focus on the complex interplay between the microproperties and their corresponding effect on the material's behaviour during the calibration procedure provides at best a general guidance. Therefore, a review on the micro-meso-level modelling using Discrete Element Method is first provided in this section to highlight the research progress in recent years in this area, followed by the broader overview of multiscale and multiphase coupling models.…”

“…Recent developments also focused on the behaviour of hydraulically pressurized intact rocks in the micro or mesoscale [44,[99][100][101]. Such an example is the work by Marina et al [43], who replicated a hydraulic fracturing test in a laboratory, and was performed on a thick-walled hollow cylinder limestone rock sample. The work studied the mechanical behaviour of the limestone sample under fluid pressure differential and the comparison between the fracturing pattern of the virtual model and the laboratory rock sample.…”

“…Furthermore, many rock engineering projects, such as mining or exploitation of geothermal energy resources, are directly related to drilling and thus fracturing, which drives research towards the investigation of the wellbore instability for hard and low porosity sedimentary rocks [109]. Fundamental and numerical analysis, such as the work performed by Zhang et al [110] and Marina et al [43], were developed to deal with the effect of rock geometry and various pressure differentials on the wellbore instability. Comparisons of the numerical results towards analytical solutions and experimental data provide a better understanding of the behaviour of the material and the propagation of cracks in both mesoscopic and large scale rocks.…”

Simulation of the hydraulic fracturing process of fractured rocks by the discrete element method

“…Extended research has been made in the past in order to analyse the hydraulic fracturing process with most of them involving the mechanical response of hydraulically pressurized intact rocks at the microscale (Eshiet et al 2013;Eshiet and Sheng (2014b) ;Haimson 2004;Hamidi and Mortazavi 2014;Nagel et al 2011;Shimizu et al 2011;Sousani et al 2014;Weng et al 2011), shale-proppant interactions (Deng et al 2014) or numerical experiments on large-scale jointed rock masses (Mas Ivars et al 2011). However, the behaviour of natural fractured rocks, and more specifically the interaction between the existing and the new hydraulic fractures, which this work deals with, is in an early stage of development and thus constitutes an essential task.…”

Unconventional gas resources in China

“…numerically investigated heat transport processes in subsurface reservoirs with horizontal wells and multiple fractures. Several studies are dealing with simulation of hydraulic fracturing processes (Lange et al 2013;Kissinger et al 2013;Zhao et al 2015a, b;Marina et al 2014;Eshiet et al 2013). Benchmarking e.g.…”