Particle clogging can occur in any scenario where a flow path or constriction is small relative to the size of objects trying to pass through it - think of flow through silos, blood flows through needles, and even the evacuation of crowds through barrieres. It originates from the formation of a single arch, behind which an entire flow path can become blocked. This work is the first time hydrodynamic clogging has been thoroughly investigated in planar channels.

Abstract The permeability of rocks is important in a range of geoscientific applications, including CO 2 sequestration, geothermal energy extraction, and in situ mineral recovery. This work presents an investigation of the change in permeability in porphyry rock samples due to blast-induced fracturing. Two samples were analysed before and after exposure to stress waves induced by the detonation of an explosive charge. Micro-computed tomography was used to image the interior of the samples at a pixel resolution of 10.

Abstract A growing number of hydraulic fracturing stimulation treatments rely solely on the deployment of 100-mesh (i.e. 150μm) proppant. Further, these may be preceded by post-pad injection of microparticles (i.e. 5-75μm) with the intent of activating natural fractures. The objective of this work is to describe fundamental new insights on the behaviour of polydisperse microparticle suspensions in hydraulic fractures in terms of screen-out and leak-off. This study was undertaken using a high-fidelity computational model of suspension transport based on the lattice Boltzmann method (for fluid mechanics) and discrete element method (for particle mechanics).

In this work we investigated the phenomenon of shear-induced migration for polydisperse suspensions for the first time. Shear-induced migration is basically the diffusion of particles in the direction of decreasing shear rate, caused by the accumlation of random particle collisions in sheared flows. In channels, it results in the accumulation of particles at the channel centre and a flattening of the velocity profile. These concepts have long been established and investigated for monodisperse suspensions (all particles of the same size), and some works have even investigated bidisperse suspensions (particles of two different sizes), demonstrating that the larger particles preferentially migrate towards the channel centre.

Abstract This paper presents a lattice Boltzmann framework for the transient simulation of blood flow using biologically inspired geometries and pressure boundary conditions. The Kuang-Luo rheological model is used to represent blood as a homogeneous continuum. This model includes the two primary non-Newtonian characteristics of blood, namely viscoplasticity and pseudoplasticity. This paper makes two contributions. First, the numerical challenges associated with zero strain rates and infinite viscosity, as a consequence of the yield stress in the Kuang-Luo model, were addressed by regularising the constitutive equation so that the viscosity tends towards a finite value at low strain rates.

Abstract This study analyzes the thermocapillary flow of recalcitrant bubbles within thin channels using a hybrid finite difference lattice Boltzmann method (LBM). It extends a recently developed phase-field LBM to account for temperature effects by coupling the scheme with a fourth-order Runge-Kutta algorithm to solve the governing energy equation. The LBM makes use of a weighted-multiple relaxation-time collision scheme, which has been previously shown to capture high density and viscosity contrasts.

Abstract Screenout of micro-proppants in narrow fractures is a significant issue for this emerging stimulation technique, however the predictive tools currently used in hydraulic fracturing simulators are inadequate. This work investigates screenout using numerical simulations. Data from the numerical test cell is translated to regions of screenout, which are dependent on the proppant solid volume fraction, ø, and the ratio of fracture width to proppant diameter, w/d. The dependence on w/d which is demonstrated is commensurate with existing bridging modelling.

Abstract This study analyses the flow of Taylor bubbles through vertical and inclined annular pipes using high-fidelity numerical modeling. A recently developed phase-field lattice Boltzmann method is employed for the investigation. This approach resolves the two-phase flow behavior by coupling the conservative Allen-Cahn equation to the Navier-Stokes hydrodynamics. This paper makes contributions in three fundamental areas relating to the flow of Taylor bubbles. First, the model is used to determine the relationship between the dimensionless parameters (Eötvös and Morton numbers) and the bubble rise velocity (Froude number).

Abstract Optimal proppant placement is critical to maintaining productivity from stress-sensitive reservoirs, in which gas conductivity depends on the connectivity of the network of secondary fractures to the wellbore. In a colloquial sense, this research places micro-proppants in induced and natural fractures, shows how they are excluded from reaching far into the reservoir, and describes which sizes of proppants this occurs for. Micromechanical modelling of a hydraulic fracturing fluid, in which the hydrodynamics between the fluid and solid phases are fully resolved, is achieved via the lattice Boltzmann method (LBM) for fluids coupled with the discrete element method (DEM) for particles.

Abstract A detailed understanding of wellbore flow is essential for production engineers in both the design of site equipment and optimisation of operation conditions. With the depletion of conventional resources, the need for unconventional extraction techniques to leverage untapped reserves has seen the generation of new downhole flow conditions. In particular, the extraction of natural gas from coal seams has led to scenarios where liquid removal from the reservoir can cause the development of a counter-current multiphase flow in the well annulus in pumped wells.

Abstract New models for particle embedment during micro-particle injection into naturally fractured reservoirs are developed. The proposed models aim to predict production benefit from the application of micro-particle injection during coal seam gas (CSG) stimulation with broader applications to other naturally fractured reservoirs. The elastoplastic finite element modelling is applied to coal sample from Surat basin (Australia), to predict micro-particle embedment and fracture deformation under various packing densities and closure stresses.

Abstract In this study long bubble rising in a narrow channel was investigated using multiphase lattice Boltzmann method. The problem is known as a Bretherton or Taylor bubble flow [2] and is used here to verify the performance of the scheme proposed by [13]. The scheme is modified by incorporation of multiple relaxation time (MRT) collision scheme according to the original suggestion of the author. The purpose is to improve the stability of the method.

Abstract Current design tools used for predicting the placement of proppant in fractures are based on the solution of a simplified conservation equation that is heavily dependent on empirical relationships for particle settling and suspension viscosity. In light of these shortcomings, this paper presents the development of a computational fluid dynamics (CFD) model capable of micromechanical simulation of hydraulic fracturing fluids. The model developed in this research employs the discrete element method (DEM) to represent the proppant for a range of sizes and densities.