Fluid Flow In Fractures Research Articles

Strain-induced trace element mobility in a quartz-sulphide vein system: An example from the ONKALO™ spent nuclear fuel repository (Olkiluoto, SW Finland)

This work investigates element mobility and deformation mechanisms in sulphide-bearing quartz veins associated with a strike-slip fault exposed in the ONKALO™ Finnish deep repository for spent nuclear fuel (Olkiluoto Island, southwest Finland). It combines petrography, trace element mapping by Laser Ablation Inductively Coupled Plasma Time-of-Flight Mass Spectrometry (LA-ICP-TOFMS) and Electron Backscattered Diffraction (EBSD) analysis of representative microstructures. The fault core was reactivated by brittle deformation episodes assisted by hydrothermal fluid batches with distinct trace element signatures. LA-ICP-TOFMS element distribution maps and EBSD on sulphides reveal local, syn-deformational intragrain enrichment of primary and secondary elements (i.e., As, Co, Cu, Ag, Sn, Sb, Pb, Se, In, Te). Trace element enrichments occur by a combination of microscale plastic distortions and microfracturing at the reaction fronts. Fluid ingress along microcracks enhanced chemical replacement of pyrite that combined with element diffusion along dislocations and tilt boundaries controlled trace element mobility in sulphides at the small scale. At the scale of the vein system, the competence contrast between inclusions of soft sulphides in the harder host quartz may have favored local fracture nucleation and fluid flow.

Assessing fluid flow in rough rock fractures based on machine learning and electrical circuit model

What hinders current models for fluid transportation in three-dimensional (3D) fracture system from considering fracture roughness is model complexity, which makes it hard to get convergent results. Therefore, we propose an electrical circuit (EC) model to simulate fracture flow, with each rough rock fracture taken as an EC with distributed electrical resistances, where the voltage and current are taken as the counterparts of pressure and flow rate, respectively. The robustness of EC model is validated against the computational fluid dynamics (CFD) simulations and laboratory experiments. Additionally, the EC model exhibits a very high computational efficiency (takes several seconds) compared with that of the CFD model (takes a couple of minutes). The proposed EC model is expected to have broader applications in fracture flow analysis as it applies not only to persistent fractures with tiny mechanical apertures but also to non-persistent fractures having substantial portions of contact areas.

On the Relationship Between Normal Stiffness and Permeability of Rock Fractures

AbstractThe hydraulic permeability and normal stiffness of rock fractures are fundamentally related, which can serve as a probe for assessing hydro‐mechanical properties in a variety of geo‐engineering contexts. We present experimentally validated numerical simulations of fracture closure and fluid flow processes in realistic aperture structures with mean in the range of 0.01–2 mm. A relatively simple relationship between permeability and normal stiffness is derived in the effective medium regime, using the elastic modulus of the rock matrix, the mean mechanical aperture, and the relative standard deviation (RSD) of the local mechanical aperture. The established relationship between stiffness and permeability appears independent of scale or orientation.

Factors that influence fluid flow in a single fracture

ABSTRACTTo investigate the influence of compression, Poisson effect and turbulence on the fluid flow process and the inversion for fracture surface geometries, we simulate two sets of fractures: one with a defined fracture height standard deviation σ constant and a varying autocorrelation length λ and another with a fixed λ and a changing σ. Under compression, the normal stress closes fractures with a large aperture and thus reduces the effective permeability. However, the Poisson effect, which is induced by the compression, has little influence on the fluid flow properties and does not affect the inversion for fracture height standard deviation or the autocorrelation length. When introducing turbulence, we observe a significant difference between the performance of the Navier–Stokes equation and the local cubic law; compared with the Navier–Stokes equation, the local cubic law overestimates the peak value of the breakthrough time curve and effective permeability, thereby underestimating the mean fracture aperture.

Impact of shear displacement on advective transport in a laboratory-scale fracture

The impact of shear displacement under different mechanical boundary conditions on fluid flow and advective transport in a single fracture at the laboratory scale is demonstrated in the present study. The shear-induced changes of fracture aperture structures are determined by using the measured normal displacements and digitalized fracture surfaces from laboratory shear tests. Five shear tests on concrete replicas of the same fracture under different mechanical boundary conditions, including constant normal loading (CNL) and constant normal stiffness (CNS), are conducted to analyse the influence of mechanical boundary conditions on the shear-flow-transport processes. Fluid flow in the fracture with different shear displacements are simulated by solving the Reynolds equation. The Lagrangian particle tracking method is applied to model the advective transport in the fracture after shearing. The results generally show that the shear displacements and the normal loading conditions can significantly affect flow patterns and advective travel time distributions in the fracture. For mated fractures, the flow and transport will be enhanced by the increasing shear displacement because of shear dilation. For cases with the same shear displacement, the median advective travel time increases with the increasing boundary normal stiffness. The median advective travel time under the CNS boundary condition is generally longer than that under the CNL boundary condition. The results from this study can help to improve our understanding of stress-dependent solute transport processes in natural rock fractures.

Characteristics of Fluid Flow and Solute Transport in Multicrossed Rough Rock Fractures Based on Three-Dimensional Simulation

Fluid flow and solute transport in rock fractures are important for controlling pollutant migration in groundwater and radionuclide migration in nuclear waste disposal. The quantitative characterization of fluid flow and mass transport in crossed fractures is the key to defining solute transport in a fracture network. In this study, the characteristics of fluid flow and solute transport in rock fractures were investigated through experiments and simulation. The surface topography of these fractures was reconstructed using 3D laser scanning technology. The solute transport in crossed parallel plates and rough fractures with intersecting angles of 30°, 60°, 90°, 120°, and 150° was investigated under different initial conditions. Results show that the intersection angle and fluid velocity significantly affect the fluid flow pattern at the intersection. As the flow velocity and intersection angle increase, streamlines at the intersection of rough fractures are unevenly distributed. The fluid tends to seep into the dominant channel and has different degrees of channeling flow at the intersection of fractures. An eddy phenomenon is observed at the intersection, indicating that the seepage behavior transforms into a non-Darcy flow. As the Peclet number (Pe) increases, solute migration and diffusion gradually decrease; however, the convection part gradually increases. Thus, the solute transport mode gradually changes into a streamline path mode at the intersection of fractures.

Numerical simulation of hydro-mechanically coupled mud loss in fractured reservoirs

Mud loss is a common phenomenon in the drilling process with an important impact on the efficiency and safety of drilling. Mud loss in fractured formations is serious and previous methods have been based mostly on the single-fracture model, which had difficulty dealing with the loss of complex fracture networks in fractured reservoirs. A hydro-mechanically coupled model was constructed based on the poroelasticity. This model also coupled the fluid flow in fractures and matrix by fluid exchange term across fracture surface. The fully coupled model was solved using the extended finite element method (XFEM). The physical field characteristics were represented by enrichment functions, and grids were decoupled from fractures. Thus, the efficiency was improved greatly. A simple single-fracture model was used to verify this method, and a multi-fracture numerical model was then constructed to examine the influence of the fracture aperture, matrix permeability, fracture deformation, and mud viscosity on mud loss.

The Investigation of Proppant Particle-Fluid Flow in the Vertical Fracture with a Contracted Aperture

Summary Proppant placement plays a crucial role in maintaining the conductivity of fractures after a hydraulic fracturing treatment. The process involves the transport of particles by fluid flow in complex fractures. Many studies have focused on proppant transport and distribution in the fracture with a constant aperture, but relatively few studies have investigated the proppant-fluid flow in a vertical fracture with a contracted aperture. In this work, we examine experimentally proppant transport in a fracture with a contracted aperture. The objective is to evaluate the distribution of particle beds in the contracted fracture at different flow conditions. In this paper, particle-fluid flow in the contracted fracture is studied experimentally by a laboratory size slot. A planar slot with a constant width is used to benchmark the experimental results, and a published correlation validates the bed equilibrium heights in the planar slot. Six types of particles are chosen to simulate the effects of particle density and size. The proppant distribution is evaluated by the bed height when the bed reaches the equilibrium states. The effects of fluid velocity, fluid viscosity, particle density, particle size, and particle volume fraction on particle distribution are investigated. The results confirm that the proppant particle-fluid flow in the contracted slot is more complicated than that in the planar slot. The phenomena of particle vortices and resuspension were observed at the contraction of the cross-section. The shape on the top of the bed is like a descending stair in which the height gradually decreases in the length direction. The bed height in the contracted slot is lower and more irregular than that in the planar slot at the same flow conditions. Smaller sands injected at a high flow rate and fluid viscosity can form a lower bed. The trend would be reversed by using denser particles and high particle volume fraction. A reliable model expressed by four dimensionless numbers is developed by the linear regression method for predicting the bed equilibrium height. The model and experimental results provide directions to quantitatively evaluate the particle transport and distribution in a fracture with a contracted aperture.

The Impact of Layering and Permeable Frictional Interfaces on Hydraulic Fracturing in Unconventional Reservoirs

Summary The impacts of formation layering on hydraulic fracture containment and on pumping energy are critical factors in a successful stimulation treatment. Conventionally, it is considered that the in-situ stress is the dominant factor controlling the fracture height. The influence of mechanical properties on fracture height growth is often ignored or is limited to consideration of different Young’s moduli. Also, it is commonly assumed that the interfaces between different layers are perfectly bounded without slippage, and interface permeability is not considered. In-situ experiments have demonstrated that variation of modulus and in-situ stress alone cannot explain the containment of hydraulic fractures observed in the field (Warpinski et al. 1998). Enhanced toughness, in-situ stress, interface slip, and energy dissipation in the layered rocks should be combined to contribute to the fracture containment analysis. In this study, we consider these factors in a fully coupled 3D hydraulic fracture simulator developed based on the finite element method. We use laboratory and numerical simulations to investigate these factors and how they affect hydraulic fracture propagation, height growth, and injection pressure. The 3D fully coupled hydromechanical model uses a special zero-thickness interface element and the cohesive zone model (CZM) to simulate fracture propagation, interface slippage, and fluid flow in fractures. The nonlinear mechanical behavior of frictional sliding along interface surfaces is considered. The hydromechanical model has been verified successfully through benchmarked analytical solutions. The influence of layered Young’s modulus on fracture height growth in layered formations is analyzed. The formation interfaces between different layers are simulated explicitly through the use of the hydromechanical interface element. The impacts of mechanical and hydraulic properties of the formation interfaces on hydraulic fracture propagation are studied. Hydraulic fractures tend to propagate in the layer with lower Young’s modulus so that soft layers could potentially act as barriers to limit the height growth of hydraulic fractures. Contrary to the conventional view, the location of hydraulic fracturing (in softer vs. stiffer layers) does affect fracture geometry evolution. In addition, depending on the mechanical properties and the conductivity of the interfaces, the shear slippage and/or opening along the formation interfaces could result in flow along the interface surfaces and terminate the fracture growth. The frictional slippage along the interfaces can serve as an effective mechanism of containment of hydraulic fractures in layered formations. It is suggested that whether a hydraulic fracture would cross a discontinuity depends not only on the layers’ mechanical properties but also on the hydraulic properties of the discontinuity; both the frictional slippage and fluid pressure along horizontal formation interfaces contribute to the reinitiation of a hydraulic fracture from a pre-existing flaw along the interfaces, producing an offset from the interception point to the reinitiation point.

Study on Deliverability Evaluation of Staged Fractured Horizontal Wells in Tight Oil Reservoirs

At present, the existing deliverability evaluation models mainly consider the impact of specific factors on production, and the description of the complex fracture network structure primarily remains at the stage of an ideal dual-pore medium with uniform distribution. However, this cannot reflect the actual fracture network structure and fluid flow law of fractured horizontal wells. Thus, in this paper, a non-uniform fracture network structure is proposed considering the influence of the threshold pressure gradient and stress sensitivity characteristics on the production performance of horizontal wells. The stress sensitivity and the fractal theory are combined to characterize the permeability of the complex fracture network, and a three-zone compound unsteady deliverability model for staged fractured horizontal wells in tight oil reservoirs is successfully developed. Laplace transformation, perturbation theory, and numerical inversion are applied to obtain the semi-analytical solution of the proposed deliverability model. The reliability and accuracy of the analytical solution are verified by the classical tri-linear flow model and an oil field example. The effects of related influential parameters on the production of horizontal wells are analyzed. The deliverability evaluation method proposed in this paper can provide a theoretical basis for formulating rational development technology policies for tight oil reservoirs.

A novel LBM-DEM based pore-scale thermal-hydro-mechanical model for the fracture propagation process

Fracture propagation in rocks is a complex thermal-hydro-mechanical (THM) phenomenon present in geotechnics, such as enhanced geothermal systems, CO2 sequestration, and shale gas exploitation. Numerical simulation is an essential way to study its mechanism. In this study, a pore-scale model combined with the lattice Boltzmann method (LBM) and the discrete element method (DEM) is developed, in which the comprehensive THM coupling phenomena are considered, consisting of convective heat transport, conjugate heat transfer, hydrodynamic force, and thermal strain. In addition, to couple the temperature and anisotropic thermal expansion of rock in LBM-DEM, a novel method based on the deformation of sphero-triangle particle is presented, where the deformation is calculated using the principle of minimum potential energy. The main features of the proposed THM model are that it can accurately calculate the fluid flow in fractures and the temperature in both fractures and DEM particles, and it takes full consideration of multiple anisotropic properties in rock. After validations, the THM fracturing mechanism is preliminarily investigated using the proposed model.

A methodology to investigate fluid flow in sheared rock fractures exposed to dynamic normal load

Understanding the flow characteristics in sheared rock fractures is with significance for many engineering projects (e.g., geothermal reservoirs, dams, oil or gas explorations, etc.). This study reports a FLAC3D FEM-based fluent CFD - methodology to investigate the fluid flow patterns in sheared rock joints exposed to complex stress states. First, a direct shear experiment of a rough basalt fracture, subjected to dynamic normal force is performed. A FLAC3D numerical model is setup to simulate the experimental process. Using a self-designed algorithm, the fracture contact area, aperture size, and fracture volume are analyzed at different shear displacements in the numerical model. The two-dimensional apertures, obtained from the FLAC3D model, are applied to FEM-based fluent CFD to analyze variation patterns of the relevant fluid flow during the shear process. Results show that the flow characteristics including the generation and development of eddy currents, and the estimated value of the Reynolds number, flow rate, and apparent permeability, are associated with both the shearing and the dynamic normal force. These findings provide a new horizon on features of aperture flow in rock mass under complex geological stresses.

Impact of fracture shear dilation on long-term heat extraction in Enhanced Geothermal Systems: Insights from a fully-coupled thermo-hydro-mechanical simulation

Shear dilation of fractures has been recognized as a main mechanism of permeability enhancement by hydraulic stimulation in Enhanced Geothermal Systems (EGSs); however, the interactive role of fracture shear dilation and thermo-hydro-mechanical (THM) coupling processes in long-term heat extraction performance of EGSs remains unclear. In this study, we develop a novel THM coupling model based on the discrete fracture network approach, which can realistically capture important processes including hybrid normal-shear deformation of fractures, thermal expansion of rocks, fluid flow in both fractures and rocks, and heat convection/conduction as well as local thermal non-equilibrium effect and changes in physical parameters of fluid. We quantitatively investigate the effects of fracture network geometries and geomechanical boundary constraints on fracture shear dilatancy, and the resulting heat transfer characteristics of EGSs. Numerical results reveal that shear dilation of fractures can be triggered by transient pore pressurization and thermal stress under anisotropic in-situ stress condition, and would severely engender flow channeling as well as anisotropic heat transfer, which strongly impact the heat extraction performance. The production temperature tends to be overestimated while the thermal production rate may be underestimated, if the shear dilatational behavior is not incorporated. Increased in-situ stress ratio and injection/production pressure would magnify the effects of shear dilation, and lead to considerable enhancement of fracture permeability, eventually resulting in much earlier and quicker temperature drop. Excessive increase of fracture density and the location of injection-production wells parallel to potential channelized flow paths, formed by intersected fractures preferentially oriented for shear sliding, tend to form short circulating flow paths and reduce the heat extraction performance. Our study demonstrates the importance of considering fracture shear dilation and fully-coupled THM behaviors when evaluating the long-term performance and efficiency of heat extraction in EGSs.

Photogrammetry based characterization of hydro-mechanical properties of a rock fracture

Hydro-mechanical properties of a single fracture are governed by several parameters such as contact area, roughness, tortuosity, aperture, channeling, matedness, sample sizes, normal stress, flow regime, and flow boundary conditions. In this study, photogrammetry with numerical modeling and laboratory measurements were used to investigate the influences of roughness, normal stress, aperture, water pressure, and different flow boundary conditions on fluid flow in an artificial granite fracture. A Finnish Kuru grey granite block was mechanically split, and a 250 mm × 250 mm × 100 mm slab pair sample with a tensile crack in the middle was extracted. A photogrammetry-based method was used to reconstruct a 3D model of the fracture geometry. The resulting model was numerically simulated with COMSOL using the Navier-Stokes equations. Fluid flow experiments were computed with the Forchheimer equation. Comparison between the numerical modeling results and the analytical solution confirms that the 3D roughness geometry has a crucial role in defining the transmissivity, especially for nonlinear flow. On the other hand, normal stress increases fracture closure and increases contact areas, decreasing the hydraulic aperture and changing the flow paths. The presented method can be used in the contactless estimation of fluid flow properties of rock joints.

Hydrogeological Models of Water Flow and Pollutant Transport in Karstic and Fractured Reservoirs

AbstractIn a literature review of the recent advancements in mathematical hydrologic models applied in fractured karstic formations, we highlight the necessary improvements in the fluid dynamic equations that are commonly applied to the flow in a discrete fracture network (DFN) via channel network models. Fluid flow and pollutant transport modeling in karst aquifers should consider the simultaneous occurrence of laminar, nonlaminar, and turbulent fluxes in the fractures rather than the laminar flow by the cubic law that has been widely applied in the scientific literature. Some simulations show overestimations up to 75% of the groundwater velocity when non‐laminar flows are neglected. Moreover, further model development is needed to address the issues of tortuosity of preferential saturated fluid flow in fractures suggesting adjustments of the size of the mean aperture in DFN models. During the past decade, DFN mathematical models have been significantly developed aimed at relating the three‐dimensional structure of interconnected fractures within rocky systems to the specific fracture properties measurable on the rock outcrops with the use of reliefs, tracer/pumping tests, and geotechnical field surveys. The capabilities and limitations of previous reported hydrological models together with specific research advancements and findings in modeling equations are described herein. New software is needed for creating three‐dimensional contour maps in fractured aquifers corresponding to the outputs of particle tracking simulations. Existing software based on the equivalent continuum or multiple‐interacting continua cannot delineate the spread of pollutant migrations affected by the tortuous preferential flow pathways that occur in DFNs.

Comparison between typical numerical models for fluid flow and heat transfer through single rock fractures

Numerical models can explicitly characterize fluid flow and heat transfer processes in rock fractures including randomly distributed asperities and contacts and have been widely used to understand the behaviors of fluid flow and heat transfer in fractured rocks. The differences between three-dimensional and two-dimensional numerical models for single rock fractures were compared in terms of fluid flow and heat transfer behaviors and properties. Both the artificial fractures created by Brazilian tension method and the hypothetical fractures created by duplicating a fracture surface were considered. The results showed that hypothetical fractures and two-dimensional models cannot capture the channeling flow and the non-uniform thermal fronts in artificial fractures, but two-dimensional models can predict the similar streamlines and thermal fronts as hypothetical fractures. The relationship between heat transfer coefficient and flow rate in a single rock fracture can be described by a logarithmic function, and the heat transfer coefficients of two-dimensional and three-dimensional models can be well correlated by an empirical function of fracture surface areas. The comparison between three-dimensional and quasi-three-dimensional models of artificial fractures is also conducted. Both channeling flow and non-uniform thermal fronts from quasi-three-dimensional models became similar to the results of three-dimensional models with increasing numbers of computational elements.

Fluid and heat flow in enhanced geothermal systems considering fracture geometrical and topological complexities: An extended embedded discrete fracture model

Accurate and efficient simulation of fluid and heat flow in fractures has long been a topic of interest for fractured reservoirs, e.g., enhanced geothermal systems (EGS) and unconventional oil/gas formations. In this paper, we propose a flexible and effective modeling approach, the extended embedded discrete fracture model (XEDFM), to simulate fluid and heat flow in fractured reservoirs with 3-D non-planar fracture networks. Compared with the conventional embedded discrete fracture model (EDFM), the XEDFM possesses two major merits: (1) separation of fracture discretization and matrix gridding provides maximum flexibility in handling fractures with complex geometry/topology, regardless of the resolution of the matrix grid; and (2) the combination of connection-list strategy and the concept of non-neighboring connection facilitates the construction of fluid-heat flux between the fracture and the matrix/fracture. With systematically validated XEDFM, the impacts of fracture roughness and heat extraction strategy on hydrothermal behaviors and heat mining efficiency are investigated. Another example introduces a workflow for design and modeling of 3-D non-planar fracture networks, with which the performance of horizontal and vertical wells in tapping heat energy from EGS are explored. This work presents a flexible and effective approach for modeling fluid/heat transfer accurately in 3-D non-planar fractures, and provides a set of framework and efficient algorithms for non-planar fractures design, discretization and simulation, establishing the foundation to build and simulate models with complicated fractures.

Electrical imaging of hydraulic fracturing fluid using steel-cased wells and a deep-learning method

Steel-cased wells used as long electrodes (LEs) in a surface-electric or electromagnetic survey can enhance anomalous signals from deep hydraulic fracturing zones filled by injected fluid. Although recent research has been published on the algorithms designed for the simulation of the effect of casings, feasibility studies on resolving the small-scale fracturing fluid flow from surface data are lacking. We have carried out a detectability and recoverability study for a top-casing electric source configuration. Applying a fast 3D DC modeling code using the concept of the equivalent resistor network, the detectability study shows that favorable conditions for detecting the fluid flow direction include multiple electrically coupled wells and different electric conductivities above and below the shale layer. The observed behavior is then modeled through a circuit analog. For the purpose of fracturing fluid imaging, the model for recovery is simplified as a distribution of full fluid saturation on a 2D fracture plane. A deep-learning (DL) framework is adopted to solve the imaging problem, which is difficult for conventional regularized inversions. Our DL implementation uses a supervised deep fully convolutional network to learn the relationship between data patterns on the surface and the model of fracturing fluid distribution, encoded in a large number of synthetic data-model pairs. Once trained, the neural network can make a real-time and pixel-wise prediction of the fluid distribution. The robustness of our DL approach is tested in the presence of ambient noise and inaccuracies in casing conductivity. A reasonably consistent prediction performance has been observed. Our numerical feasibility study results demonstrate that electric surveys using steel casings as LEs have great potentials in real-time monitoring of fracturing fluid flow.

A semi-analytical approach to model drilling fluid leakage into fractured formation

Loss of circulation while drilling is a challenging problem that may interrupt operations and contaminate the subsurface formation. Analytical modeling of fluid flow in fractures is a tool that can be quickly deployed to assess drilling mud leakage into fractures. A new semi-analytical solution is developed to model the flow of non-Newtonian drilling fluid in fractured formation. The model is applicable for various fluid types exhibiting yield-power law (Herschel-Bulkley). We use finite-element simulations to verify our solutions. We also generate type curves and compare them to others in the literature. We then demonstrate the applicability of the proposed model for two field cases encountering lost circulations. To address the subsurface uncertainty, we combine the semi-analytical solutions with Monte Carlo and generate probabilistic predictions. The solution method can estimate the range of fracture conductivity, parametrized by the fracture hydraulic aperture, and time-dependent fluid loss rate that can predict the cumulative volume of lost fluid.

THM response of a borehole in naturally fractured media

The response of a circular borehole to a constant fluid flow rate and a temperature step-change in a coupled hydraulic-thermal-mechanical system is formulated and quantified. A new coupled formulation is developed, based on a dual-porosity model to simulate a naturally fractured stratum under non-isothermal and two-phase fluid flow conditions. The semi-analytical closed-form solutions for pore pressure, temperature and stresses including rotational displacement effects are developed by coupling an averaged conductive heat transfer process and extended single-phase Darcy fluid flow in both fracture and matrix systems. Deformations and stress changes can be induced on the bulk skeleton during a temperature change, potentially leading to shear and tensile mechanical yield. Effective stresses on the borehole wall corresponding to either fracture or shear yield initiation are calculated and explained. In a fractured medium, tensile and shear yield may initiate along the natural fractures thus take place earlier than in a continuum, displaced from the immediate borehole wall. A negative pore pressure near the wellbore may be induced during cold fluid injection when the thermally induced back flow volumes may surpass those from the injected fluid. Thus, unexpected higher effective compressive stresses may be induced on the wellbore wall, leading to yield or formation damage for the injection well. This semi-analytical development permits rapid assessment of potential fracturing initiation and shear yield to be analyzed for various cases such as injection and production in a geothermal extraction system, fluid waste disposal including CO2 sequestration, and oil and gas related EOR processes such as an initiation stage of hydraulic fracturing.