A dissertation submitted in fulfilment of the requirements for the degree of Master of Environmental Science. with Witwatersrand University, Johannesburg, South Africa, (School of Geography, Archaeological and Environmental Science within the Faculty of Science) 2nd June 2017. / Hydraulic fracturing in the Karoo is said to be a game changer of energy sector in South Africa, but it is said to pose potential groundwater contamination. Therefore the aim of the study was to investigate the extent to which current institutional set up in South Africa can deal and address potential environmental challenges that are associated to fracking. The study was particularly interested in investigating the institutional capabilities in the context of water management. The literature review of this study showed that water resource is a major environmental concern that revolves around hydraulic fracturing, including the water resources use and potential contamination. In addition, it should be considered that hydraulic fracturing is a new mining process in South Africa and Africa as a whole with controversial mining techniques and environmental impacts involved within this process. The review indicates that the biggest issue with proposed hydraulic fracking mining process in the Karoo is if the South African Government has taken into consideration the resources, infrastructures and skills to execute the process successfully. The literature asserts that even if proper enforcement of any regulations on this rapidly expanding industry will still be difficult as the regulation is insufficient due to certain explicit exemptions. In South Africa, the starting point for hydraulic fracturing and the associated regulations that governs fracking, is the recognition of an argument that South Africa does not possess any fracking specific laws, guidelines or even polices. Research participants were asked to give their views on the research topic by answering the semi structured interview questions. Data from the semi-structured interviews and literature review was analysed and discussed to address the research questions. The results of the investigation confirmed that there was no any legislation in place to govern this mining process in South Africa. Currently there are legislations which are under review and development to also address hydraulic fracking and the protection of water resources. The government should also involve other research institutes in the drafting and decision making of the legal institute governing hydraulic fracking to ensure that all gaps are identified before fracking can be permitted in the Karoo. / MT 2017

The process of natural gas extraction known as hydraulic fracturing, or fracking, is a controversial energy acquisition technique often viewed with disdain by the public, due to its potential for environmental harm. However, the mental health and psychological well-being of fracking communities, including potential benefits and detriments, are often overlooked. We reviewed the literature on the association between fracking and psychological functioning, finding that although persons living in fracking communities may experience some minimal, initial benefits such as land lease income or infrastructure development, they may also experience worry, anxiety, and depression about lifestyle, health, safety, and financial security, as well as exposure to neurotoxins and changes to the physical landscape. Indeed, entire communities can experience collective trauma as a result of the “boom/bust” cycle that often occurs when industries impinge on community life. Impacted communities are often already vulnerable, including poor, rural, or indigenous persons, who may continue to experience the deleterious effects of fracking for generations. An influx of workers to fracking communities often stokes fears about outsiders and crime; yet, it must be recognized that this population of mobile workers is also vulnerable, often ostracized, and without social support. Practitioners, researchers, and policy makers alike should continue to investigate the potential psychological ramifications of fracking, so that effective and targeted intervention strategies can be developed, disseminated, and implemented to improve mental health in fracking communities.

<p>There is an increased discharge of produced water in the USA, which is causing decrease in the amount of usable water and is being rendered useless by refinery and extraction operations. Produced water that is obtained from these activities is usually not feasible to be used in any form. So, it becomes necessary to get the water to a quality standard, as per the US EPA, which will make this water suitable for both commercial as well as household purposes.</p><p> </p><p>There have been a number of studies on Au, Ag and Carbon Nanotubes solar enabled steam generation with potential applications in water purification, distillation and sterilization of medical equipment. The key challenge with these nanoparticles is cost of production, hence limiting its wide application for clean water production. This work, for the first time, reports on activated carbon enabled steam generation hence addressing the cost limitations of metallic nanoparticles. Activated carbon has high solar absorptivity at various wavelengths of visible light.</p><p> </p>This work uses Activated Carbon coated Polyurethane foam to simultaneously adsorb oil from the produced water and also yield surface vapors under application of solar light to get a clean distillate which can be used in various ways be it commercial or household. The given fabricated system will be an inexpensive and simple method to get clean water. The temporal evolution of the distillate has been measured as well as the temperature characteristics. Experiments were carried out using activated carbon and CNT nanofluids and polyurethane membrane with immobilized activated carbon and CNT. A simulated solar light of 1 KW ~1 Sun was used. The rate of evaporation, temporal and spatial evolution of bulk temperature in the water were monitored automatically and recorded for further data reductions. Parametric studies of the effect of nanoparticle concentration, water quality and salinity were performed. Experimental evidence showed that activated carbon has potential. Previous work reported for the first time that optimal activated carbon concentration for maximum steam generation is 60 % vol. There was a 160 % increase in steam production rate at 60 % concentration of activated carbon when compared with D.I. water.Different atmospheric conditions were varied and the concentration of the sun to see the effects on the production of water. The recovery capacity of the foam was also tested so as to determine the waste oil that can be obtained from the foam and if the foam can be reused without being disposed of. More than 95% oil can be recovered The quality analysis has been performed and is an integral focus of the work as the comparison with the USA EPA (Environmental Protection Agency) will make it more robust and real world ready. The inclusion of Polyurethane foam, which is a major accumulating waste in the environment because of its use in packaging industry, and solar light as the energy source, to drive the distillation process, makes this a very clean and green process to treat produced water.

Hydraulic fracturing is used to extract oil and natural gas from low permeability formations. The potential of fluids migrating from depth through adjacent wellbores and through the production wellbore was investigated using statistical modeling and predic-tive classifiers. The probability of a hydraulic fracturing well becoming hydraulically connected to an adjacent well in the Marcellus shale of New York was determined to be between 0.00% and 3.45% at the time of the study. This means that the chance of an in-duced fracture from hydraulic fracturing intersecting an existing well is highly dependent on the area of increased permeability caused by fracturing. The chance of intersecting an existing well does not mean that fluid will flow upwards; for upward migration to occur, a pathway must exist and a pressure gradient is required to drive flow, with the exception of gas flow caused by buoyancy. Predictive classifiers were employed on a dataset of wells in Alberta Canada to identify well characteristics most associated to fluid migration along the production well. The models, specifically a random forest, were able to identify pathways better than random guessing with 78% of wells in the data set identified cor-rectly. Magnetic resonance imaging (MRI) was used to visualize and quantify contami-nant transport in a soil column using a full body scanner. T1 quantification was used to determine the concentration of a contaminant surrogate in the form of Magnevist, an MRI contrast agent. Imaging showed a strong impact from density driven convection when the density difference between the two fluids was small (0.3%). MRI also identified a buildup of contrast agent concentration at the interface between a low permeability ground silica and higher permeability AFS 50-70 testing sand when density driven con-vection was eliminated.

Effects of hydraulic fracturing (HF) have become a controversial public health issue in the United States. The purpose of this qualitative case study was to explore community members' perceptions of economic, health, and environmental effects of HF in Gibson County, Indiana. The conceptual framework was adapted from the health belief model and was named the HF health impact belief model (HFHIBM). Data were collected from stratified purposeful non-randomly selected 32 Gibson community members, using semi structured questionnaires, complete observations, and existing documents. Stratification was based on factors influencing perception, such as, gender, race, level of education, age or technology exposure, and level of media use. The observed community showed no economic boom or prevalent diseases, with functional and few abandoned pump jacks located on some of the farmlands. Data collected from the returned questionnaires were analyzed using hand coding and software. The results revealed that 72% of participants lacked awareness of HF, 90.6% reported lack of involvement in the decision-making process to locate HF near their community, and 21.6% of the 40.6% of participants with awareness reported that HF should be continued if the benefits outweigh the negative effects. Based on the constructs of HFHIBM, the low awareness of HF has implications on the community's acceptance of HF, and the use of sustainable and environmentally safe alternatives may result in better acceptance of HF. Increased awareness of HF may lead to the development of environmentally friendly, sustainable preventive actions, better community health outcomes such as reduced morbidity and mortality rates, and improved drinking water quality in neighboring communities.

Each hydraulic fracturing well uses up to 5,000 tons of silica-containing sand, or proppant, during its operational lifetime. Over one million wells are currently in operation across the continental United States. The resulting increase in demand resulted in the production of 54 million metric tons of sand for use as hydraulic fracturing proppant in 2015. The goal of this study was to determine the relative risk of occupational exposure to respirable crystalline silica to workers performing tasks associated with mining, processing, and transport of proppant. Sand samples were aerosolized in an enclosed chamber. Bulk and respirable samples were submitted to a commercial lab for silica analysis. A risk ratio was calculated by comparing respirable dust concentrations to the current occupational safety regulations. Raw sand produced higher concentrations of respirable dust and a higher risk ratio (3.2), while processed dust contained higher percentages of respirable crystalline silica but a lower risk ratio (0.5). When vibration was introduced prior to aerosolization, concentrations tended to increase as vibration times increased, resulting in an increase of the associated risk ratio (2.3). Results of the study indicate that workers in sand mines and workers exposed to proppant that has undergone low-frequency vibration are at increased risk of exposure to respirable crystalline silica compared to workers who are exposed to proppant that has not undergone vibration.

Hydraulic fracturing is an important and abundant process in both industrial applications and natural environments. The current work is the first systematic quantitative study of the effect of interaction in and between complex hydraulic fractures at different spatial scales. A mathematical model, based on the boundary collocation method, has been developed. The model has been employed for a typical field case, a highly segmented vein. This vein is well-mapped, and therefore, represents a well constrained example. The computed apertures are compared to the measured apertures. By using the simplest constitutive model, based on an ideal elastic material, and including the effect of interaction between the segments, it was possible to obtain an excellent match at all considered scales. It was also shown that the concept of effective fracture, as currently accepted in the literature, is not always applicable and may lead to unbounded inaccuracy. Unfortunately, in most cases, very little (if any) directly measured data on fracture and material properties is available. An important example of such a weakly constrained case, involving hydraulic fracturing, is diking beneath the seafloor at mid-oceanic ridges. In this study, it is shown that the commonly accepted scenario of a dike propagating from the center of the pressurized magma chamber to the ocean floor is not consistent with conventional fracture mechanics due to the fact that the chamber has the shape of a thin lens. Even at such a large scale (i.e., a kilometer or more), the mechanical principles of elastic interaction appear to be applicable. Since diking is likely to generate a region of high permeability near its margin, in addition to heat, the ongoing hydrothermal activity becomes localized. Our modeling suggests the probable positions of the propagating dikes. Consequently, comparing the observed locations of hydrothermal sites with respect to that of the magma chamber could be useful for constraining the mechanisms of magma lens evolution.

This dissertation focuses mainly on three topics: (1) mixed-mode branching and segmentation of hydraulic fractures in brittle materials, (2) hydraulic fracture propagation in particulate materials, and (3) hydraulic fracturing in water flooding conditions. Mixed-mode loading is one of the primary causes of fracture branching and segmentation in brittle materials. We conducted the first laboratory experiments on the mixed mode I+III hydraulic fracturing. We found that a KIII/KI ratio as small as ~1% is sufficient for fracture front segmentation. In reality, such a small mode III component is always expected, for example, due to the small deviations of the fracture shape from planar. Thus, we concluded that fracture segmentation is likely to accompany growth of most, if not all, real hydraulic fractures. We also proposed a theoretical model that captures the main features of experimental observations and indicates the importance of the hydraulic effect of segmentation. Particulate materials often exhibit pronounced non-linear behavior and yielding even at relatively small loads. In order to adequately describe hydraulic fracturing in particulate materials with low or no cohesion, plasticity at the crack tip must be explicitly considered. We investigated the shear band mechanism of strain localization at the fracture front. This mechanism takes into account the fact that cohesionless material can not bear tension, and is in compression everywhere, including near the fracture front. To verify the shear band hypothesis, we conducted numerical simulations of the plastic deformation at the tip of a fracture in particulate material with strain softening. Our model describes the shear bands by properly placed and oriented dislocations. The model results are consistent with experimental observations. Water flooding, which in certain important cases, can result in processes resembly hydraulic fracturing by a low-viscosity fluid with extremely high leak-off. It is difficult to simulate this process in the laboratory. To investigate the fracture initiation mechanism in water flooding conditions, we conducted a numerical simulation of fluid injection into particulate material by using the discrete element code PFC2D. We also considered an analytical model of cavity initiation based on the fluidization mechanism. The estimates given by this model fit remarkably well with the numerical simulation results.

Success of acid fracturing depends on uneven etching along the fracture surfaces caused by heterogeneities such as variations in local mineralogy and variations in leakoff behavior. The heterogeneities tend to create channeling characteristics, which provide lasting conductivity after fracture closure, and occur on a scale that is neither used in laboratory measurements of acid fracture conductivity, which use core samples that are too small to observe such a feature, nor in typical acid fracture simulations in which the grid block size is much larger than the scale of local heterogeneities. Acid fracture conductivity depends on fracture surface etching patterns. Existing acid fracture conductivity correlations are for random asperity distributions and do not consider the contribution of channels to the conductivity. An acid fracture conductivity correlation needs the average fracture width at zero closure stress. Existing correlations calculate average fracture width using dissolved rock equivalent width without considering the effect of reservoir characteristics. The purpose of this work is to develop an intermediate-scale acid fracture model with grid size small enough and the whole dimension big enough to capture local and macro heterogeneity effects and channeling characteristics in acid fracturing. The model predicts pressure field, flow field, acid concentration profiles, and fracture surface profiles as a function of acid contact time. By extensive numerical experiments with the model, we develop correlations of fracture conductivity and average fracture width at zero closure stress as a function of statistical parameters of permeability and mineralogy distributions. With the model, we analyzed the relationships among fracture surface etching patterns, conductivities, and the distributions of permeability and mineralogy. From result analysis, we found that a fracture with channels extending from the inlet to the outlet of the fracture has a high conductivity because fluid flow in deep channels needs a very small pressure drop. Such long and highly conductive channels can be created by acids if the formation has heterogeneities in either permeability or mineralogy, or both, with high correlation length in the direction of the fracture, which is the case in laminated formations.

The conductivity of acid-etched fractures highly depends on spaces along the fracture created by uneven etching of the fracture walls remaining open after fracture closure. Formation heterogeneities such as variations of mineralogy and permeability result in channels that contribute significantly to the fracture conductivity. Current numerical simulators or empirical correlations do not account for this channeling characteristic because of the scale limitations. The purpose of this study is to develop new correlations for conductivity of acid-etched fracturing at the intermediate scale. The new correlations close the gap between laboratory scale measurements and macro scale acid fracture models. Beginning with acid-etched fracture width profiles and conductivity at zero closure stress obtained by the previous work, I modeled the deformation of the fracture surfaces as closure stress is applied to the fracture. At any cross-section along the fracture, I approximated the fracture shape as being a series of elliptical openings. With the assumption of elastic behavior for the rock, the numerical simulation presents how many elliptical openings remain open and their sizes as a function of the applied stress. The sections of the fracture that are closed are assigned a conductivity because of small-scale roughness features using a correlation obtained from laboratory measurements of acid fracture conductivity as a function of closure stress. The overall conductivity of the fracture is then obtained by numerically modeling the flow through this heterogeneous system. The statistical parameters of permeability distribution and the mineralogy distribution, and Young’s modulus are the primary aspects that affect the overall conductivity in acid-etched fracturing. A large number of deep, narrow channels through the entire fracture leads to high conductivity when the rock is strong enough to resist closure stress effectively. Based on extensive numerical experiments, I developed the new correlations in three categories to predict the fracture conductivity after closure. Essentially, they are the exponential functions that incorporate the influential parameters. Combined with the correlations for conductivity at zero closure stress from previous work, the new correlations are applicable to a wide range of situations.