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Transport phenomena in heterogeneous media play a crucial role in numerous engineering applications such as hydrocarbon recovery from shales and material processing. Understanding and predicting these phenomena is critical for the success of these applications. In this dissertation, nanoscale transport phenomena in porous media are studied through physics-based simulations, and the effective solution of forward and inverse transport phenomena problems in heterogeneous media is tackled using data-driven, deep learning approaches. For nanoscale transport in porous media, the storage and recovery of gas from ultra-tight shale formations are investigated at the single-pore scale using molecular dynamics simulations. In the single-component gas recovery, a super-diffusive scaling law was found for the gas production due to the strong gas adsorption-desorption effects. For binary gas (methane/ethane) mixtures, surface adsorption contributes greatly to the storage of both gas in nanopores, with ethane enriched compared to methane. Ethane is produced from nanopores as effectively as the lighter methane despite its slower self-diffusion than the methane, and this phenomenon is traced to the strong couplings between the transport of the two species in the nanopore. The dying of solvent-loaded nanoporous filtration cakes by a purge gas flowing through them is next studied. The novelty and challenge of this problem lie in the fact that the drainage and evaporation can occur simultaneously. Using pore-network modeling, three distinct drying stages are identified. While drainage contributes less and less as drying proceeds through the first two stages, it can still contribute considerably to the net drying rate because of the strong coupling between the drainage and evaporation processes in the filtration cake. For the solution of transport phenomena problems using deep learning, first, convolutional neural networks with various architectures are trained to predict the effective diffusivity of two-dimensional (2D) porous media with complex and realistic structures from their images. Next, the inverse problem of reconstructing the structure of 2D heterogeneous composites featuring high-conductivity, circular fillers from the composites' temperature field is studied. This problem is challenging because of the high dimensionality of the temperature and conductivity fields. A deep-learning model based on convolutional neural networks with a U-shape architecture and the encoding-decoding processes is developed. The trained model can predict the distribution of fillers with good accuracy even when coarse-grained temperature data (less than 1% of the full data) are used as an input. Incorporating the temperature measurements in regions where the deep learning model has low prediction confidence can improve the model's prediction accuracy. / Doctor of Philosophy / Multiphysics transport phenomena inside structures with non-uniform pores or properties are common in engineering applications, e.g., gas recovery from shale reservoirs and drying of porous materials. Research on these transport phenomena can help improve related applications. In this dissertation, multiphysics transport in several types of structures is studied using physics-based simulations and data-driven deep learning models. In physics-based simulations, the multicomponent and multiphase transport phenomena in porous media are solved at the pore scale. The recovery of methane and methane-ethane mixtures from nanopores is studied using simulations to track motions and interactions of methane and ethane molecules inside the nanopores. The strong gas-pore wall interactions lead to significant adsorption of gas near the pore wall and contribute greatly to the gas storage in these pores. Because of strong gas adsorption and couplings between the transport of different gas species, several interesting and practically important observations have been found during the gas recovery process. For example, lighter methane and heavier ethane are recovered at similar rates. Pore-scale modeling are applied to study the drying of nanoporous filtration cakes, during which drainage and evaporation can occur concurrently. The drying is found to proceed in three distinct stages and the drainage-evaporation coupling greatly affects the drying rate. In deep learning modeling, convolutional neural networks are trained to predict the diffusivity of two-dimensional porous media by taking the image of their structures as input. The model can predict the diffusivity of the porous media accurately with computational cost orders of magnitude lower than physics-based simulations. A deep learning model is also developed to reconstruct the structure of fillers inside a two-dimensional matrix from its temperature field. The trained model can predict the structure of fillers accurately using full-scale and coarse-grained temperature input data. The predictions of the deep learning model can be improved by adding additional true temperature data in regions where the model has low prediction confidence.

High total organic carbon (TOC) and low clay content are two criteria to identify the "sweet spots" in shale gas plays. Recently, machine learning has been proved to be effective to estimate TOC and clay from well loggings. The remaining questions are what algorithm we should choose in the first place and whether we can improve the already built models. Automatic machine learning (AutoML) appears as a promising tool to solve those realistic questions by training multiple models and compares them automatically. Two wells with conventional well loggings and elemental capture spectroscopy are selected from a shale gas play to test the AutoML's ability in TOC and clay estimation. TOC and clay content are extracted from the Schlumberger's ELAN interpretation and calibrated to cores. Generalizability is proved in the blind test well and the mean absolute test errors for TOC and clay estimation are 0.23% and 3.77%. 829 data points are used to generate the final models with the train-test ratio of 75:25. The mean absolute test errors are 0.26% and 2.68% for TOC and clay, respectively, which are very low for TOC ranging from 0-6% and clay from 35-65%. The results show the AutoML's success and efficiency in the estimation. The trained models are interpreted to understand the variables effects in predictions. 235 wells are selected through data quality checking and feed into the models to create TOC and clay distribution maps. The maps provide guidance on where to drill a new well for higher shale gas production. / Master of Science / Locating "sweet spots", where the shale gas production is much higher than the average areas, is critical for a shale reservoir's successful commercial exploitation. Among the properties of shale, total organic carbon (TOC) and clay content are often selected to evaluate the gas production potential. For TOC and clay estimation, multiple machine learning models have been tested in recent studies and are proved successful. The questions are what algorithm to choose for a specific task and whether the already built models can be improved. Automatic machine learning (AutoML) has the potential to solve the problems by automatically training multiple models and comparing them to achieve the best performance. In our study, AutoML is tested to estimate TOC and clay using data from two gas wells in a shale gas field. First, one well is treated as blind test well and the other is used as trained well to examine the generalizability. The mean absolute errors for TOC and clay content are 0.23% and 3.77%, indicating reliable generalization. Final models are built using 829 data points which are split into train-test sets with the ratio of 75:25. The mean absolute test errors are 0.26% and 2.68% for TOC and clay, respectively, which are very low for TOC ranging from 0-6% and clay from 35-65%. Moreover, AutoML requires very limited human efforts and liberate researchers or engineers from tedious parameter-tuning process that is the critical part of machine learning. Trained models are interpreted to understand the mechanism behind the models. Distribution maps of TOC and clay are created by selecting 235 gas wells that pass the data quality checking, feeding them into trained models, and interpolating. The maps provide guidance on where to drill a new well for higher shale gas production.

Yes / This paper focuses on the robustness of the regulatory system of British Columbia (BC) from the environmental point of view. It argues that the enforcement of existing regulations is effective due to the active monitoring of compliance by the provincial oil and gas regulator. The regulator has a key role in promoting transparency, public participation and safety and sustainability of shale gas operations. The paper argues that although certain elements in the provincial legislative framework are covered by non-binding guidelines, rather than legislation, the regulator has responded to many of the concerns raised by the public over the shale gas development in BC, including impacts on regional air quality, fresh water contamination and access to water, deforestation, biodiversity and induced seismicity. The regulator has also recognized several key issues, such as baseline water monitoring as an issue requiring further research. This paper concludes that BC has one of the most robust regulatory systems in North America for regulating hydraulic fracturing.

Yes / This chapter evaluates the consistency of the United Kingdom (UK) regulatory framework on shale gas with Commission Recommendation 2014/70/EU on minimum principles for the exploration and production of unconventional oil and gas. In the absence of European-wide legislation, European Union (EU) Member States have the right to determine the conditions for exploiting their unconventional energy sources. However, due to the environmental and human health risks associated with hydraulic fracturing, the EU has expressed its interest in ensuring adequate protection of the environment and to creating clear and transparent common standards for the benefit of operators, investors and the public while promoting the interests of those Member States which are currently exploring unconventional energy. It can be argued that the UK regime has been designed to address the environmental risks arising from hydraulic fracturing operations and as such it sets a high environmental threshold for operations. In fact, the UK legislation appears to be more comprehensive than in many other jurisdictions commercially exploiting shale gas, and therefore it has a potential to inform the content of any future harmonising measures on the exploration and extraction of such resources at the EU level.

Thesis (MA)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Since its arrival onto the U.S. energy scene in the early 2000s, shale gas has had a significant impact on the global energy market. The fact that the shale gas supply of a single country has had such a widespread influence on the global energy market hints at the power that this energy resource holds as a ‘game changer’. With the fifth largest estimated shale gas reserves in the world, South Africa now faces the challenge of developing its own shale gas resources in the Karoo Basin. Having lifted the moratorium on hydraulic fracturing in September 2012, the South African government has indicated its interest in pursuing the commercial extraction of the country’s estimated shale gas reserves. This comes in light of the country’s potential energy crisis, as well as an increased role for natural gas in the country’s energy mix. South Africa has no history of shale gas extraction and currently has no legislation or regulatory practices in place to deal specifically with shale gas and hydraulic fracturing. The South African government thus faces the challenge of drawing policy lessons from other experienced shale gas-producing nations, such as the U.S., to close these regulatory gaps and exploit its national shale gas resources in an environmentally and economically responsible way. Consequently, this thesis focuses on the regulation of the American shale gas industry by asking what policy lessons the South African government can draw from the United States of America on its regulation of shale gas extraction. Richard Rose’s lesson-drawing approach to policy learning was adopted as the theoretical framework for this study and can also be applied as an analytical tool to aid in data collection and data analysis. Furthermore, the framework was operationalised through the research methods used for this case study, which consisted of a review of literature on the U.S. regulation of shale gas extraction. This research produced a number of key findings in the form of policy lessons for South Africa. Four main policy lessons were drawn on the regulation of shale gas extraction: regulation of shale gas extraction must occur at all levels of government—national, provincial and local; policy research must be used to inform policymaking for the development of new legislation specific to shale gas and hydraulic fracturing, so as to avoid regulatory exemptions often linked to ad hoc policymaking on shale gas extraction; each level of government and their related regulatory agencies must have clearly defined regulatory roles relating to shale gas and hydraulic fracturing; and finally, there must be uniformity in terms of the regulatory focus of shale gas regulators at all levels of government. / AFRIKAANSE OPSOMMING: Sedert skaliegas vroeg in die jare sedert 2000 op die Amerikaanse energietoneel verskyn het, het dit ‘n beduidende impak op die globale energiemark gehad. Die feit dat die voorraad skaliegas van een land so ‘n wydverspreide invloed gehad het op die globale energiemark is ‘n aanduiding van die mag van hierdie energiebron as ‘n spel-wisselaar.Suid-Afrika het die vyfde-grootste skaliegasreserwes ter wêreld, en staan nou voor die uitdaging om sy eie skaliegasreserwes in die Karookom te ontwikkel. Nadat die moratorium op hidrobreking in September 2012 opgehef is, het die Suid-Afrikaanse regering aangedui dat hulle belangstel om die land se beraamde skaliegasreserwes kommersieel te ontgin. Dit het ontstaan in die lig van die potensiële energiekrisis wat Suid-Afrika in die gesig staar, asook die begeerte dat aardgas ‘n groter rol moet speel in die land se mengsel van energiebronne. Suid-Afrika het geen geskiedenis van skaliegasontginning nie en tans is daar geen wetgewing of regulerende praktyke in plek wat spesifiek te make het met skaliegas en hidrobreking nie. Die Suid-Afrikaanse regering staan dus voor die uitdaging om te leer uit die beleidsrigtings van ander ervare skaliegaslande soos die V.S.A. ten einde hierdie leemtes in regulering op te hef en sy nasionale skaliegasreserwes op ‘n omgewingsvriendelike en ekonomies-verantwoordelike manier te ontgin. Gevolglik fokus hierdie tesis op die regulering van die Amerikaanse skaliegas-industrie deur te vra watter beleidslesse die Suid-Afrikaanse regering kan leer by die Amerikaanse regering oor die regulering van hulle skaliegasontginning. Richard Rose se 'lesson-drawing'-benadering tot die leer van beleid is aanvaar as die teoretiese raamwerk vir hierdie studie en kan ook aangewend word as 'n analitiese instrument om te help met dataversameling en -analise. Die raamwerk is verder geoperasionaliseer deur die navorsingsmetodes wat gebruik is vir hierdie gevallestudie, wat bestaan het uit 'n oorsig van die literatuur oor die V.S.A. se regulering van skaliegasontginning. Hierdie navorsing het ‘n aantal sleutelbevindinge opgelewer in terme van beleidslesse vir Suid-Afrika. Die vier vernaamste beleidslesse oor die regulering van skaliegasontginning wat na vore gekom het, is die volgende: die regulering van skaliegas moet op alle vlakke van regering geskied – nasionaal, provinsiaal en op plaaslike vlak; navorsing oor beleid moet gebruik word om beleidsvorming in te lig sodat nuwe wetgewing ontwikkel kan word wat spesifiek gerig is op skaliegas en hidrobreking, ten einde uitsonderings op regulering te voorkom wat dikwels verbind word met ad hoc beleidsformulering; elke vlak van regering en sy verwante reguleringsagentskappe moet duidelik gedefinieerde reguleringsrolle hê ten opsigte van skaliegas en hidrobreking; en, ten slotte, daar moet eenvormigheid wees in die reguleringsfokus van skaliegasreguleerders op alle vlakke van regering. / National Research Foundation (DAAD-NRF)

The Karoo Basin of South Africa holds an estimated 906 billion to 11 trillion cubic meters of unconventional shale gas within the shales of the Whitehill and Collingham formations of the Ecca Group. Evaluation of this potential resource has been limited due to the lack of exploration and a scarcity of existing drill core data. In order to circumnavigate this problem this study was undertaken to evaluate the potential target horizons exposed in outcrops along the southern portion of the Karoo Basin, north of Grahamstown in the Eastern Cape Province. Detailed field logging was done on the exposed Whitehill and Collingham formations as well as a possible conventional sandstone (turbidite) reservoir, the Ripon Formation, along road cuttings of the Ecca Pass. Palaeocurrent data, jointing directions and fossil material were also documented. Samples were analysed for mineralogy, porosity, permeability, and total organic carbon content (TOC). The extensively weathered black shales of the Whitehill Formation contain a maximum TOC value of 0.9% and the Collingham Formation shales contain a maximum TOC value of 0.6%. The organic lithic arkose sandstones of the Ripon Formation are classified as ‘tight rock’ with an average porosity of 1% and an average permeability of 0.05 mD. The Whitehill Formation in the southern portion of the Karoo Basin has experienced organic matter loss due to low grade metamorphism as well as burial to extreme depths, thus reducing shale gas potential. The Ripon Formation is an unsuitable conventional reservoir along the southern basin boundary due to extensive cementation and filling of pore spaces.

The increase in unconventional shale gas extraction in Pennsylvania has resulted in an increased number of groundwater contamination claims. Well water quality was investigated in southern Butler County, PA where 387 unconventional gas wells have been drilled since 2006. A total of 121 households participated in a survey and 238 well water samples were tested. Specific conductivity, pH, and dissolved oxygen in these samples were measured in the field and seven anion concentrations and thirty metal concentrations were measured in the lab. A subset of 91 water wells was also tested for light hydrocarbons (methane, ethane, ethylene, propylene, propane, butane). Pennsylvania DEP file reviews were used to create GIS maps indicating legacy oil and gas, unconventional wells, and plot water testing results. Results indicate few wells had high quality groundwater, with 86% containing one or more contaminants above (secondary) Maximum Contaminant Levels, with manganese (56%), iron (47%), fluoride (18%), TDS (18%), pH (17%), aluminum (17%) the most common. / Bayer School of Natural and Environmental Sciences; / Environmental Science and Management (ESM) / MS; / Thesis;

This dissertation aims to explain the conditions under which expertise can undermine democratic decision making. I argue that the root of the conflict between expertise and democracy lies in what I call insufficiently “representative” expertise – that is forms of scientific research that are not relevant to the policy questions at hand and that fail to make visible their hidden values dimensions. I claim that the scholarly literature on the problem of expertise fails to recognize and address the issue correctly, because it does not open the black box of scientific methodologies. I maintain that only by making sense of the methodological choices of experts in the context of policy making can we determine the relevance of research and reveal the hidden socio-political values and consequences. Using the case of natural gas fracking, I demonstrate how expert contributions – even though epistemically sound – can muddle democratic policy processes. I present four case studies from controversies about fracking to show how to contextualize scientific methodologies in the pertinent political process. I argue that the common problem across all case studies is the failure of expertise to sufficiently represent stakeholders’ problems and concerns. In this context, “representation” has three criteria: (1) the operational research questions on which the qualified experts work are relevant to stakeholders’ problems and concerns; (2) the non-epistemic values and consequences of epistemic choices of experts are compatible with social and political values and priorities; and (3) hidden values attached to facts are fully transparent and openly debated. In the conclusion, I propose a normative version of this representation theory that can be used to evaluate the appropriateness of expertise for democratic policy making. Instead of the value-free science ideal, I propose a new ideal to legitimately allow non-epistemic values in scientific reasoning without compromising the soundness of research.

Master of Science / Department of Chemical Engineering / James Edgar / In the past decade the technique of horizontal drilling and hydraulic fracturing has been improved so much that it has become a cost effective method to extract natural gas from shale formations deep below the earth’s surface. Natural gas extraction has boomed in the past few years in the United States, enough that it has driven prices to an all time low. The amount of natural gas reserves in the U.S. has led to claims that it can lead the country to energy independence. It has also been touted as a cleaner fuel for electricity generation and to power vehicles. This report explains hydraulic fracturing and horizontal drilling particularly with regards to utilizing the techniques for natural gas extraction from shale gas. It also discusses the environmental impact due to the drilling and gas extraction. It demonstrates that although the natural gas beneath the U.S. is a valuable resource, the impacts to the planet and mankind are not to be taken lightly. There is the potential for the effects to be long term and detrimental if measures are not taken now to control them. In addition although on the surface natural gas seems to be a greener fuel, particularly in comparison to gasoline, it is also considered worse for the environment.