Experiments exploring transport and bio-containment of contaminants in fractured rock were completed using fractured-limestone samples obtained in eastern Ontario, Canada. Three single-fracture samples, a fracture-intersection sample and a fracture-network sample were set into vertical flow systems. Three phases of experiments focused on the transport and hydraulic properties of each sample, the effects of biobarriers on diffusion processes in fracture rock, and methods of improving biobarrier stability and survivability. Hydraulic apertures were determined from constant-flow measurements and transport properties were interpreted from Lissamine and KBr tracer experiments with velocities of up to 8500 m/d for all five samples. At Re > 16, linear to non-linear transitions were observed in enlarged single fracture A and the fracture intersection samples. Reversible increases in aperture were observed at Reynolds numbers (Re) of 7, 4, and 3 for single fractures A and B, and the fracture-network, respectively. Non-linear effects were not observed in these samples over the range of velocities studied (up to Re = 20). Results from the 1-D analytical transport model overestimated values of matrix porosity, suggesting that diffusion from dead zones and slow-flowing regions are also contributing to observed breakthrough curves. Methods of improving biobarrier stability in fractured rock were studied in two single-fracture samples and the fracture-network sample by stimulating naturally-occurring groundwater bacteria. Survivability was improved with successive cycles of feeding and starving and stimulating growth at lower temperatures. Modeled values of matrix porosity decreased by up to 50%, indicating that diffusion processes are strongly influenced by biofilm development. Back diffusion of Lissamine was measured using one single-fracture sample and the fracture-intersection sample. Lissamine was allowed to diffuse into the matrix of each sample and, following a suitable loading period, the back-diffusion of residual Lissamine concentrations were measured from the outflow. This was done in the presence and absence of biofilm, and following the introduction of biofilm onto the fracture surfaces, diffusion was no longer a governing process affecting transport and only advective transport was observed. Experiments were interpreted using a 3-D finite difference model with a three-layer porosity approach, and indicated a decrease in aperture and porosity following biostimulation. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2012-11-22 11:23:24.065

To obtain better well performance and improved production from shale gas reservoirs, it is important to understand the behavior of shale gas wells and to identify different flow regions in them over a period of time. It is also important to understand best fracture and stimulation practice to increase productivity of wells. These objectives require that accurate production analysis be performed. For accurate production analysis, it is important to analyze the production behavior of wells, and field production data should be interpreted in such a way that it will identify well parameters. This can be done by performing a detailed analysis on a number of wells over whole reservoirs. This study is an approach that will lead to identifying different flow regions in shale gas wells that include linear and bilinear flow. Important field parameters can be calculated from those observations to help improve future performance. The detailed plots of several wells in this study show some good numbers for linear and bilinear flow, and some unique observations were made. The purpose of this work is to also manage the large amount of data in such a way that they can be used with ease for future studies. A program was developed to automate the analysis and generation of different plots. The program can also be used to perform the simple calculations to calculate different parameters. The goal was to develop a friendly user interface that would facilitate reservoir analysis. Examples were shown for each flow period, i.e. linear and bilinear flow. Different plots were generated (e.g; Bob Plot (square root of time plot) and Fourth Root of Time Plot, that will help in measuring slopes and thus reservoir parameters such as fracture permeability and drainage area. Different unique cases were also observed that show a different behavior of well in one type of plot from another.

Fractured reservoirs have been traditionally idealized using dual-porosity models. In these models, all matrix and fractures systems have identical properties. However, it is not uncommon for naturally fractured reservoirs to have orthogonal fractures with different properties. In addition, for hydraulically fractured reservoirs that have preexisting natural fractures such as shale gas reservoirs, it is almost certain that these types of fractures are present. Therefore, a triple-porosity (dual-fracture) model is developed in this work for characterizing fractured reservoirs with different fractures properties. The model consists of three contiguous porous media: the matrix, less permeable micro-fractures and more permeable macro-fractures. Only the macro-fractures produce to the well while they are fed by the micro-fractures only. Consequently, the matrix feeds the micro-fractures only. Therefore, the flow is sequential from one medium to the other. Four sub-models are derived based on the interporosity flow assumption between adjacent media, i.e., pseudosteady state or transient flow assumption. These are fully transient flow model (Model 1), fully pseudosteady state flow model (Model 4) and two mixed flow models (Model 2 and 3). The solutions were mainly derived for linear flow which makes this model the first triple-porosity model for linear reservoirs. In addition, the Laplace domain solutions are also new and have not been presented in the literature before in this form. Model 1 is used to analyze fractured shale gas horizontal wells. Non-linear regression using least absolute value method is used to match field data, mainly gas rate. Once a match is achieved, the well model is completely described. Consequently, original gas in place (OGIP) can be estimated and well future performance can be forecasted.

The vast shale gas and tight oil reservoirs in North America cannot be economically developed without multi-stage hydraulic fracture treatments. Owing to the disparity in the density of natural fractures in addition to the disparate in-situ stress conditions in these kinds of formations, microseismic fracture mapping has shown that hydraulic fracture treatments develop a range of large-scale fracture networks in the shale plays. In this thesis, an approach is presented, where the fracture networks approximated with microseismic mapping are integrated with a commercial numerical production simulator that discretely models the network structure in both vertical and horizontal wells. A novel approach for reservoir simulation is used, where porosity (instead of permeability) is used as a scaling parameter for the fracture width. Two different fracture geometries have been broadly proposed for a multi stage horizontal well, orthogonal and transverse. The orthogonal pattern represents a complex network with cross cutting fractures orthogonal to each other; whereas transverse pattern maps uninterrupted fractures achieving maximum depth of penetration into the reservoir. The response for a vii single-stage fracture is further investigated by comparing the propagation of the stage to be dendritic versus planar. A dendritic propagation is bifurcation of the hydraulic fracture due to intersection with the natural fracture (failure along the plane of weakness). The impact of fracture spacing to optimize these fracture geometries is studied. A systematic optimization for designing the fracture length and width is also presented. The simulation is motivated by the oil window of Eagle Ford shale formation and the results of this work illustrate how different fracture network geometries impact well performance, which is critical for improving future horizontal well completions and fracturing strategies in low permeability shale and tight oil reservoirs. A rate transient analysis (RTA) technique employing a rate normalized pressure (RNP) vs. superposition time function (STF) plot is used for the linear flow analysis. The parameters that influence linear flow are analytically derived. It is found that picking a straight line on this curve can lead to erroneous results because multiple solutions exist. A new technique for linear flow analysis is used. The ratio of derivative of inverse production and derivative of square root time is plotted against square root time and the constant derivative region is seen to be indicative of linear flow. The analysis is found to be robust because different simulation cases are modeled and permeability and fracture half-length are estimated. / text

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The circular economy is promoted by the EU, governments, and businesses all over the world as a concept to reach a sustainable future. The concept is embedded into the UN Sustainable Development Goals for 2030 and aims to decouple economic growth and environmental pressure. Many studies have been conducted on the circular economy in recent years but the research on the actual environmental performance of the concept is limited. To move forward with the concept of the circular economy and reach a sustainable future, the environmental performance must be investigated. In this thesis, the environmental impact of circularity in products is investigated by comparing the environmental impact from one circular and one linear product case. To achieve this, the environmental impact and the degree of circularity is calculated with two different methods. The circularity is calculated with a circularity indicator called the Linear Flow Ratio and the environmental impact is assessed with the environmental evaluation technique Life Cycle Assessment (LCA). In the LCAs, the cases are compared for different environmental impact categories (e.g. global warming). The product that is investigated is an LED lighting fixture from the company 2P1. The circular case is based on a leasing business model and includes remanufacturing, reuse and recycling. The linear case includes production, sales, use, and disposal. The LCA results show that the environmental impact from the circular case is lower for all environmental impact categories. The environmental impact is almost exclusively from the manufacturing phase (including extraction and production of raw materials) and the use phase. The circularity results from the Linear Flow Ratio show contradicting results, presenting that the degree of circularity is higher for the linear case. By comparing the results to calculations from another circularity indicator (Material Circularity Indicator), it is concluded that a unified framework for circularity measurements is required. / Cirkulär ekonomi är introducerat av EU, länder och företag över hela världen som ett koncept för att nå en hållbar framtid. Den cirkulära ekonomin är en del av arbetet mot agenda 2030 för hållbar utveckling och strävar efter att frånkoppla ekonomisk tillväxt från miljöpåverkan. Det har forskats mycket på cirkulär ekonomi under de senaste åren men studier som undersöker det miljömässiga utförandet av konceptet saknas. För att fortsätta att utveckla konceptet och för att nå en hållbar framtid så måste den miljömässiga påverkan från cirkularitet undersökas. I denna studie undersöks miljöpåverkan från cirkularitet hos produkter genom att jämföra miljöpåverkan från ett cirkulärt och ett linjärt fall. Miljöpåverkan och cirkularitetsgraden beräknas med två olika metoder. Cirkulariteten beräknas med cirkularitetsindikatorn Linear Flow Ratio och miljöpåverkan analyseras men livscykelanalys. I livscykelanalyserna värderas miljöpåverkan för de två fallen för olika påverkanskategorier (t.ex. global uppvärmning). Produkten som undersökt är en LED-armatur från företaget 2P1. Det cirkulära fallet basers på uthyrning av armaturerna och innehåller renovering, återanvändning och återvinning. Det linjära fallet innehåller produktion, försäljning, användning och bortskaffande av produkten. Resultaten från livscykelanalyserna visar att det cirkulära fallet medför mindre miljöpåverkan för alla kategorier. Miljöpåverkan kommer nästan enbart från produktion (inklusive material) samt användning. Cirkularitetsresultaten från Linear Flow Ratio visar motsägelsefulla resultat då det linjära fallet har en högre cirkularitetsgrad än det cirkulära fallet. Genom att jämföra resultaten med beräkningar från en annan cirkularitetsindikator (Material Circularity Indicator) kan det fastställas att ett enhetligt ramverk för beräkning av cirkularitet är nödvändigt framöver.

Shale oil (tight oil) is oil trapped in low permeability shale or sandstone. Shale oil is a resource with great potential as it is heavily supplementing oil production in the United States (U.S. Energy Information Administration, 2013). The shale rock must be stimulated using hydraulic fracturing before the production of shale oil. When the hydrocarbons are produced from fractured systems, the resulting flow is influenced by the fracture, the stimulated rock, and the matrix rock. The production decline rates from shale oil reservoirs experience flow regimes starting with fracture linear flow (fracture dominated), then bilinear flow (fracture and stimulated rock dominated), then formation linear flow (stimulated rock dominated), and finally pseudo-radial flow (unstimulated matrix rock dominated) (Cinco-Ley 1982). In this thesis, daily production rates from a shale oil reservoir are modeled using a simple spreadsheet-based, finite difference serial flow simulator that models the single-phase flow of a slightly-compressible oil. This simulator is equivalent to flow through multiple tanks (subsequent part of the thesis will call these cells) through which flow passes serially through one tank into the other. The simulator consists of 11 tanks. The user must specify the compressibility-pore volume product of each tank and the transmissibility that governs flow from one tank to another. The calculated rate was fitted to the given data using the Solver function in Excel. The fitted matches were excellent. Although we can adjust all 22 parameters (2 per cell) to affect the simulation results, we found that adjusting only the first three cells nearest to the well was sufficient. In many cases, only two cells were enough. Adjusting 4 or more cells resulted in non-unique matches. Furthermore, the properties of the very first cells proved insensitive to the matches when using the 3 cells to match the data. The cells in the 2 cell model represent the stimulated zone and the unstimulated rock. Likewise, the cells in the 3 cell model represent the hydraulic fracture, the stimulated zone, and the unstimulated rock. The accessed pore volume and transmissibility were responsive to the injected sand mass and fluid volume up to approximately 10⁶ kg and 7000 m³ respectively; injecting more sand and fluids than this caused negligible increases in the accessed pore volume and transmissibility. This observation suggests that the sand does not migrate far into the fractures. Similarly, it was observed that the number of stages was positively correlated with cell transmissibility and pore volume up to 20 stages. These results suggest that fracture treatments were significantly over designed and injecting less sand and water in fewer stages would optimize the economics of similar projects. To our knowledge this is the first work to analyze the results of fracture treatments by matching with pore volumes and transmissibility in a simple serial cell flow. / text

Un origami, ou encore une surface à petits carreaux, est l'exemple le plus simple d'une surface de translation. Il s'obtient en collant entre eux un nombre fini de carreaux identiques. Le point le plus intéressant est l'étude du flot linéaire sur un origami, qui est un système dynamique continu lié à la dynamique des billards ou encore celle des échanges d'intervalles. Nous pouvons aussi nous intéresser au stabilisateur de l'action naturelle du groupe spécial linéaire sur les origamis, que nous appelons groupe de Veech de l'origami. Le but de cette thèse est l'étude de ces deux notions sur des exemples d'origamis infinis, obtenus en collant une infinité dénombrable de carreaux entre eux. Ces exemples sont obtenus comme revêtement galoisiens d'origamis finis, avec comme groupe de Galois des groupes abéliens, nilpotents ou plus compliqués. / An origami, or a square-tiled surface, is the simplest example of translation surface. An origami can be viewed as a finite collection of identical squares, glued together along their edges. We can study the linear flow on this origami, which is the geodesic flow for this kind of surfaces. This dynamical system is related to the dynamical system of billiard, or interval exchange transformations. We can also study the Veech group of an origami. The special linear group acts on the space of translation surface, and the Veech group of an origami is the stabilizer of this origami under this action. We know in particular that the Veech group is a fuchsian group. In this thesis, we work on some example of infinite origamis. These origamis are constructed as Galois covering of finite origamis. In these examples, the deck group will be an abelian group, a niltpotent group or something more difficult.

Different methods have been proposed for history matching production of shale gas/oil wells which are drilled horizontally and usually hydraulically fractured with multiple stages. These methods are simulation, analytical models, and empirical equations. It has been well known that among the methods listed above, analytical models are more favorable in application to field data for two reasons. First, analytical solutions are faster than simulation, and second, they are more rigorous than empirical equations. Production behavior of horizontally drilled shale gas/oil wells has never been completely matched with the models which are described in this thesis. For shale gas wells, correction due to adsorption is explained with derived equations. The algorithm which is used for history matching and forecasting is explained in detail with a computer program as an implementation of it that is written in Excel's VBA. As an objective of this research, robust method is presented with a computer program which is applied to field data. The method presented in this thesis is applied to analyze the production performance of gas wells from Barnett, Woodford, and Fayetteville shales. It is shown that the method works well to understand reservoir description and predict future performance of shale gas wells. Moreover, synthetic shale oil well also was used to validate application of the method to oil wells. Given the huge unconventional resource potential and increasing energy demand in the world, the method described in this thesis will be the "game changing" technology to understand the reservoir properties and make future predictions in short period of time.