This analysis focused primarily on three main treatment methods which were re-use, recycle, and disposal wells. The re-use treatment option is when wastewater is mixed with source water in order to meet fracturing water requirements. With this option, the hope is that the wastewater for re-use will require little or no treatment at all. The second treatment option is the recycle option. This option provides high quality water for re-use or discharge to the environment using a recycling technology. The credibility of this option is heavily dependent on its ability to recycle almost all of the wastewater with little or none left for disposal or treatment. The third option is well disposal. This entails disposing all of the wastewater into a deep formation. The software used for building the model is called @Risk. The model’s costs were estimates from recent research to capture the risks and uncertainties associated with wastewater disposal. The model revealed that re-use option remains the most cost effective treatment method to reduce overall water management cost in the Marcellus. The re-use option is most viable when a hydraulic fracturing schedule is continuous (no significant storage requirement) and infrastructure is available to transport wastewater from one fracturing operation to the other. The recycle option is the second most viable disposal option. This option is most effective when the hydraulic fracturing schedule is staggered in both time and distance because distilled water from recycling facilities can be easily discharged into the environment or stored. The most unfavorable option for wastewater management at the Marcellus is the well disposal option due to the high cost of trucking wastewater to disposal wells in neighboring states or counties. It also requires the highest usage of fresh water. A well disposal option can be favorable at the onset of a hydraulic fracturing schedule when there are low levels of infrastructure, hydraulic fracturing programs are not continuous or localized in proximity, and the volume of wastewater does not exceed the capacity for injection. In this case, disposal wells can be more favorable than recycle or re-use if they are in close proximity to drilling sites. / text

A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, South Africa, in fulfilment of the requirements for the degree of Doctor of Philosophy, 2013. / The aim of the thesis is to derive group invariant, exact, approximate analytical and numerical solutions for a two-dimensional laminar, non-Newtonian pre-existing hydraulic fracture propagating in impermeable and permeable elastic media. The fracture is driven by the injection of an incompressible, viscous non-Newtonian fluid of power law rheology in which the fluid viscosity depends on the magnitude of the shear rate and on the power law index n > 0. By the application of lubrication theory, a nonlinear diffusion equation relating the half-width of the fracture to the fluid pressure is obtained. When the interface is permeable the nonlinear diffusion equation has a leak-off velocity sink term. The half-width of the fracture and the net fluid pressure are linearly related through the PKN approximation. A condition, in the form of a first order partial differential equation for the leak-off velocity, is obtained for the nonlinear diffusion equation to have Lie point symmetries. The general form of the leak-off velocity is derived. Using the Lie point symmetries the problem is reduced to a boundary value problem for a second order ordinary differential equation. The leak-off velocity is further specified by assuming that it is proportional to the fracture half-width. Only fluid injection at the fracture entry is considered. This is the case of practical importance in industry. Two exact analytical solutions are derived. In the first solution there is no fluid injection at the fracture entry while in the second solution the fluid velocity averaged over the width of the fracture is constant along the length of the fracture. For other working conditions at the fracture entry the problem is solved numerically by transforming the boundary value problem to a pair of initial value problems. The numerical solution is matched to the asymptotic solution at the fracture tip. Since the fracture is thin the fluid velocity averaged over the width of the fracture is considered. For the two analytical solutions the ratio of the averaged fluid velocity to the velocity of the fracture tip varies linearly along the fracture. For other working conditions the variation is approximately linear. Using this observation approximate analytical solutions are derived for the fracture half-width. The approximate analytical solutions are compared with the numerical solutions and found to be accurate over a wide range of values of the power-law index n and leak-off parameter β. The conservation laws for the nonlinear diffusion equation are investigated. When there is fluid leak-off conservation laws of two kinds are found which depend in which component of the conserved vector the leak-off term is included. For a Newtonian fluid two conservation laws of each kind are found. For a non-Newtonian fluid the second conservation law does not exist. The behaviour of the solutions for shear thinning, Newtonian and shear thickening fluids are qualitatively similar. The characteristic time depends on the properties of the fluid which gives quantitative differences in the solution for shear thinning, Newtonian and shear thickening fluids.

A dissertation submitted to the Faculty of Science,University of the Witwatersrand, in fulfilment of the requirements for the degree of Master of Science. December 2016. / This research is concerned with the analysis of a two-dimensional Newtonian fluid-driven fracture in a permeable rock. The fluid flow in the fracture is laminar and the fracture is driven by the injection of a Newtonian fluid into it. Most of the problems in litera- ture involving fluid flow in permeable rock formation have been modeled with the use of Darcy's law. It is however known that Darcy's model breaks down for flows involv- ing high fluid velocity, such as the flow in a porous rock formation during hydraulic fracturing. The Forchheimer flow model is used to describe the non-Darcy fluid flow in the porous medium. The objective of this study is to investigate the problem of a fluid-driven fracture in a porous medium such that the flow in the porous medium is non-Darcy. Lubrication theory is applied to the system of partial di erential equations since the fracture that is considered is thin and its width slowly varies along its length. For this same reason, Perkins-Kern-Nordgren approximation is adopted. The theory of Lie group analysis of differential equations is used to solve the nonlinear coupled sys- tem of partial differential equations to obtain group invariant solutions for the fracture half-width, leak-o depth and length of the fracture. The strength of fluid leak-off at the fracture wall is classi ed into three forms, namely, weak, strong and moderate. A group invariant solution of the traveling wave form is obtained and an exact solution for the case in which there is weak fluid leak-off at the interface is found. A dimensionless parameter, F0, termed the Forchheimer number was obtained and investigated. Nu- merical results are obtained for both the case of Darcy and non-Darcy flow. Computer generated graphs are used to illustrate the analytical and numerical results. / MT2017

BACKGROUND: Over the past decade hydraulic fracturing, the high-pressure injection of water and chemicals into an oil or gas well, has been widely adopted to maximize oil and gas recovery despite debate about potential health impacts. Often the debate is contentious and complicated by incomplete information. The purpose of this dissertation was to implement and assess the usefulness of a process for communities to identify, prioritize, and respond to potential health effects of hydraulic fracturing. METHODS: The study was conducted in a community in Kern County, California, the epi-center of hydraulic fracturing in the state. Mixed methods were used to develop an inventory of known or potential health effects associated with exposure to hydraulic fracturing: a systematic review of literature published before April 1, 2017 to determine health outcomes reported in exposed communities; a Delphi study to elicit expert opinion; and focus groups to determine residents’ health concerns. The resulting inventory of 60 health effects derived from one or more of these sources was presented to community residents in ballot form and multi-voting was used to prioritize health effects. Focus group and multi-voting results were used to develop an action plan. RESULTS: The Delphi panel endorsed 13 health outcomes associated with hydraulic fracturing for oil and/or gas; all but one were reported in the scientific literature. Focus groups generated 17 health effects; 13 of these were reported in the scientific literature and/or endorsed by the Delphi panel. Multi-voting results indicated that priority health effects were: problems with sleep; breathing; eyes, ears, nose, and throat; heart disease and hypertension; cancer; headache; nausea; and a group of symptoms known as “Shale Gas Syndrome”. CONCLUSION: The process described in this dissertation could be used by communities across the US that are debating the potential health impacts of hydraulic fracturing. It engages community residents, requires few resources, and can be completed in a relatively short period of time. The results can inform a community-specific response to the priority health concerns identified.

As unconventional drilling has emerged as a major industry in the US and around the world, many environmental health and pollution risks have surfaced. One emerging concern is the risk of environmental contamination arising from unconventional wastes that are enriched in naturally-occurring radioactive materials (NORM). Although NORM has been a well-documented contaminant of oil and gas wastes for decades, there are new challenges associated with unconventional drilling. This thesis discusses several of these challenges, focusing on NORM from black shale formations. Chapter 1 provides background information on environmental radioactivity and unconventional drilling. Chapter 2 describes the potential for NORM to migrate into groundwater around unconventional drilling operations. Chapters 3 and 4 describe radiochemical methods developed for the analysis of Marcellus Shale unconventional drilling wastes. Chapter 5 describes environmental partitioning of Marcellus Shale unconventional drilling wastes. Collectively, this thesis attempts to broaden the scientific understanding of NORM in unconventional drilling wastes so that potential environmental impacts may be mitigated.

Unconventional natural gas extraction from the Marcellus Shale requires millions of gallons of water to fracture shale and release natural gas from the formation. This process produces water with high levels of total dissolved solids (TDS); and, efforts to recycle these fluids has stimulated microbial growth in produced water. The objective of this study was to analyze the ionic composition of and characterize microorganisms from Marcellus produced water samples. A semi-synthetic culture medium was designed with high TDS to enrich for halophilic microbes, which yielded robust cultures that were able to grow over a wide range of salinities. DNA extracted from aerobic cultures was used for 16s rDNA clone libraries and Automated Ribosomal Intergenic Spacer Analysis (ARISA). ARISA and 16S gene sequencing revealed differences in bacterial composition between Marcellus and freshwater samples. Sequencing of 16S gene indicated the presence of Halomonas, Thalassospira and other genera related to halophilic and petroleum degrading species. / Bayer School of Natural and Environmental Sciences / Environmental Science and Management (ESM) / MS / Thesis

The hydraulic fracturing treatment is an essential tight sand gas reservoir stimulation that employs viscous fluid to break the formation rock to create a fracture and transport the propping agent to support the fracture from naturally healing. Despite proven economic benefit, the hydraulic fracture fluid damages the producing formation and the propped fracture. To analyze the gel damage effect quantitatively, the filter cake thickness is used as a parameter that has not been measured before. This project was divided into two stages. The first stage built up a filter cake and measured the filter cake thickness by a laser profilometer. A correlation between leakoff volume and filter cake thickness was produced. The second stage eroded the filter cake by flowing original fracturing fluid through the core sample to study the fracturing fluid shear clean up effect on filter cake thickness. The filter cake was built up in the lab and the thickness was measured with different methods. The profilometer has been tested as an effective tool to measure the filter cake thickness. A correlation for crosslinked guar fracture fluid filter cake thickness was produced. An experiment setup used to shear erode the filter cake was built and tested. The results showed the filter cake was not eroded at 200 s-1 shear rate.

Unbroken gel and residue from guar-based fracturing gels can be a cause for formation damage. The effectiveness of a fracturing treatment depends on better achieveing desired fracture geometry, proper proppant placement and after that, a good clean-up. The clean-up is achieved by reducing the fluid viscosity using chemical additives called "Breakers". There are many different types of breakers used in the industry, but they can be broadly divided into two categories: oxidizers and enzymes. Breaker perfromance depends on bottomhole temperature, breaker concentration and polymer loading. Different kind of breakers, used at different concentrations and temperatures, give different kind of "break" results. Therefore, the amount of unbroken gel and residue generated is also different. This project was aimed at studying basic guar-breaker interactions using some of the most common breakers used in the industry. The breakers studied cover a working temperature range of 75 degrees F to 300 degrees F. The effectiveness of each breaker was studied and also the amount of damage that it causes. Viscosity profiles were developed for various field concentrations of breakers. The concentrations were tested over temperature ranges corresponding to the temperatures at which each breaker is used in the field. The majority of these viscosity tests were 6 hours long, with a few exceptions. Early time viscosity data, for the intial 10 minutes of the test, was also plotted from these tests for fracturing applications where the breaker is required to degrade the fluid by the time it reached downhole. This was needed to prevent the damage to the pumping equipment at the surface yet still have almost water-like fluid entering into the formation. The study provides a better understanding of different breaker systems, which can be used in the industry, while designing fracturing fluid systems in order to optimize the breaker performance and achieve a better, cleaner break to minimize the formation damage caused by polymer degradation.

Productivity index (PI) is an important indicator of a well?s production capacity. For conventional reservoirs, well productivity is usually calculated using the pressure response of the reservoir in its pseudosteady-state period. There are numerous studies for different well completion schemes which developed correlations for pseudosteady-state productivity index for specific cases, such as horizontal wells and fractured wells. Most of the developed models for complex well completion schemes use some approximations for productivity index calculation and they have some limitations in use. Furthermore, as the petroleum industry goes toward producing lower quality reservoirs like low- and ultra low-permeability reservoirs, the period of transient flow covers a larger part of the well lifetime and these pseudosteady-state productivity calculations become less applicable in prediction of the reservoir?s production behavior. The Distributed Volumetric Sources (DVS) method seems able to fill this gap. Our method is able to predict the productivity index of a general well completion scheme for transient as well as pseudosteady-state flow periods. In this study, we focus on a typical well completion scheme ? vertical well intersected by a vertical fracture of finite conductivity. Parametric study is performed by varying the proppant pack permeability with a linear distribution, varying fracture width with an elliptical distribution and varying fracture height with an elliptical distribution. The details of hydraulic fracture are integrated into the calculation of well productivity. By combining the well productivity with gas material balance, production forecasting of the hydraulically fractured wells could be easily obtained. The result of production forecasting could be used to aid in decision making of choosing the best stimulation treatment. Field examples are presented to illustrate the application of this technology for production modeling the complicated reservoir cases involving fracture stimulation.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 140-146). Available also in a digital version from Dissertation Abstracts.