Oil companies need to evaluate the risk of annular fluid or gas migration if cement fails during the life of the well. Sustained casing pressure can lead to shutting in the wells to avoid health, safety, and environment (HSE) risks and government fines. To understand the long-term integrity of cement in high temperature and high pressure (HTHP) conditions and the mechanical properties that affect the ability of cements to seal fluids, this project used finite-element models (FEMs) to study the stress-causing phenomena. FEM analyses in ABAQUS version 6.11 were used to determine the potential of cement failure in oil wells. The model uses a 3D section of a well that can be used for different casing and formation types under different loading conditions. The model built in ABAQUS version 6.11 allows incorporating materials with nonlinear mechanical properties; it also uses FEM analysis to forecast fractures inside the cement under different loading scenarios like hydraulic fracture jobs or casing tests. The finite-element model included cases for cement cracking, cement debonding, and plastic deformation of the cement and rock that can generate loss of zonal isolation. Linear manner: set cements behave elastically until a failure criterion is reached, and then they can behave plastically. The FEM approach can reproduce stresses, strains, and volume changes in the material under different environmental HTHP conditions. Cemented wells have both tensile and compressive stresses that make some parts of the cement sheath experience fracture initiation, plastic deformation, or debonding. This dissertation provides a model that will help drillers design the set cement for long-term integrity in HPHT well conditions. The FEM predicts if the cement sheath can develop debonding, cracks or plastic deformations during the life of the well. The cement sheath needs to be designed for long-term zonal isolation to avoid interzonal communications, remedial costs and environmental problems related to cement seal. A CMS™-300 Automated Permeameter, a mechanical properties analyzer, HPHT cement consistometer, annular expansion molds, and tri-axial test equipment were used in this study to test cements for specific applications in three Colombian oil fields, including an oil field with in-situ combustion project.

Thermal and fatigue cracking are pavement distresses that deteriorate asphalt pavements in Canada. However, the current AASHTO M320 standard specification protocol does not give satisfactory correlation between the properties measured in the laboratory to thermal and fatigue cracking performance of the asphalt in service. This thesis is aimed at validating the newly developed MTO LS-299 and LS-308 specification test methods for predicting pavement distress. A secondary objective is to determine how well laboratory-aged and field-aged binders correlate with each other in terms of their chemical and physical properties. Chemical testing using infrared (IR) spectroscopy and X-ray fluorescence (XRF), as well as physical and mechanical testing using the regular bending beam rheometer (BBR), extended BBR (eBBR), dynamic shear rheometer (DSR), and double edge notched tension (DENT) tests were performed on laboratory-aged and recovered binders from Highway 417. Asphalt cements with significant amounts of waste engine oil residues as determined by XRF data were found to have cracked severely due to their high tendency for chemical aging. Western Canadian binders modified with styrene-butadiene-styrene polymer showed low affinity for both chemical and physical aging as determined from their carbonyl indices. Asphalt binders with smaller paraffinic structures exhibited insignificant pavement deterioration while the opposite occurred to those with low aromatic indices according to their IR data. The DSR data show that chemical aging occurs much faster in the laboratory-aged binders than the field-aged binders. The DENT test is able to separate superior performing binders from inferior ones with 86% accuracy according to their CTOD data. The regular BBR gave poor correlation between the laboratory test methods and the performance of the pavements. Good correlation exists between the laboratory test methods and the performance of the pavements in service according to the eBBR data. Pavements without any cracks showed lower grade losses, while pavements with severe thermal cracking recorded higher grade losses after three days of conditioning prior to testing. The study has shown that the eBBR and DENT tests are better tools for predicting pavement performance and provide good specification tests for the control of thermal and fatigue cracking in modern pavements. / Thesis (Master, Chemistry) -- Queen's University, 2012-02-28 13:16:02.222

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Pasiūlytas mangano nustatymo metodas geriamajame vandenyje inversinės voltamperometrijos metodu naudojant gyvsidabrio plėvelinį elektrodą. Manganui nustatyti vandens mėginio nereikia chemiškai apdoroti. Optimalios nustatymo sąlygos: kaupimo potencialas –1,75 V, kaupimo trukmė 5–30 s, anodinis tirpinimas atliekamas naudojant kvadratinės bangos voltamperometriją. Mangano aptikimo riba kaupiant jį 30 s yra apie 0,4 μg l–1, o santykiniai standartiniai nuokrypiai darbiniame koncentracijų intervale ne didesni kaip 0,10. Realios kalcio, magnio ir geležies jonų koncentracijos geriamojo vandens mėginiuose netrukdo nustatyti manganą. Metodo palyginimas su standartiniu fotometriniu metodu parodė, kad jie yra ekvivalentiški, tačiau elektrocheminis metodas gali būti taikomas labai mažoms mangano koncentracijoms nustatyti, be to, jam netrukdo geriamajame vandenyje esantys geležies jonai. Chromo nustatymui cemente gali būti naudojamas katalitinės adsorbcinės voltamperometrijos metodas naudojant kabančio gyvsidabrio lašo elektrodą. Terpės sudėtis Cr(VI) nustatyti: 0,15 mol l-1 CH3COONa, 5 mmol l-1 dietilentriaminpentaacto rūgšties (DTPA), 0.7 mol l-1 NaNO3, pH = 6. Optimalios votamperometrijos sąlygos: kaupimo potencialas –0.9 V, kaupimo trukmė 5-10 s, kvadratinės bangos voltamperometrijos režimas. Cr(VI) aptikimo riba yra apie 0,05 µg l 1, santykinis standartinis nuokrypis neviršija 3%. Iš cemento mėginių chromas išekstrahuojamas vandeniu arba azoto rūgštimi. Bendras chromo kiekis... [toliau žr. visą tekstą] / There was proposed method for the determination of manganese in drinking water by inverse voltammetry using a mercury film electrode. The determination of manganese in drinking water does not need chemical treatment of a sample. Optimal detection conditions: accumulation potential of -1.75 V, accumulation time 5-30 s, anodic dissolution is performed using square wave voltammetry. Manganese accumulation by the detection limit of 30 seconds is about 0.4 mg l-1, and the relative standard deviations of the working range of concentrations do not exceed 0.10. Actual calcium, magnesium and iron ion concentration in samples of drinking water does not influence the manganese determination. Method comparison with a standard photometric method showed that they are equivalent, but the electrochemical method can be applied in very small concentrations of the manganese, in addition, it does not influence the iron ions in the drinking water. Determination of chromium in cement can be performed by catalytic adsorption voltammetry method using a hanging mercury drop electrode. The medium composition for Cr (VI) determination: 0.15 mol L-1 CH3COONa, 5 mmol l-1 diethylenetriaminepentaacetic acid (DTPA), 0.7 mol l-1 NaNO3, pH = 6. Optimal voltammetry conditions: accumulation potential of -0.9 V, accumulation time 5-10 s, square wave voltammetry mode. Cr (VI) detection limit is about 0.05 mg l-1, the relative standard deviation does not exceed 3%. Chromium was extracted from the cement samples... [to full text]

There was proposed method for the determination of manganese in drinking water by inverse voltammetry using a mercury film electrode. The determination of manganese in drinking water does not need chemical treatment of a sample. Optimal detection conditions: accumulation potential of -1.75 V, accumulation time 5-30 s, anodic dissolution is performed using square wave voltammetry. Manganese accumulation by the detection limit of 30 seconds is about 0.4 mg l-1, and the relative standard deviations of the working range of concentrations do not exceed 0.10. Actual calcium, magnesium and iron ion concentration in samples of drinking water does not influence the manganese determination. Method comparison with a standard photometric method showed that they are equivalent, but the electrochemical method can be applied in very small concentrations of the manganese, in addition, it does not influence the iron ions in the drinking water. Determination of chromium in cement can be performed by catalytic adsorption voltammetry method using a hanging mercury drop electrode. The medium composition for Cr (VI) determination: 0.15 mol L-1 CH3COONa, 5 mmol l-1 diethylenetriaminepentaacetic acid (DTPA), 0.7 mol l-1 NaNO3, pH = 6. Optimal voltammetry conditions: accumulation potential of -0.9 V, accumulation time 5-10 s, square wave voltammetry mode. Cr (VI) detection limit is about 0.05 mg l-1, the relative standard deviation does not exceed 3%. Chromium was extracted from the cement samples... [to full text] / Pasiūlytas mangano nustatymo metodas geriamajame vandenyje inversinės voltamperometrijos metodu naudojant gyvsidabrio plėvelinį elektrodą. Manganui nustatyti vandens mėginio nereikia chemiškai apdoroti. Optimalios nustatymo sąlygos: kaupimo potencialas –1,75 V, kaupimo trukmė 5–30 s, anodinis tirpinimas atliekamas naudojant kvadratinės bangos voltamperometriją. Mangano aptikimo riba kaupiant jį 30 s yra apie 0,4 μg l–1, o santykiniai standartiniai nuokrypiai darbiniame koncentracijų intervale ne didesni kaip 0,10. Realios kalcio, magnio ir geležies jonų koncentracijos geriamojo vandens mėginiuose netrukdo nustatyti manganą. Metodo palyginimas su standartiniu fotometriniu metodu parodė, kad jie yra ekvivalentiški, tačiau elektrocheminis metodas gali būti taikomas labai mažoms mangano koncentracijoms nustatyti, be to, jam netrukdo geriamajame vandenyje esantys geležies jonai. Chromo nustatymui cemente gali būti naudojamas katalitinės adsorbcinės voltamperometrijos metodas naudojant kabančio gyvsidabrio lašo elektrodą. Terpės sudėtis Cr(VI) nustatyti: 0,15 mol l-1 CH3COONa, 5 mmol l-1 dietilentriaminpentaacto rūgšties (DTPA), 0.7 mol l-1 NaNO3, pH = 6. Optimalios votamperometrijos sąlygos: kaupimo potencialas –0.9 V, kaupimo trukmė 5-10 s, kvadratinės bangos voltamperometrijos režimas. Cr(VI) aptikimo riba yra apie 0,05 µg l 1, santykinis standartinis nuokrypis neviršija 3%. Iš cemento mėginių chromas išekstrahuojamas vandeniu arba azoto rūgštimi. Bendras chromo kiekis... [toliau žr. visą tekstą]

Cement-based materials are of importance in the construction of geothermal wells and high-temperature oil and gas wells. These materials fill the annulus between the well casing and the rock forming a protective layer, known as sealant, which is used primarily to secure and support the casing inside the well. In addition it prevents entry of unwanted fluids into the well and communication between formation fluids at different levels. These cement based sealants need to perform for many years at high temperatures and in severe chemical environments; conditions which can cause the material of the well-casing to degrade resulting in reduced strength and increased permeability. The aim of this study is to develop new materials which will have the potential properties (high strength and low permeability) for use as sealants in geothermal and deep, hot oil wells. In order to do this special cement slurries, based on the CaO−Al2O3−SiO2−H2O (CASH) hydroceramic system, have been synthesised over the temperature range 200 to 350 °C (i.e. the typical working temperature of these wells). The additives used in these cement slurries are silica flour and alumina. A detailed description of a suite of novel hydroceramic compositions over the temperature range 200 to 350 °C is given. X-ray diffraction has been used to determine the mineralogical composition and Rietveld refinement to quantify the known phases present at different temperatures. In addition the chemistry of some of the major phases present has been examined using electron probe microanalysis. Scanning electron microprobe and simulation software have been employed to study the crystal shape of these major minerals. The engineering properties of the hydroceramic materials are very important. A study of the compressive strength and permeability has been carried out over a range of temperature (200 to 350 °C). In addition permeability has been calculated using simulation software and the results compared with experimental values. Hydroceramic formulations with excellent strength and permeability measurements have been found. Some of these formulations have been tested for durability under simulated well conditions. These materials have been immersed into different brines for a certain period of time at temperatures between 200 to 300 °C. Some preliminary results regarding the changes in mineralogy in these samples are presented in this thesis. These experiments have been carried out at the Synchrotron Radiation Source (SRS) using tomographic energy-dispersive diffraction imaging (TEDII).

The cement industry releases large quantities of CO₂ into the atmosphere during the manufacture of Portland Cement. The intrinsic property of the cement to reabsorb some of this CO₂ over its life time through a process called recarbonation has been investigated. This thesis reports on the development of an accelerated recarbonation apparatus for studying the recarbonation of crushed concrete under controlled conditions. The apparatus involved a series of airtight desiccators into which were placed the crushed concrete samples. The desiccators were then filled to ~50,000 ppm CO₂, which is significantly greater than the ~380 ppm by volume CO₂ available in the earth’s atmosphere. The CO₂ concentration was then monitored with respect to time inside the desiccator using CO₂ specific infrared probes. Two concrete design strengths of 20MPa and 40MPa with various crushed particle sizes were exposed to conditions of 50-60 % relative humidity, a temperature of 20 ± 1.5 °C, an exposure period of 21 days and a maximum CO₂ concentration of ~50,000 ppm by volume. The CO₂ uptake measured by the infrared probes was verified using other detection methods of FTIR, TGA, XRF, phenolphthalein indicator and the weight gain of the crushed concrete samples. The research found that a concrete of 20 MPa design strength and a water to cement ratio of 0.67 could absorb 12-83 % of the original calcination emissions for particle sizes <40, <20 and <10 mm in the 21 day time period. Similar behaviour was also exhibited by the 40 MPa design strength (w/c 0.49) but the extent of CO₂ uptake was not as pronounced. The 40 MPa (w/c 0.49) design mix absorbed 9-70 % of the original calcination emissions for the same particle sizes of <40, <20 and <10 mm. It was found that significant quantities of CO₂ could be absorbed by the smaller crushed sizes of <10 and <20 mm for both design mixes, owing to their much larger surface area. It was also found that about 80 % of the total CO₂ absorbed occurred within the first 10 days of exposure. It is envisaged that the results contained in this thesis will assist in future investigations into crushed concrete recarbonation.

The ever-increasing quantity of by-products generated from burning coal in the production of electricity has brought about the need for new areas of utilization. This study examined the use of FGD gypsum and fluidized bed combustion ash along with Class F fly ash in the production of low-energy, 100% by-product cement blends. The cement blends used the advantageous properties of the by-product materials to create cementing properties rather than energy intensive clinker used in ordinary portland cement. The FGD gypsum was converted to hemihydrate which rapidly hydrated to provide the cement with early strength gains, whilst the fluidized bed combustion ash reacted with the Class F fly ash to form pozzolanic cementitious phases which provided the longer-term compressive strength and possibly resistance to weathering. The rate of compressive strength gains and minimizing detrimental expansion were two properties of particular interest in the study. Chemical admixtures were used to improve the compressive strengths of the cement mortars and decrease their solubility.

Grouting techniques have been in used for many years, but several new grout materials have surfaced in recent decades that have re-defined the boundaries of the limitations of grouting programs. Typically these applications are used for seepage control in earthen impoundments, but strength of these earthen impoundments should be considered where there is potential for movement in the grouted soil mass. This study investigated initial conditions that could affect grout application effectiveness. The initial conditions in question were soil grain size and in situ moisture content. Two grouts were used, ultrafine and acrylate, and variations in pure grout properties were studied. An apparatus was developed so that a uniform grout could penetrate the pore spaces of a soil specimen. The rate of penetration of the grout into the soil was studied. The unconfined compressive strength of the resulting grouted soil was then analyzed. In testing neat ultrafine grout, it was shown that increased water-to-cement ratios had negative effects on the stability of the grout. Increasing the water-to-cement ratio from 0.5 to 2.5 resulted in a decrease in strength by a factor of 100. An inhibitor chemical was used to increase the time for reaction in the acrylate grout. During the chemical reaction, the curing temperature and gel times were monitored. A grout mix was selected for the acrylate grout that achieved appropriate gel times. In general, this study found that the grout penetrations rates into the soil increased as the initial moisture was increased from dry conditions to a gravimetric moisture content of nine percent. In each study, increased initial moisture decreased the grouted soil strength, with decreases in strength exceeding 50 percent. Empirical relationships were realized when compared to the initial matric suction of the soil. This suggests initial matric suction may be a useful initial condition for estimating increases in soil strength upon implementation of a grouting program for both the acrylate and ultrafine grouts.