Understanding how swirl flows can be applied to processes in the oil and gas industry and how problems might hinder them, are the focus of this thesis. Three application areas were identified: wet gas metering, liquid loading in gas wells and erosion at pipe bends due to sand transport. For all three areas, Computational Fluid Dynamics (CFD) simulations were performed. Where available, experimental data were used to validate the CFD results. As a part of this project, a new test loop was conceived for the investigation of sand erosion in pipes. The results obtained from CFD simulations of two-phase (air-water) flow through a pipe with a swirl-inducing device show that generating swirl flow leads to separation of the phases and creates distinct flow patterns within the pipe. This effect can be used in each of the three application areas of interest. For the wet gas metering application, a chart was generated, which suggests the location of maximum liquid deposition downstream of the swirling device used in the ANUMET meter. This will allow taking pressure and phase fraction measurements (from which the liquid flow rate can be determined) where they are most representative of the flow pattern assumed for the ANUMET calculation algorithms. For the liquid loading application, which was taken as an upscaling of the dimensions investigated for the wet gas metering application, the main focus was on the liquid hold-up. This parameter is defined as the ratio of the flowing area occupied by liquid to the total area. Results obtained with CFD simulations showed that as the water rate increases, the liquid hold-up increases, implying a more effective liquid removal. Thus, it was concluded that the introduction of a swirler can help unload liquid from a gas well, although no investigation was carried out on the persistance of the swirl motion downstream of the device. For the third and final application, the erosion at pipe bends due to sand transport, the main focus was to check the erosion rate on the pipe wall with and without the introduction of a swirler. The erosion rate was predicted by CFD simulations. The flow that was investigated consisted of a liquid phase with solid particles suspended in it. The CFD results showed a significant reduction in erosion rate at the pipe walls when the swirler was introduced, which could translate into an extended working life for the pipe. An extensive literature review performed on this topic, complemented by the CFD simulations, showed the need for a dedicated multiphase test loop for the investigation of sand erosion in horizontal pipes and at bends. The design of a facility of this type is included in this thesis. The results obtained with this work are very encouraging and provide a broad perspective of applications of swirl flows and CFD for the oil and gas industry.

Iron oxide-bearing minerals have long been recognized as an effective reactive media for arsenic-contaminated groundwater remediation. This research aimed to develop a technique that could facilitate in situ oxidative precipitation of Fe3+ in a soil (sand) media for generating a subsurface iron oxide-based reactive barrier that could immobilize arsenic (As) and other dissolved metals in groundwater. A simple in situ arsenic treatment process was successfully developed for treating contaminated rural groundwater using iron oxide-coated sand (IOCS). Using imbibition flow, the system facilitated the dispersive transport of ferrous iron (Fe2+) and oxidant solutions in porous sand to generate an overlaying blanket where the Fe2+ was oxidized and precipitated onto the surface as ferric oxide. The iron oxide (FeOx) emplacement process was significantly affected by (1) the initial surface area and surface-bound iron content of the sand, (2) the pH and solubility of the coating reagents, (3) the stability of the oxidant solution, and (4) the chemical injection schedule. In contrast to conventional excavate-and-fill treatment technologies, this technique could be used to in situ replace a fresh iron oxide blanket on the sand and rejuvenate its treatment capacity for additional arsenic removal. Several bench-scale experiments revealed that the resultant IOCS could treat arsenic-laden groundwater for extended periods of time before approaching its effective life cycle. The adsorption capacity for As(III) and As(V) was influenced by (1) the amount of iron oxide accumulated on the sand surface, (2) the system pH, and (3) competition for adsorption sites from other groundwater constituents such as silicon (Si) and total dissolved solids (TDS). Although the IOCS could be replenished several times before exhaustion, the life cycle of the FeOx reactive barrier may be limited by the gradual loss of hydraulic conductivity induced by the imminent reduction of pore space over time.

The design and development of isolation or backfill materials, which seal the disposal facility, are important for disposing the wastes. The use of compacted bentonite-sand for construction of shaft seals and liners for waste containment structures has been proposed by various studies. Therefore / it is aimed in this study to develop an isolation material to be used in underground waste repositories. For such designs to be effective, their performance need to be assessed and a minimum hydraulic conductivity requirement defined by regulatory agencies should be satisfied (i.e. 1x10-8 m/s in Turkey, 1x10-9 m/s in USA). Therefore / this study assesses the performance of compacted bentonite/sand mixtures in terms of hydrological and mechanical properties. To be able to assess the performance of this material, a variety of laboratory tests were carried out. Engineering geological tests such as compaction, falling head permeability, swelling, unconfined compression and shear strength tests were conducted to select an optimum mixture. Finally, an optimum bentonite-sand mixture possessing 30% bentonite was recommended for the isolation of underground waste disposal facilities.

In this study, fracture grouting technique of saturated, granular soils of different fine content were investigated. Model tests were carried out by using fluid particulate grouts namely micro fine cement and ordinary portland cement grouts. Basically, relationships were obtained between soil conditions (grain size distribution, relative density, overburden stress) and grouting parameters (type of grout, grouting pressure, amount of injected grout, rheological properties of the grout or water/solids ratio). At the end of the tests the soil specimens were exposed and the final grout shapes were observed and correlated with the grouting parameters. Response of soil specimens to grouting process under different grouting pressures and grout compositions was analyzed. Amount of heave occurred at the top of the specimen during injections was recorded at each test. Micro fine cement grout and ordinary portland cement grout showed significant differences rheologically. Micro fine cement grout, with much higher Blaine fineness, lower specific gravity, lower viscosity and cohesion, lower bleed and filtration coefficients, made it possible to fracture the fine sandy soils of different fine content. Results of tests performed with micro fine cement grouts show that fracturing pressure generally decreases with an increase in the water content of the grout but generally increases as the fine content of the soil increases. A higher relative density of the soil increases the fracturing pressure significantly. The volumes of grout injected into soil specimens until fracturing show an increasing tendency as the water/solids ratio decrease. Ordinary portland cement grout, on the other hand, exposed to high pressure filtration during grouting in relatively clean sand and addition of some amount of kaolinite or fines is required to reduce the filtration percentages during grouting in order to fracture grout the sandy soil. Filtration due to high permeabilities results in accumulation of cement particles around the injection point and grouting tends to take a form similar to compaction grouting.

Expansive soils are a worldwide problem that poses several challenges for civil engineers. Such soils swell when given an access to water and shrink when they dry out. The most common and economical method for stabilizing these soils is using admixtures that prevent volume changes. In this study the effect of using Bigadic zeolite (boron by-product) in reducing the swelling potential is examined. The expansive soil is prepared in the laboratory by mixturing kaolinite and bentonite. Bigadic zeolite (boron by-product) is added to the soil at 0 to 25 percent by weight. Grain size distribution, Atterberg limits and swell percent and rate of swell of the mixtures are determined. Specimens are cured for 7 and 28 days. As a result of the experimental study, it was seen that addition of Bigadic zeolite (boronby-product) decreased swelling potential and rate of swell of the artificially prepared expansive soil specimen at laboratory conditions. The swell percentage and rate of swell of the stabilized specimens are affected positively by curing.

No description available.

With the rapidly increasing demand for energy and the increasing prices for oil and gas, the role of unconventional gas reservoirs (UGRs) as energy sources is becoming more important throughout the world. Because of high risks and uncertainties associated with UGRs, their profitable development requires experts to be involved in the most critical development stages, such as drilling, completion, stimulation, and production. However, many companies operating UGRs lack this expertise. The advisory system we developed will help them make efficient decisions by providing insight from analogous basins that can be applied to the wells drilled in target basins. In North America, UGRs have been in development for more than 50 years. The petroleum literature has thousands of papers describing best practices in management of these resources. If we can define the characteristics of the target basin anywhere in the world and find an analogous basin in North America, we should be able to study the best practices in the analogous basin or formation and provide the best practices to the operators. In this research, we have built an advisory system that we call the Unconventional Gas Reservoir (UGR) Advisor. UGR Advisor incorporates three major modules: BASIN, PRISE and Drilling & Completion (D&C) Advisor. BASIN is used to identify the reference basin and formations in North America that are the best analogs to the target basin or formation. With these data, PRISE is used to estimate the technically recoverable gas volume in the target basin. Finally, by analogy with data from the reference formation, we use D&C Advisor to find the best practice for drilling and producing the target reservoir. To create this module, we reviewed the literature and interviewed experts to gather the information required to determine best completion and stimulation practices as a function of reservoir properties. We used these best practices to build decision trees that allow the user to take an elementary data set and end up with a decision that honors the best practices. From the decision trees, we developed simple computer algorithms that streamline the process.

Back grinding (BG) wastewater consists mainly of high-purity water and high concentrations of inorganic particles. If the BG wastewater could be treated and recycled efficiently, it should be sort of economic benefit. In this study, appropriate pre-treatment technologies are evaluated to obtain the feasible recycle system. From the chemical coagulation experiment, the addition of PAC or FeCl3, both of them can obviously reduce the turbidity and suspended solid concentrations (SS). In addition, polymer can advance the sedimentation process. Considering the cost of practical operation, the turbidity of BG waste water could be removed up to 97% by using polyaluminum chloride as the coagulant (2.2 mg/L) and polymer as the coagulant aid (0.5 mg/L) in the pH=7 condition . In sand filtration experiment, the turbidity and SS can¡¦t be effectively removed if the coagulation isn¡¦t used on BG wastewater. It demonstrates that BG wastewater contains high concentration of nano-scale particles. The rate of removable turbidity can reach 99% under applying coagulation, sedimentation, and sand filtration. In ultra-filtration experiment, both of spiral-wound (SW) and hollow-fiber (HF) can remove more than 99.9% of turbidity. For the flux of behavior, the performance of pre-treatment water is better than non-treatment water. Thus, it reveals that appropriate pre-treatment can lower the load of membrane filtration system. For the obtained recycle water, the grade of standard can achieve the grade of the cooling tower required. However, due to its high particle-containing characteristics, the commonly used reverse-osmoses (RO) membrane filtration technology can not be directly applied for purification process because the fouling/clogging problem would cause the frequent membrane replacement. In this lab-scale feasibility study, pre-treatment technologies (e.g., sand filtration, chemical coagulation, ultra-filtration) were applied to reduce the turbidity and particle concentrations of the BG wastewater (collected from a semiconductor manufacturing plant) before RO filtration unit. The BG wastewater contained turbidity and suspended solid concentrations of 3,200 NTU and 96 mg/L, respectively. The measured pH and conductivity of the BG wastewater were in the ranges of 6.8 to 7.2 and 14 to 18 £gS/cm, respectively. Moreover, the particle sizes of the solids varied from 300 to 700 nm. Thus, applying conventional sand filtration along could not effectively remove the nano-scale particles. Results from the chemical coagulation experiment reveal that the turbidity and particles of the BG wastewater could be significantly removed (up to 95% of turbidity and particle removal) by the coagulation/sedimentation process using polyaluminum chloride as the coagulant (2.2 mg/L) and polymer as the coagulant aid (0.5 mg/L). Results also indicate that up to 99% of turbidity and particle removal could be obtained with the application of ultra-filtration unit after the coagulation/sedimentation process. Results from this study indicate that applying appropriate pre-treatment technologies (coagulation and ultra-filtration) would lower the fouling rate and extend the life of RO membrane used for BG wastewater purification.

This work shows that toughness (resistance) to fracture propagation is an inherent characteristic of cohesionless particulate materials, which is significant for understanding hydraulic fracturing in geotechnical, geological, and petroleum applications. We have developed experimental techniques to quantify the initiation and propagation of fluid-driven fractures in saturated particulate materials. The fracturing liquid is injected into particulate materials, where the fluid flow is localized in thin crack-like conduits. By analogy, we call them 'cracks' or 'hydraulic fractures'. Based on the laboratory observations and scale analysis, this work offers physical concepts to explain the observed phenomena. When a fracture propagates in a solid, new surfaces are created by breaking material bonds. Consequently, the material is in tension at the fracture tip. In contrast, all parts of the cohesionless particulate material (including the tip zone of hydraulic fracture) are likely to be in compression. In solid materials, the fluid front lags behind the front of the propagating fracture, while the lag zone is absent for fluid-driven fractures in cohesionless materials. The compressive stress state and the absence of the fluid lag are important characteristics of hydraulic fracturing in particulate materials with low, or no, cohesion. Our experimental results show that the primary factor affecting peak (initiation) pressure is the magnitude of the remote stresses. The morphology of fracture and fluid leak-off zone, however, changes significantly not only with stresses, but also with other parameters such as flow rate, fluid rheology, and permeability. Typical features of the observed fractures are multiple off-shots and the bluntness of the fracture tip. This suggests the importance of inelastic deformation in the process of fracture propagation in cohesionless materials. Similar to solid materials, fractures propagated perpendicular to the least compressive stress. However, peak injection pressures are significantly greater than the maximum principle stresses in the experiments. Further, by incorporating the dominate experimental parameters into dimensionless form; a reasonable power-law fit is achieved between a dimensionless peak injection pressure and dimensionless stress. Scaling indicates that there is a high pressure gradient in the leak-off zone in the direction normal to the fracture. Fluid pressure does not decrease considerably along the fracture, however, due to the relatively wide fracture aperture. This suggests that hydraulic fractures in unconsolidated materials propagate within the toughness-dominated regime. Furthermore, the theoretical model of toughness-dominated hydraulic fracturing can be matched to the experimental pressure-time dependences with only one fitting parameter. Scale analysis shows that large apertures at the fracture tip correspond to relatively large 'effective' fracture (surface) energy, which can be orders of magnitude greater than typical for hard rocks.

Reproduction de : Thèse de doctorat : Sciences de l'éducation : Lyon 2 : 2003. / Titre provenant de l'écran-titre. Bibliogr.