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Carbons and graphites have many industrial applications e.g. synthetic graphite (as moderators in the nuclear industry), natural flake graphites (for application in the manufacture of anti-piping agents) and metallurgical coke (for use in the blast furnace). The overall objective of this Thesis is to study effects of changes in properties of graphites and cokes by (i) radiolytic gasification of graphite, (ii) intercalation of natural flake graphites by sulphuric acid and (iii) intercalation of metallurgical cokes by potassium. (i) Radiolytic gasification Methods of image analysis have been developed to study the pore structure of graphite. These methods have been used to investigate the change in pore structure of a series of radiolytically gasified graphites. To examine the pore structure of the graphites by optical and scanning electron microscopy, each sample was vacuum-impregnated with a slow-setting resin containing a yellow dye. A semi-automatic image analysis system (Micromeasurements VrDS) linked to the optical microscope, enabled data on porosity to be obtained. The pore outline data, so obtained, were used by programmes on the controlling microcomputer to provide pore parameters such as cross-sectional areas, perimeters, Feret's diameters and shape factors. The results show that pores less than 100 ~m2 cross-sectional area are gasified because of the inability of the inhibitors (carbon monoxide and methane) to deactivate activated CO2* species before reaching the pore wall. Pores >1000 ~m2 cross-sectional area show only small changes in size and shape because of the deposition of carbon from methane inhibitor in these pores and are only developed at weight losses >17.0 wt.% by coalescence of open porosity <100 ~m2 cross-sectional area. (ii) Intercalation of natural flake graphite's Techniques have been developed to distinguish between natural flake graphite's and establish those suitable for use as anti-piping agents. Techniques used to examine the structure of natural flake graphite's include EDAX analysis to monitor amounts and distributions of elements, bromine intercalation to assess crystallographic ordering and image analysis to examine size and shape of the natural flake graphite's before and after intercalation. Results indicated that performances of the natural flake graphite's for use in intercalation studies can be predicted by assessing morphology and extents of fissures, bromine uptake, and mineral distribution of the flakes. Flakes suitable for intercalation studies have a mean flake thickness of ~25 ~m. Bromine uptake can be used to give an indication of the perfection of stacking. A high bromine uptake is desirable indicating a high stacking order i.e. good crystal perfection. Fissures in the natural flake graphite's are advantageous particularly in flakes of 40-70 ~m thick, by facilitating, a mean flake thickness of ~25 ~m. Fissures in the intercalated flake are detrimental as they may allow an 'escape route' to desorbing intercalate. Mineral impurities in the graphite flakes are of importance as they influence the flake thickness and cleavage properties. (iii) Intercalation of metallurgical cokes by potassium It is considered that the alkali metals, particularly potassium, have a crucial role in the breakdown of coke material during blast furnace operation. Extents of degradation, related to coke structure (optical texture) are examined to identify those structural aspects of cokes which are susceptible to alkali attack. The mechanism of potassium entering into metallurgical coke is investigated, ~. solid state diffusion, intercalation, absorption and adsorption. Metallurgical cokes, with a range of heat-treatment temperatures, graphitic carbon, and a shot-coke of small sized optical texture were heated with potassium vapour, either from direct addition of metal, or formed by heating a mixture of potassium carbonate with carbon black.Results of the study indicate that the rank of coking coal, and hence the optical texture of the derived coke, influenced the extents of degradation of the metallurgical cokes. Cokes from high rank coals (204 and 30lb) were consistently less degraded than those from lower rank coals (401 and 502 rank). Optical texture studies indicated that those optical textures most resistant to degradation by potassium vapour were of single component textures (flow anisotropy and isotropic). Multi-component textures as found in metallurgical cokes were less resistant to alkali attack. Heat-treatment of metallurgical cokes increased their resistance to degradation (2800 > 2400 > 2000 > 1500 > 11000C HTT). Degradation of metallurgical coke is thought to be due to mixed staging (yellow/blue/black colouration) of intercalates in graphitizable carbons because of non-uniform concentration of potassium causing high stresses and leading to break-up by macro-crack formation.

An investigation of shale pore structure and compositional/geochemical heterogeneities has been undertaken to elucidate the controls upon gas capacities of potential shale gas reservoirs in northeastern British Columbia, western Canada. Methane sorption isotherms, pore structure and surface area data indicate a complex interrelationship of total organic carbon (TOC) content, mineral matter and thermal maturity affect gas sorption characteristics of Devonian-Mississippian (D-M) and Jurassic strata. Methane and carbon dioxide sorption capacities of D-M shales increase with TOC content, due to the microporous nature of the organic matter. Clay mineral phases are also capable of sorbing gas to their internal structure; hence D-M shales which are both TOC- and clay-rich have the largest micropore volumes and sorption capacities on a dry basis. Jurassic shales, which are invariably less thermally mature than D-M shales, do not have micropore volumes which correlate with TOC. The covariance of methane sorption capacity with TOC, independent of micropore volume, indicates a solute gas contribution (within matrix bituminite) to the total gas capacity. On a wt% TOC basis, D-M shales sorb more gas than Jurassic shales: a result of thermal-maturation induced, structural transformation of the D-M organic fraction. Organic-rich D-M strata are considered to be excellent candidates for gas shales in Western Canada. These strata have TOC contents ranging between 1-5.7 wt%, thermal maturities into the dry-gas region, and thicknesses in places of over 1000 m. Total gas capacity estimates range between 60 and 600 bcf/section where a substantial percentage of the gas capacity is free gas, due to high reservoir temperatures and pressures. Inorganic material influences modal pore size, total porosity and sorption characteristics of D-M shales. Carbonate-rich samples often have lower organic carbon contents (oxic deposition) and porosity, hence potentially lower sorbed and free-gas capacities. Highly mature Devonian shales are both silica and TOC-rich (up to 85% quartz and 5 wt% TOC) and as such, deemed excellent potential shale gas reservoirs because they are both brittle(fracable), and gas-charged. However, quartz-rich Devonian shales display tight-rock characteristics, with poorly developed fabric, small median pore diameters and low permeabilities. Hence potential `frac-zones' will require an increased density of hydraulic fracture networks for optimum gas production.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第15393号 / 工博第3272号 / 新制||工||1493(附属図書館) / 27871 / 京都大学大学院工学研究科物質エネルギー化学専攻 / (主査)教授 井上 正志, 教授 江口 浩一, 教授 大江 浩一 / 学位規則第4条第1項該当

<p>In this thesis, the strength-enhancing mechanisms of dry binders in direct compression were studied. The systems investigated were binary mixtures containing various compounds and binders. Among the binders used were a series of different molecular weights of polyethylene glycol. The proposed simplified tablet model describing the fracture path in a tablet during strength testing offers an explanation for the increase in tablet strength caused by the binder. The model and results in this thesis indicate that fractures will usually propagate around the tablet particles and through the interparticulate voids during tablet strength testing.</p><p>One important characteristic of the binder is its ability to be effectively and evenly distributed through the interparticulate voids in a compound tablet. Characteristics such as high plasticity, low elasticity and a small particle size were associated with a more even distribution and a consequent pronounced effect on pore structure and marked improvement in tablet strength. The strength of tablets containing less plastic binders was governed more by the compactibility of the binder. The tablet porosity, bonding mechanisms and volume reduction mechanisms of the compound also influenced the effect of the binder. For example, the plasticity and particle size of the binder had the most significant effects on tablet strength when the tablet porosity of the com-pound was relatively low. A combination of the plasticity and the compactibility of the binder determined the strength of tablets when the tablet of a compound was more porous. The positive effect of a binder on pore structure and tablet strength resulted in an increase in the disintegration time. Although addition of a superdisintegrant generally improved the disintegration time, the effect was decreased when the formulation included more deformable binders.</p><p>The choice of a suitable binder for a tablet formulation requires extensive knowledge of the relative importance of binder properties for enhancing the strength of the tablet and also of the interactions between the various materials constituting a tablet. Thus, the increased knowledge of the functionality of a binder obtained in this thesis enables a more rational approach to tablet formulation.</p>

In this thesis, the strength-enhancing mechanisms of dry binders in direct compression were studied. The systems investigated were binary mixtures containing various compounds and binders. Among the binders used were a series of different molecular weights of polyethylene glycol. The proposed simplified tablet model describing the fracture path in a tablet during strength testing offers an explanation for the increase in tablet strength caused by the binder. The model and results in this thesis indicate that fractures will usually propagate around the tablet particles and through the interparticulate voids during tablet strength testing. One important characteristic of the binder is its ability to be effectively and evenly distributed through the interparticulate voids in a compound tablet. Characteristics such as high plasticity, low elasticity and a small particle size were associated with a more even distribution and a consequent pronounced effect on pore structure and marked improvement in tablet strength. The strength of tablets containing less plastic binders was governed more by the compactibility of the binder. The tablet porosity, bonding mechanisms and volume reduction mechanisms of the compound also influenced the effect of the binder. For example, the plasticity and particle size of the binder had the most significant effects on tablet strength when the tablet porosity of the com-pound was relatively low. A combination of the plasticity and the compactibility of the binder determined the strength of tablets when the tablet of a compound was more porous. The positive effect of a binder on pore structure and tablet strength resulted in an increase in the disintegration time. Although addition of a superdisintegrant generally improved the disintegration time, the effect was decreased when the formulation included more deformable binders. The choice of a suitable binder for a tablet formulation requires extensive knowledge of the relative importance of binder properties for enhancing the strength of the tablet and also of the interactions between the various materials constituting a tablet. Thus, the increased knowledge of the functionality of a binder obtained in this thesis enables a more rational approach to tablet formulation.

One of the most important, but often ignored, factors affecting the transport and the seismic properties of hydrocarbon reservoir is pore shape. Transport properties depend on the dimensions, geometry, and distribution of pores and cracks. Knowledge of pore shape distribution is needed to explain the often-encountered complex interrelationship between seismic parameters (e.g. seismic velocity) and the independent physical properties (e.g. porosity) of hydrocarbon reservoirs. However, our knowledge of reservoir pore shape distribution is very limited. This dissertation employs a pore structure parameter via a rock physics model to characterize mean reservoir pore shape. The parameter was used to develop a new physical concept of critical clay content in the context of pore compressibility as a function of pore aspect ratio for a better understanding of seismic velocity as a function of porosity. This study makes use of well log dataset from offshore Norway and from North Viking Graben in the North Sea. In the studied North Sea reservoir, porosity and measured horizontal permeability was found to increase with increasing pore aspect ratio (PAR). PAR is relatively constant at 0.23 for volumes of clay (V_cl) less than 32% with a significant decrease to 0.04 for V_cl above 32%. The point of inflexion at 32% in the PAR –V_cl plane is defined as the critical clay volume. Much of the scatters in the compressional velocity-porosity cross-plots are observed where V_cl is above this critical value. For clay content higher than the critical value, Hertz-Mindlin (HM) contact theory over-predicts compressional velocity (V_p) by about 69%. This was reduced to 4% when PAR distribution was accounted for in the original HM formulation. The pore structure parameter was also used to study a fractured carbonate reservoir in the Sichuan basin, China. Using the parameter, the reservoir interval can be distinguished from those with no fracture. The former has a pore structure parameter value that is ≥ 3.8 whereas it was < 3.8 for the latter. This finding was consistent with the result of fracture analysis, which was based on FMI image. The results from this dissertation will find application in reservoir characterization as the industry target more complex, deeper, and unconventional reservoirs.

Modeling of airflow resistance in grain bulk requires knowledge of the tortuosity and velocity of the air flow through the grain bulk. In this study, experiments were carried out to determine these characteristics of airflow paths by analyzing digital images of smoke-visualized airflow paths inside a grain bulk obtained with a high speed camera. Colored smoke with approximately the same density as air was introduced into the test box for the visualization of the airflow through the grain bulk. Soybeans with a moisture content of 8.82% on wet basis were used in this study. The high quality videos obtained by recoding the fast movement of the smoke through the grain bulk was first separated into frames using a commercial software, VirtualDub (CRIM, Montreal, Québec, Canada), and the 512× 384 pixel RGB image files (frames) extracted from the recorded videos and read into ImageJ an image processing Java-based software developed by the United State National institute of Health, to track the movement of the smoke in the images, frame by frame to determine lengths, tortuosities of the different flow paths, as well as their velocities.

The permeability in siliclastic rocks can vary due to different pore geometries. The pore properties of a formation can also have significant effects on reflection coefficient. The pore structure of clastic rock may be predicted from a wave reflection using mathematical models. Biot-Gassmann and Sun’s equations are examples of two models which were used in this research to quantify the pore property. The purpose of this thesis is to measure variations in porosity and permeability using 3-D time lapsed seismic during a CO_(2) flood. CO_(2) sequestration EOR will most likely cause permanent diagenetic effects that will alter pore geometry and permeability. This research shows compelling evidence that the pore structure changes in an active CO_(2) flood at the Delhi Holt-Bryant reservoir can be measured with acoustic data. The pore property change is measured by using the Baechle ratio, the Gassmann model, and the Sun framework flexibility factor. The change in the pore properties of the formation also indicates a increase in the permeability of the reservoir as a result of CO_(2) interaction.