Polarization-dependent far-infrared reflectivity measurements were carried out on single crystals of anatase TiO 2. The results were analyzed to yield the dielectric dispersion properties of anatase in the lattice fundamentals regime. The frequencies ͑in cm Ϫ1 ͒ of the transverse optical ͑TO͒ and longitudinal optical ͑LO͒ zone-center phonons were determined to be 367͑755͒ for the TO ͑LO͒ of the A 2u mode, 262͑366͒ and 435͑876͒ for the E u modes. The large TO-LO splittings were used to estimate effective charges. ͓S0163-1829͑97͒02009-2͔

Shale gas and other unconventional gas plays have become an important factor in the United States energy market and are often referred to as statistical plays due to their high heterogeneity. They present real engineering challenges for characterization and exploitation, and their productivity depends upon an inter-related set of reservoir, completion and production characteristics.The Devonian Ohio shale of eastern Kentucky is the State's most prolific gas producer. The gas shale underlies approximately two-thirds of the state, cropping out around the Bluegrass Region of central Kentucky and having a sub crop beneath the Mississippi Embayment in western Kentucky. This paper describes the reservoir modeling and history matching of a Devonian Gas Shale Play, eastern Kentucky, its potential for CO 2 enhanced gas recovery and storage.A geologic model of the shale has been compiled from mineralogical, petrographic, core, production, and wireline data. The COMET3 multi-phase, dual porosity simulator is being used to investigate CO 2 injection into the shale for enhanced gas recovery. To accomplish this, a subset of wells surrounding the potential injection site has been selected for further study. These eight wells cover approximately 5,300 acres of productive shale. The reservoir was subdivided into the Upper Ohio and Lower Huron members. To capture geological heterogeneity, gas production rates for these wells served as a proxy to characterize fracture permeability using geostatistical methods. Well production was history matched applying an automated process. Finally, several CO 2 injection scenarios spanning huff-n-puff to continuous injection were reviewed to evaluate the enhanced gas recovery potential and assess the CO 2 storage capacity of these shale reservoirs.

Ultrafine titania particles were synthesized from titanium tetraethoxide (TEOT) dissolved in ethanol. The concentration of water and of the soluble polymer hydroxypropylcellulose (HPC) were varied to control particle size. The HPC adsorbed onto the titania particles during growth, providing a steric barrier to aggregation. Electron microscopy showed that particles smaller than 70 nm were formed at high water concentrations (R > 120 where R is the molar ratio [H2O]/[TEOT]) and in the presence of HPC. The annealing-induced, phase-transformation behavior of these particles (amorphous → anatase → rutile) from 100 to 1000 °C was characterized by x-ray, Raman, and infrared techniques. The conversion of anatase to rutile occurred more readily for particles made at high water concentrations and with HPC. For particles formed by premixing TEOT with HPC prior to hydrolysis at R = 155, an 800 °C anneal yielded a rutile fraction exceeding 95%; particles made at R = 5.5 with no HPC showed negligible conversion at this temperature.

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An integrated methodology combining clustering analysis techniques, geostatistical methods and evolutionary strategy technologies was developed and applied to an area in the SACROC Unit (Permian basin). Clustering methods were applied to well logs and core data with high vertical resolution for many wells to predict porosity, permeability and rock type. Geostatistics was applied to extend the characterization into the inter-well area. Evolutionary strategies were used to refine the characterization to match historical production performance. The complete approach was tested on an area within the SACROC Unit, acknowledged as a highly heterogeneous carbonate reservoir with complex production history. Three cored wells provided porosity and permeability measurements on a foot-by-foot basis. These measurements coupled with well logs were used to predict porosity, permeability and flow units. Twenty two wells in the study area having foot-by-foot profiles of porosity and permeability were considered sufficient to characterize porosity and permeability in three dimensions. Geostatistical methods were then used to build porosity and permeability models. As a validation of the characterization procedure, evolutionary strategy jointly coupled with a black oil reservoir model was used to history match production performance of a 0.5 mi2 area. The 65,340 grid-block model had over 50 years of production. Thirteen (13) input parameters were varied during the history match. Among them, a multiplying factor was applied to the permeability realization to account for upscaling effects, varying permeability values without modifying geological heterogeneities identified during the characterization process. No adjustment to porosity characterization was permitted. A very good history match of individual production was achieved for the center wells of the area, and a good match was also obtained for outer wells production and reservoir pressure where boundary effects existed. This validates the new integrated clustering/geostatistical/evolutionary-strategy approach in this highly heterogeneous carbonate reservoir. Introduction An integrated methodology combining clustering analysis techniques, geostatistical methods and evolutionary strategy technologies was developed and applied to a study area in the SACROC Unit (Permian basin). Initially, a two-step "soft-computing" procedure was developed capable of efficiently generating core-scale porosity and permeability profiles at well locations where no core data existed. The approach applies clustering methods based on maximum likelihood principles to well logs and core data for lithology interpretation, reservoir quality characterization, and prediction of "core" parameter profiles, with high vertical resolution for many wells. This procedure permites to populate any well location with core-scale estimates of porosity and permeability (P&P), and rock types facilitating direct application of geostatistical techniques to build 3D reservoir models. Geostatistical methods are then applied to the resulting dataset, and three-dimensional spatial models of variability for clusters, porosity, and permeability are utilized to generate reservoir representations of P&P for flow simulation purposes. Finally, a computer assisted history matching based on application of evolutionary strategy technologies was used to history match the production performance of a selected subregion in the SACROC Unit (Permian basin).