The effects of organoclay and polyhedral oligomeric silsesquioxanes (POSS) nanoparticles on the crystallization behavior of high molecular weight poly(ethylene terephthalate) (HMWPET; inherent viscosity of 1.05) were investigated in terms of nanoparticle content and shear rate. Both nanoparticles played a role of nucleating agent for PET and increased the cold crystallization temperature by about 24°C. The half‐time of crystallization was also decreased with increasing the nanoparticle content. Clay proved to be more effective than POSS; a notable nucleating effect was observed at 0.3 wt% for clay and 2 wt% for POSS. Introducing 1 wt% of clay gave the highest crystallization rate among all PET nanocomposite samples examined. Isothermal crystallization of the nanocomposites under dynamic shear exhibited similar crystallization behavior. As in the DSC measurement, clay appeared to be more effective to promote the crystallization of PET under shear. The nucleating effects were more noticeable at higher shear rate. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers

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Horizontal drilling and hydraulic fracturing is necessary to reach economical success in shale gas reservoirs. PTA for shale gas reservoirs requires comprehensive understanding related to nonlinear gas flow process as well as hydraulic fracture properties. Even though significant progresses made in the past few years, there appears to be a lack of information regarding the characterization of shale gas formations. A major purpose of this study is to demonstrate how this issue may be addressed by pressure transient analysis for multiple fractured horizontal wells in shale gas reservoirs. Extensive numerical simulations were conducted to model transient pressure behavior of a fractured horizontal well and applied the results to well test analysis in shale gas reservoirs. The pressure transient response for a horizontal well with transverse multiple fractures is controlled by many of important fracture properties and nonlinear flow processes. This paper presents a comprehensive reservoir simulation model to investigate the characteristics of pressure transient responses under the influences of hydraulic fracture properties and nonlinear gas flow mechanism. Factors considered in this study include the number of hydraulic fractures, fracture half-length, fracture spacing, adsorption, non-Darcy flow, and Klinkenberg effect under reservoir flow condition as well as skin effect. The numerical simulations for nonlinear gas flow provided various type curves in terms of dimensionless pseudopressure and time for transient pressure responses in fractured horizontal production wells. Results from type-curve matching for synthetic pressure data in shale gas reservoirs demonstrate that the conventional analysis approach may still be applicable for analysis of shale gas reservoirs. The results can be used for quantitative studies of transient gas flow behavior and determination of formation properties.

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