Paraffins in the cracked naphtha can be transformed into aromatics and isoparaffin to improve the octane number. In this article, a series of Ni/HZSM-5 bifunctional catalysts were prepared and were characterized by temperature-programmed desorption of NH 3 (NH 3 -TPD), FT-IR analysis with adsorbed pyridine as well as by x-ray powder diffraction analysis. The monolayer dispersion threshold value of Ni on HZSM-5 was determined and the cracking and aromatization activities of the catalysts were investigated in the transformation of n-heptane. The experimental results show that the catalyst with a monolayer dispersion threshold value of Ni shows the best aromatization and isomerization activity. The products selectivity of n-heptane over different catalysts was analyzed and it was revealed that low hydrogen pressure can reduce the conversion of n-heptane, but at the same time accelerate the production of aromatics. The aromatization activity of the catalysts increases with the elevation of the reaction temperature, and the incorporation of metal in HZSM-5 decreases the cracking reaction on the catalysts, while at the same time increases the reactions that may result in the production of aromatics.
Multi-scale fracture distribution is a unique feature in shale gas reservoirs development. For a reservoir engineer, establishing a utility method which can be both numerically efficient and practically accurate is the greatest challenge of shale gas reservoirs numerical simulation.
Naturally fractured shale gas reservoirs, which must be fractured before production, include many complex fracture networks (natural fracture and hydraulic fracture) that cannot be easily modeled by the simple continuous medium model (CMM), the discrete fracture model (DFM) or the discrete fracture network (DFN) model. In this paper, we propose a utility discrete fracture network (UDFN) model in which natural fractures are modeled by an analytic correction to matrix permeability, and hydraulic fractures are modeled by the DFN in which fractures are modeled explicitly. The partial differential equations are solved by Newton Raphson method through the C Sharp programing.
Case studies reveal that the UDFN's computational speed improves orders of magnitude than those of the DFN and DFM when dealing with the same problem, while the numerical result from UDFN method keeps enough accuracy to match the production curves as well as the results from the DFN. Meanwhile, the UDFN not only can simulate individual fracture's effects explicitly like DFM, but also can match up better to the field production than the DFM.
The method developed in this paper improved the simulation of multiple stage fractured horizontal wells performance in naturally fractured formations. It also makes the naturally fractured shale gas reservoirs numerical model much more concise and practical to the field case appplication.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.