Nano-Scale Pore Structure and Its Multi-Fractal Characteristics of Tight Sandstone by N2 Adsorption/Desorption Analyses: A Case Study of Shihezi Formation from the Sulige Gas Filed, Ordos Basin, China

Abstract

Fractal dimension is a critical parameter to evaluate the heterogeneity of complex pore structure in tight sandstone gas and other low permeability reservoirs. To quantify the fractal dimension of tight sandstone at various pore size classes and evaluate their implications on mineral composition and nano pore structure parameters, we conducted an integrated approach of N2 adsorption/desorption experiment (N2-GA), X-ray diffraction (X-RD), and field emission scanning electron microscopy (FE-SEM) on Sulige tight sandstone reservoirs. By comparing the nine types of fractal dimensions calculated from N2 adsorption data, we put forward the concept of “concentrated” fractal dimensions and “scattered” fractal dimensions (DN2, DN3, DN5, DN7 and DN8) for the first time according to its concentration extent of distribute in different samples. Result shows that mineral composition has a significant influence of a different level on specific surface area (SSA), pore volume (PV), and fractal dimensions (DN), respectively, where the “scattered” fractal dimension is more sensitive to certain specific property of the reservoir, including mineral content and the specific surface area contribution rate (Sr) of type II mesopores (Mesopore-II: 10~50nm). In addition, three type of hysteresis loops were distinguished corresponding to different pore shape combination of N2-GA isotherm curve, which reveals that pore structure heterogeneity is mainly controlled by inkbottle-shaped pores and the volume contribution rate (Vr) of mesopores in this study area. These findings could contribute to a better understanding of the controlling effect of pore heterogeneity on natural gas storage and adsorption.

The Effects of CeO2 and Co Doping on the Properties and the Performance of the Ni/Al2O3-MgO Catalyst for the Combined Steam and CO2 Reforming of Methane Using Ultra-Low Steam to Carbon Ratio

“…The isotherms of all catalysts are categorized as type IV according to the International Union of Pure and Applied Chemistry (IUPAC) classification and the pore sizes of samples are mainly in the range of 4.6-6.1 nm, implying the characteristic of mesoporous materials. Hysteresis loops of types H1 and H3 corresponding to the combination of cylindrical pores and parallel plate-shaped pores are found in all catalysts [33]. The surface area and total pore volume of samples are listed in Table 1.…”

Co/Zn‐based bimetallic MOF ‐derived hierarchical porous Co/C composite as cathode material for high‐performance lithium‐air batteries

“…Interestingly, the shape of the pores can be inferred from the hysteresis loop in isotherms. The H1‐type loops of the isotherm in Co@C(700‐1000) indicate the presence of cylindrical pores 47 . The cylindrical pores can be explained to be originated from the rod‐shaped zinc oxides.…”

“…The H1-type loops of the isotherm in Co@C (700-1000) indicate the presence of cylindrical pores. 47 The cylindrical pores can be explained to be originated from the rod-shaped zinc oxides. Consequently, the hierarchical porous structure of Co@C(700-1000) can be beneficial for improving the electrochemical performance by promoting the diffusion of the electrolyte into the air cathode and exposing more active sites for reaction with lithium ions.…”

Quasi Natural Approach for Crystallization of Zeolites from Different Fly Ashes and Their Application as Adsorbent Media for Malachite Green Removal from Polluted Waters

“…The desorption branches go above the adsorption isotherms, describing hysteresis loops which are closed at p/p 0 = 0.45 for all samples. The type of all hysteresis loops is H3, which corresponds to parallel plate-shaped pores with different widths, depending on the hysteresis area [39]. The most intensive monolayer filling is observed for samples from series FAV and FARE, as the quantity of the adsorbed gas reaches 4.3 mmol/g at p/p 0 = 0.025, and their specific surface area is expected to be the highest.…”