Fractal Characteristics of Pores in Taiyuan Formation Shale From Hedong Coal Field, China

Abstract

For the purpose of investigating the fractal characteristics of pores in Taiyuan formation shale, a series of qualitative and quantitative experiments were conducted on 17 shale samples from well HD-1 in Hedong coal field of North China. The results of geochemical experiments show that Corresponding author. This is an Open Access article published by World Scientific Publishing Company. It is distributed under the terms of the Creative Commons Attribution 4.0 (CC-BY) License. Further distribution of this work is permitted, provided the original work is properly cited. 1840006-1Fractals 2018.26. Downloaded from www.worldscientific.com by 13.66.222.141 on 06/06/19. Re-use and distribution is strictly not permitted, except for Open Access articles. K. Li et al.Total organic carbon (TOC) varies from 0.67% to 5.32% and the organic matters are in the high mature or over mature stage. The shale samples consist mainly of clay minerals and quartz with minor pyrite and carbonates. The FE-SEM images indicate that three types of pores, organicrelated pores, inorganic-related pores and micro-fractures related pores, are developed well, and a certain number of intragranular pores are found inside quartz and carbonates formed by acid liquid corrosion. The pore size distributions (PSDs) broadly range from several to hundreds nanometers, but most pores are smaller than 10 nm. As the result of different adsorption features at relative pressure (0-0.5) and (0.5-1) on the N 2 adsorption isotherm, two fractal dimensions D 1 and D 2 were obtained with the Frenkel-Halsey-Hill (FHH) model. D 1 and D 2 vary from 2.4227 to 2.6219 and from 2.6049 to 2.7877, respectively. Both TOC and brittle minerals have positive effect on D 1 and D 2 , whereas clay minerals, have a negative influence on them. The fractal dimensions are also influenced by the pore structure parameters, such as the specific surface area, BJH pore volume, etc. Shale samples with higher D 1 could provide more adsorption sites leading to a greater methane adsorption capacity, whereas shale samples with higher D 2 have little influence on methane adsorption capacity.

Determining Soil-Water Characteristic Curves from Mercury Intrusion Porosimeter Test Data Using Fractal Theory

“…Fractal theory has been increasingly recognized as a valid approach for describing the complex structures of geomaterials [7][8][9][10][11]. Ghanbarian and Hunt [12] in particular have stressed the application of fractal theory to geomaterials.…”

Microstructural characterisation of organic matter pores in coal-measure shale

“…The meso-macropore volume was obtained with the Barrette Joynere Halenda (BJH) method, and the micropores volume (0.64-2 nm) was determined applying the SF (Saito-Foley) model. Pore size distributions were determined using the BJH method with N 2 adsorption data (Jarvie et al, 2007;Sun et al, 2016;Zhou et al, 2016;Ko et al, 2017;Shao et al, 2017;Li et al, 2018a;Zou et al, 2019) .…”

“…Many researches have focused on the role of OM in pore structure by analyzing the correlation between OM parameters (such as TOC, OM maturity, etc.) and pore structure parameters (pore volume, surface area and pore fractal dimensions) (Bhargava et al, 2005;Sun et al, 2016;Ko et al, 2017;Shao et al, 2017;Li et al, 2018aLi et al, , 2018b. However, the size of OM pores within shale is from micron to nanometer, and is dominated by nanometer, which falls into the range of OM macromolecular size and controlled by OM microstructure to a large extent.…”

Multifractal Characteristics and Classification of Tight Sandstone Reservoirs: A Case Study from the Triassic Yanchang Formation, Ordos Basin, China

“…where χ q (ε) is a partition function of q with the scale of ε; τ(q) is the mass exponent. The number of the boxes in multifractals is defined as N α (ε), which is related to scale ε and can be expressed as [43,44]:…”