Understanding
the anisotropy-controlling factors of shale within
organic matter can provide novel insight into the transport process
and gas storage in typical shale. A series of techniques, such as
low-temperature CO2/N2 adsorption (LP CO2/N2), scanning electron microscopy (SEM), energy-dispersive
spectrometry (EDS), and reflected light microscopy (RLM), has been
used to characterize the pore structure characteristics and the heterogeneity
of the pore size distribution. In this study, LP gas adsorption experiments
of the Shahezi Formation in the Changling Fault Depression, Songliao
Basin, China were conducted to calculate the multifractal parameter
Δα (the multifractal spectral width) and H (Hurst exponent) and investigate the pore structure and heterogeneity
characteristic. The results demonstrate that the pore volume (PV)
and surface area (SA) of the kerogen samples have a range of 0.045–0.131
cm3/g and 18.921–135.707 m2/g which are
1.180–3.066 fold and 1.431–5.583 fold greater than those
of the volume and surface area of the corresponding bulk shale samples,
respectively. The Δα value of the bulk shale samples are
similar to the corresponding isolated kerogen samples in the micropores,
whereas the value of the isolated kerogen samples of Δα
are higher than that of the bulk shale samples in the meso-macropores.
The PV and SA have similar influences on the multifractal parameters,
suggesting that the multifractal parameters are closely related to
the pore structure parameters and significant for evaluating the development
of pores in shale. The clay and quartz contents have an obvious impact
on the heterogeneity of the nanopore structure in the full pore size
of the Shahezi shale. Other factors, such as the TOC content and R
o, play an inconspicuous role in the pore structure–heterogeneity
connection. On the basis of SEM, EDS, and RLM imaging, OM pores show
significant heterogeneities among different kerogen particles. According
to the pore geometrical morphology and genetic types, the main controlling
factors of the heterogeneity kerogen pores can be summarized as the
remaining original kerogen pores and differences in hydrocarbon generation
potential.