Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1757408 | Journal of Natural Gas Science and Engineering | 2015 | 12 Pages |
•Clear inflection points are observed on the fractal curves of log (SHg) versus log(Pc).•Fractal curves break into two segments at rapex.•Small pores (
Pore structure is one of important factors affecting the properties of sedimentary rocks, however, it is difficult to describe microscopic parameters of the pore structure such as pore geometry, pore-size distribution, and pore space topology. Fractal theory is an effective and available method to quantify the complex and irregular pore structure of rocks. Routine rock properties measurements and high-pressure mercury intrusion tests (HPMI) were performed on a suite of the Bashijiqike tight gas sandstone samples to delineate the pore network characteristics of these reservoir rocks. Thin section epifluorescence and scanning electron microscopy (SEM) analyses were used to gain insight into pore geometry and pore size distribution of these sandstones.The results show that the pore system of the sandstones mainly consists of intergranular macropores and intragranular micropores. The HPMI analysis shows that these reservoir rocks have complex, heterogeneous microscopic pore structure. There are clear inflection points on the fractal curves of log (SHg) versus log(Pc), i.e., the fractal curves break into two segments at the capillary pressures corresponding to the apex of the Pittman's hyperbola (plot of the ratio of mercury saturation over capillary pressure against mercury saturation). Fractal dimensions were calculated using the slope of straight part of each curves. Small pores (