Single and multi‐fractal dimension variation of tight sandstone by using centrifuge T2 spectral curve

Shuailong Feng, Mingyang Li, Junjian Zhang, Guangwei Xu, Veerle Vandeginste, Pengfei Zhang and Wei Ju

Greenhouse Gases: Science and Technology, 2024, vol. 14, issue 1, 111-137

Abstract: Pore‐fracture structure distribution heterogeneity (PFSH) affects dynamic variation of porosity‐permeability of tight sandstone reservoirs, then restricting gas production performance. A fractal model by low‐field nuclear magnetic resonance technology (LF‐NMR) has been used in the quantitative characterization of PFSH. Among some literature, PFSH was studied by using a saturated T2 spectrum. However, there are few studies on fractal characteristics of T2 spectral morphology in a centrifugal state and its influence on porosity‐permeability parameters. In this paper, 30 tight sandstone samples were collected from Taiyuan Formation in Qinshui Basin. Then LF‐NMR technology was used to analyze PFSH, and sample types were divided by using T2 spectra difference under saturated and centrifugal conditions. Meanwhile, single (model 1 and 2) and multi‐fractal model are adopted to calculate fractal parameters of saturated and centrifugal T2 spectra, and then a difference in fractal parameters under different water conditions was compared. Correlation between different fractal parameters, pore structure and T2 cut‐off value are studied, and a mathematical prediction model for T2 cut‐off value by using fractal and pore structure parameters are established. The results are as follows. (1) All the samples are divided into four types A/B/C/D. For example, the type A sample is characterized by a single peak of T2 spectrum and T2 value is less than 10 ms, which indicates that this type belongs a smaller‐pore developed. Type B sample is characterized by a single peak of T2 spectrum and T2 value is10–100 ms, which indicates that this type belongs to mesopore developed. (2) In saturated state (DS), PFSH of type A sample by using model 1 and 2 is stronger than that of type B, followed by type C and D. Then the multifractal model shows that PFSH of type B sample is stronger than that of other sample types. Correlation between fractal dimension calculated by using single fractal and pore structure parameters is stronger than that of multifractal dimension. (3) T2 spectrum in centrifugal state has fractal characteristics (Di), and there are certain correlation Di with Ds. Therefore, a mathematical prediction model for T2 cut‐off value by using fractal and pore structure parameters is established. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd.

Date: 2024
References: View complete reference list from CitEc
Citations:

Downloads: (external link)
https://doi.org/10.1002/ghg.2255

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:wly:greenh:v:14:y:2024:i:1:p:111-137

Access Statistics for this article

More articles in Greenhouse Gases: Science and Technology from Blackwell Publishing
Bibliographic data for series maintained by Wiley Content Delivery ().