Fractal Characteristics of Pore Throat and Throat of Tight Sandstone Sweet Spot: A Case Study in the East China Sea Basin

The study of the fractal characteristics of the pore throat radius (PTR) and throat radius of sweet spots is crucial for the exploration and development of tight gas sandstone. This study used conventional core analysis, X-ray diffraction analysis, scanning electron microscopy (SEM), and constant-ra...

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Main Authors: Wenguang Wang, Chengyan Lin, Xianguo Zhang
Format: Article
Language:English
Published: MDPI AG 2024-11-01
Series:Fractal and Fractional
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Online Access:https://www.mdpi.com/2504-3110/8/12/684
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author Wenguang Wang
Chengyan Lin
Xianguo Zhang
author_facet Wenguang Wang
Chengyan Lin
Xianguo Zhang
author_sort Wenguang Wang
collection DOAJ
description The study of the fractal characteristics of the pore throat radius (PTR) and throat radius of sweet spots is crucial for the exploration and development of tight gas sandstone. This study used conventional core analysis, X-ray diffraction analysis, scanning electron microscopy (SEM), and constant-rate mercury injection experiment (CRMI), high-pressure mercury injection experiment (HPMI), and nuclear magnetic resonance (NMR) techniques to investigate the fractal characteristics of the PTR and throat radius of the tight sandstone sweet spots of the Huagang Formation in the central uplift belt of the East China Sea Basin. Based on conventional core analysis and SEM, the main pore types of the tight sandstone samples in the Huagang Formation were determined to be intergranular dissolved pore, intragranular dissolved pore, intergranular pore, and moldic pore. HPMI and NMR techniques were used to evaluate the full-size PTR distribution of type I (TI), type II (TII), and type III (TIII) sweet spots. Based on fractal theory, CRMI was used to calculate the fractal dimension of the PTR and throat radius of three types of sweet spots, and the relationship between the fractal dimensions and pore throat structure parameters and mineral composition were investigated. The results showed that the full-size PTR distribution curve exhibited bimodal or unimodal characteristics. The peak values of the PTR distribution of the TI, TII, and TIII sweet spots were mainly concentrated at 0.002–22.5 μm, 0.001–2.5 μm, and 0.0004–0.9 μm, respectively. The fractal dimensions of the PTR and throat radius were calculated. The average throat radius fractal dimensions of the TI, TIII, and TIII sweet spots were 2.925, 2.875, and 2.786, respectively. The average PTR fractal dimensions of the TI, TII, and TIII sweet spots were 2.677, 2.684, and 2.702, respectively. The throat radius fractal dimension of the TI, TII, and TIII sweet spots was positively correlated with mercury saturation, average throat radius, feldspar content, and clay mineral content and negatively correlated with displacement pressure, quartz content, and carbonate cement content. The PTR fractal dimension of the TI, TII, and TIII sweet spots was positively correlated with displacement pressure, quartz content, and carbonate cement content and negatively correlated with feldspar content. The throat size of the TI sweet spot was large, and the heterogeneity of the throat was strong. The PTR heterogeneity of the TI sweet spot was lower than that of the TII and TIII sweet spots. The findings of this study can provide important guidance for the exploration and development of tight gas sandstone.
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spelling doaj-art-e020f8c823ea4e1f94d4970cc13e1bd02025-08-20T02:53:38ZengMDPI AGFractal and Fractional2504-31102024-11-0181268410.3390/fractalfract8120684Fractal Characteristics of Pore Throat and Throat of Tight Sandstone Sweet Spot: A Case Study in the East China Sea BasinWenguang Wang0Chengyan Lin1Xianguo Zhang2Institute of Unconventional Oil & Gas, Northeast Petroleum University, Daqing 163318, ChinaSchool of Geosciences, China University of Petroleum (East China), Qingdao 266580, ChinaSchool of Geosciences, China University of Petroleum (East China), Qingdao 266580, ChinaThe study of the fractal characteristics of the pore throat radius (PTR) and throat radius of sweet spots is crucial for the exploration and development of tight gas sandstone. This study used conventional core analysis, X-ray diffraction analysis, scanning electron microscopy (SEM), and constant-rate mercury injection experiment (CRMI), high-pressure mercury injection experiment (HPMI), and nuclear magnetic resonance (NMR) techniques to investigate the fractal characteristics of the PTR and throat radius of the tight sandstone sweet spots of the Huagang Formation in the central uplift belt of the East China Sea Basin. Based on conventional core analysis and SEM, the main pore types of the tight sandstone samples in the Huagang Formation were determined to be intergranular dissolved pore, intragranular dissolved pore, intergranular pore, and moldic pore. HPMI and NMR techniques were used to evaluate the full-size PTR distribution of type I (TI), type II (TII), and type III (TIII) sweet spots. Based on fractal theory, CRMI was used to calculate the fractal dimension of the PTR and throat radius of three types of sweet spots, and the relationship between the fractal dimensions and pore throat structure parameters and mineral composition were investigated. The results showed that the full-size PTR distribution curve exhibited bimodal or unimodal characteristics. The peak values of the PTR distribution of the TI, TII, and TIII sweet spots were mainly concentrated at 0.002–22.5 μm, 0.001–2.5 μm, and 0.0004–0.9 μm, respectively. The fractal dimensions of the PTR and throat radius were calculated. The average throat radius fractal dimensions of the TI, TIII, and TIII sweet spots were 2.925, 2.875, and 2.786, respectively. The average PTR fractal dimensions of the TI, TII, and TIII sweet spots were 2.677, 2.684, and 2.702, respectively. The throat radius fractal dimension of the TI, TII, and TIII sweet spots was positively correlated with mercury saturation, average throat radius, feldspar content, and clay mineral content and negatively correlated with displacement pressure, quartz content, and carbonate cement content. The PTR fractal dimension of the TI, TII, and TIII sweet spots was positively correlated with displacement pressure, quartz content, and carbonate cement content and negatively correlated with feldspar content. The throat size of the TI sweet spot was large, and the heterogeneity of the throat was strong. The PTR heterogeneity of the TI sweet spot was lower than that of the TII and TIII sweet spots. The findings of this study can provide important guidance for the exploration and development of tight gas sandstone.https://www.mdpi.com/2504-3110/8/12/684throat radiusfractal dimensionsweet spotpore throat radiustight sandstone
spellingShingle Wenguang Wang
Chengyan Lin
Xianguo Zhang
Fractal Characteristics of Pore Throat and Throat of Tight Sandstone Sweet Spot: A Case Study in the East China Sea Basin
Fractal and Fractional
throat radius
fractal dimension
sweet spot
pore throat radius
tight sandstone
title Fractal Characteristics of Pore Throat and Throat of Tight Sandstone Sweet Spot: A Case Study in the East China Sea Basin
title_full Fractal Characteristics of Pore Throat and Throat of Tight Sandstone Sweet Spot: A Case Study in the East China Sea Basin
title_fullStr Fractal Characteristics of Pore Throat and Throat of Tight Sandstone Sweet Spot: A Case Study in the East China Sea Basin
title_full_unstemmed Fractal Characteristics of Pore Throat and Throat of Tight Sandstone Sweet Spot: A Case Study in the East China Sea Basin
title_short Fractal Characteristics of Pore Throat and Throat of Tight Sandstone Sweet Spot: A Case Study in the East China Sea Basin
title_sort fractal characteristics of pore throat and throat of tight sandstone sweet spot a case study in the east china sea basin
topic throat radius
fractal dimension
sweet spot
pore throat radius
tight sandstone
url https://www.mdpi.com/2504-3110/8/12/684
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