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{"title":"利用离心分离机 T2 频谱曲线分析致密砂岩的单分形和多分形维度变化","authors":"Shuailong Feng, Mingyang Li, Junjian Zhang, Guangwei Xu, Veerle Vandeginste, Pengfei Zhang, Wei Ju","doi":"10.1002/ghg.2255","DOIUrl":null,"url":null,"abstract":"<p>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 <i>T</i><sub>2</sub> spectrum. However, there are few studies on fractal characteristics of <i>T</i><sub>2</sub> 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 <i>T</i><sub>2</sub> 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 <i>T</i><sub>2</sub> spectra, and then a difference in fractal parameters under different water conditions was compared. Correlation between different fractal parameters, pore structure and <i>T</i><sub>2 cut-off</sub> value are studied, and a mathematical prediction model for <i>T</i><sub>2 cut-off</sub> 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 <i>T</i><sub>2</sub> spectrum and <i>T</i><sub>2</sub> 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 <i>T</i><sub>2</sub> spectrum and <i>T</i><sub>2</sub> value is10–100 ms, which indicates that this type belongs to mesopore developed. (2) In saturated state (<i>D</i><sub>S</sub>), 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) <i>T</i><sub>2</sub> spectrum in centrifugal state has fractal characteristics (<i>D</i><sub>i</sub>), and there are certain correlation <i>D</i><sub>i</sub> with <i>D</i><sub>s</sub>. Therefore, a mathematical prediction model for <i>T</i><sub>2 cut-off</sub> value by using fractal and pore structure parameters is established. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd.</p>","PeriodicalId":12796,"journal":{"name":"Greenhouse Gases: Science and Technology","volume":null,"pages":null},"PeriodicalIF":2.7000,"publicationDate":"2023-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Single and multi-fractal dimension variation of tight sandstone by using centrifuge T2 spectral curve\",\"authors\":\"Shuailong Feng, Mingyang Li, Junjian Zhang, Guangwei Xu, Veerle Vandeginste, Pengfei Zhang, Wei Ju\",\"doi\":\"10.1002/ghg.2255\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p>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 <i>T</i><sub>2</sub> spectrum. However, there are few studies on fractal characteristics of <i>T</i><sub>2</sub> 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 <i>T</i><sub>2</sub> 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 <i>T</i><sub>2</sub> spectra, and then a difference in fractal parameters under different water conditions was compared. Correlation between different fractal parameters, pore structure and <i>T</i><sub>2 cut-off</sub> value are studied, and a mathematical prediction model for <i>T</i><sub>2 cut-off</sub> 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 <i>T</i><sub>2</sub> spectrum and <i>T</i><sub>2</sub> 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 <i>T</i><sub>2</sub> spectrum and <i>T</i><sub>2</sub> value is10–100 ms, which indicates that this type belongs to mesopore developed. (2) In saturated state (<i>D</i><sub>S</sub>), 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) <i>T</i><sub>2</sub> spectrum in centrifugal state has fractal characteristics (<i>D</i><sub>i</sub>), and there are certain correlation <i>D</i><sub>i</sub> with <i>D</i><sub>s</sub>. Therefore, a mathematical prediction model for <i>T</i><sub>2 cut-off</sub> value by using fractal and pore structure parameters is established. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd.</p>\",\"PeriodicalId\":12796,\"journal\":{\"name\":\"Greenhouse Gases: Science and Technology\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":2.7000,\"publicationDate\":\"2023-12-24\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Greenhouse Gases: Science and Technology\",\"FirstCategoryId\":\"93\",\"ListUrlMain\":\"https://onlinelibrary.wiley.com/doi/10.1002/ghg.2255\",\"RegionNum\":4,\"RegionCategory\":\"环境科学与生态学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q3\",\"JCRName\":\"ENERGY & FUELS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Greenhouse Gases: Science and Technology","FirstCategoryId":"93","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1002/ghg.2255","RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"ENERGY & FUELS","Score":null,"Total":0}
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