Lithologic Reservoirs ›› 2025, Vol. 37 ›› Issue (6): 88-98.doi: 10.12108/yxyqc.20250608

• PETROLEUM EXPLORATION • Previous Articles    

Fractal characteristics of pore throat structure and their influence on reservoir physical properties of tight sandstone reservoir: A case study of Triassic Chang 8 member in Fuxian area, Ordos Basin

SU Shuai1, QU Hongjun1, YIN Hu1,2, ZHANG Leigang1, YANG Xiaofeng1   

  1. 1. State Key Laboratory of Continental Evolution and Early Life/Department of Geology, Northwest University, Xi'an 710069, China;
    2. Fuxian Oil Production Plant of Yanchang Oilfield Co., Ltd., Fuxian 727500, Shaanxi, China
  • Received:2025-05-14 Revised:2025-07-14 Published:2025-11-07

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Abstract: Pore throat structure is a key factor that affects the reservoir and seepage capacity of tight sandstone reservoirs, and its fine characterization is very important for the exploration and development of tight reservoirs. The pore throat structure and fractal characteristics of the tight sandstone reservoir of Triassic Chang 8 member in Fuxian area of Ordos Basin were studied by various testing methods, such as casting thin section, physical property analysis, and mercury pressure. The influence of pore throat structure on reservoir physical property were clarified. The results show that: (1) Pore types of tight sandstone in Triassic Chang 8 member in Fuxian area of Ordos Basin are mainly dissolved intergranular pores and feldspar dissolved pores, while throat types are mainly lamellar and curved lamellar. According to the displacement pressure, average pore throat radius, and maximum pore throat radius, reservoirs are classified as three categories. From type Ⅰ to type Ⅲ reservoirs, pore sorting and connectivity gradually deteriorate, pore throat radius gradually decrease, and the pore throat full aperture is 0.001-10.000 μm.(2) The pore throat structures of the three types of reservoirs in the research area all have triple fractal characteristics, with large-scale pore throats (D1) > mesoscale pore throats (D2) > small-scale pore throats (D3). Larg-scale pore throats have complex pore throat networks and relative large fractal dimensions due to strong dissolution, while small-scale pore throats have regular morphology and relative small fractal dimensions due to strong compaction. According to the weighted results, the total fractal dimension(DT) of the pore throats ranges from 2.05 to 2.44, with an average value of 2.26. From type Ⅰ to type Ⅲ reservoirs, the average DT gradually increases, and the heterogeneity of the pore throats gradually strengthens.(3) The permeability of Chang 8 tight sandstone reservoir is mainly controlled by the average throat radius. DT, D1 and D3 are negatively correlated with average pore throat radius, reservoir porosity and permeability, and positively correlated with displacement pressure and sorting coefficient, indicating that the more complex pore throat structure results the poorer pore connectivity, sorting and reservoir physical properties. The correlation of D1 with porosity and permeability is the best, indicating that the physical properties of Chang 8 reservoir are mainly affected by large-scale pore throat. Reservoirs with larger average throats, higher proportion of large pores, and lower fractal dimension are of higher quality.

Key words: reservoir physical property, pore throat structure, fractal dimension, tight sandstone, Chang 8 member, Triassic, Fuxian area, Ordos Basin

CLC Number: 

  • TE122.2
[1] CHEN Yiguo, FENG Congjun, WEI Dengfeng, et al. Formation, distribution, and exploration strategies of tight oil in the Member 6 of Triassic Yanchang Formation in southeastern Ordos Basin[J]. Acta Petrolei Sinica, 2025, 46(2): 335-354. 陈义国, 封从军, 魏登峰, 等. 鄂尔多斯盆地东南部三叠系延长组6段致密油的形成、分布与勘探对策[J]. 石油学报, 2025, 46(2): 335-354.
[2] ZHOU Jiaquan, ZHANG Liqiang, WANG Xiangzeng, et al. Diagenetic difference and its influence on reservoir physical properties of Chang8 tight sandstone in Fuxian area, Ordos Basin [J]. Petroleum Geology and Recovery Efficiency, 2019, 26(3): 54-62. 周家全, 张立强, 王香增, 等. 鄂尔多斯盆地富县地区长8致密砂岩成岩差异性及对储层物性的影响[J]. 油气地质与采收率, 2019, 26(3): 54-62.
[3] MENG Xiangzhen, MENG Wangcai, CHEN Lijun, et al. The reservoir characteristics of Chang 6 and Chang 9 reservoirs in Fuxian-Ganquan area of Ordos Basin[J]. Journal of Yangtze University(Natural Science Edition), 2018, 15(23): 17-20. 孟祥振, 孟旺才, 陈立军, 等. 鄂尔多斯盆地富县-甘泉地区长6-长9油层组储层特征研究[J]. 长江大学学报(自然科学版), 2018, 15(23): 17-20.
[4] GUO Lan, DING Chao, MEN Yanping, et al. Research on tight reservoir of Chang-82 member of Triassic Yanchang Formation in Fuxian oilfield[J]. Reservoir Evaluation and Development, 2017, 7(5): 5-9. 郭兰, 丁超, 门艳萍, 等. 富县油田三叠系延长组长82致密储层评价[J]. 油气藏评价与开发, 2017, 7(5): 5-9.
[5] SONG Jian, MENG Wangcai, DENG Nantao, et al. Features and influencing factors of Yanchang Formation reservoir in Fuxian-Huangling exploration area, Ordos Basin[J]. Northwestern Geology, 2019, 52(1): 98-108. 宋健, 孟旺才, 邓南涛, 等. 鄂尔多斯盆地富-黄地区延长组储层特征及物性影响因素分析[J]. 西北地质, 2019, 52(1): 98-108.
[6] GE Yunjin, MA Fangxia. Discussion of microstructure and densification process of Chang 8 tight reservoir in Fuxian area[J]. Fault-Block Oil & Gas Field, 2018, 25(3): 300-304. 葛云锦, 马芳侠. 富县地区长8致密储层微观结构及致密化[J]. 断块油气田, 2018, 25(3): 300-304.
[7] WANG Wei, ZHU Yushuang, LIANG Zhengzhong. Ternary pore structure characteristics of the tight sandstone: A case study from the Chang 7 member of the Triassic Yanchang Formation in the Ordos Basin, China[J]. Journal of Central South University(Science and Technology), 2024, 55(4): 1361-1373. 王伟, 朱玉双, 梁正中. 致密砂岩三元孔喉结构特征: 以鄂尔多斯盆地三叠系延长组7段致密砂岩为例[J]. 中南大学学报(自然科学版), 2024, 55(4): 1361-1373.
[8] LIU Xiuchan, CHEN Xipan. Analysis on main controlling factors of tight oil reservoirs in Chang-8 reservoir of Fu County, Ordos Basin[J]. Reservoir Evaluation and Development, 2019, 9(1): 1-7. 刘秀婵, 陈西泮. 鄂尔多斯盆地富县地区长8油层组致密油成藏主控因素分析[J]. 油气藏评价与开发, 2019, 9(1): 1-7.
[9] ZHONG Hongli, WU Yufeng, ZHANG Fengqi, et al. Pore throat distribution of tight sandstone in the southeast of the Northern Shaanxi slope and its influence on oil-bearing property[J]. FaultBlock Oil & Gas Field, 2021, 28(1): 21-27. 钟红利, 吴雨风, 张凤奇, 等. 陕北斜坡东南部致密砂岩孔喉分布及其对含油性的影响[J]. 断块油气田, 2021, 28(1): 21-27.
[10] DENG Yaren, REN Zhanli, MA Wenqiang, et al. Reservoir properties and hydrocarbon charging threshold of Chang 8 tight sandstones in Fuxian area, Ordos Basin[J]. Petroleum Geology & Experiment, 2018, 40(2): 288-294. 邓亚仁, 任战利, 马文强, 等. 鄂尔多斯盆地富县地区长8层段致密砂岩储层特征及充注下限[J]. 石油实验地质, 2018, 40(2): 288-294.
[11] WANG Youli, ZHANG Shaonan, DING Xiaoqi, et al. The study of relationship between the diagenesis and the quality reservoir of Yanchang Formation in Fuxian area of Ordos Basin, China [J]. Xinjiang Geology, 2013, 31(2): 207-212. 万友利, 张哨楠, 丁晓琪, 等. 鄂尔多斯盆地富县地区延长组成岩作用与优质储层关系研究[J]. 新疆地质, 2013, 31(2): 207-212.
[12] GUO Deyun, GUO Yanqin, LI Wenhou, et al. Diagenesis and pore structure characteristic of Yanchang Formation of Upper Triassic in Fuxian exploration area[J]. Acta Sedimentologica Sinica, 2010, 28(2): 264-273. 郭德运, 郭艳琴, 李文厚, 等. 富县探区上三叠统延长组成岩作用及孔隙结构特征[J]. 沉积学报, 2010, 28(2): 264-273.
[13] ZHANG Hailin. Comprehensive study on tight reservoirs of Chang 8 member from Upper Triassic Yanchang Formation in Fuxian exploration area, Ordos Basin[D]. Xi'an: Northwest University, 2016. 张海林. 鄂尔多斯盆地富县探区三叠系延长组长8致密油层综合研究[D]. 西安: 西北大学, 2016.
[14] MANDELBROT B B. On the geometry of homogenous turbulence, with stress on the fractal dimension of the iso-surfaces of scalars[J]. Journal of Fluid Mechanics, 1975, 72(3): 401-416.
[15] MANDELBROT B B, PASSOJA D E, PAULLAY A J. Fractal character of fracture surfaces of metals[J]. Nature, 1984, 308 (5961): 721-722.
[16] ZHANG Quanpei, WANG Haihong, LIU Meirong, et al. Study of the full pore size distribution and fractal characteristics of ultra-low permeability reservoir[J]. Journal of China University of Mining & Technology, 2020, 49(6): 1137-1149. 张全培, 王海红, 刘美荣, 等. 超低渗透储层全孔径分布及其分形特征研究[J]. 中国矿业大学学报, 2020, 49(6): 1137-1149.
[17] ZHANG Fengqi, LI Yinong, LUO Julan, et al. Microscopic pore structure characteristics of shale of Ordovician Wulalike Formation in western Ordos Basin[J]. Lithologic Reservoirs, 2022, 34(5): 50-62. 张凤奇, 李宜浓, 罗菊兰, 等. 鄂尔多斯盆地西部奥陶系乌拉力克组页岩微观孔隙结构特征[J]. 岩性油气藏, 2022, 34(5): 50-62.
[18] HUANG Hexin, CHEN Lei, SUN Wei, et al. Pore-throat structure and fractal characteristics of Shihezi Formation tight gas sandstone in the Ordos Basin, China[J]. Fractals, 2018, 26(2): 1840005.
[19] LUO Bin, TAO Rongde, CUI Xiaoli, et al. Fractal characteristics of pore throat structure of Chang 8 member tight sandstone reservoir in Wuqi-Zhidan area, Ordos Basin[J]. Natural Gas Geoscience, 2023, 34(8): 1305-1315. 雒斌, 陶荣德, 崔小丽, 等. 鄂尔多斯盆地吴起-志丹地区长8段致密砂岩储层孔喉结构分形特征[J]. 天然气地球科学, 2023, 34(8): 1305-1315.
[20] ZHANG Zhaohui, ZHANG Jiaosheng, LIU Jungang, et al. Lithofacies identification using conventional logging curves and its exploration significance, Triassic Chang 81 sub-member, Longdong area, Ordos Basin[J]. Lithologic Reservoirs, 2025, 37(3): 95-107. 张兆辉, 张皎生, 刘俊刚, 等. 鄂尔多斯盆地陇东地区三叠系长8 1亚段岩石相测井识别及勘探意义[J]. 岩性油气藏, 2025, 37(3): 95-107.
[21] ZHANG Xiaohui, ZHANG Juan, YUAN Jingsu, et al. Micro pore throat structure and its influence on seepage of Chang 81 tight reservoir in Nanliang-Huachi area, Ordos Basin[J]. Lithologic Reservoirs, 2021, 33(2): 36-48. 张晓辉, 张娟, 袁京素, 等. 鄂尔多斯盆地南梁-华池地区长8 1致密储层微观孔喉结构及其对渗流的影响[J]. 岩性油气藏, 2021, 33(2): 36-48.
[22] LIU Huaqing, YUAN Jianying, LI Xiangbo, et al. Lake basin evolution of Ordos Basin during Middle-Late Triassic and its origin analysis[J]. Lithologic Reservoirs, 2007, 19(1): 52-56. 刘化清, 袁剑英, 李相博, 等. 鄂尔多斯盆地延长期湖盆演化及其成因分析[J]. 岩性油气藏, 2007, 19(1): 52-56.
[23] DENG Xiuqin, PANG Jinlian, SUN Bo. Evolution characteristics of Ordos Basin in sedimentary period of Chang 10-Chang 8 member of Yanchang Formation[J]. Journal of Northwest University(Natural Science Edition), 2024, 54(6): 1078-1090. 邓秀芹, 庞锦莲, 孙勃. 鄂尔多斯盆地三叠系延长组长10- 长8段沉积演化特征[J]. 西北大学学报(自然科学版), 2024, 54(6): 1078-1090.
[24] WANG Baoping, CUI Weilan, ZHANG Fengqi, et al. Analysis on exploration potential of Chang 8 Pay zone in Fuxian-Huanglong area, Southeastern Ordos Basin[J]. Unconventional Oil & Gas, 2015, 2(3): 27-33. 王宝萍, 崔维兰, 张凤奇, 等. 鄂尔多斯盆地东南部富县-黄龙地区长8油层组勘探潜力分析[J]. 非常规油气, 2015, 2 (3): 27-33.
[25] WANG Peng, SUN Linghui, WANG He, et al. Reservoir characteristics and controlling factors of Chang 6 of Yanchang Formation in Wuqi area, Ordos Basin[J]. Lithologic Reservoirs, 2020, 32(5): 63-72. 王朋, 孙灵辉, 王核, 等. 鄂尔多斯盆地吴起地区延长组长6储层特征及其控制因素[J]. 岩性油气藏, 2020, 32(5): 63-72.
[26] LIU Biao, YAO Suping, HU Wenxuan, et al. Application of nuclear magnetic resonance cryoporometry in unconventional reservoir rocks[J]. Acta Petrolei Sinica, 2017, 38(12): 1401-1410. 刘标, 姚素平, 胡文瑄, 等. 核磁共振冻融法表征非常规油气储层孔隙的适用性[J]. 石油学报, 2017, 38(12): 1401-1410.
[27] LIU Chang, CHEN Guihua, LU Yuanyuan, et al. Micro pore throat structural characterization of Upper Paleozoic tight sandstone reservoir of block A in the eastern margin of Ordos Basin [J]. China Offshore Oil and Gas, 2022, 34(4): 122-131. 刘畅, 陈桂华, 路媛媛, 等. 鄂尔多斯盆地东缘A区块上古生界致密砂岩储层微观孔喉结构表征[J]. 中国海上油气, 2022, 34(4): 122-131.
[28] WU Yuping, LIU Chenglin, OUYANG Siqi, et al. Investigation of pore-throat structure and fractal characteristics of tight sandstones using HPMI, CRMI, and NMR methods: A case study of the lower Shihezi Formation in the Sulige area, Ordos Basin[J]. Journal of Petroleum Science and Engineering, 2022, 210: 110053.
[29] QU Yiqian, SUN Wei, TAO Rongde, et al. Pore-throat structure and fractal characteristics of tight sandstones in Yanchang Formation, Ordos Basin[J]. Marine and Petroleum Geology, 2020, 120: 104573.
[30] DENG Haoyang, SIMA Liqiang, WU Wen, et al. Fractal characteristics of pore structure and permeability calculation for tight sandstone reservoirs: A case of Penglaizhen Formation and Shaximiao Formation in Western Sichuan Depression[J]. Lithologic Reservoirs, 2018, 30(6): 76-82. 邓浩阳, 司马立强, 吴玟, 等. 致密砂岩储层孔隙结构分形研究与渗透率计算: 以川西坳陷蓬莱镇组、沙溪庙组储层为例[J]. 岩性油气藏, 2018, 30(6): 76-82.
[31] YANG Yi, ZHANG Hengrong, YUAN Wei, et al. Fractal characteristics comparison and genesis of conventional sandstone and glutenite[J]. Geoscience, 2022, 36(1): 149-158. 杨毅, 张恒荣, 袁伟, 等. 常规砂岩与砂砾岩分形特征对比及成因分析: 以乌石凹陷X构造流沙港组为例[J]. 现代地质, 2022, 36(1): 149-158.
[32] LIU Shuo, WANG Fei, YU Rui, et al. Micro pore throat structure and fractal characteristics of tight sandstone reservoir[J]. Journal of Jilin University(Earth Science Edition), 2024, 54 (1): 96-107. 刘硕, 王飞, 于瑞, 等. 致密砂岩储层微观孔喉结构及其分形特征[J]. 吉林大学学报(地球科学版), 2024, 54(1): 96-107.
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