In view of the scale limitations of pore characterization by a single technology and the difficulty in integrating qualitative, structural and quantitative data, the shale in the third member of the Shahejie Formation in the Dongpu Depression, Bohai Bay Basin was taken as the research object, the pore characteristics of the main rock facies (organic-rich massive calcareous shale, organic-containing lamellar clay-feldspar/calcareous mixed shale, and organic-containing lamellar clay shale) were systematically characterized from the micrometer to nanometer scale and from two-dimensional parameters to three-dimensional structures by using multi-scale CT digital core, high-pressure mercury intrusion and low-temperature nitrogen adsorption techniques. Considering that the microscopic pore characteristics at different scales can affect various physical properties of the reservoir, combined with the relative comparison results of rocks, the differences in the microscopic pore characteristics of reservoirs of different lithofacies types were clarified and the factors influencing pore development in this area were explored. The results show as follows. The clay-calcareous mixed shale has the best pore throat connectivity, and the porosity of calcareous shale is the highest. The pore diameters of nitrogen adsorption micro-pores are mainly dominated by those in the range of 3.8 nm to 4.0 nm.. The mercury pressure experiment shows that the meso-macropores are poorly developed due to deep compaction. The pore diameters larger than 3 000 nm in the digital core are mainly concentrated in the range of 1 000 nm to 10 000 nm, among which the throat radius of the clayey-feldspar mixed shale pores is well developed. The pore development of the third member of the Shahejie Formation is influenced by the mineral composition, pore-throat harmony, as well as the type of grain layer and interface characteristics. The results reveal the micro-pore characteristics of different rock phases in the third member of the Shahejie Formation and the influencing factors of pore development, providing a scientific basis for the efficient exploration and development of continental shale oil.
ZHU Xu-liang, HU Wang-shui, LI Ling-xi, XU Yun-long, YUAN Bo, WANG De-bo, CHAI Hua, WANG Cheng-lin, HE Ping.
Microscopic Pore Characteristics and Influencing Factors of Different Lithofacies Types: Shales in Qianliyuan and Puwei Subsags[J].
Science Technology and Engineering, 2026, 26(25): 10767-10782 DOI:10.12404/j.issn.1671-1815.2506527
中国陆相页岩油气资源潜力巨大,渤海湾、松辽及鄂尔多斯等主要含油气盆地页岩油气已经取得重大突破[1-3],东濮凹陷位于渤海湾盆地的西南端,已经历40余年的勘探,已探明石油地质储量6.01亿t,天然气地质储量1 388亿m3[4-5],该地区储层孔隙以纳米-微米级为主,非均质性较强,岩性横向变化剧烈。微观孔隙结构特征是油气储层的“灵魂”,直接决定了油气的储集能力、渗流效率、开采难度及最终采收率[6-9]。文献[10-11]对该地区孔隙发育特征多集中于单一实验,对于不同尺度下的微观孔隙特征研究较为独立、笼统,不能直观展示不同尺度下微观孔隙结构差异对储层物性带来的影响。此外,单一实验技术往往受限于表征尺度或参数类型,难以全面揭示孔隙系统的复杂性。例如,CT 扫描三维数字岩心重构(three-dimensional digital core reconstruction via CT scanning)虽能直观呈现孔隙三维形貌,却在微小孔隙的定量精度上存在局限[12-13];高压压汞实验擅长表征中-大尺度孔喉的动态渗流参数,却无法捕捉纳米级微孔的精细结构[14];氮气吸附实验可实现微-介孔的高精度分析,却缺乏对孔隙宏观连通性的刻画能力[15]。因此,构建多技术融合的研究体系,实现不同尺度孔隙特征的互补表征,是当前岩心微观孔隙结构研究的关键。
LiuXinrui, WuShiqiang, ChenFengling, et al. Study on reservoir characteristics of inter-salt shale oil in Qianjiang Formation of Qianjiang Sag, Jianghan Basin: taking Qianshan 34-10 rhythm as an example[J]. Petroleum Geology & Experiment, 2021, 43(2): 268-275.
WangYouxian. Geological conditions for continental shale oil accumulation and main controlling factors for enrichment and high production: taking the Biyang Sag as an example[J]. Fault-Block Oil and Gas Field, 2015, 22(5): 588-593.
FuSuotang, JinZhijun, FuJinhua, et al. The transformation of understanding from tight oil to shale oil in member 7 of Yanchang Formation, Ordos Basin and its significance for exploration and development[J]. Acta Petrolei Sinica, 2021, 42(5): 561-569.
XuTianwu, ZhangHong’an. Analysis of oil and gas distribution laws and exploration potential in oil-rich sags: taking the Dongpu Sag as an example[J]. Geoscience Frontiers, 2024, 31(6): 368-380.
ZhaoWenzhi, ZhuRukai, LiuWei, et al. Enrichment conditions and distribution characteristics of continental medium-high mature shale oil in China[J]. Geoscience Frontiers, 2023, 30(1): 116-127.
ChenChen, JiangZaixing, KongXiangxin, et al. Sedimentary characteristics of inter-salt fine-grained rocks in Qianjiang Formation of Qianjiang Sag and their control on shale oil-bearing property[J]. Geoscience Frontiers, 2021, 28(5): 421-435.
WuXiaozhi, LiuZhuangxiaoxue, WangJian, et al. Potential, distribution and key exploration areas of oil and gas resources in China[J]. Geoscience Frontiers, 2022, 29(6): 146-155.
[17]
LiangC, CaoY C, JiangZ X, et al. Shale oil potential of lacustrine black shale in the eocene Dongying Depression: implications for geochemistry and reservoir characteristics[J]. AAPG Bulletin, 2017, 101(11): 1835-1858.
HuangYuqi, ZhangJinchuan, ZhangPeng, et al. Microscopic reservoir space characteristics of Mud Shale in the third member of the Shahejie Formation in the northern Dongpu Sag and its main controlling factors[J]. Journal of Shandong University of Science and Technology(Natural Science), 2016, 35(3): 8-16.
ShaoXinhe, PangXiongqi, HuTao, et al. Microscopic pore characteristics of shale reservoirs in the 3rd member of the Shahejie Formation, Dongpu Sag, Bohai Bay Basin and their significance for hydrocarbon retention[J]. Oil & Gas Geology, 2019, 40(1): 67-77.
YangXuan, ZhaoYi, TianZeyu, et al. Advances in microstructure study on asphalt mixtures by using CT technology[J]. Applied Chemical Industry, 2022, 51(1): 256-262.
[24]
YuW, WangL H, WangJ Q, et al. Investigating microstructure of Longmaxi shale in Shizhu area, Sichuan Basin, by optical microscopy, scanning electron microscopy and micro-computed tomography[J]. Nuclear Science and Techniques, 2017, 28(11): 163.
HaoMianzhu, JiangZhenxue, NieZhou, et al. Development characteristics of pore connectivity in deep shale reservoirs and its controlling factors: a case study of Longmaxi Formation in southern Sichuan Basin[J]. Fault-Block Oil & Gas Field, 2022, 29(6): 761-768.
ZhangQin, QiuZhen, GaoWanli, et al. Adsorption characteristics of different components of shale and their implications for shale gas exploration: a case study of the Longmaxi Formation in southern Sichuan and the Shanxi Formation in the eastern margin of Hubei[J]. Science Technology and Engineering, 2025, 25(30): 12854-12864.
[29]
SchmittM, FernandesC P, NetoJ C, et al. Characterization of pore systems in seal rocks using nitrogen gas adsorption combined with mercury injection capillary pressure techniques[J]. Marine and Petroleum Geology, 2013, 39(1): 138-149.
[30]
GouQ, XuS, HaoF, et al. Full-scale pores and micro-fracture characterization using FESEM, gas adsorption, nano-CT and micro-CT: a case study of the Silurian Longmaxi Formation shale in the Fuling area, Sichuan Basin, China[J]. Fuel, 2019, 253: 167-179.
LiuQingbing, CaiZhongxian, XueYufang, et al. Full-pore-size characterization of dolomite pore structure in the Keping peripheral area of Tarim Basin[J]. Science Technology and Engineering, 2022, 22(13): 5213-5221.
XuYunlong, ZhangHong’an, LiJidong, et al. Reservoir characteristics and main controlling factors of continental shale series in Dongpu Sag, Bohai Bay Basin[J]. Fault-Block Oil and Gas Field, 2022, 29(6): 729-735.
WangYujun, JinYaqin, GuoJinlan. Distribution and reservoir characteristics of deep sand bodies under the tectonic-sedimentary coupling framework: a case study of the middle sub member of the Paleogene Es3 Member in Dongpu Sag[J]. Science Technology and Engineering, 2023, 23(5): 1912-1922.
YuHaibo, ChengXiushen, QiJiafu, et al. Control of paleogene fault activities on sedimentation in Dongpu Sag[J]. Lithologic Reservoirs, 2019, 31(5): 12-23.
XuHan. Numerical simulation and tectonic analysis of formation and evolution of Dongpu Sag, Bohai Bay Basin[D]. Beijing: China University of Geosciences, Beijing, 2018.
XuTianwu, ZhangHong’an, LiJidong, et al. Hydrocarbon generation and accumulation characteristics of salt lake facies in Dongpu Sag, Bohai Bay Basin[J]. Oil & Gas Geology, 2019, 40(2): 248-261.
LiBei, LiuChiyang, HuangLei, et al. Sedimentary environment analysis of the middle submember of the third member of Shahejie Formation in northern Dongpu Sag[J]. Geoscience, 2018, 32(2): 227-239.
JinYaqin, YangDongdong, JiangFeihu, et al. Sedimentary filling characteristics of clastic rocks in Dongpu Sag and their response to tectonic activities[J]. Science Technology and Engineering, 2019, 19(29): 83-89.
XuWenshuo, LiangLixi, GouJianru, et al. Pore structure characterization of glutenite based on micro-CT scanning[J]. Science Technology and Engineering, 2025, 25(3): 999-1007.
WangTao, JiangYuqiang, YangChangcheng, et al. Pore structure and fluid mobility of tight sandstone reservoirs in the 4th Member of Xujiahe Formation, Tianfu Gas Area, Sichuan Basin[J]. Science Technology and Engineering, 2025, 25(12): 4900-4912.
ZhangShun, LiuHuimin, ChenShiyue, et al. Discussion on lithofacies classification scheme of fine-grained sedimentary rocks in faulted lacustrine basins of eastern China: a case study of paleogene fine-grained sedimentary rocks in southern Bohai Bay Basin[J]. Acta Geologica Sinica, 2017, 91(5): 1108-1119.
RanBo, LiuShugen, SunWei, et al. Lithofacies classification of shales of the Lower Paleozoic Wufeng-Longmaxi Formations in the Sichuan Basin and its surrounding areas, China[J]. Earth Science Frontiers, 2016, 23(2): 96-107.
JiangYuqiang, SongYitao, QiLin, et al. Fine lithofacies of China’s marine shale and its logging prediction: a case study of the Lower Silurian Longmaxi marine shale in Weiyuan area, southern Sichuan Basin, China[J]. Earth Science Frontiers, 2016, 23(1): 107-118.
MaYiquan, DuXuebin, LiuHuimin, et al. Characteristics, depositional processes, and evolution of shale lithofacies of the upper submember of E2s4 in the Dongying Depression[J]. Earth Science, 2017, 42(7): 1195-1208.
LiuZhongbao, LiuGuangxiang, HuZongquan, et al. Lithofacies types, assemblage characteristics of continental shale series and their significance for oil and gas exploration: a case study of middle-lower Jurassic in Sichuan Basin[J]. Natural Gas Industry, 2019, 39(12): 10-21.
ZhangQiyan, LiuXiao, ShiWeixin, et al. Microstructural characteristics analysis of carbonate rocks based on micro-CT and scanning electron microscopy[J]. Science Technology and Engineering, 2022, 22(34): 15043-15051.
ZhaoJianpeng, CuiLikai, ChenHui, et al. Quantitative characterization method of rock microstructure based on CT scanning digital core[J]. Geoscience, 2020, 34(6): 1205-1213.
XieChaoyang, ZhangWei, YaoDongfang, et al. Quantitative characterization of soil spatial pore network based on maximum ball algorithm[J]. Journal of Engineering Geology, 2020, 28(1): 60-68.
MaYunfeng, ZhaoJianguo, SunLong, et al. Microscopic occurrence characteristics and seepage law of water bodies in gas reservoir under stress: a case study of tight reservoirs in the eighth member of Permian Shihezi Formation, Shenmu Gas Field, Ordos Basin[J]. Petroleum Geology & Experiment, 2023, 45(3): 466-473.
JiangZaixing, ZhangWenzhao, LiangChao, et al. Characteristics and evaluation elements of shale oil reservoir[J]. Acta Petrolei Sinica, 2014, 35(1): 184-196.
WangYujun, ZhaoXiaodong, ZhouBoyu, et al. Evaluation of pore structure in low permeability sandstone reservoir based on high pressure-constant velocity mercury injection[J]. Fault-Block Oil and Gas Field, 2022, 29(6): 824-830.
DuJinhu, WangZecheng, ZouCaineng, et al. Discovery of intra-cratonic rift in the Upper Yangtze andits control effect on the formation of Anyue Giant Gas Field[J]. Acta Petrolei Sinica, 2016, 37(1): 116.
[81]
WangQ T, LuH, WangT L, et al. Pore characterization of lower silurian shale gas reservoirsin the middle Yangtze Region, central China[J]. Marineand Petroleum Geology, 2018, 89: 14-26.
[82]
WangQ T, WangT L, LiuW P, et al. Relationships among composition, porosity and permeability of Longmaxi shale reservoir in the Weiyuan Block, Sichuan Basin, China[J]. Marine and Petroleum Geology, 2019, 102: 33-47.
WangZhangfei, FangHuihuang, SangShuxun, et al. Three-dimensional visualization of pore structure of low permeability coal seam in Liang-Huai Coal Field and its connectivity[J]. Science Technology and Engineering, 2024, 24(26): 11195-11207.
WeiXiangfeng, LiuRuobing, ZhangTingshan, et al. Microscopic pore structure characteristics and development controlling factors of shale gas reservoirs: a case study of Longmaxi Formation in XX area, southern Sichuan-northern Guizhou[J]. Natural Gas Geoscience, 2013, 24(5): 1048-1059.
HuHuiting, MaYong, ZhangSui’an, et al. Anisotropic characteristics and influencing factors of fractures and matrix permeability in shale[J]. Science Technology and Engineering, 2023, 23(24): 10252-10263.