Pore Throat Structure and Evolution in Chang 6 Tight Sandstone Reservoirs in Southeastern Ordos Basin

doi:10.7657/XJPG20230605

Abstract

Abstract:

Based on the analyses of cast thin section, scanning electron microscopy (SEM), X-ray diffraction (XRD) of whole rock and clay minerals, high-pressure mercury intrusion, and CT scanning, a detailed study was conducted on the dynamic diagenesis-pore evolution of the Chang 6 heterogeneous tight sandstone reservoirs in the southeastern Ordos basin. Then the characteristics of diagenesis and pore-throat evolution of different reservoir spaces were discussed.The accommodation of Chang 6 reservoir in the study area is classified into 3 types such as reservoir spaces dominated by residual primary intergranular pores, dominated by dissolution pores, and mixed pores. The mineral composition and textural maturity control the initial pore-throat structure of the reservoir, cementation and its intensity influence the tightness of the reservoir, and the pore throats formed due to dissolution affect reservoir storage performance. If the reservoir is mainly affected by compaction and chlorite cementation, then residual primary intergranular pores are dominant, and the fractures are isolated, mostly leading to reservoir spaces consisting of mesopores with sparse reticular throats, indicative of good storage but poor connectivity. If the reservoir is influenced by zeolite cementation-strong dissolution, then zeolite dissolution pores are dominant, resulting in excellent pore throat connectivity, often appearing as reservoir spaces consisting of mesopores with tree-like throats, indicative of the optimal accommodation. If the reservoir has undergone cementation of chlorite, and cementation-weak dissolution of zeolite, both zeolite dissolution pores and residual primary intergranular pores contribute to relatively good pore throat connectivity, often exhibiting reservoir spaces consisting of micropores to mesopores with dense reticular throats, with the storage and transportation capacity falling between the above mentioned two.

Key words: Ordos basin, Yanchang formation, Chang 6 member, tight sandstone reservoir, reservoir space, microscopic pore-throat structure, high-pressure mercury intrusion, CT scanning

CLC Number:

TE122.2

YAN Min, ZHAO Jingzhou, HUANG Yanzhao, YANG Zhenya, FANG Yue, WU Heyuan. Pore Throat Structure and Evolution in Chang 6 Tight Sandstone Reservoirs in Southeastern Ordos Basin[J]. Xinjiang Petroleum Geology, 2023, 44(6): 674-682.

Figures/Tables 9

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References 24

[1]	李建忠, 郑民, 陈晓明, 等. 非常规油气内涵辨析、源-储组合类型及中国非常规油气发展潜力[J]. 石油学报, 2015, 36(5):521-532.
	LI Jianzhong, ZHENG Min, CHEN Xiaoming, et al. Connotation analyses,source-reservoir assemblage types and development potential of unconventional hydrocarbon in China[J]. Acta Petrolei Sinica, 2015, 36(5):521-532.
[2]	王社教, 蔚远江, 郭秋麟, 等. 致密油资源评价新进展[J]. 石油学报, 2014, 35(6):1095-1105. doi: 10.7623/syxb201406007
	WANG Shejiao, YU Yuanjiang, GUO Qiulin, et al. New advance in resources evaluation of tight oil[J]. Acta Petrolei Sinica, 2014, 35(6):1095-1105. doi: 10.7623/syxb201406007
[3]	李国欣, 朱如凯. 中国石油非常规油气发展现状、挑战与关注问题[J]. 中国石油勘探, 2020, 25(2):1-13. doi: 10.3969/j.issn.1672-7703.2020.02.001
	LI Guoxin, ZHU Rukai. Progress,challenges and key issues of unconventional oil and gas development of CNPC[J]. China Petroleum Exploration, 2020, 25(2):1-13. doi: 10.3969/j.issn.1672-7703.2020.02.001
[4]	叶素娟, 李嵘, 杨克明, 等. 川西坳陷叠覆型致密砂岩气区储层特征及定量预测评价[J]. 石油学报, 2015, 36(12):1484-1494. doi: 10.7623/syxb201512003
	YE Sujuan, LI Rong, YANG Keming, et al. Characteristics and quantitative prediction of tight sand gas reservoirs in superimposed tight sandstone gas-bearing area,western Sichuan depression[J]. Acta Petrolei Sinica, 2015, 36(12):1484-1494. doi: 10.7623/syxb201512003
[5]	SOEDER D J. Reservoir properties and pore structure of tight gas sands[J]. AAPG Bulletin, 1984, 68:530.
[6]	ZOU Caineng, ZHU Rukai, LIU Keyu, et al. Tight gas sandstone reservoirs in China:Characteristics and recognition criteria[J]. Journal of Petroleum Science and Engineering, 2012(88/89):82-91.
[7]	LIU Hongping, ZHAO Yanchao, LUO Yang, et al. Diagenetic facies controls on pore structure and rock electrical parameters in tight gas sandstone[J]. Journal of Geophysics and Engineering, 2015, 12(4):587-600. doi: 10.1088/1742-2132/12/4/587
[8]	XIAO Dianshi, JIANG Shu, THUL D, et al. Combining ratecontrolled porosimetry and NMR to probe full-range pore throat structures and their evolution features in tight sands:A case study in the Songliao basin,China[J]. Marine and Petroleum Geology, 2017, 83:111-123. doi: 10.1016/j.marpetgeo.2017.03.003
[9]	朱如凯, 吴松涛, 苏玲, 等. 中国致密储层孔隙结构表征需注意的问题及未来发展方向[J]. 石油学报, 2016, 37(11):1323-1336. doi: 10.7623/syxb201611001
	ZHU Rukai, WU Songtao, SU Ling, et al. Problems and future works of porous texture characterization of tight reservoirs in China[J]. Acta Petrolei Sinica, 2016, 37(11):1323-1336. doi: 10.7623/syxb201611001
[10]	邹敏, 夏东领, 庞雯, 等. 致密砂岩储层微观孔喉结构表征方法及其应用:以鄂尔多斯盆地红河地区长8层为例[J]. 西安石油大学学报(自然科学版), 2019, 34(2):46-53.
	ZOU Min, XIA Dongling, PANG Wen, et al. Characterization method of micropore-throat structure of tight sandstone reservoir and its application:Taking Chang 8 reservoir of Honghe area,southern Ordos basin as an example[J]. Journal of Xi’an Shiyou University(Natural Science Edition), 2019, 34(2):46-53.
[11]	蔡来星, 卢双舫, 张训华, 等. 基于孔喉结构建立致密砂岩储层评价方案:以松南中央坳陷泉四段为例[J]. 吉林大学学报(地球科学版), 2017, 47(6):1654-1667.
	CAI Laixing, LU Shuangfang, ZHANG Xunhua, et al. Establishment of evaluation scheme of tight sandstone reservoirs based on pore throat:A case study on the 4th member of Quantou formation at central depression of southern Songliao basin[J]. Journal of Jilin University(Earth Science Edition), 2017, 47(6):1654-1667.
[12]	操应长, 葸克来, 朱如凯, 等. 松辽盆地南部泉四段扶余油层致密砂岩储层微观孔喉结构特征[J]. 中国石油大学学报(自然科学版), 2015, 39(5):7-17.
	CAO Yingchang, XI Kelai, ZHU Rukai, et al. Microscopic pore throat characteristics of tight sandstone reservoirs in Fuyu layer of the fourth member of Quantou formation in southern Songliao basin[J]. Journal of China University of Petroleum(Edition of Natural Science), 2015, 39(5):7-17.
[13]	张晓辉, 辛红刚, 曹润荣, 等. 鄂尔多斯盆地南梁—华池地区长8储层微观孔喉结构差异及成藏意义[J]. 地质与勘探, 2023, 59(2):418-432.
	ZHANG Xiaohui, XIN Honggang, CAO Runrong, et al. Differences in microscopic pore-throat structure of reservoirs and their significance for hydrocarbon accumulation of Chang 8 reservoir in the Nanliang-Huachi area,Ordos basin[J]. Geology and Exploration, 2023, 59(2):418-432.
[14]	黄奕铭, Richard COLLIER. 致密砂岩储集层微观孔喉结构及其分形特征:以西加拿大盆地A区块Upper Montney段为例[J]. 新疆石油地质, 2021, 42(4):506-513.
	HUANG Yiming, COLLIER R. Pore throat structure and fractal characteristics of tight sandstone reservoirs:A case study of Upper Montney formation in Block A in western Canada sedimentary basin[J]. Xinjiang Petroleum Geology, 2021, 42(4):506-513.
[15]	丁强, 成健, 杨博, 等. 鄂尔多斯盆地胡154区块长4+5段孔隙结构定量表征及分类[J]. 新疆石油地质, 2021, 42(4):410-417.
	DING Qiang, CHENG Jian, YANG Bo, et al. Quantitative characterization and classification of pore structures in Chang 4+5 member in Block Hu-154,Ordos basin[J]. Xinjiang Petroleum Geology, 2021, 42(4):410-417.
[16]	ROUQUEROL J, AVNIR D, FAIRBRIDGE C W, et al. Recommendations for the characterization of porous solids(technical report)[J]. Pure and Applied Chemistry, 1994, 66(8):1739-1758. doi: 10.1351/pac199466081739
[17]	袁珍, 郑艳忠, 袁海莉, 等. 鄂尔多斯盆地东南缘延长组浊沸石胶结物特征及其成岩模式[J]. 西北大学学报(自然科学版), 2020, 50(1):124-134.
	YUAN Zhen, ZHENG Yanzhong, YUAN Haili, et al. Study on the characteristics and diagenesis model of laumontite cement in Yanchang formation in the southeastern margin of Ordos basin[J]. Journal of Northwest University(Natural Science Edition), 2020, 50(1):124-134.
[18]	SCHERER M. Parameters influencing porosity in sandstones:A model for sandstone porosity prediction[J]. AAPG Bulletin, 1987, 71(5):485-491.
[19]	韩载华. 鄂尔多斯盆地七里村油田长7烃源岩与成藏动力研究[D]. 西安: 西安石油大学, 2020.
	HAN Zaihua. Study on source rock and reservoir forming dynamic of Chang 7 member in Qilicun oilfield,Ordos basin[D]. Xi’an: Xi’an Shiyou University, 2020.
[20]	曹江骏, 罗静兰, 范彩伟, 等. 深部热流体活动对储层成岩作用及孔隙演化的影响:以莺歌海盆地LDX区中新统黄流组为例[J]. 地学前缘, 2022, 29(4):412-429. doi: 10.13745/j.esf.sf.2022.2.57
	CAO Jiangjun, LUO Jinglan, FAN Caiwei, et al. Deep thermal fluid activity and its influence on the diagenesis and pore evolution of reservoirs:A case study from the Miocene Huangliu formation reservoir in the LDX area,Yinggehai basin,northern South China Sea[J]. Earth Science Frontiers, 2022, 29(4):412-429. doi: 10.13745/j.esf.sf.2022.2.57
[21]	任大忠, 孙卫, 屈雪峰, 等. 鄂尔多斯盆地延长组长6储层成岩作用特征及孔隙度致密演化[J]. 中南大学学报(自然科学版), 2016, 47(8):2706-2714.
	REN Dazhong, SUN Wei, QU Xuefeng, et al. Characteristic of diagenesis and pore dense evolution of Chang 6 reservoir of Triassic Yanchang formation,Ordos basin[J]. Journal of Central South University(Science and Technology), 2016, 47(8):2706-2714.
[22]	单祥, 郭华军, 郭旭光, 等. 低渗透储层孔隙结构影响因素及其定量评价:以准噶尔盆地金龙2地区二叠系上乌尔禾组二段为例[J]. 吉林大学学报(地球科学版), 2019, 49(3):637-649.
	SHAN Xiang, GUO Huajun, GUO Xuguang, et al. Influencing factors and quantitative assessment of pore structure in low permeability reservoirs:A case study of the 2nd member of Permian upper Urho formation in Jinlong 2 area,Junggar basin[J]. Journal of Jilin University(Earth Science Edition), 2019, 49(3):637-649.
[23]	EHRENBERG S N. Assessing the relative importance of compaction processes and cementation to reduction of porosity in sandstones:Discussion;compaction and porosity evolution of Pliocene sandstones;Ventura basin,California:Discussion[J]. AAPG Bulletin, 1989, 73(10):1274-1276.
[24]	罗静兰, 罗晓容, 白玉彬, 等. 差异性成岩演化过程对储层致密化时序与孔隙演化的影响:以鄂尔多斯盆地西南部长7致密浊积砂岩储层为例[J]. 地球科学与环境学报, 2016, 38(1):79-92.
	LUO Jinglan, LUO Xiaorong, BAI Yubin, et al. Impact of differential diagenetic evolution on the chronological tightening and pore evolution of tight sandstone reservoirs:A case study from the Chang-7 tight turbidite sandstone reservoir in the southwestern Ordos basin[J]. Journal of Earth Science and Environment, 2016, 38(1):79-92.

储集层类型	样品块数	渗透率/ mD	最大进汞饱和度/%	退汞效率/%	最大孔喉半径/μm	孔喉中值半径/μm	平均孔喉半径/μm	均质系数	特征结构系数
残余原生粒间孔主导型	88	0.097~1.070 （0.337）	76.23~92.37 （85.93）	13.66~47.92 （25.24）	0.09~5.25 （1.19）	0.04~0.26 （0.13）	0.01~0.59 （0.23）	0.09~0.75 （0.21）	0.13~0.99 （0.82）
溶蚀孔主导型	103	0.024~0.835 （0.510）	56.13~89.17 （79.88）	8.29~44.87 （21.06）	0.09~7.94 （1.27）	0.04~0.22 （0.14）	0.01~0.67 （0.20）	0.17~0.89（0.43）	1.42~18.37 （2.48）
混合孔型	71	0.020~1.284 （0.359）	46.83~96.08 （86.42）	13.93~43.29 （28.46）	0.09~2.80 （0.63）	0.03~0.20 （0.10）	0.01~0.33 （0.12）	0.02~0.46（0.12）	1.30~4.08 （1.69）

储集层类型	样品块数	碎屑颗粒			胶结物				粒度
储集层类型	样品块数	石英含量/%	长石含量/%	岩屑含量/%	绿泥石含量/%	浊沸石含量/%	硅质含量/%	方解石含量/%	粒度中值/ mm	分选系数
残余原生粒间孔主导型	88	22~32 （25）	40~58 （52）	0~9 （8）	3.9~14.8 （6.8）	0.4~4.8 （2.2）	0~3.1 （1.3）	0~2.0 （0.9）	0.01~0.40 （0.20）	1.20~1.51 （1.30）
溶蚀孔主导型	103	28~37 （32）	40~52 （44）	0~8 （5）	0~5.5 （1.6）	4.1~26.4 （11.1）	0~0.7 （0.5）	0~2.3 （0.9）	0.01~0.41 （0.22）	1.39~2.37 （1.69）
混合孔型	71	23~35 （27）	42~56 （48）	0~9 （7）	0~4.1 （3.7）	1.3~8.4 （4.2）	0~3.5 （1.9）	0~4.9 （2.5）	0.01~0.35 （0.18）	0.95~1.22 （1.02）