Characteristics of eogenetic karst and its influence on reservoir of the Member 2 of Dengying Formation from Wellblock GS1, central Sichuan Basin
ZENG Jianjun1,2, TAN Xiucheng1,2, ZHAO Dongfang1,2, HE Ruyi1,2, LUO Wenjun3, LIU Yun3, XU Wei3, LI Shaorui1,2, DENG Yu1,2, WU Hao1,2
1 State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu 610500,China; 2 Southwest Petroleum University Division of Key Laboratory of Carbonate Reservoirs,CNPC,Chengdu 610500,China; 3 Research Institute of Exploration and Development,PetroChina Southwest Oil & Gas Field Company,Chengdu 610041,China
Abstract The genesis of reservoirs in Member 2 of the Sinian Dengying Formation in the Sichuan Basin has long been a subject of debate,including weathered crust karst,pene-sedimentary karst and buried hydrothermal karst,which significantly impedes the establishment of reservoir prediction model and the exploration and development benefit. This paper uses Member 2 of the Dengying Formation from Wellblock Gaoshi 1 as a case study. By analyzing drilling core samples,thin sections,well logging data,etc.,the karst characteristics of Member 2 of the Dengying Formation is identified and categorized. Furthermore,the variations in karst features and their impact on reservoir development and maintenance have been discussed. The results indicate that: (1)Member 2 of the Dengying Formation exhibits features such as high-frequency corrosion surface,fabric-selective corrosion cavity,geopetal structure,semi-dissociation zone,graniphyric textures,spongy corrosion structures,and karst breccias;(2)The dissolution characteristics are closely associated with the high-frequency shallower-upward sedimentary sequence,predominantly developing in the middle and upper parts of this sequence;(3)Based on the karst strength,three types of karst sequences can be identified: fabric selective corrosion,karst zonation,and integral brecciation;(4)Additionally,a negative bias in δ13C and δ18O as well as a positive bias in87Sr/86Sr,are observed at the high-frequency cycle interface. Further analysis indicates that the thin reservoir of Member 2 of the Dengying Formation is also developed in the middle and upper parts of the high-frequency shallower-upward sedimentary sequence. A significant number of residual karst caverns are filled with micritic envelopes and fibrous isopachous cements. Additionally,some of these caverns exhibit geopetal structures,indicating that they re-entered the submarine diagenetic environment after the formation of karst caverns. Considering the characteristics of negative carbon and oxygen isotope biases and positive strontium isotope biases at high-frequency cycle interfaces,it is proposed that the development of this kind of porous thin reservoir is primarily influenced by eogenetic karst processes driven by the high-frequency sea level changes. The vertical superposition exhibits a distribution pattern characterized by “multiple thin layers”,with distinct facies-controlling features. The karstification with different intensities change the connectivity of pores. Relatively isolated small dissolved pores are primarily formed during the fabric selective solution stage,where they remain more isolated and preserved for extended periods due to seabed cements. In contrast,during the karst zonation and integral brecciation stage,these dissolved pores become increasingly interconnected. In the later stages,they are more prone to mechanical filling and chemical bonding,which enhances reservoir heterogeneity and can significantly deteriorate reservoir performance. Furthermore,it has been revealed that the connectivity of the karst system controls the maintenance pathway of dissolution pores during the early diagenetic stage,under different karst strength transformation. This finding offers a new perspective for understanding the formation and preservation of ancient deep carbonate reservoirs.
Fund:Science and Technology Cooperation Project of PetroChina-Southwest Petroleum University Innovation Consortium(No.2020CX010300)and the Young Scientists Foundation of National Natural Science Foundation of China(No.42302169)
Corresponding Authors:
TAN Xiucheng,born in 1970,is a professor and Ph.D. advisor of Southwest Petroleum University. He is mainly engaged in researches on carbonate sedimentology and reservoir geology. E-mail: tanxiucheng70@163.com.
About author: ZENG Jianjun,born in 1999,master degree candidate, is engaged in research on geology. E-mail: zengjianjun0804@163.com.
Cite this article:
ZENG Jianjun,TAN Xiucheng,ZHAO Dongfang et al. Characteristics of eogenetic karst and its influence on reservoir of the Member 2 of Dengying Formation from Wellblock GS1, central Sichuan Basin[J]. JOPC, 2024, 26(5): 1221-1234.
ZENG Jianjun,TAN Xiucheng,ZHAO Dongfang et al. Characteristics of eogenetic karst and its influence on reservoir of the Member 2 of Dengying Formation from Wellblock GS1, central Sichuan Basin[J]. JOPC, 2024, 26(5): 1221-1234.
[1] 陈景山,李忠,王振宇,谭秀成,李凌,马青. 2007. 塔里木盆地奥陶系碳酸盐岩古岩溶作用与储层分布. 沉积学报, 25(6): 858-868. [Chen J S,Li Z,Wang Z Y,Tan X C,Li L,Ma Q.2007. Paleokarstification and reservoir distribution of Ordovician carbonates in Tarim Basin. Acta Sedimentologica Sinica, 25(6): 858-868] [2] 李勇,王兴志,冯明友,曾德铭,谢圣阳,凡睿,王良军,曾韬,杨雪飞. 2019. 四川盆地北部及周缘地区震旦系灯影组二段、四段储集层特征及成因差异. 石油勘探与开发, 46(1): 52-64. [Li Y,Wang X Z,Feng M Y,Zeng D M,Xie S Y,Fan R,Wang L J,Zeng T,Yang X F.2019. Reservoir characteristics and genetic differences between the second and fourth members of Sinian Dengying Formation in northern Sichuan Basin and its surrounding areas. Petroleum Exploration and Development, 46(1): 52-64] [3] 刘存革,李国蓉,张一伟,韩拥强,吕海涛,杨新勇,崔泽宏. 2007. 锶同位素在古岩溶研究中的应用: 以塔河油田奥陶系为例. 地质学报, 81(10): 1398-1406. [Liu C G,Li G R,Zhang Y W,Han Y Q,Lü H T,Yang X Y,Cui Z H.2007. Application of strontium isotope to the study of paleokarst: an case from Ordovician in the Tahe oilfield,Tarim Basin. Acta Geologica Sinica, 81(10): 1398-1406] [4] 芦飞凡,谭秀成,钟原,罗冰,张本健,张亚,李明隆,肖笛,王小芳,曾伟. 2020. 四川盆地西北部二叠系栖霞组准同生期砂糖状白云岩特征及成因. 石油勘探与开发, 47(6): 1134-1148,1173. [Lu F F,Tan X C,Zhong Y,Luo B,Zhang B J,Zhang Y,Li M L,Xiao D,Wang X F,Zeng W.2020. Origin of the penecontemporaneous sucrosic dolomite in the Permian Qixia Formation,northwestern Sichuan Basin,SW China. Petroleum Exploration and Development, 47(6): 1134-1148,1173] [5] 罗冰,杨跃明,罗文军,文龙,王文之,陈康. 2015. 川中古隆起灯影组储层发育控制因素及展布. 石油学报, 36(4): 416-426. [Luo B,Yang Y M,Luo W J,Wen L,Wang W Z,Chen K.2015. Controlling factors and distribution of reservoir development in Dengying Formation of paleo-uplift in central Sichuan Basin. Acta Petrolei Sinica, 36(4): 416-426] [6] 罗垚,谭秀成,赵东方,罗文军,刘耘,肖笛,乔占峰,曾伟. 2022. 埃迪卡拉系微生物碳酸盐岩沉积特征及其地质意义: 以川中磨溪8井区灯影组四段为例. 古地理学报, 24(2): 278-291. [Luo Y,Tan X C,Zhao D F,Luo W J,Liu Y,Xiao D,Qiao Z F,Zeng W.2022. Sedimentary characteristics of the Ediacaran microbial carbonates and their geological implications: a case study of the Member 4 of Dengying Formation from Wellblock MX8 in central Sichuan Basin. Journal of Palaeogeography(Chinese Edition), 24(2): 278-291] [7] 莫静,王兴志,冷胜远,林刚,熊剑文,谢林,周正. 2013. 川中地区震旦系灯影组储层特征及其主控因素. 中国地质, 40(5): 1505-1514. [Mo J,Wang X Z,Leng S Y,Lin G,Xiong J W,Xie L,Zhou Z.2013. Reservoir characteristics and control Factors of Sinian Dengying Formation in central Sichuan. Geology in China, 40(5): 1505-1514] [8] 谭秀成. 2007. 多旋回复杂碳酸盐岩储层地质模型: 以川中磨溪构造嘉二气藏为例. 成都理工大学博士学位论文. [Tan X C.2007. Geological Model of Complicated Carbonate Reservoir with Multi-cycle: Exampled by Jia2 Gas Pool of Moxi Structrue of Middle Sichuan. Doctoral dissertation of Chengdu University of Technology] [9] 谭秀成,肖笛,陈景山,李凌,刘宏. 2015. 早成岩期喀斯特化研究新进展及意义. 古地理学报, 17(4): 441-456. [Tan X C,Xiao D,Chen J S,Li L,Liu H.2015. New advance and enlightenment of eogenetic karstification. Journal of Palaeogeography(Chinese Edition), 17(4): 441-456] [10] 汪泽成,赵文智,胡素云,徐安娜,江青春,姜华,黄士鹏,李秋芬. 2017. 克拉通盆地构造分异对大油气田形成的控制作用: 以四川盆地震旦系—三叠系为例. 天然气工业, 37(1): 9-23. [Wang Z C,Zhao W Z,Hu S Y,Xu A N,Jiang Q C,Jiang H,Huang S P,Li Q F.2017. Control of tectonic differentiation on the formation of large oil and gas fields in craton basins: a case study of Sinian-Triassic of the Sichuan Basin. Natural Gas Industry, 37(1): 9-23] [11] 王剑. 2000. 华南新元古代裂谷盆地演化: 兼论与Rodinia 解体的关系. 北京: 地质出版社. [Wang J.2000. Sedimentary Evolution of Neoproterozoic Rift Basin in Southern China: Discussion on the Relationship with Rodinia Breakup. Beijing: Geological Publishing House] [12] 王兴志,黄继祥,侯方浩,刘仲宣,吕中刚,夏绍文. 1996. 四川资阳及邻区震旦系灯影组储层段沉积及层序地层学特征. 西南石油学院学报, 18(3): 3-11. [Wang X Z,Huang J X,Hou F H,Liu Z X,Lü Z G,Xiao Z W.1996. Characteristics of deposition and sequence stratigraphy of reservoir interval in Sinian Dengying Formation in Ziyang and its neighboring area. Journal of Southwest Petroleum Institute, 18(3): 3-11] [13] 魏国齐,谢增业,宋家荣,杨威,王志宏,李剑,王东良,李志生,谢武仁. 2015. 四川盆地川中古隆起震旦系—寒武系天然气特征及成因. 石油勘探与开发, 42(6): 702-711. [Wei G Q,Xie Z Y,Song J R,Yang W,Wang Z H,Li J,Wang D L,Li Z S,Xie W R.2015. Features and origin of natural gas in the Sinian-Cambrian of central Sichuan paleo-uplift,Sichuan Basin, SW China. Petroleum Exploration and Development, 42(6): 702-711] [14] 徐哲航,兰才俊,郝芳,陈浩如,杨伟强,马肖琳,邹华耀. 2020. 四川盆地震旦系灯影组不同古地理环境下丘滩储集体的差异性. 古地理学报, 22(2): 235-250. [Xu Z H,Lan C J,Hao F,Chen H R,Yang W Q,Ma X L,Zou H Y.2020. Difference of mound-bank complex reservoir under different palaeogeographic environment of the Sinian Dengying Formation in Sichuan Basin. Journal of Palaeogeography(Chinese Edition), 22(2): 235-250] [15] 杨跃明,文龙,罗冰,王文之,山述娇. 2016. 四川盆地乐山—龙女寺古隆起震旦系天然气成藏特征. 石油勘探与开发, 43(2): 179-188. [Yang Y M,Wen L,Luo B,Wang W Z,Shan S J.2016. Hydrocarbon accumulation of Sinian natural gas reservoirs,Leshan-Longnüsi paleohigh,Sichuan Basin,SW China. Petroleum Exploration and Development, 43(2): 179-188] [16] 袁道先,蒋勇军,沈立成,蒲俊兵,肖琼. 2016. 现代岩溶学. 北京: 科学出版社. [Yuan D X,Jiang Y J,Shen L C,Pu J B,Xiao Q.2016. Modern Karstology. Beijing: Science Press] [17] 张本健,马华灵,李文正,张亚,张自力,严威,曾乙洋,王鑫,钟原,李堃宇,谷明峰,杨岱林,徐哲航. 2023. 四川盆地蓬莱气区灯二段储集层特征及主控因素. 天然气地球科学, 34(11): 1899-1915. [Zhang B J,Ma H L,Li W Z,Zhang Y,Zhang Z L,Yan W,Zeng Y Y,Wang X,Zhong Y,Li K Y,Gu M F,Yang D L,Xu Z H.2023. Reservoir characteristics and main controlling factors in the second member of the Dengying Formation in the Penglai Gas Field,Sichuan Basin. Natural Gas Geoscience, 34(11): 1899-1915] [18] 张玺华,李勇,张本健,蒋航,彭瀚霖,马奎,徐少立,张新. 2023. 四川盆地中江—蓬莱地区灯二段储层特征及优质储层成因机制. 成都理工大学学报(自然科学版), 50(3): 301-312. [Zhang X H,Li Y,Zhang B J,Jiang H,Peng H L,Ma K,Xu S L,Zhang X.2023. Characteristics and formation mechanism of high quality reservoir of the second member of the Dengying Formation in Zhongjiang-Penglai area,Sichuan Basin,China. Journal of Chengdu University of Technology: Science & Technology Edition, 50(3): 301-312] [19] 赵东方,谭秀成,罗文军,王小芳,徐伟,罗思聪,唐大海,罗垚,曾伟. 2022. 早成岩期岩溶特征及其对古老深层碳酸盐岩储层的成因启示: 以川中地区磨溪8井区灯影组四段为例. 石油学报, 43(9): 1236-1252. [Zhao D F,Tan X C,Luo W J,Wang X F,Xu W,Luo S C,Tang D H,Luo Y,Zeng W.2022. Karst characteristics at early diagenetic stage and their enlightenment for the origin of ancient deep carbonate reservoirs: a case study of the Member 4 of Dengying Formation in Moxi 8 well area,central Sichuan. Acta Petrolei Sinica, 43(9): 1236-1252] [20] 赵宗举,李宇平,吴兴宁,陈学时,俞广,贺训云,王双才. 2004. 塔里木盆地塔中地区奥陶系特大型岩性油气藏成藏条件及勘探潜力. 中国石油勘探, 9(5): 12-20. [Zhao Z J,Li Y P,Wu X N,Chen X S,Yu G,He X Y,Wang S C.2004. Conditions for migration and accumulation of Ordovician giant lithologic oil and gas reservoirs in Tazhong region and exploration potential. China Petroleum Exploration, 9(5): 12-20] [21] 郑剑,王振宇,杨海军,苏东坡,张正红,朱波. 2015. 高频层序格架内礁型微地貌特征及其控储机理: 以塔中东部地区上奥陶统为例. 地质学报, 89(5): 942-956. [Zheng J,Wang Z Y,Yang H J,Su D P,Zhang Z H,Zhu B.2015. The control mechanism of microtopography in the high frequency sequence framework to reef-bank complex reservoir: an example from the Upper Ordovician Lianglitage Formation in eastern Tazhong area. Acta Geologica Sinica, 89(5): 942-956] [22] 周吉羚,李国蓉,高鱼伟,雷和金,符浩. 2015. 川南地区震旦系灯影组白云岩地球化学特征及形成机制. 东北石油大学学报, 39(3): 67-75, 5. [Zhou J L,Li G R,Gao Y W,Lei H J,Fu H.2015. Geochemistry and origin of dolomites of the Sinian Dengying Formation in south Sichuan area. Journal of Northeast Petroleum University, 39(3): 67-75, 5] [23] 周进高,姚根顺,杨光,张建勇,郝毅,王芳,谷明峰,李文正. 2015. 四川盆地安岳大气田震旦系—寒武系储层的发育机制. 天然气工业, 35(1): 36-44. [Zhou J G,Yao G S,Yang G,Zhang J Y,Hao F,Wang F,Gu M F,Li W Z.2015. Genesis mechanism of the Sinian-Cambrian reservoirs in the Anyue gas field,Sichuan Basin. Natural Gas Industry, 35(1): 36-44] [24] 朱东亚,金之钧,张荣强,张殿伟,何治亮,李双建. 2014. 震旦系灯影组白云岩多级次岩溶储层叠合发育特征及机制. 地学前缘, 21(6): 335-345. [Zhu D Y,Jin Z J,Zhang R Q,Zhang D W,He Z L,Li S J.2014. Characteristics and developing mechanism of Sinian Dengying Formation dolomite reservoir with multi-stage karst. Earth Science Frontiers, 21(6): 335-345] [25] Bathurst R G C.1966. Boring algae,micrite envelopes and lithification of molluscan biosparites. Geological Journal, 5(1): 15-32. [26] Che Z Q,Tan X C,Deng J T,Jin M D.2019. The characteristics and controlling factors of facies-controlled coastal eogenetic karst: insights from the Fourth Member of Neoproterozoic Dengying Formation,Central Sichuan Basin,China. Carbonates and Evaporites, 34(4): 1771-1783. [27] Hoffiman P F,Schrag D P.2002. The snowball Earth hypothesis: testing the limits of global change. Terra Nova, 14(3): 129-155. [28] Hoffman P F,Abbot D S,Ashkenazy Y,Benn D I,Brocks J J,Cohen P A,Cox G M,Creveling J R,Donnadieu Y,Erwin D H,Fairchild I J,Ferreira D,Goodman J C,Halverson G P,Jansen M F,Le Hir G,Love G D,MacDonald F A,Maloof A C,Partin C A,Ramstein G,Rose B E J,Rose C V,Sadler P M,Tziperman E,Voigt A,Warren S G.2017. Snowball Earth climate dynamics and Cryogenian geology-geobiology. Science Advances, 3(11): e1600983. [29] Jiang G Q,Shi X Y,Zhang S H,Wang Y,Xiao S H.2011. Stratigraphy and paleogeography of the Ediacaran Doushantuo Formation(ca. 635-551 Ma)in south China. Gondwana Research, 19(4): 831-849. [30] Kirmaci M Z,Akdaġ K.2005. Origin of dolomite in the Late Cretaceous-Paleocene limestone turbidites,Eastern Pontides,Turkey. Sedimentary Geology, 181: 39-57. [31] Land L S.1980. The isotopic and trace element geochemistry of dolomite: The state of the art(in concepts and models of dolomitization). Special Publication-Society of Economic Paleontologists and Mineralogists, 28: 87-110 [32] Li Z X,Bogdanova S V,Collins A S,Davidson A,De Waele B,Ernst R E,Fitzsimons I C W,Fuck R A,Gladkochub D P,Jacobs J,Karlstrom K E,Lu S,Natapov L M,Pease V,Pisarevsky S A,Thrane K,Vernikovsky V.2008. Assembly,configuration,and break-up history of Rodinia: a synthesis. Precambrian Research, 160(1-2): 179-210. [33] Moore C,Crockett J,Hawkins C.1995. The Deep Madden Field,a super deep Madison gas reservoir,Wind River Basin,Wyoming(Abstract). AAPG Bulletin. [34] Xiao D,Tan X C,Xi A H,Liu H,Shan S J,Xia J W,Cheng Y,Lian C B.2016. An inland facies-controlled eogenetic karst of the carbonate reservoir in the Middle Permian Maokou Formation,southern Sichuan Basin,SW China. Marine and Petroleum Geology, 72: 218-233.
