Characteristics of facies-controlled and early high-frequency exposed karstification in the Qixia Formation of Middle Permian in the northwest of Sichuan Basin and its significance

doi:10.3969/j.issn.1672-7703.2020.03.007

Abstract

Abstract: This paper presents a set of deep to ultra-deep vuggy carbonate reservoirs of penecontemporaneous dolomitization genesis superposed with early-stage exposed karstification. Based on outcrops and drilling data from the study area, research has been carried out on petrology, reservoir geology and geochemistry. Two types of shallowing-upward sequences have been identified in the Qixia Formation of the Middle Permian in the Sichuan Basin. The first is the coarsening-upward type; from micrite to bioclastic micrite to micrite-sparry grain limestone. The second is the fining-upward type; from sparry grain dolomite to medium- crystalline dolomite to fine-powder crystalline algal dolomite. The early high-frequency exposed karstification of both types has the following characteristics: (1) There are exposed unconformities at the tops of the cycles, and in each cycle the initial flooding sediment of the next cycle filled in the earlier karst system and overlapped the micro paleo-geomorphic highs. (2) The porous bedrocks in the upper part of the cycle were cut by dominant karst channels and formed near in-situ breccias. (3) Patch-like karst systems are developed at the top of some cycles, which have been filled with terrigenous clay, silty clasts and some breccias. (4) Karst cave breccias are developed in some cycles, and the inter-breccia caves were filled with carbonate vadose silts. (5) The stable carbon and oxygen isotopes exhibit a certain negative bias under the exposure surface. Further study on reservoir physical properties shows that, when karstification is relatively strong, high-quality reservoirs are developed in the lower part of the cycle, and the reservoir space is primarily small vugs formed by dolomitization and dissolution expansion of the intergranular pores preserved in bedrocks. When karstification is relatively weak, high-quality reservoirs are developed in the middle and upper part of the cycle, and the reservoir space is similar to that produced by strong karstification. When the intensity of karstification is moderate, high-quality reservoirs are developed in the middle of the cycle, and the reservoir space is generally residual vugs from collapse of inter-breccias caves. The vugs formed by the early exposed karstification superimposed penecontemporaneous dolomitization of the dolomite bedrocks are preserved today as the effective reservoir space. Therefore, early high-frequency exposed karstification with different intensities is considered to be the primary factor for the formation of reservoir space in the Qixia Formation.

Key words: early high-frequency exposed karstification, deep to ultra-deep, genesis of vugs, northwestern Sichuan Basin, Middle Permian, Qixia Formation

CLC Number:

Li Minglong, Tan Xiucheng, Luo Bing, Zhang Ya, Zhang Benjian, Lu Feifan, Su Chengpeng, Xiao Di, Zhong Yuan. Characteristics of facies-controlled and early high-frequency exposed karstification in the Qixia Formation of Middle Permian in the northwest of Sichuan Basin and its significance[J]. China Petroleum Exploration, 2020, 25(3): 66-82.

References

[1] 张水昌，梁狄刚，朱光有，张兴阳，张宝民，陈建平，等. 中国海相油气田形成的地质基础[J]. 科学通报，2007,52( 增刊1):19-37. Zhang Shuichang, Liang Digang, Zhu Guangyou, Zhang Xingyang, Zhang Baomin, Chen Jianping, et al . Fundamental geological elements for the occurrence of Chinese marine oil and gas accumulations[J]. Chinese Science Bulletin, 2007,52 (S1): 19-37.
[2] 朱光有，张水昌. 中国深层油气成藏条件与勘探潜力[J]. 石油学报， 2009,30(6):793-800. Zhu Guangyou, Zhang Shuichang. Hydrocarbon accumulation conditions and exploration potential of deep reservoirs in China[J]. Acta Petrolei Sinica, 2009,30(6):793-800.
[3] 胡见义，吴因业，张静. 高海拔与超深地层石油地质若干问题[J]. 石油学报，2009,30(2):159-167. Hu Jianyi, Wu Yinye, Zhang Jing. Discussion on petroleum geology theory for high-elevation and ultra-deep formations[J]. Acta Petrolei Sinica, 2009,30(2):159-167.
[4] 赵文智，胡素云，刘伟，王铜山，李永新. 再论中国陆上深层海相碳酸盐岩油气地质特征与勘探前景[J]. 天然气工业，2014,34(4):1-9. Zhao Wenzhi, Hu Suyun, Liu Wei, Wang Tongshan, Li Yongxin. Petroleum geological features and exploration prospect in deep marine carbonate strata onshore China: a further discussion[J]. Natural Gas Industry, 2014,34(4):1-9.
[5] 何治亮，张军涛，丁茜，尤东华，彭守涛，朱东亚，等. 深层—超深层优质碳酸盐岩储层形成控制因素[J]. 石油与天然气地质，2017,38 (4):633-644. He Zhiliang, Zhang Juntao, Ding Qian, You Donghua, Peng Shoutao, Zhu Dongya, et al . Factors controlling the formation of high-quality deep to ultra-deep carbonate reservoirs[J]. Oil & Gas Geology, 2017,38(4):633-644.
[6] 朱光有，张水昌，梁英波，马永生，戴金星，周国源.TSR 对深部碳酸盐岩储层的溶蚀改造——四川盆地深部碳酸盐岩优质储层形成的重要方式[J]. 岩石学报，2006,22(8):2182-2194. Zhu Guangyou, Zhang Shuichang, Liang Yingbo, Ma Yongsheng, Dai Jinxing, Zhou Guoyuan. Dissolution and alteration of the deep carbonate reservoirs by TSR: an important type of deep-buried high-quality carbonate reservoirs in Sichuan Basin[J]. Acta Petrologica Sinica, 2006,22(8): 2182-2194.
[7] Moore C H, Druckman Y. Burial diagenesis and porosity e v o l u t i o n , U p p e r J u r a s s i c S m a c k o v e r , A r k a n s a s a n d Louisiana[J]. AAPG Bulltin, 1981,65:597-628.
[8] 蔡春芳，梅博文，马亭，赵红静，方孝林. 塔里木盆地有机酸来源、分布及对成岩作用的影响[J]. 沉积学报，1997,15(2):105-111. Cai Chunfang, Mei Bowen, Ma Ting, Zhao Hongjing, Fang Xiaolin. The source, distribution of organic acids in oilfield waters and their effects on mineral diagenesis in Tarim Basin[J]. Acta Sedimentologica Sinica, 1997,15(2):105-111.
[9] Wierzbicki Rick, Dravis Jeffrey J, Al-Aasm Ihsan, Harland Nancy. Burial dolomitization and dissolution of Upper Jurassic Abenaki platform carbonates, Deep Panuke reservoir, Nova Scotia, Canada[J]. AAPG Bulletin, 2006,90(11): 1843-1861.
[10] Bildstein R H, Worden E B. Assessment of anhydrite dissolution as the rate-limiting step during thermochemical sulfate reduction[J]. Chemical Geology, 2001,176:173-189.
[11] Cross M M, Manning D A C, Bottrell S H, Worden R H. Thermochemical sulphate reduction(TSR): Experimental determination of reaction kinetics and implications of the observed reaction rates for petroleum reservoirs[J]. Organic Geochemistry, 2004,35:393-404.
[12] 张水昌，朱光有，何坤. 硫酸盐热化学还原作用对原油裂解成气和碳酸盐岩储层改造的影响及作用机制[J]. 岩石学报，2011,27(3): 809-826. Zhang Shuichang, Zhu Guangyou, He Kun. The effects of thermochemical sulfate reduction on occurrence of oilcracking gas and reformation of deep carbonate reservoir and the interaction mechanisms[J]. Acta Petrologica Sinica, 2011,27 (3):809-826.
[13] B j?r l y k k e K n u t . R e l a t i o n s h i p s b e t w e e n d e p o s i t i o n a l environments, burial history and rock properties. Some principal aspects of diagenetic process in sedimentary basins[J]. Sedimentary Geology, 2014,301:1-14.
[14] 金之钧，朱东亚，胡文瑄，张学丰，王毅，闫相宾. 塔里木盆地热液活动地质地球化学特征及其对储层影响[J]. 地质学报，2006,80 (2):245-253. Jin Zhijun, Zhu Dongya, Hu Wenxuan, Zhang Xuefeng, Wang Yi, Yan Xiangbin. Geological and Geochemical Signatures of Hydrothermal Activity and Their Influence on Carbonate Reservoir Beds in the Tarim Basin[J]. Acta Geologica Sinica, 2006,80(2):245-253.
[15] 谭秀成. 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[D]. 成都：成都理工大学，2007. Tan Xiucheng. Geological model of complicated carbonate reservoir with multi-cycle-exampled by Jia2 gas pool of Moxi structure of middle Sichuan[D]. Chengdu: Chengdu University of Technology, 2007.
[16] 刘建强，罗冰，谭秀成，江兴福，李宗银，乔琳，等. 川东北地区飞仙关组台缘带鲕滩分布规律[J]. 地球科学——中国地质大学学报， 2012,37(4):183-192. Liu Jianqiang, Luo Bing, Tan Xiucheng, Jiang Xingfu, Li Zongyin, Qiao Lin, et al . Distribution of marginal-platform oolitic shoal in Feixianguan Formation, northeast Sichuan, China[J]. Earth Science-Journal of China University of Geosciences, 2012,37(4):183-192.
[17] 谢圣阳，王兴志，梅秋勇，霍飞，李勇，陈玉巧. 宣汉—达县地区飞仙关组层序地层与颗粒滩特征[J]. 断块油气田，2018,25(3):310-315. Xie Shengyang, Wang Xingzhi, Mei Qiuyong, Huo Fei, Li Yong, Chen Yuqiao. Sequence stratigraphy and grain shoal characteristics of Feixianguan Formation in Xuanhan-Daxian zone[J]. Fault-Block Oil & Gas Field, 2018,25(3):310-315.
[18] Xiao Di, Zhang Benjian, Tan Xiucheng, Liu Hong, Xie Jirong, Wang Lichao, et al . Discovery of a shoal-controlled karst dolomite reservoir in the Middle Permian Qixia Formation, northwestern Sichuan Basin, Southwest China[J]. Energy Exploration & Exploitation, 2018,(2):686-704.
[19] 杨海军，陈永权，田军，杜金虎，朱永峰，李洪辉，等. 塔里木盆地轮探1 井超深层油气勘探重大发现与意义[J]. 中国石油勘探， 2020,25(2):62-72. Yang Haijun, Chen Yongquan, Tian Jun, Du Jinhu, Zhu Yongfeng, Li Honghui, et al . Great discovery and its signifi cance of ultra-deep oil and gas exploration in well Luntan-1 of the Tarim Basin[J]. China Petroleum Exploration, 2020,25(2):62-72.
[20] 沈安江，陈娅娜，蒙绍兴，郑剑锋，乔占峰，倪新锋，等. 中国海相碳酸盐岩储层研究进展及油气勘探意义[J]. 海相油气地质， 2019,24(4):1-14. Shen Anjiang, Chen Yana, Meng Shaoxing, Zheng Jianfeng, Qiao Zhanfeng, Ni Xinfeng, et al . The research progress of marine carbonate resevoirs in China and its significance for oil and gas exploration[J]. Marine Origin Petroleum Geology, 2019,24(4):1-14.
[21] Lowe David, Waltham Tony. Dictionary of Karst and Caves[M]. London: British Cave Research Association, 2002: 1-39.
[22] Lundegard P D, Land L S, Galloway W E. Problem of secondary porosity: Frio Formation (Oligocene), Texas Gulf Coast[J]. Geology, 1984,12:399-402.
[23] 张单明，秦善，刘波，巫翔，张学丰，刘建强，等. 碳酸盐岩—H2S 平衡体系原位溶蚀模拟实验及其地质意义[J]. 北京大学学报：自然科学版，2015,51(4):745-754. Zhang Danming, Qin Shan, Liu Bo, Wu Xiang, Zhang Xuefeng, Liu Jianqiang, et al . In-situ simulation experiment of Carbonate-Hydrogen sulfide equilibrium system and its geological significance[J]. Acta Scientiarum Naturalium Universitatis Pekinensis, 2015,51(4):745-754.
[24] 陈启林, 黄成刚. 沉积岩中溶蚀作用对储集层的改造研究进展[J]. 地球科学进展,2018,33(11):1112-1129. Ch e n Q i l i n , Hua n g Ch e n g g a n g . R e s e a r c h p r o g r e s s o f modification of reservoirs by dissolution in sedimentary rock[J]. Advances in Earth Science, 2018,33(11):1112-1129.
[25] 朱东亚，孟庆强，胡文瑄，金之钧. 塔里木盆地深层寒武系地表岩溶型白云岩储层及后期流体改造作用[J]. 地质论评,2012,58(4): 691-701. Zhu Dongya, Meng Qinqiang, Hu Wenxuan, Jin Zhijun. Deep Cambrian surface karst dolomite reservoir and its alteration by later fluid in Tarim Basin[J]. Geological Review, 2012,58 (4):691-701.
[26] 沈安江，赵文智，胡安平，佘敏，陈娅娜，王小芳. 海相碳酸盐岩储集层发育主控因素[J]. 石油勘探与开发，2015,42(5):545-554. S h e n A n j i a n g , Z h a o We n z h i , Hu A n p i n g , S h e M i n , Chen Yana, Wang Xiaofang. Major factors controlling the development of marine carbonate reservoirs[J]. Petroleum Exploration and Development, 2015,42(5):545-554.
[27] Tang Hao, Tan Xiucheng, Liu Hong, Zhou Yan, Li Ling, Ding Xiong, Tang Qingsong, et al . Genesis and dolomitization of “Khali” powder crystal dolomite in Triassic Jialingjiang Formation, Moxi gas field, central Sichuan Basin, SW China[J]. Petroleum Exploration and Development, 2014. 41(4):553-562.
[28] 谭秀成，肖笛，陈景山，李凌，刘宏. 早成岩期喀斯特化研究新进展及意义[J]. 古地理学报，2015,17(4):441-456. Tan Xiucheng, Xiao Di, Chen Jingshan, Li Ling, Liu Hong. New advance and enlightenment of eogenetic karstification[J]. Journal of Palaeogeography, 2015,17(4):441-456.
[29] Xiao Di, Tan Xiucheng, Xi Aihua, Liu Hong, Shan Shujiao, Xia Jiwen, et al . An inland facies-controlled eogenetic karst of the carbonate reservoir in the Middle Permian Maokou Formation, southern Sichuan Basin, SW China[J]. Marine and Petroleum Geology, 2016,72:218-233.
[30] 肖笛. 海相碳酸盐岩早成岩期岩溶及其储层特征研究——以中国西部三大盆地为例[D]. 成都：西南石油大学，2017. Xiao Di. Research on eogenetic karst of marine carbonate and its reservoir in the three major basins, western China[D]. Chengdu: Southwest Petroleum University, 2017.
[31] Xiao Di, Tan Xiucheng, Zhang Daofeng, He Wei, Li Ling, Shi Yunhe, et al . Discovery of syngenetic and eogenetic karsts in the Middle Ordovician gypsum-bearing dolomites of the eastern Ordos Basin (central China) and their heterogeneous impact on reservoir quality[J]. Marine and Petroleum Geology, 2019,99:190-207.
[32] Xiong Ying, Tan Xiucheng, Zuo Zhifeng, Zou Guoliang,Liu Mingjie, Liu Yun, et al. Middle Ordovician multi-stage penecontemporaneous karstification in North China: Implications for reservoir genesis and sea level fluctuations[J]. Journal of Asian Earth Sciences, 2019,183:1-14.
[33] Li Ling, Tan Xiucheng, Zeng Wei, Zhou Tao, Yang Yu, Hong Haitao, et al . Development and reservoir significance of mud mounds in Sinian Dengying Formation, Sichuan Basin[J]. Petroleum Exploration and Development, 2013,40(6):714-721.
[34] 王海真，池英柳，赵宗举，江青春，鲁卫华. 四川盆地栖霞组岩溶储层及勘探选区[J]. 石油学报，2013,34(5):833-842. Wang Haizhen, Chi Yingliu, Zhao Zongju, Jiang Qingchun, Lu Weihua. Karst reservoirs developed in the Middle Permian Qixia Formation of Sichuan Basin and selection of exploration regions[J]. Acta Petrolei Sinica, 2013,34(5):833-842.
[35] 胡安平，潘立银，郝毅，沈安江，谷明峰. 四川盆地二叠系栖霞组、茅口组白云岩储层特征、成因和分布[J]. 海相油气地质，2018,23 (2):39-52. Hu Anping, Pan Liyin, Hao Yi, Shen Anjiang, Gu Mingfeng. Origin, characteristics and distribution of dolostone reservoir in Qixia Formation and Maokou Formation, Sichuan Basin, China[J]. Marine Origin Petroleum Geology, 2018,23(2):39-52.