Characteristics and Formation Mechanism of Limestone Reservoir of Shoals in the Middle Permian Maokou Formation: A Case Study of Shuanghechang Outcrop in Southeastern Sichuan

doi:10.19657/j.geoscience.1000-8527.2025.029

Abstract

Abstract:

The Permian Maokou Formation in the Sichuan Basin hosts diverse carbonate reservoirs with significant exploration potential. Previous studies have focused on dolomite and karst limestone reservoirs, leaving gaps in understanding the genesis of shoal-type porous limestone reservoirs, particularly their pore formation mechanisms and accumulation processes. Based on field outcrop observations, thin-section analysis, physical property testing, and geochemical data from eastern Sichuan, this study identifies pore types and diagenetic processes in Maokou Formation shoal limestones, reconstructs pore evolution histories, and establishes porosity-depth curves for reservoir characterization.Results show that shoal limestones are primarily sparitic bioclastic limestones, with locally dolomitized dolomite-bearing bioclastic limestones and cloud-patchy bioclastic limestones. Dolomite in dolomite-bearing limestones occurs as euhedral, scattered crystals, preferentially replacing bioclasts or aligning along microstylolites. Pore types are dominated by moldic pores, crystal moldic pores, and intragranular dissolved pores, with widespread asphalt linings on pore walls. Patchy dolomites in bioclastic limestones contain minor intercrystalline pores. Key diagenetic processes include compaction, dolomitization, pressure solution, burial dissolution, and burial cementation. Pore development is closely linked to penecontemporaneous meteoric water dissolution and selective burial dissolution of dolomite. Meteoric dissolution during early exposure formed isolated bioclast moldic pores, while burial dissolution along stylolites/fractures reflects organic acid leachingduring oil migration, preferentially dissolving dolomite along fluid pathways. These findings provide a theoretical framework for exploring Maokou Formation limestone reservoirs in the Sichuan Basin.

Key words: Southeastern Sichuan, Maokou Formation, limestone reservoir, pore evolution, dolomitization, meteoric water dissolution, burial dissolution, organic acid leaching

CLC Number:

PAN Lei, QUAN Li, YANG Hao, XU Rui, WANG Guangwei. Characteristics and Formation Mechanism of Limestone Reservoir of Shoals in the Middle Permian Maokou Formation: A Case Study of Shuanghechang Outcrop in Southeastern Sichuan[J]. Geoscience, 2025, 39(04): 1180-1192.

Figures/Tables 11

References 38

[1]	胡东风. 四川盆地元坝地区茅口组台缘浅滩天然气勘探的突破与启示[J]. 天然气工业, 2019, 39(3): 1-10.
[2]	曾德铭, 谢晓斌, 黄董, 等. 四川盆地北部二叠系茅口组沉积特征及油气意义[J]. 西南石油大学学报(自然科学版), 2023, 45(1):1-12. DOI
[3]	李素华. 川中资阳地区茅口组岩溶储层识别模式及分布预测[J]. 断块油气田, 2023, 30(4):648-655.
[4]	黎霆, 诸丹诚, 李海平, 等. 中二叠统茅口组白云岩发育机理: 以川中-川东地区为例[J]. 现代地质, 2020, 34(2): 345-355.
[5]	胡东风, 王良军, 张汉荣, 等. 碳酸盐岩烃源岩气藏的发现及其油气地质意义——以四川盆地涪陵地区中二叠统茅口组一段气藏为例[J]. 天然气工业, 2020, 40(7): 23-33.
[6]	易海永, 张本健, 谷明峰, 等. 四川盆地东部地区二叠系茅口组孤立浅滩的发现及天然气勘探潜力[J]. 天然气工业, 2024, 44(6): 1-11.
[7]	匡明志, 张小兵, 袁海锋, 等. 川中地区茅口组碳酸盐岩层序地层及沉积相特征[J]. 古地理学报, 2024: 26(5):1201-1202. DOI
[8]	肖笛, 黄天海, 张本健, 等. 四川盆地南部向斜区二叠系岩溶孔隙型石灰岩储层成因与天然气勘探新领域[J]. 天然气工业, 2024, 44(2): 52-67.
[9]	江青春, 胡素云, 姜华, 等. 四川盆地中二叠统茅口组地层缺失量计算及成因探讨[J]. 天然气工业, 2018, 38(1): 21-29.
[10]	LI G J, CHEN J, CHEN Y. Primary and secondary carbonate in Chinese loess discriminated by trace element composition[J]. Geochimica et Cosmochimica Acta, 2013, 103: 26-35.
[11]	DUNHAM R J. Classification of carbonate rocks according to depositional texture[M]// HAM W E. Classification of Carbonate Rocks: AAPG Memoir 1,1962.
[12]	冯增昭. 碳酸盐岩分类[J]. 石油学报, 1982, 3(1): 11-18,96-98. DOI
[13]	SCHOLLE P A, ULMER-SCHOLLE D S. A color guide to the petrography of carbonate rocks:grains, textures, porosity, diagenesis[M]. Tulas: Americcan Association of Petroleum Geologists, 2003.
[14]	DUNCAN F, SIBLEY JAY M, GREG G. Classification of dolomite rock textures[J]. SEPM Journal of Sedimentary Research, 1987,57: 967-975.
[15]	SHIELDS G, STILLE P. Diagenetic constraints on the use of cerium anomalies as palaeoseawater redox proxies: An isotopic and REE study of Cambrian phosphorites[J]. Chemical Geology, 2001, 175(1/2): 29-48.
[16]	MCLENNAN S M. Relationships between the trace element composition of sedimentary rocks and upper continental crust[J]. Geochemistry, Geophysics, Geosystems, 2001, 2(4): 1021.
[17]	黄思静. 碳酸盐岩的成岩作用[M]. 北京: 地质出版社, 2010.
[18]	KAUFMAN A J, KNOLL A H. Neoproterozoic variations in the C-isotopic composition of seawater: Stratigraphic and biogeochemical implications[J]. Precambrian Research, 1995, 73: 27-49.
[19]	BAU M, KOSCHINSKY A, DULSKI P, et al. Comparison of the partitioning behaviours of yttrium, rare earth elements, and titanium between hydrogenetic marine ferromanganese crusts and seawater[J]. Geochimica et Cosmochimica Acta, 1996, 60(10): 1709-1725.
[20]	MCKENZIE J A, KENNETH J H S, SCHNEIDER J F. Movement of subsurface waters under the sabkha, Abu Dhabi, UAE, and its relation to evaporative dolomite genesis[M]// Concepts Models of Dolomitization. Talsa: SEPM Society for Sedimenta Geolog,1980.
[21]	CORLETT H J, JONES B. Petrographic and geochemical contrasts between calcite- and dolomite-filled burrows in the middle Devonian lonely bay formation, northwest territories, Canada: Implications for dolomite formation in Paleozoic burrows[J]. Journal of Sedimentary Research, 2012, 82(9): 648-663.
[22]	MACHEL H G. Concepts and models of dolomitization: A critical reappraisal[J]. Geological Society, London, Special Publications, 2004, 235(1): 7-63.
[23]	ALIBO D S, NOZAKI Y. Dissolved rare earth elements in the South China Sea: Geochemical characterization of the water masses[J]. Journal of Geophysical Research: Oceans, 2000, 105(C12): 28771-28783.
[24]	黄思静, 成欣怡, 赵杰, 等. 近地表温压条件下白云岩溶解过程的实验研究[J]. 中国岩溶, 2012, 31(4): 349-359.
[25]	LONGMAN M W. Carbonate diagenetic textures from nearsurface diagenetic environments[J]. AAPG Bulletin, 1980, 64(4): 461-487.
[26]	威尔逊(J. L. Wilson). 地质历史中的碳酸盐相[M]. 冯增昭等,译. 北京: 地质出版社, 1981.
[27]	李峰峰, 郭睿, 宋世琦. 中东M油田白垩系Mishrif组碳酸盐岩储层特征及主控因素[J]. 中国石油大学学报(自然科学版), 2021, 45(6): 12-24.
[28]	DAVIES G R, SMITH L B Jr. Structurally controlled hydrothermal dolomite reservoir facies: An overview[J]. AAPG Bulletin, 2006, 90(11): 1641-1690.
[29]	胡力文, 邹华耀, 杨伟强, 等. 川北寒武系碳酸盐岩压溶作用的影响因素[J]. 现代地质, 2023, 37(5): 1221-1231.
[30]	WIERZBICKI R, DRAVIS J J, AL-AASM I, et al. Burial dolomitization and dissolution of Upper Jurassic Abenaki platform carbonates, Deep Panuke Reservoir, Nova Scotia, Canada[J]. AAPG Bulletin, 2006, 90(11): 1843-1861.
[31]	韩睿, 张尚锋, 罗顺社, 等. 碎屑岩与碳酸盐岩混合沉积模式——以新疆塔西南地区上石炭统卡拉乌依组为例[J]. 断块油气田, 2023, 30(2):269-276.
[32]	佘敏, 寿建峰, 沈安江, 等. 埋藏有机酸性流体对白云岩储层溶蚀作用的模拟实验[J]. 中国石油大学学报(自然科学版), 2014, 38(3): 10-17.
[33]	谢淑云, 雷蕾, 焦存礼, 等. 鲕粒白云岩内部溶蚀及孔隙非均质性演化研究[J]. 现代地质, 2019, 33(6): 1174-1187.
[34]	王炳森, 袁海锋, 王涛, 等. 川中蓬莱地区震旦系灯影组四段储层成岩作用、孔隙演化及油气充注[J/OL]. 沉积学报,1-24[2024-06-13]. https://doi.org/10.14027/j.issn.1000-0550.2024.012.
[35]	孟宪武, 尤东华, 李蓉, 等. 四川盆地茅口组一段缝洞充填物特征及成因——以A1井为例[J]. 石油实验地质, 2024, 46(3):483-490.
[36]	丁梦, 樊太亮, 吴俊, 等. 塔里木盆地塔河油田T738井区一间房组高精度层序地层格架内沉积微相特征[J]. 现代地质, 2024, 38(5):1270-1290.
[37]	孙自明, 卞昌蓉, 刘光祥. 峨眉山地幔柱主要研究进展及四川盆地二叠纪成盆动力学机制[J]. 现代地质, 2023, 37(5): 1089-1099.
[38]	邵威猛, 牛永斌, 程梦园, 等. 豫西北奥陶系马家沟组碳酸盐岩中裂缝-溶洞的发育特征及成因机制[J]. 现代地质, 2023, 37(5): 1306-1320.

样号	岩性	层数	Mn	Sr	Y	La	Ce	Pr	Nd	Sm	Eu	Gd	Tb
SHC-9	含云生屑灰岩	第四层	13.652	891.172	0.704	0.093	0.166	0.021	0.092	0.021	0.008	0.024	0.005
SHC-14-1	含云生屑灰岩	第七层	8.573	1433.916	0.428	0.149	0.252	0.026	0.119	0.025	0.010	0.026	0.006
SHC-14-2	斑状白云石	第七层	16.857	764.049	0.352	0.091	0.178	0.021	0.081	0.020	0.005	0.021	0.004
SHC-15-1	含云生屑灰岩	第七层	6.363	1509.878	0.363	0.106	0.204	0.023	0.091	0.021	0.007	0.021	0.004
SHC-15-2	斑状白云石	第七层	20.182	850.299	0.321	0.141	0.268	0.031	0.126	0.022	0.006	0.030	0.004
SHC-23	斑状白云石	第七层	27.083	1844.276	0.607	0.243	0.444	0.050	0.203	0.046	0.021	0.052	0.010
样号	岩性	层数	Dy	Ho	Er	Tm	Yb	Lu	Mn/Sr	∑REE	La_N/Yb_N	Y/Ho	δCe_N
SHC-9	斑状白云石	第四层	0.028	0.009	0.031	0.004	0.031	0.005	0.015	0.539	0.219	80.800	1.781
SHC-14-1	含云生屑灰岩	第七层	0.021	0.006	0.020	0.003	0.020	0.004	0.006	0.686	0.562	76.333	1.812
SHC-14-2	斑状白云石	第七层	0.021	0.005	0.017	0.003	0.015	0.003	0.022	0.484	0.435	68.500	2.039
SHC-15-1	含云生屑灰岩	第七层	0.020	0.005	0.016	0.002	0.017	0.003	0.004	0.538	0.469	73.600	2.016
SHC-15-2	斑状白云石	第七层	0.023	0.004	0.015	0.002	0.013	0.003	0.024	0.690	0.773	71.400	1.969
SHC-23	斑状白云石	第七层	0.040	0.009	0.030	0.004	0.031	0.005	0.015	1.191	0.571	64.333	1.933

样号	岩性	层数	Mn	Sr	Y	La	Ce	Pr	Nd	Sm	Eu	Gd	Tb
SHC-9	含云生屑灰岩	第四层	13.652	891.172	0.704	0.093	0.166	0.021	0.092	0.021	0.008	0.024	0.005
SHC-14-1	含云生屑灰岩	第七层	8.573	1433.916	0.428	0.149	0.252	0.026	0.119	0.025	0.010	0.026	0.006
SHC-14-2	斑状白云石	第七层	16.857	764.049	0.352	0.091	0.178	0.021	0.081	0.020	0.005	0.021	0.004
SHC-15-1	含云生屑灰岩	第七层	6.363	1509.878	0.363	0.106	0.204	0.023	0.091	0.021	0.007	0.021	0.004
SHC-15-2	斑状白云石	第七层	20.182	850.299	0.321	0.141	0.268	0.031	0.126	0.022	0.006	0.030	0.004
SHC-23	斑状白云石	第七层	27.083	1844.276	0.607	0.243	0.444	0.050	0.203	0.046	0.021	0.052	0.010
样号	岩性	层数	Dy	Ho	Er	Tm	Yb	Lu	Mn/Sr	∑REE	La_N/Yb_N	Y/Ho	δCe_N
SHC-9	斑状白云石	第四层	0.028	0.009	0.031	0.004	0.031	0.005	0.015	0.539	0.219	80.800	1.781
SHC-14-1	含云生屑灰岩	第七层	0.021	0.006	0.020	0.003	0.020	0.004	0.006	0.686	0.562	76.333	1.812
SHC-14-2	斑状白云石	第七层	0.021	0.005	0.017	0.003	0.015	0.003	0.022	0.484	0.435	68.500	2.039
SHC-15-1	含云生屑灰岩	第七层	0.020	0.005	0.016	0.002	0.017	0.003	0.004	0.538	0.469	73.600	2.016
SHC-15-2	斑状白云石	第七层	0.023	0.004	0.015	0.002	0.013	0.003	0.024	0.690	0.773	71.400	1.969
SHC-23	斑状白云石	第七层	0.040	0.009	0.030	0.004	0.031	0.005	0.015	1.191	0.571	64.333	1.933

序号	样号	层数	岩性	δ¹³C (‰VPDB)	δ¹⁸O (‰VPDB)
1	SHC-2	第一层	泥晶生屑灰岩	2.61	-10.17
2	SHC-3	第二层	含云生屑灰岩	3.90	-9.03
3	SHC-4	第三层	含云生屑灰岩	4.04	-9.89
4	SHC-6	第四层	含云生屑灰岩	4.10	-9.01
5	SHC-7	第四层	含云生屑灰岩	1.74	-9.67
6	SHC-9	第四层	含云生屑灰岩	5.01	-7.16
7	SHC-10	第五层	含云生屑灰岩	4.30	-9.76
8	SHC-11	第六层	含云生屑灰岩	2.39	-8.49
9	SHC-12	第六层	含云生屑灰岩	3.58	-8.69
10	SHC-14-1	第七层	斑状白云石	5.45	-6.08
11	SHC-14-2	第七层	含云生屑灰岩	3.93	-7.92
12	SHC-15-1	第七层	斑状白云石	5.12	-7.14
13	SHC-23	第七层	斑状白云石	3.67	-7.90
14	SHC-15-2	第七层	含云生屑灰岩	3.60	-7.87
15	SHC-16	第七层	含云生屑灰岩	2.78	-8.69
16	SHC-17	第七层	含云生屑灰岩	2.83	-7.90
17	SHC-18	第八层	含云生屑灰岩	3.56	-7.59
18	SHC-20	第八层	含云生屑灰岩	2.93	-7.24
19	SHC-21	第十层	含云生屑灰岩	2.68	-7.21
20	SHC-22	第十层	含云生屑灰岩	2.67	-8.04

序号	样号	层数	岩性	δ¹³C (‰VPDB)	δ¹⁸O (‰VPDB)
1	SHC-2	第一层	泥晶生屑灰岩	2.61	-10.17
2	SHC-3	第二层	含云生屑灰岩	3.90	-9.03
3	SHC-4	第三层	含云生屑灰岩	4.04	-9.89
4	SHC-6	第四层	含云生屑灰岩	4.10	-9.01
5	SHC-7	第四层	含云生屑灰岩	1.74	-9.67
6	SHC-9	第四层	含云生屑灰岩	5.01	-7.16
7	SHC-10	第五层	含云生屑灰岩	4.30	-9.76
8	SHC-11	第六层	含云生屑灰岩	2.39	-8.49
9	SHC-12	第六层	含云生屑灰岩	3.58	-8.69
10	SHC-14-1	第七层	斑状白云石	5.45	-6.08
11	SHC-14-2	第七层	含云生屑灰岩	3.93	-7.92
12	SHC-15-1	第七层	斑状白云石	5.12	-7.14
13	SHC-23	第七层	斑状白云石	3.67	-7.90
14	SHC-15-2	第七层	含云生屑灰岩	3.60	-7.87
15	SHC-16	第七层	含云生屑灰岩	2.78	-8.69
16	SHC-17	第七层	含云生屑灰岩	2.83	-7.90
17	SHC-18	第八层	含云生屑灰岩	3.56	-7.59
18	SHC-20	第八层	含云生屑灰岩	2.93	-7.24
19	SHC-21	第十层	含云生屑灰岩	2.68	-7.21
20	SHC-22	第十层	含云生屑灰岩	2.67	-8.04