四川盆地北部栖霞组-茅口组热液白云岩特征与成因

doi:10.11743/ogg20120314

摘要/Abstract

摘要：

以四川盆地北部广元峡沟煤矿剖面白云岩为研究对象,剖面由下部地层向上,白云岩化程度逐渐增强,颜色由深到浅,岩性由生屑灰岩逐渐过渡到斑状白云岩,然后再到中-粗晶白云岩,上部覆盖茅口组泥灰(云)岩。中-粗晶白云岩发育于栖霞组顶部和茅口组底部,由中晶到粗晶的半自形-自形白云石组成,其中可见鞍状白云石。岩石中溶蚀孔洞发育,孔隙内有沥青充填。微晶灰岩的δ¹³C(PDB)值为3.23‰,δ¹⁸O(PDB)值为-5.03‰;白云石样品的碳、氧同位素具有一定的差异,δ¹³C(PDB)值为3.29‰~4.14‰,δ¹⁸O(PDB)值为-6.07‰~-6.75‰。流体来源可能为岩浆热液,或者是经历了深循环的大气降水。在断裂活动时,深部热液流体沿断裂向上运移,当运移到栖霞组和茅口组时,由于吴家坪组泥灰岩和泥云岩的封堵,流体的运移被减缓甚至停滞,促使围岩发生白云岩化,溶蚀作用也同时发生,产生溶蚀孔隙。由此,在栖霞组顶部和茅口组底部可能形成热液白云岩储层,该储层具有一定的储集意义。

关键词: 热液白云岩, 溶蚀孔隙, 断裂, 油气储层, 中二叠统, 四川盆地

Abstract:

Taking outcrop dolomites in Guangyuan Xiagou coal mine in northern Sichuan Basin as an example,this paper studies the characteristics and genesis of hydrothermal dolomite reservoir.From the bottom to the top of the outcrop cross section,the dolomitization gradually enhances;the color of rocks changes from dark to light;the lithologies change from bioclastic limestones to patchy dolostones,then to medium-and coarse-grained dolomites,and end up with the Maokou Formation marlstones.The medium-to coarse-grained dolomites occur at the top of the Qixia Formation and the bottom of the Maokou Formation,and are composed of medium-to coarse-grained subhedral or euhedral dolomites and some saddle-like dolomites.Dissolved caverns and pores are well-developed and filled with asphaltares.The δ¹³C value (PDB) and δ¹⁸O value (PDB) of micritic limestones are 3.23‰ and -5.03‰,respectively.The δ¹³C value (PDB) and δ¹⁸O value (PDB) of the dolomites are 3.29~4.14‰ and -6.07~-6.75‰ respectively.Fluids may be sourced from magmatic hydrothermal fluid,or meteoric water experiencing deep circulation.The deep hydrothermal fluids migrated up along open faults and slowed down or even stopped when arriving at the Qixia and Maokou Formations due to the sealing of marl and politic dolostones in the Wu Jiaping Formation.The stagnant thermal fluids caused dolomitization dissolution of the surrounding rocks.Therefore, it is possible that hydrothermal dolomite reservoirs occur at the top of Qixia Formation and the bottom of Maokou Formation.

Key words: hydrothermal dolomite, dissolution pore, fracture, reservoir, Middle Permian, Sichuan Basin

中图分类号:

TE122.2

舒晓辉,张军涛,李国蓉,等. 四川盆地北部栖霞组-茅口组热液白云岩特征与成因[J]. 石油与天然气地质, 2012, 33(3): 442-448,458. doi: 10.11743/ogg20120314 Shu Xiaohui,Zhang Juntao,Li Guorong,et al. Characteristics and genesis of hydrothermal dolomites of Qixia and Maokou Formations in northern Sichuan Basin[J]. Oil & Gas Geology, 2012, 33(3): 442-448,458. doi: 10.11743/ogg20120314

参考文献

[1] Machel H G.Concepts and models of dolomitization:a critical reappraisal.The geometry and petrogenesis of dolomite hydrocarbon reservoirs.Geological Society Special Publications,2004,235:7-63.
[2] Lavoie D,Morin C.Hydrothermal dolomitization in the Lower Silurian Sayabec Formation in northern Gaspé-Matapédia(Québec):constraint on timing of porosity and regional significance for hydrocarbon reservoirs[J].Bulletin of Canadian Petroleum Geology,2004,52(3):256-269.
[3] Davies G R,Smith Jr L B.Structurally controlled hydrothermal dolomite reservoir facies:an overview[J].AAPG Bulletin,2006,90(11):1641-1690.
[4] 陈明启.川西南下二叠阳新统白云岩成因探讨[J].沉积学报,1989,7(2):45-50. Chen Mingqi.A discussion of the origin of Yangxin dolomite of Lower Permian in southwest Sichuan[J].Acta Sedimentologica Sinica,1989,7(2):45-50.
[5] 李茂竹,王玉英.四川华蓥山中段下二叠统灰岩中"砂糖状白云岩"特征及其白云化作用的讨论[J].川煤地勘,1991,9(1):45-48. Li Maozhu,Wang Yuying.Character and origin of saccharoidal dolomite in Lower Permian limestone in middle Huayinshan mountain,Sichuan basin[J].Sichuan Coal Exploration,1991,9(1):45-48.
[6] 何幼斌,冯增昭.四川盆地及其周缘下二叠统细-粗晶白云岩成因探讨[J].江汉石油学院学报,1996,18(4):5-20. He Youbin,Feng Zengzhao.Origni of fine-to coarse-grained dolostones of Lower Permian in Sichuan basin and its peripheral regions[J].Journal of Jianghan Petroleum Institute,1996,18(4):5-20.
[7] 王运生,金以钟.四川盆地下二叠统白云岩及古岩溶的形成与峨眉地裂运动的关系[J].成都理工学院学报,1997,24(1):8-16. Wang Yunsheng,Jin Yizhong.The formation of dolomite and paleokarst of the Lower Permian series in Sichuan Basin and relation to the Emei taphrogenesis[J].Journal of Chengdu University of Technology,1997,24(1):8-16.
[8] 金振奎,冯增昭.滇东-川西下二叠统白云岩的形成机理——玄武岩淋滤白云化[J].沉积学报,1999,17(3):383-389. Jin Zhenkui,Feng Zengzhao.Origin of dolostones of the Lower Permian in East Yunnan-West Sichuan-dolomitization through leaching of basalts[J].Acta Sedimentology Sinica,1999,17(3):383-389.
[9] 王宓君,包茨,肖明德,等.中国石油地质志(卷十):四川油气区[M].北京:石油工业出版社,1989:1-151. Wang Bijun,Bao Ci,Xiao Mingde,et al.Petroleum geology of China(V10):Sichuan region[M].Beijing:Petroleum Industry Press,1989:1-151.
[10] 李嵘,张娣,朱丽霞.四川盆地川西坳陷须家河组砂岩致密化研究[J].石油实验地质,2011,33(3):274-281. Li Rong,Zhang Di,Zhu Lixia.Densification of Upper Triassic Xujiahe tight sandstones,Western Sichuan,China[J].Petro-leum Geology & Experiment,2011,33(3):274-281.
[11] 谯述蓉,赵爽,谢雄光.川西MJ地区蓬莱镇组储层含气性识别模式研究[J].石油物探,2011,50(4):386-392. Qiao Shurong,Zhao Shuang,Xie Xiongguang.Research on the gas-bearing identification patlerns of Penglaizhen Formation in MJ area,Western Sichuan Basin[J].Geophysical Prospecting for Petroleum,2011,50(4):386-392.
[12] Esteban M,Taberner C.Secondary porosity development during late burial in carbonate reservoirs as a result of mixing and/or cooling of brines[J].Journal of Geochemical Exploration,2003,78-79(1-3):355-359.
[13] 黄思静,王春梅.碳酸盐成岩作用的研究前沿和值得思考的问题[J].成都理工大学学报(自然科学版),2008,35(1):1-10. Huang Sijing,Wang Chunmei.Scientific research frontiers and considerable questions of carbonate diagenesis[J].Journal of Chendu University of Technology(Science & Technology Edition),2008,35(1):1-10.
[14] 张军涛,胡文瑄.塔里木盆地中央隆起区上寒武统-下奥陶统白云岩储层中两类白云石充填物:特征与成因[J].沉积学报,2008,26(6):957-966. Zhang Juntao,Hu Wenxuan.Feature and origin of dolomite fil-ling in the Upper Cambrian-Lower Ordovician dolostone of the central uplift,Tarim Basin[J].Acta Sedimentology Sinica,2008,26(6):957-966.
[15] Zhang Juntao,Hu Wenxuan.Formation of saddle dolomites in Upper Cambrian carbonates,western Tarim Basin,(NW China):implication for fault-controlled fluid flow events[J].Marine and Petroleum Geology,2009,26(8):1428-1440.
[16] 魏国齐,杨威,朱永刚,等.川西地区中二叠统栖霞组沉积体系[J].石油与天然气地质,2010,31(4):442-448. Wei Guoqi,Yang Wei,Zhu Yonggang,et al.Depositional system of the Middle Permian Qixia Formation in the western Sichuan Basin[J].Oil & Gas Geology,2010,31(4):442-448.
[17] 胡文瑄,陈琪,王小林,等.白云岩储层形成演化过程中不同流体作用的稀土元素判别模式[J].石油与天然气地质,2010,31(6):810-818. Hu Wenxuan,Chen Qi,Wang Xiaolin,et al.REE models for the discrimination of fluids in the formation and evolution of dolomite reservoirs[J].Oil & Gas Geology,2010,31(6):810-818.
[18] 何治亮,魏修成,钱一雄,等.海相碳酸盐岩优质储层形成机理与分布预测[J].石油与天然气地质,2011,32(4): 489-498. He Zhiliang,Wei Xiucheng,Qian Yixiong,et al.Forming mechanism and distribution prediction of quality marine carbonate reservoirs[J].Oil & Gas Geology,2011,32(4):489-498.