摘要
通过地表地质与地下地质相结合,对川东南丁山-林滩场构造的上震旦统灯影组热液白云岩岩石学特征、地球化学特征、储层物性特征进行了研究。研究区热液白云岩在岩相学上表现为充填或交代状马鞍状白云石,发育条带状、角砾状构造。同时出现MVT型铅锌矿、马鞍状白云石-石英、马鞍状白云石-沥青、马鞍状白云石-天青石等热液矿物组合。马鞍状白云石的碳、氧、锶同位素值较灯影组围岩表现出明显的低碳、低氧,而富锶同位素:Δδ13CPDB(脉-围岩)在-1.312‰^-0.501‰之间,Δ1δ8OPDB(脉-围岩)在-4.257‰^-1.974‰之间,Δ(87Sr/86Sr)(脉-围岩)在0.002 3~0.004 1之间,显示出热液活动的特征。热液活动使灯影组白云岩产生重结晶及热液溶蚀作用,使储层晶间孔、次生溶蚀孔在原岩基础上增加3%~10%。热液白云岩比未受热液影响的白云岩基质孔隙度平均值增加1.1%,渗透率平均值增加1.415×10-3μm2。热液白云岩的分布受桑木场断裂、现今构造高点及桐湾期不整合面控制。平面上,以现今桑木场背斜核部、桑木场断层及与之较近的林滩场构造较为发育,而较远的丁山构造则相对少见。纵向上,主要分布在距震旦系与寒武系之间的不整合面以下300 m之内,分布呈断续状。结合该区构造演化、油气热演化史,认为热液白云岩可能形成于早二叠世。
Combining the study of surface geology with subsurface geology,this paper studies the petrology,geochemistry and physical characteristics of the Upper Sinian Dengying Formation hydrothermal dolomite（HTD）.In the study area,the replacive and void-filling type saddle dolomites are characteristic of HTD facies.Zebra and breccias fabrics of hydrothermal origin are common.In addition,a series of typical hydrothermal-related mineral assemblages are identified,such as MVT lead-zinc ore bodies,saddle dolomite-quartz assemblage,saddle dolomite-bitumen assemblage and saddle dolomite-celestite assemblage.Isotopic comparison between HTD and host dolomite（HD） indicates that HTD is deficient of the carbon and oxygen isotopes,but rich in radiogenic strontium isotope.The Δδ13CPDB（HTD-HD） is-1.312‰ ^-0.501‰,Δδ18OPDB（HTD-HD） is-4.257‰ ^-1.974‰ and Δ（87Sr/86Sr）HTD-HD is 0.0023~0.0041.Hydrothermal fluids cause extensive recrystallization and dissolution,which can give birth to 3%~10% porosity.Compared to HD,the HTD owns additional 1.1% porosity and additional 1.415×10-3 μm2 permeability.Therefore,hydrothermal activity is constructive to hydrocarbon reservoir formation.It is suggested that hydrothermal dolomite is controlled by faults,high points of structures,and disconformity between Sinian and Cambrian.Laterally,hydrothermal dolomite is abundant in the axis of Sangmuchang and Lintanchang anticlines.Vertically,it occurs within 300 m from the disconformity between Cambrian and Sinian.Taking the burial-thermal history,tectonic evolution history and other constraints into consideration,the hydrothermal emplacement forming HTD in Upper Sinian Dengying Formation probably took place at Early Permian.
出处
《成都理工大学学报（自然科学版）》
CAS
CSCD
北大核心
2009年第6期706-715,共10页
Journal of Chengdu University of Technology: Science & Technology Edition
基金
国家重点基础研究发展计划"973"项目(2005CB422106)
中国石化海相前瞻性项目(PH08001)
关键词
热液白云岩
震旦系
储层特征
丁山-林滩场构造
四川盆地
hydrothermal dolomite reservoir characteristics Dengying Formation Sinian Sichuan Basin
