| XU Hong,ZHU Yurui,EBERLI G. P.,LUO Wei,ZHAO Xinwei,CAI Ying,LIU Xinyu,YAN Guijing,ZHANG Bolin,WEI Kai,CUI Ruyong. 2015. Characteristics of porosity and permeability layer of fossil Halimeda reef mineral rock of Miocene in the Xisha Islands and its genetic model. Acta Oceanologica Sinica, 34(4):74－83 |
| Characteristics of porosity and permeability layer of fossil Halimeda reef mineral rock of Miocene in the Xisha Islands and its genetic model |
| 西沙中新世化石仙掌藻礁矿物岩石孔渗层特征及成因模式 |
| Received:June 21, 2014 Revised:September 30, 2014 |
| DOI：10.1007/s13131-015-0638-3 |
| Key words:Xisha Islands Miocene fossil Halimeda segment dolostone reservoir evolution model |
| 中文关键词: 西沙群岛 中新世 化石仙掌藻 节片白云岩 储层演化模式 |
| 基金项目: |
| Author Name | Affiliation | E-mail | | XU Hong | Key Laboratory of Marine Hydrocarbon Resources and Environment Geology, Qingdao Institute of Marine Geology, Ministry of Land and Resources, Qingdao 266071, China | qdxhong@163.com | | ZHU Yurui | Chengdu University of Technology, Chengdu 610059, China | | | EBERLI G. P. | Comparative Sedimentology Laboratory, University of Miami, Miami 33149, USA | | | LUO Wei | Zhanjiang Branch of China National Offshore Oil Corporation (CNOOC) Limited, Zhanjiang 524057, China | | | ZHAO Xinwei | China University of Geosciences, Beijing100083, China | | | CAI Ying | Key Laboratory of Marine Hydrocarbon Resources and Environment Geology, Qingdao Institute of Marine Geology, Ministry of Land and Resources, Qingdao 266071, China | | | LIU Xinyu | Zhanjiang Branch of China National Offshore Oil Corporation (CNOOC) Limited, Zhanjiang 524057, China | | | YAN Guijing | Key Laboratory of Marine Hydrocarbon Resources and Environment Geology, Qingdao Institute of Marine Geology, Ministry of Land and Resources, Qingdao 266071, China | | | ZHANG Bolin | Key Laboratory of Marine Hydrocarbon Resources and Environment Geology, Qingdao Institute of Marine Geology, Ministry of Land and Resources, Qingdao 266071, China | | | WEI Kai | Key Laboratory of Marine Hydrocarbon Resources and Environment Geology, Qingdao Institute of Marine Geology, Ministry of Land and Resources, Qingdao 266071, China | | | CUI Ruyong | Key Laboratory of Marine Hydrocarbon Resources and Environment Geology, Qingdao Institute of Marine Geology, Ministry of Land and Resources, Qingdao 266071, China | |
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| Abstract: |
| Halimeda is one of the major reef-building algas in the middle Miocene of Xisha, and one of the significant reefbuilding algas in the algal reef oil and gas field of the South China Sea. However, there have been few reports regarding the characteristics of mineral rocks, reservoir porosity and permeability layers, and sedimentationdiagenetic- evolution of fossil Halimeda systems. The present paper briefly introduces the relevant studies on chlorophyta Halimeda and the research status of oil and gas exploration. Through the 1 043 m core of the Xichen- 1 well, we studied the characteristics of the mineral rocks and porosity and permeability of the middle Miocene Halimeda of the Yongle Atoll, identified and described the segments of fossil Halimeda, and pointed out that most of the segment slides are vertical sections in ovular, irregular or long strips. The overwhelming majority of these fossil Halimeda found and studied are vertical sections instead of cross sections. In this paper, knowledge regarding the cross sections of fossil Halimeda is reported and proven to be similar with the microscopic characteristics of modern living Halimeda; fossil Halimeda are buried in superposition; it is shown that there are different structures present, including typical bio-segment structure, and due to its feature of coexisting with red alga, tying structure, twining structure and encrusting structure are all present; and finally, it is suggested to classify the fossil Halimeda into segment algal reef dolomites. In addition, all of the studied intervals are moderately dolomitized. Secondary microcrystalline-dolosparite dominates the original aragonite raphide zones, and aphanitic-micrite dolomite plays the leading role in the cortexes and medullas; in the aragonite raphide zones between medulla and cysts, secondary dissolved pores and intercrystalline pores are formed inside the segments, and algal frame holes are formed between segments; therefore, a pore space network system (dissolved pores + intragranular dissolved pores—intercrystalline pores + algal frame holes) is established. Segment Halimeda dolomite has a porosity of 16.2%-46.1%, a permeability of 0.203×10-3-2 641×10-3 μm2, and a throat radius of 23.42-90.43 μm, therefore it is shown to be a good oil and gas reservoir. For the reasons mentioned above, we suggest building the neogene organic reef-modern reef sedimentation-diagenetic-evolution models for the Xisha Islands. |
| 中文摘要: |
| 仙掌藻是西沙中新世生物礁主要造礁藻类之一和南海藻礁油气田重要造礁绿藻之一.但是,迄今缺乏化石仙掌藻系统的矿物岩石特征、储层孔渗层特征和沉积成岩演化成因特征研究的报道.本文简述了国内外有关绿藻门仙掌藻相关研究和油气勘探发现研究现状.通过西琛1井104.3 m岩心,研究了永乐环礁中新世化石仙掌藻的矿物岩石和孔渗层特征,鉴定描述了化石仙掌藻节片,指出节片切片绝大多数为纵切面,呈长条状、椭圆状、不规则状,很难获得横切面切片,本文报道了获得的横切面切片研究认识,与现代活体仙掌藻横切面显微特征近似.化石仙掌藻埋藏分布呈叠置状;形成典型生物节片结构,与红藻共生形成节片捆扎、缠绕包裹结构;提出划分化石仙掌藻岩石类型为节片藻礁白云岩.研究井段全部中等程度白云石化,在原文石针晶区域以形成次生微晶-亮晶白云石为主,在皮层、髓部以形成隐晶和淀晶白云石化作用为主;在髓部及孢囊间文石针晶区域形成节片内次生溶孔、晶间孔,节片间形成藻架孔;这些孔隙空间组合形成溶蚀孔+粒内溶蚀孔-晶间孔+藻架孔孔隙网络体系.测得孔隙度16.2%-46.1%,渗透率0.203×10-3-2 641×10-3 μm2;喉道半径（23.42-90.43 μm）,属于优良仙掌藻礁油气储层;首次提出建立了西沙群岛新近系生物礁-现代岛礁环境沉积成岩演化成因的模式. |
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