Characteristics of porosity and permeability layer of fossil Halimeda reef mineral rock of Miocene in the Xisha Islands and its genetic model  

作　　者：XU Hong ZHU Yurui EBERLI G.P. LUO Wei ZHAO Xinwei CAI Ying LIU Xinyu YAN Guijing ZHANG Bolin WEI Kai CUI Ruyong 

机构地区：[1]Key Laboratory of Marine Hydrocarbon Resources and Environment Geology,Qingdao Institute of Marine Geology,Ministry of Land and Resources [2]Chengdu University of Technology [3]Comparative Sedimentology Laboratory, University of Miami [4]Zhanjiang Branch of China National Offshore Oil Corporation (CNOOC) Limited [5]China University of Geosciences

出　　处：《Acta Oceanologica Sinica》2015年第4期74-83,共10页海洋学报（英文版）

基　　金：The National Science and Technology Major Project for Large Oil-Gas Fields and Coal-formed Gas Development under contract Nos 2008ZX05023 and 2011ZX05025-002;the National Natural Science Foundation of China under contract Nos 49206061 and 41106064;the National Basic Research Program(973 Program) of China under contract Nos 2012CB956004 and 2009CB219406

摘　　要：Halimeda is one of the major reef-building algas in the middle Miocene of Xisha, and one of the significant reef-building 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 sedimentation-diagenetic-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—inHalimeda is one of the major reef-building algas in the middle Miocene of Xisha, and one of the significant reef-building 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 sedimentation-diagenetic-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—in

关 键 词：Xisha Islands MIOCENE fossil Halimeda segment dolostone reservoir evolution model 

分 类 号：P618.13[天文地球—矿床学] P736.22[天文地球—地质学]