琼东南盆地陵水17-2深水气田开发区表层沉积物类型及工程地质特性  

Surface sediments and their geotechnical characteristics in the development area of deepwater gas field LS17-2

作　　者：朱友生 王艳秋[1] 冯湘子[1] 王大伟 王姝 ZHU Yousheng;WANG Yanqiu;FENG Xiangzi;WANG Dawei;WANG Shu(China Oilfield Services Limited,Tianjin 300459,China;Institute of Deep Sea Science and Engineering,Chinese Academy of Sciences,Sanya 572000,China;Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai),Zhuhai 519080,China)

机构地区：[1]中海油田服务股份有限公司,天津300459 [2]中国科学院深海科学与工程研究所,三亚572000 [3]南方海洋科学与工程广东省实验室(珠海),珠海519080

出　　处：《海洋地质与第四纪地质》2022年第1期45-56,共12页Marine Geology & Quaternary Geology

基　　金：中海油田服务股份有限公司项目“土动力实验和分析技术研究”(E-23202009);海南省重点研发计划科技合作方向项目“南海海底滑坡-海啸灾害预测及评估技术开发”(ZDYF2020209);广东省重点领域研发计划项目“海底沉积物多参量原位环境监测设备研制及应用示范”(2020B1111020002)。

摘　　要：陵水17-2气田位于中国南海琼东南盆地,是中国海油自营勘探发现的第一个深水高产气田,探明储量规模超千亿立方米。在水深200~1 600 m区域,采用工程调查船与自主式水下潜器调查结合的方式,进行地球物理资料采集、海底表层取样及钻探取样,并对多波束测深、后向散射强度、侧扫声呐、浅地层剖面、室内测试分析等数据进行综合分析,研究了海底表层沉积物类型、分布规律及工程地质特性。按照海底地形地貌特征,陵水17-2深水气田开发区可划分为陆架区、缓坡区和滑塌区;陆架区表层沉积物以黏土和粉质黏土为主,不同站位物理力学性质差异较大,局部夹砂层;缓坡区和滑塌区具有高含水率、低密度、高孔隙比、高液限、高可塑性、低强度等典型深水沉积特点。区域内海底泥面至泥面之下0.3 m,土质不排水抗剪强度为0~4 kPa,非常有利于海底电缆、海底管道、脐带缆的铺设。缓坡区浅层土质条件非常适合吸力式、防沉板及抓力锚施工,滑塌区浅层土质条件适合防沉板、抓力锚及打入桩基础施工。研究成果将对琼东南盆地深水油气田开发工程的设计和安装施工具有指导意义。The gas field LS17-2, the first deep-water and high-yield gas field discovered independently by CNOOC in the Qiongdongnan Basin,South China Sea, is a large gas field with a proven reserve more than 100 billion cubic meters. Studied in this paper are the geophysical data,such as multi-beam echo sounder data, backscatter strength data, side scan sonar data, and sub-bottom profiler data as well as seabed surface sampling and drilling data, collected by the engineering survey vessels and autonomous underwater vehicles within the development zone of the gas field LS17-2 in the water depth between 200 m and 1 600 m. Types, distribution patterns and geotechnical properties of subsurface sediments are described. The bathymetry data suggests that the study area of the development zone of the gas field LS17-2 could be subdivided into three subareas, i.e. the shelf subarea, gentle slope subarea and slumping subarea. The seabed sediments are predominated by clay and silty clay, with sandy deposits in some places. The geotechnical characteristics are quite different in different sampling locations. The geotechnical characteristics of seabed sediments within the gentle slope subarea and slumping subarea are typical deep-water sediments, characterized by high water content, low density, high void ratio, high liquid limit, high plasticity and low strength. The undrained shear strength of the soil layers between seabed and the layer about 0.3 m below seabed varies between 0~ 4 kPa, and it is conducive to the laying of submarine cables,submarine pipelines and umbilical cables. Soil conditions in the shallow part are suitable for the foundation of suction type, mud mat and grab anchor in the gentle slope subarea, and for the types of mud mat, grab anchor and driven piles in the slumping subarea. The research results are believed useful as a reference to the design and installation of subsea facilities for the coming deep-water oil and gas field development projects in the Qiongdongnan Basin.

关 键 词：表层沉积物 后向散射强度 沉积物类型 工程地质特性 

分 类 号：P642[天文地球—工程地质学]