中国南海珊瑚岛礁泻湖砂层钻探取心技术

中国南海珊瑚岛礁拥有巨大的资源潜力和科研价值。科学钻探是珊瑚岛礁研究工作中获取地层资料的重要技术手段。南海珊瑚岛礁地下普遍存在多层厚层泻湖砂层,主要结构为无胶结或轻微胶结的细粒珊瑚砂,这种层位钻探取心极端困难,是影响钻探成果的主要难题之一。南海两个岛礁所实施的3口千米以上深井施工过程中,为解决泻湖砂层钻探取心难题,在分析泻湖砂层性状的基础上,综合研究钻具合理选用、钻进参数控制、钻井液性能控制等钻探工程核心内容,形成了较完整的适用于泻湖砂层钻探取心的“多要素组合钻探取心技术”。使用该技术能确保珊瑚岛礁泻湖砂层岩心采取率达到95%以上,并基本保持岩心原状性。该研究成果对于珊瑚岛礁钻探具有重要的借鉴作用。

Coring drilling technology for the coral-reef lagoon sandstone formation in the South China Sea

Coral islands and reefs in the South China Sea host a huge resource potential and scientific research value. Scientific drilling is an important technical means to obtain stratigraphic data in the research of coral islands and reefs. Multiple thick layers of lagoon sands exist pervasively under the coral islands and reefs in the South China Sea, where the main structure is fine-grained coral sands without cementation or slight cementation. This type of strata is extremely difficult to drill and core and is one of the main problems affecting drilling results. During the construction of deep wells over 3 kilometers on two islands and reefs in the South China Sea, this work attempted to solve the problem of drilling and coring in the lagoon sand layer. Based on the analysis of the properties of the lagoon sand layer, a comprehensive study was made for the reasonable selection of drilling tools, the control of drilling parameters and drilling fluid performance control, forming a relatively complete "multiple-element combination drilling and coring technology" suitable for the lagoon sand layers. The use of this technology can ensure that the core collection rate in the coral island reef lagoon sand layer reaches more than 95% and the core shape is basically maintained. The research results have an important reference for drilling in coral island reefs.