南海珊瑚礁本底调查“琛科一井”钻探工艺

Drilling Technologies of "Chenke-1 well" for the Background Value Survey of Coral Reef in South China Sea

南海珊瑚礁拥有巨大的资源潜力和科研价值,通过西沙群岛琛航岛"琛科一井"的实施,拟摸清南海珊瑚礁大致分层及地质本底。从钻孔基本信息、工程概况、钻进工艺等方面,介绍和探讨了南海珊瑚礁本底调查"琛科一井"的钻探工艺。结果表明:(1)3套钻具配合扫孔、无固相钻井液配合正循环大泵量工艺异地层洗孔、"水锤效应"震动砂液化等工艺能有效处理泻湖相珊瑚砂层的埋钻事故;(2)超前钻头和半合管配合使用能确保礁格架地层岩心采取率;(3)在受钻孔摄像限制不能使用低固相钻井液条件下,不同标准多口径钻孔级配快速穿越后套管封隔是有效的成井方法。研究成果可为类似区域的珊瑚礁取心钻探提供借鉴作用。

The coral reef in South China Sea has a huge resource potential and scientific research value. The implement of ＂Chenke-1 well＂ in the Chenhang island, Xisha islands helps to find out the geological stratification and background of coral reefs in South China Sea. The drilling technologies of ＂Chenke-1 well＂ were introduced and discussed from the aspects of basic information, drilling survey, drilling technologies, problems and discussion. The results show that borehole cleaning with three sets of drilling tools, borehole washing with normal circulation, high pumping rate and solid free drilling fluids, sand liquation based on water hammer effect by shocking could effectively handle the accidents of bit or drilling tools burying. Advanced drill bits integrated with semi-closed pipe ensured the core recovery rate in reef framework layer. On the condition that low solid drilling fluid could not be used for the limitation of borehole camera technology, fast drilling with different criteria and multiple borehole diameter and then casing isolation was an effective well completion method. The achievements will be helpful to coral reef coring drilling in similar areas.