浅海伸缩套管钻探工艺研究

Research on shallow sea drilling technology with telescopic casing

摘要:

浅海取心钻探中钻遇易坍塌地层时，需要下放套管封隔地层，保证泥浆循环，换径继续钻进。现有常规下套管方法为使用带有钻台层甲板和套管层甲板的钻井船进行下放套管作业，部分无套管层甲板钻井船在遇到必须下套管的工况时，需临时搭建套管层平台进行下放套管作业，但受钻机和钻具体积及质量的限制。为解决无套管层甲板的钻井船在海洋钻探取心时需要下入套管的难题，设计了一种海洋钻探下入多层套管的工艺方法，利用可伸缩套管及相关设备，在海底井口与小型钻井船之间建立泥浆上返通道，封隔不稳定地层，实现泥浆回收循环及钻具升沉补偿。在钻井过程中，伸缩套管还可以起到导向定位的作用，防止潮差水流流速变化影响钻具下入，为浅海钻井节省时间和成本。

Abstract:

When drilling into a stratum that is prone to collapse in shallow sea coring drilling， it is necessary to install casing to seal the stratum to ensure mud circulation and to continue drilling at smaller diameter. The conventional casing installation method is used to install casing from the drilling ship with both the drill floor platform deck and the casing platform deck； while for the drilling ships without the casing platform deck， it needs to be temporarily installed if casing must be installed. But installation of the casing platform is limited by the volume and mass of the drill rig and drill string. In order to solve the problem of installing casing in offshore drilling and coring with drilling ships without casing platform decks， a casing running process for installing multi-tier casing in offshore drilling is designed， where telescopic casing and related equipment is used to establish a mud return channel from the subsea wellhead to the small drilling ship to isolate unstable formations， and realize mud recycling and drilling heave compensation. In the drilling process， the telescopic casing can also provide guiding and positioning to prevent the drilling tool from influence of changes in tidal current flow speeds， saving time and cost for shallow sea drilling.