双层连续管双梯度钻井井筒钻井液当量循环密度分布特征

Well ECD distribution characteristics during dual-layer coiled tubing dual-gradient drilling

双层连续管钻井是一种新型双梯度钻井技术,为了分析双层连续管钻井井筒ECD分布特征,研究基于双层连续管钻井工艺特点,考虑井筒温度、压力和岩屑浓度等参数影响,建立了双层连续管双梯度钻井井筒ECD计算模型,分析了钻井液排量和钻井液密度等因素对井筒ECD的影响规律。案例井计算结果表明,井筒ECD随着钻井液排量和密度的增加而增大,机械钻速的增加对井筒ECD的影响较小,双层管尺寸需结合井眼尺寸和循环压耗进行优选。双层连续管双梯度钻井可有效降低井底ECD,在钻井过程中可通过调整钻井液排量和密度实现井筒压力的动态控制,为应对深水钻井压力窗口窄和浅层易发生漏失等难题提供了一种有效的解决方法。

Dual-layer coiled tubing drilling is a novel dual-gradient drilling technique.In order to analyze the ECD distribution characteristics in the well during dual-layer coiled tubing drilling,a computational model for calculating well ECD based on the characteristics of dual-layer coiled tubing drilling technology was developed,taking into account parameters such as well temperature,pressure and cuttings concentration.The impacts of drilling fluid displacement and density on well ECD were analyzed.The case study indicate that the well ECD increases with the increase of drilling fluid displacement and density,while slightly influenced by the increase of penetration rate.And the dimensions of the dual-layer coiled tubing need to be optimized based on the well size and circulating pressure loss.The dual-layer coiled tubing dual-gradient drilling technique can effectively reduce the bottomhole ECD,and achieve dynamic control of well pressure by adjusting drilling fluid displacement and density during drilling,providing an effective solution for addressing challenges such as narrow pressure windows in deepwater drilling and shallow leakage.