东海西湖凹陷安全高效钻井技术优化研究

东海西湖凹陷钻井作业钻井速度较慢，深部井段井下复杂情况频发，作业效率不高。为了增加东海西湖凹陷的钻井速度、提高钻井效率，在表层井段采取了减小井眼尺寸并建立力学模型分析下入深度的技术方案；优化了井身结构，减少了作业开次；中下部井段改用油基钻井液；使用了一体化钻具组合，优化了钻井参数。通过对表层提速、井身结构、钻井液性能、提速工具四个方面的技术进行了研究，形成了东海西湖凹陷安全高效钻井技术，能够提高机械钻速、增强井壁稳定性和井眼清洁能力、缩短钻井周期、降低深部地层的井下故障率。该项技术在东海西湖凹陷数个构造的10余口井进行了现场应用，与东海同期作业相比，全井段机械钻速提高20%，钻井周期缩短23%。该技术成果可以为海洋钻井提速提效提供行之有效的技术思路。

Study on Optimization of Safe and Efficient Drilling Technology in Xihu Sag of East China Sea

Drilling speed of the exploration well in Xihu Sag of East China Sea is slow, the deep well section is frequently complicated downhole, and the operation efficiency is low. In order to increase the drilling speed and improve the drilling efficiency in Xihu Sag of East China Sea, the following methods are adopted. In the surface section, a technical scheme is adopted to reduce the hole size and establish a mechanical model to analyze the depth. The well structure was optimized to reduce operation schedule. Oil based drilling fluid was used in the middle and lower well section. The integrated drilling tool assembly was used to optimize drilling parameters. Through research on four aspects of surface speed-raising technology, casing structure, drilling fluid performance and speed-raising tools, the safe and efficient drilling technology in Xihu Sag of East China Sea has been formed, which can improve the ROP, enhance the sidewall stability and wellbore cleaning ability, shorten the drilling cycle and reduce the downhole failure rate of deep strata. The technology has been applied on-site in more than 10 Wells in several structures in Xihu Sag of East China Sea. Compared with exploration wells of East China Sea during the same period, the drilling rate of the whole well has been increased by 20% and the drilling cycle has been shortened by 23%. Results of this technology can provide effective technical ideas for improving the speed and efficiency of offshore drilling.