北部湾盆地海上勘探井钻井提效关键技术

南海西部北部湾盆地海上古近系地层具有构造运动强烈、地层倾角大、夹层频繁和水敏性强等特点，钻进过程中存在井壁易失稳、井眼轨迹控制困难、导向钻进效率低和机械钻速低等问题。为解决这些问题，在区域勘探井传统钻井作业采用四开井身结构及常规钻井技术的基础上，结合区域工程地质特征，对制约钻井提效的关键因素进行了系统分析，简化了井身结构，构建了适用于南海西部北部湾盆地古近系地层的高性能强封堵钻井液，并进行了高效PDC钻头优选和钻具组合优化设计，形成了北部湾盆地海上勘探井钻井提效关键技术。该技术在北部湾盆地多口勘探井进行了应用，在井深及钻井难度相似的情况下，钻井周期与传统钻井方式相比缩短了36.1%。研究认为，北部湾盆地海上勘探井钻井提效关键技术可为北部湾盆地油气资源的高效勘探开发提供技术支持。 

Key Techniques for Drilling and Efficiency Improvement of Offshore Exploration Wells in the Beibu Gulf Basin

The offshore Paleogene strata in the Beibu Gulf Basin in the western South China Sea are characterized by strong tectonic movement,large dip angle,frequent interlayer and strong water sensitivity.There is a high probability of borehole instability,difficulty in controlling the well trajectory,experiencing low steering drilling efficiency and low ROP while drilling.Therefore,based on the traditional four-section casing program of exploration wells in this region and the conventional drilling technologies,combined with the regional engineering geological features,the key factors restricting drilling efficiency were systematically analyzed.,This resulted in a simplified casing program.It also resulted in the development of a high-performance strong sealing drilling fluid system,which is suitable for the Paleogene strata of Beibu Gulf Basin in the western South China Sea,Further,the study optimized high-efficiency PDC bit and BHA design,so as to form the key technologies for drilling and efficiency improvement of offshore exploration wells in the Beibu Gulf Basin.These technologies have been applied in several exploration wells in the Beibu Gulf Basin,and the drilling period was reduced by 36.1% compared with conventional drilling operation under similar depths and drilling difficulties.These key technologies would provide a technical basis for the efficient exploration and development of oil and gas resources in the Beibu Gulf Basin.