渤中凹陷西南环深层探井钻井难点与技术对策

渤海油田渤中凹陷西南环深层含油气构造储量丰富，开发潜力巨大。但该区块存在地质条件复杂、目的层高温高压、压力系统复杂、深部地层可钻性差等难点，给钻探作业带来诸多挑战。针对渤中凹陷西南环深层探井作业的技术难点，创新采用“非标井眼+随钻扩眼+非标套管”的井身结构设计方法，保证封隔各层位的必封点，可以满足地层评价要求；针对不同井段优化钻具组合，形成了一套全井段提速技术体系，破岩效率显著增加；研发出一套抗温无固相储层保护钻井液体系，抗温极限由170 ℃提升至200 ℃以上，满足了潜山地层储层保护的性能要求；针对潜山地层构建精细压力技术，提高机械钻速，有效降低了潜山井漏及压差卡钻风险。研究成果对确保渤中区域深层探井钻井安全、提高钻速、降低成本具有借鉴作用。

Drilling difficulties of deep explorations wells in the southwest zone of Bozhong sag and their technical countermeasures

The deep oil/gas bearing structures in the southwest zone of Bozhong sag, Bohai Oilfield have abundant reserves and their development potential is great, but this block is characterized by complex geological conditions, high-temperature and high-pressure target layers, complex pressure systems and poor drillability of deep strata, which bring several challenges to the drilling operation. To deal with the technical difficulties in the deep drilling operation in the southwest zone of Bozhong sag, the casing program of “non-standard borehole + reaming while drilling + non-standard casing” is adopted innovatively to ensure the isolation of setting positions in each horizon and meet the requirements of formation evaluation. A set of full-hole ROP (rate of penetration) improvement technologies are formed by optimizing the BHA (bottom hole assemblage) based on the conditions of different hole sections, so that the rock breaking efficiency is improved greatly. A high-temperature, solid-free drilling fluid system with the capacity of reservoir protection is developed, whose limit temperature tolerance is increased from 170 ℃ to 200 ℃, so as to meet the performance requirements of reservoir protection in buried hills. The precise pressure technology is developed for buried hill reservoirs to improve the ROP, which effectively alleviates the risks of lost circulation and pressure difference induced pipe sticking in buried hill reservoirs. The research results play a guiding role in ensuring the safe drilling, ROP improvement and cost reduction of deep exploration wells in the Bozhong area.