高性能水基钻井液在莺歌海盆地高温高压井的应用

莺歌海盆地中深层高温高压领域温度高、压力大、作业安全密度窗口窄。在复杂地质环境下，常规的聚磺钻井液易变稠、流动困难、泥饼虚厚，引起遇阻、黏卡、井漏等井下复杂问题。通过室内评价，引入新型抗高温聚合物（Calovis HT、POROSEAL）替代常规聚磺钻井液体系中的聚合物（PAC-LV、EMI1045），构建出高性能水基钻井液体系。室内评价证实，该钻井液在高密度2.30~2.40 g/cm3、高温200~220℃环境下，能长时间保持良好的高温热稳定性，并且有较强的抗污染能力，抗50 g/L钻屑、50 mL/L地层水及5 g/L CO₂，储层保护效果良好，渗透率恢复值为84.6%。该体系在莺歌海盆地高温高压井（压力系数2.20~2.40、温度190~200℃）中进行现场应用，解决了常规聚磺钻井液体系中高温稳定性不足的难题，证实高性能水基钻井液具有良好的高温热稳定性，并且流变性能优越，为后续高温高压复杂地层钻井液体系优选提供参考。 

The Development and Application of High Performance Water Base Muds for HTHP Wells in Yinggehai Basin

High temperature high pressure deep wells drilled in Yinggehai penetrated formations with narrow density windows. Conventional polymer sulfonate drilling fluids become highly viscous and difficult to flow in complex geological environment, and false thick mud cakes are generated. These generally result in resistance to drill pipe tripping, pipe sticking and lost circulation. A high performance water base drilling fluid has been formulated in laboratory with new high temperature polymers (Calovis HT and POROSEAL) replacing conventional polymers (PAC-LV, EMI1045 etc.). Laboratory evaluation shows that the high performance water base drilling fluid with density between 2.30 g/cm3-2.40 g/cm3 maintained its thermal stability for a long time at 200℃-220℃, was resistant to the contamination caused by 50 g/L drilled cuttings, 50 mL/L formation water and 5 g/L CO2, and performed well in reservoir protection, the return permeability reaches 84.6%. This high performance drilling fluid has been used on a well in Yinggehai with formation pressure coefficient of 2.20-2.40 and formation temperature between 190℃ and 200℃, which conventional polymer sulfonate drilling fluid has failed the drilling operation previously. This proved that the high performance water base drilling fluid had good high temperature stability and superior rheology. The successful application of the high performance drilling fluid has provided an reference for selecting drilling fluids for HTHP complex well drilling.