高密度钻井液加重材料及流变调控技术研究

Research on weighting materials and rheological control technology for high-density drilling fluids

摘要:

针对深井超深井钻探中高密度钻井液固相含量高、流变性控制困难的问题，系统研究了不同加重材料的基础性能，分析了密度、粒径及粒度级配等因素对钻井液流变性的影响，并基于材料密堆积理论开展加重剂粒度级配设计与室内试验验证。结果表明，加重材料密度越高，达到相同钻井液密度所需的固相体积分数越低，流变性越好；粒径越小、比表面积越大，黏度效应越显著，重晶石粉中粒径小于20 μm的细颗粒会导致表观黏度大幅升高；采用优化级配后的重晶石粉配制密度为2.3 g/cm3的钻井液，其塑性黏度较未优化样品降低了19%，且动切力提高，流变性显著改善。该研究为高密度钻井液流变性控制提供了基于粒度级配优化的物理调控方法，具有较强的工程应用价值。

Abstract:

To address the challenges of high solid content and difficult rheological control in high-density drilling fluids for deep and ultra-deep well drilling， this study systematically investigates the fundamental properties of various weighting materials. The effects of density， particle size， and particle size distribution （PSD） on drilling fluid rheology were analyzed. Based on the dense packing theory， the particle size distribution of weighting agents was designed and validated through laboratory experiments. The results indicate that higher material density leads to a lower solid volume fraction required to achieve the target fluid density， thereby yielding better rheological properties. Smaller particle sizes and larger specific surface areas result in more significant viscosity effects， with fine particles smaller than 20 μm in barite powder causing a substantial increase in apparent viscosity. A drilling fluid with a density of 2.3 g/cm3， formulated using barite with an optimized PSD， exhibited a 19% reduction in plastic viscosity compared to the non-optimized sample， along with an increased yield point and significantly improved rheological properties. This study provides a physical control method based on particle size distribution optimization for high-density drilling fluids， demonstrating strong engineering application value.