We use the cores from seven oilfields in Western South China Sea as the experiment samples and take the weight loss of micro PDC bit for breaking unit volume of rock as the indicator to determine abrasivity of common sedimentary rocks encountered in drilling. According to the experiment results, we determine the power function relation among the rock abrasivity, hardness and internal friction angle, establish a universal prediction model and propose a reference standard for rock abrasivity classification in drilling based on field experience and previous studies. We use the model to establish the abrasivity profile of a well in Western South China Sea. With the profile, we re-evaluate the effect of rock abrasivity on the bit wear and optimize the design of PDC bit. The new bit raised ROP by 57. 27 percent and reduced the wear in the same formation in adjacent well. It is proven that abrasivity profile played an important role in optimizing bit.%以破碎单位体积岩石PDC微钻头的磨损量作为岩石研磨性指标,以南海西部7个油田的岩心作为实验样本,测定了石油钻井中常见沉积岩的研磨性.根据实验结果确定了岩石研磨性与岩石硬度、内摩擦角存在幂函数关系,建立了通用地层研磨性预测模型,并借鉴现场经验及前人分级方案提出了钻井工程岩石研磨性分级参考标准.利用本文提出的通用模型建立了南海西部油田某井地层研磨性剖面,并根据此剖面重新评估了地层研磨性对PDC钻头的磨损,进而对钻头进行了优化设计.应用效果表明,优化后的钻头在邻井相同地层中机械钻速提高了57.27％,同时钻头磨损程度降低,地层研磨性剖面对钻头优化有指导作用.
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