Predicting the PDC bit performance during drilling operation is important for the cost effectiveness of the operation. The majority of PDC bits are assessed based on their performance that are relative to offset wells. Determination of mechanical specific energy (MSE) in real time and compare it with the known MSE for a sharp bit to assess the bit life has been utilized by several operators in the past. However, MSE still cannot be used to predict the bit performance in exploration wells and also it cannot assess the bit efficiency in the inner and outer cones.

A more precise approach needs to be devised and applied to improve the prediction of bit life and the decision when to pull the bit out of the hole. Effective mechanical specific energy (EMSE) developed in this work is a new wear and performance predictive model that is to measure the cutting efficiency based on number of cutters, which contact the rock as a function of weight on bit (WOB), rotary speed (RPM), torque, and depth of cut (DOC). This model modifies the previous MSE model by incorporating such parameters and including detailed design of the bit, number of blades, cutter density, cutter size, and cutting angle. Using this approach together with the analysis of rock hardness, a level of understanding of how the drilling variables influence the bit performance in the inner and outer cone is improved, and a convenient comparison of the bit condition in the frame of the standard bit record is achieved. This work presents a new simple model to predict the PDC cutters wear using actual data from three sections drilled in three oil wells in Libya. It is found that the obtained results are in well agreement with the actual dull grading shown in the bit record.

预测钻井作业期间的PDC钻头性能对于作业的成本效益很重要。大多数PDC钻头是根据其相对于偏移井的性能进行评估的。实时确定机械比能（MSE）并将其与已知的MSE进行比较，以获取尖锐的钻头，以评估钻头寿命，过去已被多家运营商采用。但是，MSE仍然不能用来预测勘探井中的钻头性能，也不能评估内，外锥的钻头效率。

需要设计和使用一种更精确的方法来改善钻头寿命的预测以及何时将钻头从孔中拔出的决策。这项工作中开发的有效机械比能（EMSE）是一种新的磨损和性能预测模型，该模型将根据刀具数量来测量切削效率，刀具数量随钻头重量（WOB），转速（ RPM），扭矩和切削深度（DOC）。该模型通过合并此类参数并包括钻头的详细设计，刀片数量，刀具密度，刀具尺寸和切削角度来修改以前的MSE模型。结合使用这种方法和岩石硬度分析，可以更好地了解钻削变量如何影响内，外锥的钻头性能，可以方便地比较标准位记录帧中的位情况。这项工作提出了一个新的简单模型，可以使用在利比亚三个油井中钻探的三个部分的实际数据来预测PDC刀具的磨损。发现所获得的结果与位记录中所示的实际钝度等级非常吻合。