地层岩性的随钻评估对钻井工程技术人员和地质人员十分重要。本文根据钻头破岩机理和能量守衡原理,建立了地层岩性随钻评估模型。使用PDC钻头钻井时,岩屑破碎很细,通过岩屑录井来判断地层岩性十分困难。针对PDC钻头的切削机理,从PDC钻头切削刃受力平衡角度出发,建立了PDC钻头钻井时地层岩性随钻评估模型。现场初步试验表明,该模型具有一定的合理性和实用性。 LWD assessment of formation lithology is of great importance to both drilling engineers and geologists. According to the principle of rock breaking and the principle of energy balance, this paper establishes the lithological evaluation model of rock drilling. When drilling with a PDC bit, the cuttings are very fragile, and it is very difficult to judge the lithology of the formation by cuttings logging. Aiming at the cutting mechanism of PDC bit, from the view of force balance of PDC bit cutting edge, a lithology evaluation model is established when drilling PDC bit. Preliminary test results show that the model has some rationality and practicability.