岩石塑-脆性破碎机理和塑性耗能比研究

The low drilling efficiency is the key factor influence the oil & gas reservoir exploration and development cost; how to improve the drilling efficiency and reduce the drilling cost is a long-term difficulty problem met in oil & gas drilling process. At this stage, the mechanical rock breaking is the main method in oil & gas drilling, the rock fragmentation mechanism under drill tooth cutting and penetration directly decide the drilling efficiency and cost. This project aims at the scientific problem of rock fragmentation mechanism, the ultimate goal is to improve the drilling efficiency; the problems of crack initiation and propagation, damage evolution, chip formation, ductile-brittle failure transition, mechanical specify energy, plasticity energy dissipation ratio and fragmentation efficiency etc are studied based on the research approaches of theoretical analysis, computer numerical simulation and laboratory experiment. At last, the computing methods of critical cutting/penetration depth and plasticity energy dissipation ratio and the evaluation methodology of rock fragmentation are formed, which provide theoretical basis for the bit optimization design or custom design, drilling parameter optimization and the formation of low-cost drilling speed technology.

钻进效率低是影响油气钻探成本的主要因素之一，如何提高钻进效率、降低钻进成本是油气钻采过程中长期面临的一个难点问题。现阶段，机械破岩仍是油气钻井的主要作业方式，岩石在钻齿切削和侵入作用下的破碎机理直接决定着钻探效率和钻井成本。本项目针对钻井过程中岩石破碎机理这一科学问题，以提高钻进效率为最终目的，通过理论分析、数值模拟与室内实验相结合的研究方法系统揭示岩石在钻齿作用下的裂纹萌生和扩展、损伤演化、岩屑形成、塑-脆性破碎转变、机械比功、塑性耗能比以及岩石破碎效率等问题。最终形成岩石塑-脆性转变临界切削/侵入深度和塑性耗能比的计算方法以及岩石破碎效率的评价方法，为钻头优化设计或定制设计、钻井参数优选以及形成低成本的钻井提速技术提供理论依据。

钻进效率低是影响油气 钻探成本的主要因素之一，如何提高钻进效率、降低钻进成本是油气钻采过程中长期面临的一个难点问题。现阶段，机械破岩仍是油气钻井的主要作业方式，岩石在钻齿切削和侵入作用下的破碎机理直接决定着钻探效率和钻井成本。本项目针对钻井过程中岩石破碎机理这一科学问题，以提高钻进效率为最终目的，通过理论分析、数值模拟与室内实验相结合的研究方法系统揭示了岩石在钻齿作用下的裂纹萌生和扩展、损伤演化、岩屑形成、塑-脆性破碎转变、机械比功、塑性耗能比以及岩石破碎效率等问题。最终形成了岩石塑-脆性转变临界切削/侵入深度和塑性耗能比的计算方法以及岩石破碎效率的评价方法，为钻头优化设计或定制设计、钻井参数优选以及形成低成本的钻井提速技术提供了理论依据。