硬地层稳压稳扭钻井提速技术

采用PDC钻头钻进硬地层时，如果破岩扭矩较小或波动幅度较大，易造成钻头恶性振动和钻头使用寿命短，从而导致机械钻速低和钻井周期长。因此，建立了PDC钻头破岩所需门限扭矩的计算模型，以门限扭矩定量计算为核心、平稳传递钻柱应变能为手段，形成了硬地层稳压稳扭钻井提速技术。该技术通过优化井眼尺寸、选用合适的钻头和冲击类辅助破岩工具，降低破岩门限扭矩和门限钻压；通过选择合适的井下动力钻具，为钻头提供足够的破岩能量；通过选用减振工具和优选钻井参数，降低振动，保证钻头运动平稳。稳压稳扭钻井提速技术在夏河1井古生界硬地层进行了现场试验，二叠系机械钻速提高485.6%、全井机械钻速提高70.4%，取得了显著的提速效果。研究结果表明，稳压稳扭钻井提速技术能够提高硬地层机械钻速，可为复杂地层钻井提速提供借鉴。 

Technology for Drilling Speed Increase Using Stable WOB/Torque for Hard Formations

When a PDC bit is used to drill hard rock, the large torque is required, and the fluctuating torque would cause severe vibration and short service life of drill bit, hence resulting in low ROP and long drilling period. By establishing a calculation model for the required threshold torque of rock breaking, a stable WOB/torque technology for increasing drilling speed in hard formation has been developed based on quantitative calculation of threshold torque, adhering to smooth transmitting of drill string strain energy. By means of optimizing the wellbore size, selecting the appropriate bit and impact-assisted rock breaking tools, the threshold torque and WOB of rock breaking can be reduced. By selecting the appropriate PDM drilling tools, the sufficient rock breaking energy for the bit can be provided. Through optimization of appropriate shock-absorbing tools and drilling parameters, the new technologies can reduce vibration and ensure smooth operation of drill bit. During the field test in Paleozoic hard formation of Well Xiahe-1, the ROP in Permian strata was increased by 485.6% and the whole well ROP increased by 70.4%, achieving remarkable effects for increasing drilling rate. The research results showed that stable WOB/torque drilling technology could effectively improve the ROP in hard formation, and provide reference for increasing drilling rate in complex formations.