随钻扩眼钻井技术可在全面钻进的同时实现裸眼井段的扩径,能有效减少起下钻次数、提高钻井效率.随钻扩眼过程中领眼钻头和扩眼器上钻压、扭矩的分配与地层岩石性质、钻井参数、钻具结构等多种因素有关,因此提出能反映实际随钻扩眼过程的理论或试验方案是钻压分配规律研究的关键.为了在室内试验环境下模拟实际随钻扩眼过程,设计并进行了全尺寸随钻扩眼破岩试验.设计加工了ø215.9 mm PDC领眼钻头和扩眼直径可调(242、260 mm)的试验用扩眼器,在钻头试验台架上进行了全尺寸破岩试验,研究了随钻扩眼过程中的钻压分配规律及其受岩石类型、钻压、转速及扩眼直径的影响.试验结果表明:钻压比和扭矩比随总钻压的增大而增大,随岩石强度的减小而增大,但基本不受钻速的影响;扩眼器刀翼切削区域攻击性越强,相应的钻压比越大.所得结论可为随钻扩眼作业的钻井参数和钻具组合优化提供依据.
Experimental Study on Distribution of Weight on Bit During Reaming While Drilling
Reaming while drilling(RWD)technology can realize the expansion of open hole section while fully drilling,which can effectively reduce the trip times and improve drilling efficiency.The distribution of weight on bit(WOB)and torque on the pilot bit and reamer during RWD is related to several factors such as rock proper-ties,drilling parameters and tool structure.Thus,a theoretical or experimental scheme that can reflect the actual RWD process is essential for clarifying the WOB distribution.In order to simulate the actual RWD process in the laboratory,the full-size RWD experiment was designed,and a ø215.9 mm PDC pilot bit and an experimental reamer with adjustable diameter(242 mm,260 mm)were developed.The full-size RWD experiment was per-formed using the PDC pilot bit and experimental reamer on the bit test bench to analyze the WOB distribution and how it is affected by the rock type,WOB,rotational speed and reaming diameter.The results show that the WOB ratio and torque ratio increase as the total WOB increases and also as the rock strength increases,but they are basi-cally not affected by the rate of penetration(ROP).The more aggressive the cutting part of the reamer blades,the higher the corresponding WOB.The research findings provide basis for optimization of drilling parameters and bot-tomhole assembly during RWD.
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