随钻扩眼工具钻压分配比的计算方法及对钻速的影响

为了研究随钻扩眼工具在钻井过程中的破岩特性,更好地发挥其在钻井过程中的优点,建立了随钻扩眼工具井底钻压的计算模型。依据岩石破坏的应变能密度基本原理,推导出了阶梯效应指数计算表达式,并得出了用阶梯效应指数与井眼几何参数为变量的阶梯井眼的钻压分配比计算方法,并分别进行了理论和实例分析研究。理论分析结果表明,随钻扩眼形成的阶梯式井底岩石要比领眼井底岩石接近屈服状态,岩石更容易破碎。实例分析也表明,随钻扩眼工具比相同尺寸钻头的钻具有更好的快速钻井效果,验证了理论计算结果的正确性。

Calculating Method and Effect on ROP of Ratio for WOB of RWD Tools

To learn the characteristics of the RWD （reaming while drilling） tools in the process of breaking rocks and fulfill its merits in the process of drilling, a model calculating the bottom hole WOB （weight on bit） was set up. According to the rule of the strain energy density for rock failure, the formula calculating the ladder effect factor was derived. And a calculating method of the ratio for WOB was established by the ladder effect factor and the geometry parameters of the borehole. The theoretical results showed that the rock around the ladder borehole was closer to the yield condition than the rock around the pilot hole, and was apt to fall into pieces. The practice results also showed the reaming while drilling tools could drill faster than the normal bit of the same size.