| 摘要 |
<p>The invention relates to a procedure for measuring the rate of penetration VF of a drill bit fixed to the lower end of a drill string lowered into a well. During an initial period, the well is drilled keeping, on average, the value of weight F of the drill string measured at the surface relatively constant, and the momentary values of the drill string rate of penetration VS and the weight F are measured at the surface at different successive moments. The value of the drill string average rate of penetration VSM at the surface is determined from the values of VS measured and the successive values of dF/dt of the first derivative with respect to time. The coefficient of apparent rigidity of the drill string during the initial period is then determined from the values of VSM, VS and dF/dt. Finally, the rate VF is calculated.</p> |
