Method and apparatus for monitoring fluid flow between a borehole and the surrounding formations in the course of drilling operations

摘要

A method and apparatus for establishing the rate at which fluid is transferred between a borehole 14 and the surrounding formations 16 in the course of moving drill string 20 upward or downward in the borehole 14. A bell nipple 40 is situated at the upper portion of the borehole 14. While tripping, drilling fluid is circulated into the borehole 14 and exits through an outflow port 44 in the bell nipple 40. The level of drilling fluid is maintained constant at the outflow port 44. Meters 52, 52', 54 are provided to measure inflow and outflow rates. Circuitry 66 is provided to establish the volume rate at which the amount of drill string 20 within the borehole 14 changes. The outputs of the meters 52, 52', 54 and rate establishing means 66 are summed to establish the compensated rate at which fluid is transferred between the formations 16 and the borehole 14. This compensated rate is compared to an alarm limit. An alarm 76 is activated if the compensated rate exceeds the alarm limit.