| 摘要 |
A method to detect the relative position of a drill bit with respect to a coal seam boundary using an electric-field borehole telemetry apparatus, that includes the steps: providing a measure-while-drilling apparatus that includes inclination sensors, directional sensors, logging sensors of choice and an electric-field borehole telemetry apparatus, within the electric-field borehole telemetry apparatus, in addition to monitoring the inclination, direction and logging parameters, monitoring one or more parameters of the electrical output of the telemetry apparatus, transmitting to the surface the inclination, direction and logging parameters as well as the one or more parameters of the electrical output by means of the telemetry apparatus, computing the usual drilling parameters needed to guide the drill string along the intended path, determining from the one or more transmitted parameters of the electrical output from the downhole apparatus parameters indicative of approaching or penetrating the coal boundary, and making corrections to the direction of drilling to maintain the drill string and bit in the coal seam.
|
