| 摘要 |
A method of determining the position of a drill bit 18 in a wellbore drilled in a surface of the earth, comprises providing at said surface a number of surface devices 1-7, each provided with a high precision clock; providing at or adjacent said drill bit 18 a downhole device provided with a high precision clock; for each surface device 1-7, transmitting an electromagnetic signal between said surface device 1-7 and said downhole device, and determining a transit time for said signal using said high precision clocks, said transit time being the time taken for said signal to travel between said surface device and said downhole device; and determining a set of position coordinates for said downhole device based on known position coordinates of said surface devices 1-7 and the transit time for each surface device. The clocks may be atomic clocks the method can be used to steer a drill. |
