| 摘要 |
Orientation data representing a required orientation of a core sample held in a core tube (22, 50) prior to separation of the core sample (24, 52) from the underlying rock can be recorded by a data gathering device (42, 80) at least while drilling is ceased and closest to time Tx, where Tx can be greater than, less than or equal to T-t, where T is the time recorded by the data gathering device (42, 80) and t is the recorded elapsed time commenced and recorded by a communication device (60) at the surface. Elapsed time t commences at the surface when drilling ceases and preferably before the core is to be broken from the underlying rock. For regular time intervals I between orientation data measurements, there can be a time delay W from commencing the elapsed time t. This time delay should be at least as long as (I) a time interval between taking orientation measurements plus the time to actually measure an orientation. After the delay W has elapsed, the core can be broken from the underlying rock. The data gathering device (42, 80) is interrogated at the surface by the communication device (60), and at the same time both timers are stopped or their individual times associated with each other (survey time T and elapsed time t). Target recorded orientation data Tx can be identified as the largest Tx value < T-(t-W) i.e. the oldest Tx in time from commencement of T after taking the mark and before or by the end of the delay W time. Alternatively, for elapsed time t commenced at the end of the delay period W from taking the mark, the recorded orientation data can be identified as the smallest Tx value > T-(t+W) or the largest Tx value < T-t. |
