| 摘要 |
<p>To provide stable, accurate time reference signals for control and operation of a well logging instrument (12), a temperature isolation enclosure (14) defines an internal cavity (16) for containing and protecting an electronic time base (10). An electronic timer (10) such as a crystal oscillator is located within the oven cavity (16) and is electronically stable at a predetermined temperature range slightly higher than the highest ambient temperature encountered within the wellbore. A heating element (18), control circuit (22), and a temperature sensor (24) are provided within the oven cavity (16) to maintain the timer (10) within the predetermined temperature range. An automatically energized cooling element (20) may also be provided within the oven cavity (16) for additional temperature control.</p> |
