摘要 |
<p>An apparatus and its use for measuring the differences in gravity at spaced locations in a wellbore. The apparatus includes first and second gravity measuring devices mounted at spaced vertical positions from each other and encapsulated for movement through a wellbore. A first electrical control current, proportional to the force of gravity acting upon the first gravity measuring device, is provided as a bias current to a second electrical control current. The second electrical control current is indicative of differences in gravity forces detected by the first and second gravity measuring devices, thereby providing a gravitational gradient reading.</p> |