发明名称 |
Apparatus and method for wellbore resistivity imaging using capacitive coupling |
摘要 |
An apparatus for obtaining resistivity images of a borehole includes an array of measure electrodes separated from a pad or the body of the instrument by a focusing electrode. The focusing electrode is maintained at a slightly higher potential than the measure electrodes. The apparatus is primarily intended for use with conducting fluids but may also be used with non-conducting fluids. A modulated electrical current with a carrier frequency of 1 MHz is injected into the formation. When used with a non-conducting fluid, capacitive coupling between the electrode and the conductive formation is provided by the dielectric of fluid. When used with a conducting borehole fluid, an additional capacitor may be incorporated into the circuit. The current in the measure electrode is indicative of the conductivity of the formation. To avoid cross-talk between conductors in an isolator section between the current source and the measure electrode, signals indicative of the measure currents are demodulated to a frequency of 1.1 kHz. This makes it possible to use the configuration of prior art devices designed for conductive coupling between the logging tool and the formation.
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申请公布号 |
US6714014(B2) |
申请公布日期 |
2004.03.30 |
申请号 |
US20010836980 |
申请日期 |
2001.04.18 |
申请人 |
BAKER HUGHES INCORPORATED |
发明人 |
EVANS MARTIN TOWNLEY;BURT ANDREW RICHARD;ALEXY ALBERT |
分类号 |
E21B47/024;G01V3/24;G01V3/28;(IPC1-7):G01V3/20 |
主分类号 |
E21B47/024 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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