Patent EA-005307-B1 (EA)
Title: An apparatus for accurately measuring properties of a formation
Inventor: CROSSKNO MICHAEL S
IPC: G01V3/10
Filed: 2000-12-21
Abstract: 1. A induction logging tool for measuring the properties of a geological formation adjacent a bore hole comprising: a transmitter having an electrical ground; a receiver having an electrical ground; and a controlled impedance isolating the transmitter electrical ground from the receiver electrical ground for reducing current flow between the transmitter and the receiver. 2. The logging tool of claim 1 further comprising: a galvanic electrode having an electrical ground, the galvanic electrode further comprising a controlled impedance isolating the galvanic electrical ground from the transmitter electrical ground for reducing current flow between the transmitter and the galvanic electrode. 3. The logging tool of claim 1 further comprising: a galvanic electrode having an electrical ground, the galvanic electrode further comprising a controlled impedance isolating the galvanic electrical ground from the receiver electrical ground. 4. The logging tool of claim 1 further comprising: a galvanic electrode having an electrical ground, the galvanic electrode further comprising a controlled impedance isolating the galvanic electrical ground from the receiver electrical ground and transmitter electrical ground. 5. The logging tool of claim 3 further comprising: a galvanic current source having an electrical ground, the galvanic current source further comprising a controlled impedance isolating the galvanic current source electrical ground from the galvanic electrode electrical ground. 6. The logging tool of claim 4 further comprising a galvanic current source having an electrical ground, the galvanic current source further comprising a controlled impedance isolating the galvanic current source electrical ground from the galvanic electrode electrical ground. 7. A logging tool as in one of claims 1-6 wherein the controlled impedance comprises a ten Kilo ohm resistor. 8. The logging tool of claim 1 further comprising an electrical insulator for electrically isolating the receiver from the well bore. 9. The logging tool of claim 1 further comprising a feed through pipe for housing electrical wires further comprising an insulator electrically insulating the feed through pipe and the receiver. 10. A induction logging tool for measuring the properties of a geological formation adjacent a bore hole comprising: a multi-component transmitter comprising an x, y and z-axis transmitter coil; a multi-component receiver, further comprising an x, y and z-axis receiver coil; and a controlled impedance electrically isolating the x, y and z-axis transmitter coils from the x, y and z-axis receiver coils. 11. The logging tool of claim 10 further comprising: a controlled impedance electrically isolating the x, y and z-axis receiver coils from each other. 12. The logging tool of claim 10 further comprising: a controlled impedance electrically isolating the x, v and z-axis transmitter coils from each other. 13. The logging tool of claim 10 further comprising: a galvanic electrode; and a current source. 14. The logging tool of claim 13 further comprising: a controlled impedance electrically isolating the galvanic electrode from the current source. 15. The logging tool of claim 14 wherein the controlled impedance isolating the galvanic electrode from the current source further isolates the galvanic electrode and current source from the transmitter x, y and z-axis coils. 16. The logging tool of claim 14 wherein the controlled impedance isolating the galvanic electrode from the current source further isolates the galvanic electrode and current source from the receiver x, y and z-axis coils.