| 摘要 |
A downhole measurement assembly comprising a metal casing housing a plurality of tool sections, one of which includes a detector sensitive to a magnetic field, and a DC power supply (4) for said tool sections, the power supply and the tool sections being electrically connected to the casing, characterised in that the power supply (4) is connected to at least one tool section (24) via a switching circuit (20,22) and a conductor arrangement (25, 26), the switching circuit comprising a capacitor (20), a plurality of switches (22) and control means operative alternately to charge the capacitor from the DC supply and discharge the capacitor through said at least one tool section using the conductor arrangement so as to inhibit the generation of an electro-magnetic field in the conductor arrangement between the capacitor and the said at least one tool. |
