Method and apparatus for transverse electromagnetic induction well logging
US5781436A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 26, 1996 |
| Grant date | Jul 14, 1998 |
| Priority date | — |
| Expiry date | Jul 26, 2016 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B2200/22
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method of measuring the conductivity of earth formations penetrated by a wellbore. The method comprises selectively passing an alternating current through transmitter coils inserted into the wellbore. Each of the transmitter coils has a magnetic moment direction different from the magnetic moment direction of the other ones of the transmitter coils. The alternating current includes a first and a second frequency. The amplitude at the first frequency has a predetermined relationship to the amplitude at the second frequency. The relationship corresponds to the first and the second frequencies. The method includes selectively receiving voltages induced in a receiver coil having a sensitive direction substantially parallel to the axis of the corresponding transmitter coil through which the alternating current is passed. A difference in magnitudes between a component of the received voltage at the first frequency and a component of the voltage at the second frequency is measured, and conductivity is calculated from the difference in magnitudes of the components of the received voltage at the two frequencies. In a preferred embodiment, the step of measuring the difference in magnitudes…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.