Apparatus for inductively coupling signals between a downhole sensor and the surface
US5008664A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 23, 1990 |
| Grant date | Apr 16, 1991 |
| Priority date | — |
| Expiry date | Jan 23, 2010 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B47/13
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
An apparatus employing a set of inductive coils to transmit AC data and power signals between a downhole apparatus (which may include a sensor and a safety valve) and apparatus at the surface of the earth. In a preferred embodiment, the invention inductively couples a low frequency (less than 3 KHz) AC power signal from an outer wellhead coupler coil to an inner wellhead coupler coil wound around a tubing string. The AC signal propagates down a wireline conductor along the tubing string to a first downhole coupler coil (also wound around the tubing string) and is inductively coupled from the first downhole coupler coil to a second downhole coupler coil within the tubing. The power signal is preferably rectified, and then employed to power various items of downhole equipment. Data from a downhole sensor (whose frequency is preferably in the range from about 1.0 KHz to about 1.5 KHz) is impressed on the second downhole coil to modulate the AC power signal. The modulated AC signal is inductively coupled from the second downhole coil to the first downhole coil, and from the inner wellhead coil to the outer wellhead coil, and is demodulated by phase locked loop circuitry at the wellhead…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.