Borehole guidance system having target wireline
US5074365A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 14, 1990 |
| Grant date | Dec 24, 1991 |
| Priority date | — |
| Expiry date | Sep 14, 2010 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B7/04
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
A method for guiding a borehole with respect to a target wireline carrying low frequency alternating current is disclosed. A wireline carrying an electrode at its terminal end is positioned in a target cased or uncased borehole with the electrode contact the wall of the borehole. An AC source is connected between the wireline and ground to supply current to the borehole wall near the bottom of the borehole. A sensor is positioned in a borehole being drilled to sense the magnetic field generated by current flow in the wireline, the sensor being spaced sufficiently far along the wireline from the electrode location to prevent magnetic fields due to return current through the target borehole casing on through the ground surrounding the target borehole from significantly affecting the sensor. The sensor measures the net alternating magnetic field to determine the direction to the target borehole, to permit guidance of the borehole drilling.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.