Acoustic logging while drilling tool to determine bed boundaries
US5678643A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 18, 1995 |
| Grant date | Oct 21, 1997 |
| Priority date | — |
| Expiry date | Oct 18, 2015 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B47/0224
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
A LWD tool is disclosed for detecting the existence of and distance to adjacent bed boundaries. A transmitter assembly generates either a short acoustic pulse or a swept frequency signal that is detected by an associated receiver assembly. The received signal(s) are conditioned and converted to high precision digital signals by an A/D converter. The digitized signals are accumulated and transferred to a digital signal processor via a high speed data bus. The digital signal processor also receives a digital signal representing the transmission signal and compares the transmission signal and the received signals together to enable a downhole microprocessor to derive a time lag for the received signals. The microprocessor can transmit the time lag signal to the surface via a mud pulse for real-time control, or can operate as part of a closed loop drilling system to automatically control inclination of the drilling assembly to stay within, or to enter, a pay zone based upon the time lag associated with the received signals, and the measured speed of sound of the formation. In one embodiment, the receivers in the receiver array are steered to investigate various volume cells in the form…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.