Method of and apparatus for detecting an influx into a well while drilling
US5275040A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 11, 1991 |
| Grant date | Jan 4, 1994 |
| Priority date | — |
| Expiry date | Jun 11, 2011 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B49/005
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
Gas influx into a wellbore, which is commonly referred to as a "kick", is detected during active drilling of the borehole. In a preferred embodiment of the invention a determination of mud pump noise round trip transit time T by evaluating a function T=(n-.PHI./2.pi.)f where .PHI. is the phase between standpipe and annulus signals and f is the frequency of a drill fluid oscillation caused by a mud pump and n is an integer which is incremented or decremented until the rate of change of T with respect to frequency is zero. An alarm signal is generated when the rate of change of T with respect to time exceeds a predetermined threshold. In another embodiment of the invention a determination of the Doppler frequency shift of a mud pump signal expressed as a ratio signal, .DELTA.f/f.sub.0 where .DELTA.f is the change in frequency measured at the annulus from the frequency f.sub.0 of the mud pump signal measured at the standpipe. The ratio is compared with a threshold signal to determine whether or not gas influx has entered the annulus.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.