Method of monitoring core sampling during borehole drilling
US5010765A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 25, 1989 |
| Grant date | Apr 30, 1991 |
| Priority date | — |
| Expiry date | Aug 25, 2009 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B47/00
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
Downhole measurements are made for accurately determining whether or not a core barrel contains an appropriate amount of core sample before retrieval of the coring tool is attempted. This is accomplished by using a known apparatus for measuring downhole weight on bit (WOB) at the beginning of a coring run to make a first measurement corresponding to the weight of all drillstring components suspended below the measurement point at a selected depth. Thereafter, the coring tool drills down the length of the core barrel. When sufficient drilling takes place to obtain a core, the drillstring is pulled up to the same depth as the measurement and a second measurement is taken. After correcting the data for temperature changes, the difference in between the first and second measurements is obtained and compared to a calculated weight for a full core. If the difference in measurements is less than the calculated full core weight, then it is known that a full core has not been obtained and the coring operation is continued. However, if the difference in the measurements does correspond to the calculated weight of a full core barrel, then the drillstring is retrieved and the acquired core sam…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.