Drill string system
US4036539A · kind A · utility
9Cited by
5References
11Claims
0Family size
Inventors
Key dates
| Filing date | May 9, 1975 |
| Grant date | Jul 19, 1977 |
| Priority date | — |
| Expiry date | May 9, 1995 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B41/02
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
A drill string system, having a greatly reduced tendency for balling and sticking in oil field clay or sticky shale, is provided on its non-bearing surfaces, with an adherent plastic covering, e.g. a polyurethane polymer. The plastic coating is applied to the non-bearing steel surfaces of the string, which have been cleaned of rust and have been coated with a primer.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.