Rex E. Duhn
17Patents
7h-index
5Co-inventors
59Inventor score
Filing activity: Jun 9, 1989 → Feb 8, 2023
Most-cited inventions
| Patent | Title | Area | Cited by | Status |
|---|---|---|---|---|
| US6920925B2 | Wellhead isolation tool | Fixed Constructions | 33 | Expired |
| US6199914A | Drilling quick connectors | Fixed Constructions | 25 | Expired |
| US7322407B2 | Wellhead isolation tool and method of fracturing a well | Fixed Constructions | 19 | Expired |
| US6543533B2 | Well tubing rotator | Fixed Constructions | 14 | Expired |
| US7416020B2 | Wellhead isolation tool, wellhead assembly incorporating the same, and method of fracturing a well | Fixed Constructions | 10 | Active |
| US5611398A | Two-piece drilling flange | Fixed Constructions | 9 | Expired |
| US8272433B2 | Wellhead isolation tool and wellhead assembly incorporating the same | Fixed Constructions | 8 | Active |
| US7726393B2 | Wellhead isolation tool and wellhead assembly incorporating the same | Fixed Constructions | 6 | Active |
| US7493944B2 | Wellhead isolation tool and method of fracturing a well | Fixed Constructions | 6 | Expired |
| US5303774A | Ring seal packer | Fixed Constructions | 6 | Expired |
| US7520322B2 | Wellhead isolation tool and method of fracturing a well | Fixed Constructions | 6 | Active |
| US4974676A | Ground subsiding wellhead | Fixed Constructions | 5 | Expired |
| US8333237B2 | Wellhead isolation tool and wellhead assembly incorporating the same | Fixed Constructions | 5 | Active |
| USRE43773E1 | Drilling quick connectors | General | 4 | Active |
| USRE43697E1 | Drilling quick connectors | General | 2 | Expired |
| US11976542B1 | Frac distribution tower | Fixed Constructions | 0 | Active |
| US8863829B2 | Wellhead isolation tool and wellhead assembly incorporating the same | Fixed Constructions | 0 | Active |
Source: USPTO / EPO open patent data. Inventor disambiguation is heuristic; counts are objective bibliographic measures.