 |
| |||
| difficult (igisheva); hard-to-recover (igisheva) | |||
| |||
| difficult (oil resources whose production is problematic; запасы); problematic (запасы) | |||
| трудноизвлекаемый: 23 do fraz, 7 tematyki |
| Olej i gaz | 10 |
| Pola naftowe | 4 |
| Pospolicie | 1 |
| Ropa / ropa naftowa | 3 |
| Sachalin | 2 |
| Technologia ropy i gazu | 1 |
| Tengiz | 2 |