Table 2
The main characteristics of Hutchinson, Kansas; Epe, Germany; Magnolia, Louisiana.
| Hutchinson, Kansas | Epe, Germany | Magnolia, Louisiana | ||
|---|---|---|---|---|
| Cavern information | Commissioning | Drilled in the 80’s, and abandoned. Re-opened and filled with natural gas in the 90’s | 1980 (Epe S5) | Wells 13–14 drilled in the 70’s |
| Incident date (1st noticed) | January 19, 2001 | Feb 23, 2014 | Dec 24, 2003 | |
| Geology | Bedded salt, Overlain by impermeable layers; however, thin subhorizontal fractured layers between two shale layers | Bedded salt, Zechstein (Z1), 200–400 m salt layer, roof at 1000 m, overlain by clastic and argillaceous layers | Domal salt (Napoleonville dome), salt roof at 200 m (?) | |
| Stored product | Natural gas | Oil | Natural gas | |
| Last cemented casing shoe | 9″ at 238 m | 11-¾″ at 1086.8 m | 13-⅜″ | |
| Penultimate cemented c.s. | 16″ at 212 m | |||
| Leak mechanism | Breach depth | 180 m | ≈ 217 m | ≈440 m |
| Pressure drop | yes | 0.36 MPa | ||
| Mechanism | Milling created a breach when re-drilling a cemented abandoned well. Gas migration through fractured channels to the brine aquifer below Hutchinson, and to ground levels through very old and poorly abandoned brine wells. | Casing overstretching due to caverns convergence | A flaw in the casing at a 440-m depth, attributed to poor welding job. | |
| Impact at the surface | Effects at ground level | A dozen geysers, gas + brine, | Oil seeps after April 12, 2014 | During first filling, 107 m3 of gas migrate to an aquifer layer, then to ground level |
| Distance from wellhead | 13 km | 200 m | ||
| Evacuation/Casualties | Two casualties | 10 cows put down; one family displaced for some days | 30 residents evacuated | |
| Emergency resp. & remediation | Measures taken | Bottom plug set on January 24. A video detects the breach. 36 shallow boreholes are drilled, eight of them find gas. A seismic reflection survey is undertaken, | Wellhead checks, CBL, sonar survey, measures taken for water protection, video, monitoring wells | A bottom plug is set. 36 boreholes drilled to the aquifer layer, 17 find gas. Video. |
| Remediation | Rules rescinded | An internal string is set | Caverns filled with brine |