The company reported yesterday that the well was at 2616m.
“Following cementing the previous casing at 2259 metres (7410ft), drilling proceeded with rates of penetration of 24 to 39 feet per hour, well in excess of the planned rates,” the explorer said.
“A hard section at around 2530 metres (8300ft) to 2590 metres (8500ft) resulted in severe vibrations and caused a failure of part of the bottom-hole assembly (BHA) that is approximately 200 metres long and comprises the drill bit, stabilisers and heavy drill collars.”
The failed parts were successfully retrieved to surface without difficulty and the entire BHA has been thoroughly inspected to ensure that there is no damage to other components.
“Vibrations in bottom hole assemblies are not uncommon and the detailed BHA design has been modified to better accommodate the drilling conditions,” the company said.
“Approximately five days were spent in the fishing, inspecting and modifying of the BHA.”
“Drilling the 311-millimetres diameter hole has since resumed. The redesigned BHA is working well and the current rate of penetration in the present harder formation is around 10 to 12 feet per hour.”
This episode ended more happily than the company’s last fishing expedition.
At Geodynamic’s previous well, Habanero-2, in late 2004, 245m of drill stem broke off at 4343m near the bottom of the well.
The company kept trying to free the pipe until the end of June 2006 when it decided to halt drilling.
Two weeks later, managing director and chief executive Dr Bertus de Graaf resigned due to "irreconcilable differences" with non-executive board members.
A technical review later found operational techniques used in Habanero-2 were unsuitable for drilling the large sections of granite above the target fracture zone.
The company scrapped Habanero-2 and began drilling the new well, Habanero-3 in August.
This time it is using a new $32 million rig, the most powerful onshore rig in Australia, capable of drilling to depths of around 6000m. Habanero-3 has a target depth of 4300m.
