The planned vertical well was to be drilled in 270m (MSL) water depth, targeting sand formations between 3,500m and 4,500m TVDRT using the Stena Clyde Semi-submersible. The project was executed in May 2014.
CHALLENGE
- Safely and efficiently drill, log and abandon a deep high temperature well within approx 60 days in one of Australia’s most frequent cyclone areas during cyclone season
- Logistical/Importation challenges of mobilising the required MODU from its prior location in JPDA 279 nm North-East of the Schooner-1 location, which is 228nm (422km) offshore from the Broome supply base, and a further 2,230km by road from the main O&G hub, Perth
- Drill through the notoriously troublesome Grebe sand formation where majority of surrounding offset wells have experienced stuck pipe and costly BHAs lost down hole.
- High temperature environment issues, such as:
- Drilling Fluid selection
- Staging procedures for MWD/LWD tools
- BOP elastomer limitations
- Heat considerations for mud room personnel due to predicted BHT of 360F.
The complicating factors:
- At 4,200m MDRT abnormal torque was observed while there was no hole problems evident. Further investigation found the TDS motor required changing out resulting in 3.42 days of Non-productive time (NPT).
RESULT
- The Schooner-1 well was drilled was drilled to beyond 4,000m (TVDRT) before being successfully logged, plugged & abandoned in a total of 68.45 days versus the estimated (mean) of 60.4 days. This was an exceptional result considering that most non-productive time could be attributed to waiting on weather and rig related faults
- Due to the pre-investigation by AGR into new and alternative drilling technologies, a number of pioneering firsts for the Client and the area were achieved on the Schooner-1 well. These include:
- First well in the area where the 17 1/2'' hole section was drilled in one bit run, using a Hybrid bit
- First well in the area where the 12 1/4” hole section was drilled in one bit run, using a specially selected bit
- First well in Australia to use dopeless casing
- As a result, the well was able to be delivered to the Client with minimal operational risk exposure and unprecedented drilling rates
