Negative Operational LL with Wellesley

Grosbeak West (35/11-21 S) – Reservoir section

What happened:

720 litres of crude oil was left in bottom of well after MDT sampling on wireline. The MDT run was 2 of 4 WL runs. A wiper trip after MDT sampling was not conducted. The 7″ liner was RIH and formation fluids were circulated out before cementing. This resulted in 86% gas in shaker header box, after the mud had gone through the poor boy degasser. This was over the choke manifold, with a low pump rate of 30 SPM.

What was planned:

Formation fluid wireline sampling

What was learned:

To circulate out gas with cement stand on, the BOP closed, leaving the liner static without movement for many hours may lead to stuck pipe. Also more vulnerable to weather and rig heave when the cement stand and hoses are connected.

What actions are required:

Evaluate to run the MDT fluid sampling at the end of the wireline program, and then do a wiper trip with a drilling BHA before running the liner.