Planning LL with DNO

Norma (25/7-11 S) – Reservoir section

What happened:

High gas in return and losses. Believed to be due to ballooning effect. Once the well was flow checked the lost mud came in return. The mud weight was reduced to 1.95 sg, and the losses disparaged

What was planned:

To drill the 8 1/2″ sidetrack with 1.97 sg mud to CP.

What was learned:

To evaluate to drill the reservoir section with lower mud weight if risk of ballooning effect and increase the mud weight prior to the reservoir.

What actions are required:

For future HPHT wells with increased risk of ballooning, evaluate to start the reservoir section with lower mud weight and increase prior to entering the reservoir if possible. Especially if the well is sidetracked and the formation tops and pressure is known.