Negative Operational LL with Faroe

Brasse (31/7-3 A) – Reservoir section

What happened:

Unable to release cable head after engaging fish -> reverse cut and thread operation next. Pulling speed 4-6 stands per hour. For every stand tripped, the wireline cable is shortened with ±0.2 – 0.5 m more than the length of the stand. And adjustment of the slack in the wireline cable has to be done more frequently as the string and cable is coming closer to surface. This because shorter cable is less flexible and the slack is reduced faster.

What was planned:

Wireline – Reverse cut and thread op.

What was learned:

Should avoid this operation if possible. Considerations when performing MDT on TLC; 1) Run side entry sub below rotary or not. Above rotary reduced flexibility for correlation passes and several sampling station without pulling locomotive to surface. Below rotary more flexibility but higher risk for damaging cable.
2) Correlation passes. Geologist to check log in due time to make sure to have some log spikes to correlate against.
3) Upper wireline sheave is hang off in hang off line for travelling block. The distance from drillfloor to bottom sheave is 17,40 m.
4) Rigg up of counterweight for compensation of wireline cable. Has to be planned together with side entry sub above or below rotary.
5) Depth correlation was done without drill string compensation. At sampling point active heave compensation was activated. Worked well together with Schlumbergers measurement of compressional force. Adjusted string according to Schlumberger measurements. Most of the operation was done with heave from 1,8-3,6 m. But it was observed heave up to 4,4 m at the highest.
6) Communication between G&G onshore – offshore – Drilling department. Plans has to be communicated in due time to key personnel.

What actions are required:

NA