The man behind The Friday Haggler, Neil Armstrong, Merlin ERD Engineering Director.
A reminder of last Friday’s Haggler
You are drilling an 8-1/2” section close to TD at 7,000m MD and 2,700m TVD, with a sail angle at 70 degrees inclination and dropping into the reservoir.
The Driller drilled off all weight at stand-down to neutral (0 FF / rotating off bottom weight), then he follows the connection procedure; reaming a single (9m) up and down, he then takes pick-up and slack-off weights by moving half a single up and then back in hole, where the survey is taken.
Were the PU and SO weights taken effectively?
Is the survey taken on or off bottom?
Based on previous connections we expect to see reaming up and down weights following the 0.2 FF trend lines and the picking up, slacking off weights to follow the 0.3 FF trend lines.
Short Answer: The survey was off bottom, the PU and SO weights were not taken effectively.
V. Long Answer:
Step 1: Reaming up the blocks move 9.0m and the bit moves 6.5m (from 3.5m of stretch in the ROB position to 6.0m of stretch on the 0.2FF trend line means 2.5m of stretch is taken out of the pipe before the bit will move the remaining 6.5m off bottom).
Step 2: Reaming down the blocks move 9.0m and the bit moves 4.0m (from 6.0m of stretch at the top of the single being reamed to 1.0m of stretch at the -0.2FF slack-off trend line means 5.0m of stretch needs to be taken out the pipe before the bit moves).
Step 3: Prior taking PU and SO weights we know the bit is 2.5m off bottom. To move from the -0.2FF trend line to the 0.3FF trend line (PU weight trend) 7.0m of stretch would be required to be taken out of the string. The pipe only moves 4.5m when taking the pick-up weight, therefore we still have 2.5m of stretch in the string.
Step 4: Moving the blocks 4.5m down to take the slack-off weight just puts the string back in the same position as when reaming was stopped.
Therefore the survey was taken off bottom, however the pick-up and slack-off weights were not taken effectively as the stretch was not removed from the string.