Lessons Learned: Decision Process Breakdown During Unexpected Drag

A well control decision process broke down during an incident: stuck liner due to drag and circulation issues.

This IOPG (International Association of Oil & Gas Producers) well control incident demonstrates how unexpected drag while RIH (run-in-hole) with the liner created restrictions that impacted the primary barrier.

In well control incidents, time constraints are always there, but assessing new scenarios and investing some time increases the probability of positive outcomes for safety and even reduces lost time.

What happened?

• While RIH a 7″ liner (hydraulic, rotating type hanger), wash down became necessary at about 4900m due to increment of drags.
• Pumping pressure spikes were noticed. (SPP was limited to 1200psi due to shear screw setting at 1900psi).
• Not able to continue to run/wash in hole nor to circulate. Start to POOH – hole did not take correct fill up. After pull few stands, regain circulation (with SPP<1200psi). Continue to pump out of hole until previous casing shoe.
• Circulate B/U at shoe, 20% gas recorded and gas cut mud.
• Negative flow check. Confirmed well was flowing.
• Shut in well. SIDPP 500psi SICP 600psi.
• Pressure slowly increasing: after circulate a bottom up SIDPP=950psi. SICP=900psi.
• Circulate 1.50 sg mud to lower pressures.
• SICP increase from 0 to 300psi.
• Stripped back in hole – avoid to pump down string.
• Able to reach an acceptable setting depth below the previous HDD (High-Density Drilling).
• Circulate to kill the well.
• Set liner and perform cement job.

What went wrong?

• Liner wash/ream down operation should have started at the first indication of drags. Extra care should have been taken while managing circulation attempts.
• Wrong hole fill up should have been noticed on first stand and POOH (pull out of hole) operation should have stopped to assess the situation.
• Time constrains, and the risk of getting stuck with liner and lose the well, negatively affected the decision process.

Corrective actions and recommendations

The possible hanging of the liner due to erratic pressure spikes was wrongly interpreted. Situation should have been more carefully assessed.

Content credit: IOGP (International Association of Oil & Gas Producers), “Stuck liner due to drag and circulation issues,” Well Control Incident 26-10.