Wellbore Ballooning

27 May 2020 Hi All,

 We are drilling 8.5" hole depleted zones (2-4 ppg PP) at 72 deg inclination. We use 10.5 ppg SBM with pre-treated 40 ppb bridging material.

The first depleted sand we drilled through was experienced with 200 bph dynamic losses and reduce to 80 bph in few minutes. We picked up off btm and pumped 30 bbls of 150 ppb LCM pill through PBL port and performed ECD squeeze and then the lost rate reduced to 2 bph.

We continued drilling through the second depleted sand and experience with total lost return. We did pump 30 bbls of 150 ppb LCM pill and performed ECD squeeze, but this time the hole react differently. As soon as we complete the ECD squeeze, we did flow check and we got flow back from the hole. We shut the well in three times and got 0 psi on casing and the flow back rate was reduced to static after three hours.

This condition suggest us the wellbore is ballooning.

We continued drilling with losses and stopped before entering the next depleted sand. The hole is is still ballooning when the pumps off.

What is the good option to go to cure wellbore ballooning?

Will cement plug help curing the ballooning?

Appreciate your valuable feedback.

 Regards,

Army

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