Strengthening Plugging Operations by Combining Cross-Linked Film and Chemical Consolidation in Well Ming-1

Since lost circulation occurred frequently in the 1 894.00-2 514.00 m interval in the second drilling section of the Well Ming-1,and the formation has a low pressure-bearing capacity,strengthening of plugging operations must be done for the upper interval to enhance its pressure-bearing capacity and to ensure safety while drilling of the remaining part of the second drilling section.Based on the the fact that the lithology contains weak layers and the prior experience of leak plugging,strengthening the plugging of cross-linked gel and chemical consolidation was adopted,in which a cross-linked gel plugging slurry was injected first to enhance the preliminary pressure-bearing capacity of the formation,then chemical consolidation slurry was applied to further enhance the pressure-bearing capacity of the formation to satisfy relevant requirements for safe drilling.After the plugging operation,the pressure-bearing capacity of the upper section shallower than 2 021.58 m of Well Ming-1 was increased to over 1.70 kg/L,whereas the deeper section was increased to over 1.60 kg/L,which satisfied the pertinent requirements,and no lost circulation took place in the plugged interval occurred and in the drilling of the rest interval.The results showed the cross-linked gel and chemical consolidation strengthened plugging operation could effectively enhance the pressure-bearing capacity of weak formations,which offered an effective means for strengthening the plugging operation in similar formations.