The depth of deep shale formation in Luzhou is about 4000m. It is typical high-pressure formation, where Shiniulan Formation drilled is a sandstone-rich mudstone. In this area, high-pressure formation gas was often encountered in drilling operations, increasing risks of gas-kick and lost circulation; meanwhile, pulsation wellbore leakage was observed while using high-density drilling mud. All these issues posed great challenges to drilling operations in this region. To address this issue, taking Well Y101H3-4 as an example, some wellbore plugging treatments were tested. Results showed that:①Typical wellbore plugging materials can not effectively plug wellbore leakage due to incompatible material-fracture sizes.②Based on drilling history of neighboring wells, reducing drilling mud density helped with wellbore plugging operations.③Oil-based cement plugging was the most effective method to deal with the formation with pulsated lost circulation at the prerequisite that proper mud density should be determined to prevent contamination due to contact between drilling mud and cement slurry. In conclusion, reducing mud density and use of oil-based cement plugging are the best method for pulsated lost-of-circulation in the Luzhou Block.
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李奎.泸州深层页岩气呼吸性地层井漏堵漏方法及对策分析——以Y101H3-4井为例[J].钻探工程,2022,49(5):106-110.LI Kui. Plugging of breathing formation in deep shale gas wells in Luzhou: Taking Well Y101H3-4 for example[J]. Drilling Engineering, 2022,49(5):106-110.