Research Progress of Plugging Materials for Geothermal Wells
The problem of lost circulation occurs frequently during the development of geothermal wells,which will reduce drilling efficiency,and result in major economic loss and downhole accidents,especially the total loss of geothermal reservoir with poor formation stability.When severe loss occurs in non-reservoir section of geothermal well,conventional cement,bridging plugging materials and other plugging materials often have poor plugging effect.It is therefore urgent to develop low-cost,good plugging effect and environmental friendly plugging materials for geothermal wells.This work reviewed the technical requirements of plugging in geothermal wells,the research and application status of plugging materials,the plugging materials for non-reservoir and the temporary plugging materials for geothermal reservoirs.The advantages and disadvantages of different plugging materials were analyzed.We introduced the application effect of existing plugging materials in geothermal wells and plugging principle,progress of three kinds of temporary plugging materials for geothermal reservoirs,such as self-degradable temporary sealing cement,self-degradable crosslinked gel and temperature-sensitive shape memory polymer.With the exploration and development of deep geothermal energy,the research directions of plugging materials for geothermal wells were put forward,such as broad-spectrum plugging technology with high plugging success rate,high temperature resistant lost circulation materials and application verification of temporary plugging material.This study will provide important reference for the study and engineering practice of plugging materials for geothermal wells.
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