Coating and electric heating technology for paraffin removal and prevention in horizontal shale oil wells with deep paraffin deposition
Since the large-scale development of shale oil in the Qingcheng Oilfield,frequent paraffin deposition in wells has led to failures such as paraffin sticking and blockages,accounting for over 30%of all operations,severely impacting the normal production of oil wells.Therefore,research on paraffin removal and prevention technology is crucial for ensuring efficient oilfield development.By analyzing carbon number distribution in crude oil,paraffin content,and paraffin deposition profiles,conducting downhole temperature field tests,and summarizing paraffin deposition characteristics at various production stages,the causes of deep paraffin deposition in shale oil wells were revealed.Furthermore,the rheological properties of paraffin were examined to analyze the conditions for thermal paraffin removal.There are three primary factors contributing to severe and deep paraffin deposition in wells:high paraffin content(20%),high paraffin precipitation point(25℃),and high inorganic component content in shale oil.Due to the loss effect of thermal washing fluid,the maximum effective depth of thermal washing is limited to 500 m,making it challenging to establish an ideal paraffin removal cycle.By optimizing two key processes:anti-paraffin coatings and electric heating paraffin removal,the paraffin deposition rate was reduced by 80%,and the frequency of operations due to paraffin deposition decreased from 0.16 times each well yearly to 0.07 times each well yearly,which meanwhile meets the requirements for the intelligent development of shale oil.
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