深部结蜡页岩油水平井涂层与电加热清防蜡技术

Coating and electric heating technology for paraffin removal and prevention in horizontalshale oil wells with deep paraffin deposition

庆城油田页岩油规模开发以来,井筒结蜡导致蜡卡、蜡堵故障频发,占到作业总量的30%以上,严重影响了油井正常生产,清防蜡技术研究对保障油田高效开发具有重要意义。通过分析原油碳数分布、含蜡量、结蜡剖面,开展井下温度场测试,统计不同生产阶段油井的结蜡特征,揭示了页岩油井筒深部结蜡的原因,结合蜡质流变特征分析了热洗清蜡条件。庆城油田页岩油含蜡量高(20%)、析蜡点高(25℃)、无机质组分含量高(65%)是导致井筒结蜡严重且深度深的3个主要原因,受热洗液漏失影响,热洗作用深度最深仅500 m,难以建立有效的热洗循环以实现理想排蜡效果。通过优化配套防蜡涂层、电加热清蜡这2项主体清防蜡工艺,结蜡速率下降80%,结蜡导致的作业频次由0.16次/(口·年)下降至0.07次/(口·年),为庆城油田页岩油的高效开发提供技术保障和借鉴经验。

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.