吐哈油田葡北3-12井超长封固段固井技术

葡北3-12注气井位于吐哈盆地葡北构造带中断葡北1号构造．井深为3610m。针对该区块地层承压能力低，易漏失，油气水窜严重，常规固井方法无法满足固井要求的问题，该井采用三段三凝制、常规水泥浆和泡沫水泥浆体系固井，并采用重钻井液顶替技术．降低施工压力。该技术能保证固井候凝过程中井底压力平衡，施工安全。现场应用表明，采用常规水泥浆和泡沫水泥浆固井技术．提高了低压易漏井、长封固井段的固井质量，解决了水泥返高不足的问题；并通过一次常规固井工艺实现了全井封固，简化了施工工艺，节约了成本，经济效益和社会效益十分显著。该井封固优质段累计达2600m，优质率达85％，固井结果良好。

Ultra-long isolation section cementing technology in Well Pubei 3-12, Tuha oilfield

Well Pubei 3-12 is a steam injection well located in Pubei 1# structure bone of Tuha basin with a total depth of 3610 m.Due to the low pressure bearing capacity of the formation, and such problems as lost circulation and oil/gas channeling, the conventional cementing technology is not a-vailable for this well.New technologies were applied including three -stage three -setting cementing method, combined use of conventional cement with foam cement slurries, as well as weighted mud displacement to reduce operation pressure.The technologies could ensure the well bottom pressure keeping balanced during waiting on cement and cementing safety.Field application showed that the cementing quality of easy loss well and long isolation section has been improved, and the insufficient height of cement top has also been solved.Meanwhile, full wellhole cementing has been successfully achieved through one regular cementing.Thus, cementing process could be simplified and the cost could be reduced.The excellent quality sections totaled up to 2600 m and high quality rate reached 85%.