三元共聚物抗盐降失水剂在塔河油田石炭系盐层固井中的应用

塔河油田石炭系盐层分布广泛,以纯岩盐为主,埋深在5100～5400 m之间.由于井深,井底温度高,石炭系盐层蠕动能力很强,在未下套管的裸眼中,导致盐层井段水泥浆封固质量较差,并存在不同程度的套管变形或挤毁现象,造成许多井没有完成地质任务. 研究评价了三元共聚物降失水剂DZJ-Y及其优化含盐水泥浆体系.结果表明,三元共聚物降失水剂具有良好的抗盐能力,在饱和盐水条件下能够较好地控制水泥浆失水.在塔河油田T914井φ 244.5 mm/φ 250.8 mm组合技术尾管固井取得成功,盐层段固井质量为优质.现场应用表明,抗盐水泥浆体系具有良好的流动性,失水控制良好,稠化时间可调;水泥石强度普遍较高,有利于提高水泥环的胶结质量;该水泥浆浆体均很稳定,没有析水和沉降;API失水量低,且能产生微膨胀,有助于提高固井质量.该抗盐降失水剂有效地提高了塔河油田石炭系盐层井段固井胶结质量.

Application of ternary copolymer salt-resisting fluid loss reducer in salt bed of Carboniferous system in Tahe oilfield

In Tahe oilfield, salt bed of Carboniferous system distributes widely in depth of 5100-5400 m, most of which are pure salt bed. By reasons of deep depth and high temperature down hole, the formation creates exquisite creep deformation, causing poor cementing quality in open hole in salt bed, and casing failure in different degree. A ternary copolymer salt-resisting fluid loss reducer and the relevant optimized salt-resisting cement slurry were investigated. Lab experiments established that the reducer has strong salt bearing ability, qualifying it to perform excellent fluid loss control in saturated salt solution.In-situ application showed that the salt resisting cement slurry exhibited good rheologial character,effective fluid loss control, adjustable thickening time and higher stone strength. The slurry was stable, without free water bleeding or solids setting, also providing slight expansion. In-situ data revealed that the fluid improved the cementing quality of salt bed of Carboniferous system in Tahe oilfield successfully.