油井水泥早强增韧剂ZSJ的室内研究

Laboratory study on plastifier ZSJ for oil well cement

水泥环可以认为是一个先天带有一定缺陷和微裂缝的脆性材料 ,这些微裂缝及缺陷使水泥环易受后续施工、射孔等影响 ,发生脆裂 ,或与套管、井壁剥离 ,影响油气井后期开采 ,缩短油气井的寿命。塑性水泥可以很好地解决水泥环的脆裂问题 ,它通过掺入高强度纤维 ,不仅可增加水泥石的强度 ,而且可改变水泥石的弹性。室内采用具有不同长度分布和合适长径比的混合短纤维 (纤维长度均小于 4mm)、粒径为 0 .180～ 0 .2 80mm(6 0～ 80目 )的橡胶粉、活性微粒和与之相匹配的激活剂制得了早强增韧剂ZSJ。实验发现 ,ZSJ抗盐性能优良 ,与其它外加剂有良好的配伍性 ,增韧剂ZSJ的加入对水泥浆的施工性能基本无影响 ,但能大大改善水泥石的力学性能 ,水泥石抗压强度、抗折强度和抗冲击韧性均有不同程度的增长。实弹射孔实验证明ZSJ水泥石能够抵抗射孔等后续施工的冲击 ,可有效提高水泥环封固质量 ,防止地层流体窜层 ,延长油井寿命。

The cement sheath down hole may be considered as a brittle microfissured material with some flaws in nature, and the microfissures and flaws make the sheath easy to crack down or scale from casings or well bore in continuous operations such as perforation, thus impacts later production of the oil/gaswell, sometimes even shortens the well life. Plastic cement solves cracking problem of cement sheath successfully. With high strength fiber added in, not only the strength, but also the flexibility is increased. In lab, a plastifier ZSJ was made from mixed short fiber with different length distribution (less than 4 mm),rubber powder(particle size within 0. 180～0. 280 mm), active particle and proper activator. Tests showed follow advantages of ZSJ : (1) It has good anti-salt contamination property and excellent compatibility with other additives: (2) It not only plays no role in operational property of cement slurry, but also improves dynamics property of cement stone to increase the compression strength, bending strength and impact resisting toughness in different extents. Perforating tests verified that the ZSJ cement stone could endure impaction in subsequent operations such as perforating. The cement bond quality was!improved, formation fluid channeling was prevented and oil well life was prolonged.