G级高抗硫油井水泥稠化性能异常原因分析

针对中国部分G级高抗硫油井水泥存在稠化时间短、与外加剂配伍性差、触变性强的问题,以BG厂生产的G级高抗硫油井水泥为例,从水泥原料、熟料化学成分及生产工艺角度出发,结合现场水泥质量检测和水泥浆性能实验,分析了水泥浆稠化性能不合格的原因。结果表明,原料中Mg O含量过高及化学成分不稳定造成熟料中Mg O及C3A含量过高(分别为4.51%、7.21%),水泥中碱含量及f-Ca O含量过高(为1.97%)、SO3含量过低(为0.42%),煅烧温度低、窑内物料填充率高及冷却不充分,均会导致水泥浆稠化时间过短;水泥熟料中C3A和C4AF含量过高会导致水泥浆与外加剂配伍性不良,导致水泥浆稠化性能异常。

Analysis of Abnormal Thickening Behavior of the Class G High Sulfate Resistance Oil Well Cement

Some cement slurries formulated with class G cement are studied for the improvement of their poor thickening performance. Clinkers made from raw materials containing high concentration of MgO and unstable components have higher MgO and C3A (4.51% and 7.21%, respectively), and the produced cements in turn have high alkaline and f-CaO concentration (1.97%) and low SO3 concentration (0.42%). Calcination at low temperatures, denser packing of raw material in kiln with limited space, and inadequate cooling all lead to unduly short thickening time. Higher concentrations of C3A and C4AF in clinkers will result in poor compatibility of cement slurry with additives and abnormal thickening behavior of that cement slurry.