表面活性剂型可加重固井前置液作用机理及应用

表面活性剂型可加重固井前置液是摈弃常规固井前置液中使用的无机和有机聚合物类悬浮剂,直接利用表面活性剂通过形成胶束进行增稠,使其溶液具有一定的黏度和切力,从而达到悬浮固相颗粒的目的。对该前置液的悬浮机理进行了详细的阐述,该表面活性剂型可加重固井前置液体系,适应密度范围宽、悬浮稳定性能好,最高抗温可达150℃,具有良好的流动性能,流变性能可调,与钻井液和水泥浆具有良好的相容性;可针对不同工况,改变前置液的流变性能,使体系保持较低的黏度,实现紊流或塞流顶替,最大程度地提高冲洗顶替效果;能够改善环空界面的胶结环境,兼具有隔离作用。对应用该前置液的2口具有代表性的大位移水平井及特殊工艺井进行介绍,经现场验证,该体系可依据实际井况进行流变性能调节,实现最佳的顶替流态,冲洗顶替效果好,且具有良好的抗高温沉降稳定性能,有助于固井质量的提高和确保固井施工的安全性。 

Study and Application of Mechanisms Weightable Surfactant Treated Preflush for Well Cementing

Weightable surfactant treated preflush for well cementing is a preflush viscosified directly with surfactant micelles instead of inorganic suspending agents or organic polymer suspending agents to render the preflush viscosity and gel strength necessary for the suspending of solid particles. This paper gives a detailed description of the suspending mechanisms of this kind of preflush. The weightable surfactant treated preflush can be used in cement slurries with a variety of densities and has good suspending stability and flow properties. It is resistant to high temperatures up to 150℃. It is compatible with drilling fluids and cement slurries, and its rheology can be changed to satisfy the needs of different work conditions. By controlling the viscosity of the preflush, turbulent flow and plug flow can be achieved in displacing hole fluid, and optimum flushing results can be obtained. The use of this kind of preflush improves the bonding between casing string and cement sheath, and the bonding between cement sheath and borehole wall. The weightable surfactant treated preflush also functions as a spacer in well cementing. Field operations on an extended reach horizontal well and a non-conventional well showed that the rheology of the preflush can be adjusted to satisfy the needs of the operations and to obtain optimum displacement and good well flushing. The preflush had good high temperature anti-settling property, which is helpful in improving the job quality of well cementing and guaranteeing the safety of well cementing operations.