新型DF冲洗液的研究与应用

在固井注水泥作业时，水泥浆与钻井液接触后，常常在水泥浆与钻井液交界面处形成非常粘稠的水泥或钻井液混合物，这些混合物粘附在井壁或套管上，影响水泥环与套管和井壁胶结质量，甚至造成地层间封隔不好形成窜槽。介绍了目前国内冲洗液现状，并针对水泥浆与钻井液相溶性差，对注水泥作业危害大等问题，研制开发了DF冲洗液。研究了DF冲洗液的组成、性能特点，重点从加量、温度、滤失性能、流变性、相容性等方面对DF冲洗液性能进行了全面的室内检测与评价。并进行了TK811等10多口井的现场应用。结果表明，DF冲洗液加量在3%～6%间，具有良好的冲洗、隔离作用，能明显降低钻井液的粘度和切力，降低失水量，与钻井液、水泥浆具有良好的相容性，易形成紊流顶替，有利于提高水泥环与地层间的胶结质量。

RESEARCH AND APPLICATION OF A NEW TYPE OF FLUSH FLUID

During cementing, a layer of viscous cement/drilling fluid mixture is often formed at the cement slurry-drilling fluid contact. The mixture sticks to the wellbore or casing, affecting the cement sheath and bond quality, or even causing channeling due to poor formation isolation. It is introduced the status quo of domestic flush fluids, and is described a kind of DF flush fluid, which is developed according to the problems of poor compatibility between the cement slurry and the drilling fluid and the great impact to the cementing operations. The composition and performance are discussed herein, especially the indoor inspection and evaluation of the effects of dose, temperature, filtration, rheology and compatibility on performance are focused on. This flush fluid system has been used on over 10 wells, including the well TK 811. The application results indicate the DF flush fluid has good flushing and isolation effects when the DF fluid dose is between 3% and 6%, it can decrease remarkably the viscosity and gel strength of the drilling fluid, can also reduce the water loss, have good compatibility between the drilling fluid and the cement slurry; it is proved to be easy to have turbulent displacement, being helpful to improve the bond quality between the cement sheath and the formation.