Research and application of flushing fluid BCS-020L for oil-based drilling fluid cleaning

For drilling with oil-based mud, the oil slurry and film attached on wellbore or casing wall affect severely the cementing quality of the interface. To improve the compatibility between cement sheath and well surfaces, as well as increase the interface cementing quality, a preflush system BCS-020L was developed. The BCS-020L provides good compatibility with drilling mud and spacer fluid, and can effectively remove the oil-based drilling mud attached to the well and casing wall, with high cleaning efficiency, higher than 80%. Also, the BCS-020L could change cementing interface effectively from oil wet to water wet, and improve the cementing quality of interface efficiently. The preflush system BCS-010L has been successfully applied on Well LIUPING 1 in Yumen Oilfield with excellent cementing quality.