The application of the Dual Spacer™ system is as a low-viscosity, weighted spacer (flush) for primary and secondary cementing operations. The Dual Spacer system can also be designed to displace water- and oil-based muds.
The Dual Spacer system can be formulated with freshwater, seawater, 3% KCl, and salt concentrations as high as saturation in well temperatures ranging from 60°F to 500°F (16°C to 260°C). Its rheological properties typically allow it to be pumped in turbulence at reasonable displacement rates. These properties help improve mud displacement while maintaining drilling fluid/cement slurry isolation.
The Dual Spacer system interacts with the following supplementary additives:
- Mixing aid: Dual Spacer Mixing Aid additive helps improve surface suspension properties during low shear mixing operations in offshore sludging pits or after batch-mixing operations featuring bulk-blended Dual Spacer system.
- Retarders: When the Dual Spacer system is pumped at elevated temperatures, a retarder should be added to counteract the dilution effect occurring at the cement-spacer interface. Otherwise, pump time will be significantly reduced.
- Surfactants: When oil-based muds are displaced, surfactants reduce interfacial viscosity and preferentially water-wet the pipe surface, which promotes better cement bonding.
- Defoamers: Adding D-Air 3™ defoamer helps combat the foaming tendencies of a surfactant-laden Dual Spacer system. When surfactants are not used, other defoamers, such as NF-3™ defoaming agent or D-Air 2™ antifoaming agent, can also be applied.
The Dual Spacer system has the following benefits:
- Helps improve mud displacement while maintaining drilling fluid cement/slurry isolation.
- Can be used over a wide temperature range.