Wellbore preparation is essential to helping achieve optimum cement coverage for zonal isolation integrity. Conventionally, wellbores are cleaned and prepared for cement placement with a fluid train that precedes the slurry and can include spacers, flushes, water-based muds and/or scavenger cements. In late 2012, Halliburton introduced efficiency fluids, a new family of fluids that contributes significantly to preparing the wellbore to receive cement.
While enhancing displacement efficiency via micro particulate material with a high surface area, the fluid interface provided by efficiency fluids reduces intermingling with oil-based muds (OBM). This helps improve recovery volumes of OBM for better operation’s cost management. Additionally, efficiency fluids can consolidate when left in the annular space above top of cement, helping to stabilize what would otherwise be free pipe. As a result, efficiency fluids can serve to create a protective seal shielding this portion of the casing string from the corrosive effects of water and/or water-based muds that might otherwise remain in the annular space above top of cement.
Efficiency Fluids can be used as a displacement fluid during cementing operations for surface, intermediate, or production casing strings in much the same way a spacer is used. Similarly, Efficiency Fluids are an effective replacement for water-based muds commonly used to displace expensive oil-based mud (OBM). This fluid helps improve returns and surface recovery of OBM.
The suspension properties of Efficiency Fluids increases fluid stability, making them particularly useful in horizontal applications. This property helps mitigate solids settling of cuttings carried along during cleaning. It also helps mitigate bridging off across thief zones and avoids filtrate loss to the producing zones or fresh water aquifers, while maintaining constant hydrostatic pressure.