Double-Emulsion Spacer Design for Highly Efficient Invert Emulsion Displacement

Abstract

The wellbore displacement is a necessary and critical step toward subsequent completion operations and production. A successful displacement process saves significant rig time, cuts disposal volume, reduces fluid contaminations and provides the best opportunity for a successful completion. Traditionally, a displacement train typically has multiple cleaning spacers, including a solvent spacer and a surfactant spacer. It is highly preferred to have a cleaning spacer to achieve the desired wellbore cleanliness as a single stage and with minimum circulation volume. Surfactants, solvents and emulsions are used in the cleaning spacer(s) for displacement of invert emulsion drilling fluids (IEF). The spacer system is selected depending on the displacement requirements and wellbore conditions. This paper describes innovative double–emulsion technology that shows highly efficient and effective performance in IEF displacement, as the design fully combines the power of both surfactants and solvents. This paper presents theoretical and lab testing results for fundamental understanding of IEF film removal from metal surfaces under various conditions. It was found that the solvency and surfactancy play different roles during the film removal process. A macroemulsion or microemulsion contains both solvents and surfactants but they often have a limited operational window with reduced solvency and surfactancy. Based on the analysis described in this paper, an innovative double-emulsion system was developed to fully preserve the solvent cleaning power and dispersive and water–wetting power of surfactants. It has a unique water-in-oil-in-water structure, in which the dispersed solvent droplets contain smaller droplets of a second aqueous phase. The solvent droplets effectively remove the top layer of mud film and directly deliver the surfactants to the metal surface. This technology has been applied in various successful field applications.

Fluid-Loss Control Technology: From Laboratory to Well Field

“…The paper [33] describes an experience where an emulsion suspension hydrophobic composition with a wide range of fillers is used for horizontal open holes.…”

Microfluidic-Based Analysis on the In Situ Microemulsion Formation and Transport in Fractured Porous Media

“…12,13 Besides, in situ microemulsion is also applied in wellbore cleanup and plays a good role. 14 Numerous researchers have conducted extensive static and dynamic experiments to investigate the characteristics of microemulsions and their efficacy in oil displacement. The static research experiments primarily involve salinity and oil− water ratio scanning experiments to investigate the equilibrium phase behavior in pipet experiments.…”

“…Some field tests of in situ microemulsion have been conducted. The results show that injection pressure decreased significantly, and the oil production increased obviously after the MS was injected. , Besides, in situ microemulsion is also applied in wellbore cleanup and plays a good role …”