In this Case Study, AFS examines the development of an innovative workflow to assess emulsion stability using static multiple light scattering (SMLS) analysis. This method includes an in-house automated tool to process experimental time series obtained from Turbiscan emulsion laboratory testing. These results provided quantitative insights into water separation dynamics, which were required by the client to advance topsides process equipment design. In addition, these analyses have been effective at assessing emulsion breaker (EB) performance, as well as the impact of variables such as separation temperature, EB dosage rate, and the shear rate utilized in the emulsion preparation.
Emulsions play a major role in new oil field developments having a significant impact on flow assurance assessments, as well as on the design of both subsea and topsides equipment. A client-specific request involved tracking water separation over time at multiple experimental conditions including separation temperature, oil sample, and EB dosage for a total of 88 emulsion stability laboratory tests. Turbiscan equipment makes possible quick emulsion characterization using small sample volumes. In addition, SMLS testing yields high resolution data for assessing dispersion properties; however, the manual processing and interpretation of the resulting data sets can become tedious and time-consuming for the operator, while also introducing human-related errors.
Turbiscan output time series provide insights into several aspects of emulsion stability leading to effective emulsion characterization and quick turnarounds. A proprietary tool was developed to facilitate quick processing of Turbiscan output data. Conventional signal processing methods were implemented to inspect raw light transmittance and backscattering profiles obtained from Turbiscan emulsion stability testing. Figure 1 shows a schematic of a sample vial inside a Turbiscan cell (left) and the resulting light transmittance profiles at different times (right).
Figure 1: Schematic of a sample vial within a Turbiscan cell (left) and light transmittance profiles at multiple times from emulsion stability test (right)
Initial emulsion stability tests confirmed an EB will be required to improve production chemistry in the field. Furthermore, trends in Figure 2 captured the impact of increasing water cut on water separation dynamics in samples dosed with a constant oil / EB ratio. As water cut increases, the total amount of emulsion breaker in the system decreases. Accordingly, a lower separation efficiency was found at higher water cuts during the early stages of the test (i.e., initial 30 minutes).
Figure 2: Water separation over time in samples dosed with emulsion breaker at varying water cuts
This study evaluated multiple aspects regarding emulsion stability in a greenfield development. Automated Turbiscan data processing improved emulsion testing workflow, reducing turnaround times while providing deeper insights into the test results. Additionally, water separation curves vs time were generated from Turbiscan data, saving time and fluid inventory from additional testing.