Portal de Periódicos da CAPES

Population Balance Model for Batch Gravity Separation of Crude Oil and Water Emulsions. Part II: Comparison to Experimental Crude Oil Separation Data

2012; Taylor & Francis; Volume: 33; Issue: 4 Linguagem: Inglês

10.1080/01932691.2011.574950

1532-2351

Brian A. Grimes, Carlos A. Dorao, Nils Opedal, Iva Kralova, Geir Humborstad Sørland, Johan Sjöblom,

Hydraulic Fracturing and Reservoir Analysis

Abstract The mathematical model presented in Part I of this article is compared to experimental data obtained from low-field NMR experiments on a heavy crude oil undergoing gravity separation with two different concentrations of a chemical demulsifier. Experimentally measured parameters are used in the model and include a) the water cut and drop size distribution of the emulsion (obtained directly from the NMR measurements), b) the densities and viscosities of the bulk liquids, and c) the interfacial tension; the results obtained from the model were used to analyze the experimental data in terms of these parameters. The model was formulated based on first-principle physical mechanisms, and thus, not only are the fitting parameters are kept to a minimum, good agreement between experiment and simulation results were obtained. The model reasonably predicts both sets of data for the different demulsifier concentrations with no change to the so-called fitting constants, but by the parameter that represents the magnitude of the interfacial force in the film drainage equations. Such a change in this physical parameter can be reasonably inferred by the action of the increased demulsifier concentration. Both the model and experimental NMR data indicate that the degree of poly-dispersity is a key factor in the rate of coalescence and subsequent rate of separation by sedimentation. This analysis illustrates the link between poly-dispersity and the coupling of coalescence and sedimentation rates; this is crucial for determining how different droplet size fractions will affect the overall efficiency of the separation and how physical properties of the fluids and phase interface can amplify or negate these phenomena. The separation model is a very helpful complement to the NMR technique as the model can output direct comparisons to the NMR data. Keywords: Coalescencecreamingdispersionemulsiongravity separationNMRpopulation balancesedimentation Acknowledgments The authors gratefully acknowledge support for this work from the industrial consortium JIP-1 consisting of AkzoNobel, Baker Petrolite, BP, Champion Technologies, GE Oil & Gas, Hamworthy, Maersk, Petrobras, Shell, Statoil ASA, and Total.