Title: Experimental research on phase behaviour and vapour/liquid equilibrium of N2 and heavy oil system

Authors: Fangfang Li; Shenglai Yang; Changlin Shi; Weiying Yao; Wei Wu

Addresses: CNOOC EnerTech-Drilling and Production Co., 300452, Tianjin, China ' China University of Petroleum, 102249, Beijing, China ' CNOOC EnerTech-Drilling and Production Co., 300452, Tianjin, China ' CNOOC EnerTech-Drilling and Production Co., 300452, Tianjin, China ' CNOOC EnerTech-Drilling and Production Co., 300452, Tianjin, China

Abstract: In the process of N2 injection, the dissolution and diffusion of N2 into oil will change the physical properties of crude oil and enhance oil recovery. In this paper, two experimental procedures are investigated to measure phase behaviour and equilibrium features of crude oil and injected N2. The dynamic miscibility experiment was conducted to obtain N2-oil phase behaviour and physical property change data, while the static miscibility experiment was conducted to simulate the vapour/liquid equilibrium process features. The result of dynamic miscibility experiment showed that it is difficult to achieve miscible displacement for N2 injection due to the low solubility and low extraction capability of N2; however, the solution of N2 can reduce oil viscosity and IFT, and the high compressibility coefficient of N2 can implement the displacement energy to obtain higher oil producing rate. The static miscibility result indicated that N2 dissolved in crude oil through a contacting interface and then diffused in deeper part of oil, contacting time and equilibrium pressure are key influence parameters to vapour/liquid equilibrium features.

Keywords: phase behaviour; equilibrium features; heavy oil; dissolving mechanism; diffusing mechanism.

DOI: 10.1504/IJPE.2018.093155

International Journal of Petroleum Engineering, 2018 Vol.3 No.2, pp.95 - 104

Available online: 03 Jul 2018 *

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