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Production Decline Analysis Using Simulation Model:

The Impact of Varying Mobility

Luong, Minh and Nguyen, Duc

Engineering Honours Degree, 2013

University of Adelaide


Understanding of reservoir performance and consequential production behaviour is important in optimizing field development and during reservoir management for producing fields. Specifically, it is known that for water-oil displacement, production decline is a function of mobility ratio and formation dip, the first a function of relative permeability and fluid viscosity for each phase, as well as reservoir geometry and the exact nature of the drive mechanism. The project aims at discussing production decline behaviour by using reservoir simulation models, Decline Curves Analysis (DCA) and analytical models. After construction of a conceptual model, simulation output is used as input data for DCA and analytical models, Buckley- Leverett and Welge for diffuse flow, and Dietz for segregated displacement. (Dake,1942)
The first part of the study involves the determination of the type of decline as a function of the shape of relative permeability curves, among other parameters a function of wettability. The second objective of the project involves a sensitivity analysis of production decline as a function of changing formation dip and fluid properties, i.e. oil viscosity. Other sensitivities and reservoir layering may also be studied. The third part, Buckley-Leverett analysis were base on the number of equations and fraction flow to determine the time breakthrough also the oil recovery factor and cumulative oil production. The sensitivity were analysed with the difference in oil viscosity, relative permeability and variation dip angle base on the fraction flow graphic indicated with the Welge method to figure out the impact of various mobility in oil production and made the comparison between the simulation model and theory model.
The comparison between simulation model and Buckley-Leverett were made to analysis the real case with theory case. The conclusions are in all the case the results of B-L model were always higher than the simulation model. The reason are in B-L models the fraction flow was used to construct the breakthrough time, oil recovery and cumulative oil production, however the fraction flow in B-L model could not take the capillary pressure to analysis and have to use the graphic to indicated the break through point which could change by difference elements. Moreover, the differences in simulation model are its less errors base on the amount of analysis run with the software.

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Australian School of Petroleum



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