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This paper describes the application of dynamic local grid refinement in a multiple application reservoir simulator. Using this procedure generally enables a significant procedure generally enables a significant reduction of the total number of blocks necessary for a good reservoir description. This procedure is combined with a number of EOR-options, automatic selection, variable in time of the implicitly computed variables, an ordering scheme for the equations devised specifically for the characteristics of local grid refinement, and several procedures for the solution of the system of equations. Together these features create a tool which is capable of providing quick and economic solutions to the problems encountered in reservoir simulation. Introduction In 1981 the Joanneum Research Society's Laboratory for Oil Recovery (LOR) started working on the development of SURE (Simulation Using Refinement), a new reservoir simulator. This simulation program has the following distinctive characteristics:Combination of gas/water, black-oil, compositional, steam-flooding and polymerformulation in one programImplementation of all formulations within one simulation gridAutomatic or free formulation selection and automatic or free selection per block and time step of the implicitly computed variablesImplementation of time-variable local grid refinement Acs et al and Kendall et al have already reported on the combination of different formulations in one program. It has been recognized for some time that it is possible to vary the formulations and the implicitly computed variables. The technique of local grid refinement has already been used for the solution of differential equations. The first steps in the application of local grid refinement in reservoir simulation were made by Heinemann et al and Rosenberg. To date there have been no reports on the application of local grid refinement in a multiple application reservoir simulator. THE BLOCK SYSTEM Initially a two-dimensional Cartesian coordinate system with axes I2 and I3 is selected for the representation of a block system for reservoir simulation. The coordinate plane is projected onto the top surface of the reservoir. The I1-axis is directed downwards perpendicular to this plane. A nodal point is associated with each block. Nodal points in the centre of the blocks form a block-centred grid, and a point-distributed grid is formed when the block boundaries bisect the distance between the nodal points. The advantages and disadvantages of these grid systems have been discussed at length by Settari and Aziz. The nodal points are defined by the second procedure, because the point-distributed grid ensures a consistent solution method even with non-equidistant block widths. These blocks are termed fundamental blocks. p. 205