Application of Reservoir Simulation in Torton 8 Matzen
Authors: Stockenhuber F. , Schrockenfuchs G. , Suchanek R. 
Published: December 2007

The Reservoir simulation using the two-dimensional three-phase compressible flow simulator of the International Computer Application Company showed, that a stratified reservoir such as the Torton 8 Matzen, can be simulated with a two-dimensional model in addition to a vertical equilibrium concept. Vertical inhomogeneity was simulated by so called shale factors which reduced the permeability between gassand and oilsand as well as between oilsand and watersand. Inhomogeneity in horizontal direction required regional changes of the transmissibility in i- and j-direction. Further difficult problems were caused by an extreme viscosity ratio of high viscous oil to gas and high viscous oil to water. In the twenty years of history-matching a strong gas cap expansion in the first period, a peripheral natural water drive in the following period, and finally, a ten year's period of water injection program have been successfully matched. The prediction showed on one hand that the ultimate recovery prediction showed on one hand that the ultimate recovery will be in the same amount as it was estimated by an engineering analysis with conventional methods from the successful performance of the water injection program. On the other performance of the water injection program. On the other hand the investigated runs of future production have shown a way leading to an optimal production strategy. In the near future, further production strategies on regional flooding effect, different injection schemes, regional recovery studies based upon saturation distribution and production possibilities of new production locations will be studied. In possibilities of new production locations will be studied. In this manner the primary purpose of the simulation technique is obtained in optimization of the current secondary programs in OeMV'S oilfields.

Introduction

The water injection program for the 8th Torton Reservoir is at pressent OeMV's largest secondary program. At the beginning there were considerable difficulties of different nature that were against the realization of this pressure maintenance program. Nevertheless it was necessary to reach the decision program. Nevertheless it was necessary to reach the decision to carry out this program, since an investigation of the probable recovery factor showed that the primary recovery itself would only amount to 16 percent of the original oil in place.

On the basis of a prediction from 1960 it could be seen that the recovery could be increased to 23 percent by applying a water injection program. Figure 1 shows that the secondary program was more successful, since in contrary to the prediction program was more successful, since in contrary to the prediction a stabilisation of the production rate could be achieved.

A review of the reservoir engineering analysis from the preceding year showed that the final yield of the 1960 preceding year showed that the final yield of the 1960 prediction was exceeded by 3 Mill m3 oil. prediction was exceeded by 3 Mill m3 oil. The reliability of this prediction based upon traditional reservoir engineering methods such as Stiles, Dykstra, Parson etc. should be examined in the reservoir simulation.

In addition, the 8th Torton reservoir is a typical Torton reservoir, complicated in its structure, perhaps OeMV's most complicated reservoir.

Before the simulation of this reservoir will be discussed, the structure should be mentioned briefly.