This paper shows the implementation of a workflow for quantitative use of time-lapse seismic data in computer- assisted history matching of simulation models. The use of time-lapse seismic data alone or combined with production data gives additional valuable information about the reservoir and its behaviour. Several field examples of successful qualitative use of time-lapse seismic data exist. However a quantitative integration in the history-matching loop, considering all different types of scale along with measurement uncertainties, still represents a challenging task. We present the workflow applied in a real North Sea field case, where production data and inverted seismic data from two surveys are utilized. An implemented petro-elastic model converts from reservoir to seismic parameters. Commercial optimization software is used to minimize the difference between observed and simulated data and to update the reservoir model parameters. The main focus is to identify, understand and quantify the uncertainties in the data and the model at each step of the workflow. A key to success is tight communication and teamwork between geophysicists and reservoir engineers. Results show that including information from time-lapse seismic data in the history matching process gives us a better understanding and description of the reservoir performance and an optimized static and dynamic reservoir model. Introduction Traditionally, reservoir simulation models are updated as production data are obtained through a history matching process. Parameters describing the reservoir, like structure, petrophysics, fluid flow and communication are modified as more and more information becomes available. Much manual work is required, however over the last years serious effort has been put in the development of computer aided tools. Nevertheless, the history matching process cannot be fully automized and manual considerations are inevitable. Especially in the case of combining data sets of different nature, as it is the case for production and seismic data. Production data, sampled frequently in time, is defined with respect to the wells and hence is of local type. Time-lapse seismic data, sampled sparsely in time and representing global information of fluid displacement, is regarded as an important supplement to the production data. Including both data types in the history matching loop, is expected to improve the quality of the history match, as additional and complementary data is accounted for. However, due to their different character with respect to the resolution in space and time, a quantitative combination of these data types represents a challenging task. 4D seismic data analysis has matured to a tool to be used qualitatively[10, 11] to identify drained regions of the reservoir and compartments of remaining oil. Examples of quantitative use of 4D seismic data in history matching are shown in Refs. 3, 5–9 and 13. In an earlier research project, HUTS[1,2,4] (History Matching Using Time-Lapse Seismic Data), a co-operation between Norsk Hydro, Total, Eni and Schlumberger, commercial software[14, 15] was developed which combines production data and time lapse seismic data in computer assisted history matching. This software is applied in the workflow described in this study.

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