Abstract

The petroleum reservoir is a physical system defined by static and dynamic parameters. It is also an asset requiring investment. The reservoir model is a tool that we use in order to exercise control over the reservoir so that we can produce the reserves economically. By understanding the levels of confidence in our input reservoir parameters and by adopting a controlled approach to using the reservoir model we can strive to get a greater degree of control over the asset.

In this study each reservoir parameter in the model has been scored based on six criteria;

  • Data used in parameter determination

  • Methodology for parameter computation

  • Independent verification of the computation

  • Estimation of 90% confidence interval in the result

  • Actions taken to make 90% confidence range smaller

  • Percent decrease of the confidence interval

The Thistle field in the UK sector of the North Sea is used as a reference assessment in this paper.

The assessment methodology presented here can be used by senior technical staff and management to assess the degree of control given by the model before the predictions from the model are used for field development planning. The significance of this methodology is that it provides an objective measure of the quality of a reservoir model. It avoids reliance on intuition and gut feel in establishing trust in the reliability of production profiles and reserves estimates derived using reservoir simulation.

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