A033 PRACTICAL METHODS FOR UNCERTAINTY ASSESSMENT OF FLOW PREDICTIONS FOR RESERVOIRS WITH SIGNIFICANT HISTORY -AF IELD CASE STUDY

This paper discusses two practical strategies to quantify the uncertainty in production and injection forecasts for a field with a long and complex production history with poor quality measurements. These methods are applied to a large offshore field in Africa that has been on production for more than 30 years. The first method follows an advanced Experimental Design framework and requires the use of non-linear Response Surfaces such as kriging. The second method uses sensitivity coefficients; it can be considered as a first pass to evaluate uncertainty before embarking in a more comprehensive analysis. Both methods lead to multiple acceptable representations of the history of the reservoir. The range of outcomes obtained with production forecasts allows for uncertainty quantification. In this case, both methods delivered similar prediction results.