History Matching

Abstract

To develop a model that cannot accurately predict the past and present performance of a reservoir within a reasonable engineering tolerance of error is not a good model for predicting the future performance of the same reservoir. Hence, history matching is a process of adjusting key properties of the reservoir model to fit or match the actual historic or field data. It helps to identify the weaknesses in the available field data, it improves the reservoir description and forms the basis for the future performance predictions. To history a material balance model or reservoir simulation model, the known parameters to match or tune are the production data, PVT data, hydrocarbon properties, reservoir properties, and pressures while the unknown parameters are the water or aquifer influx and reserves (Stock tank oil initially in place, STOIIP). It is often difficult to perform history matching manually, thus, there are several simulators available to successfully history match a field with minimum tolerance of error. To achieve the desired objectives, several parameters such as rock data, fluid data, relative permeability data, pressure survey data to mention a few, need to be varied either singly or collectively to minimize the differences between the observed data and those calculated by the simulator. These variables are further quantified as low and high uncertainty. Also presented in this chapter, are the steps to match reservoir pressure, saturation, well productivity index, identification of history match problems and possible modifications and the methods of history matching.