Field Analysis through Integrated Modeling and Simulation

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Abstract

Simulation to predict the well and reservoir performance is a very important and established process in reservoir engineering. Integrated production modeling allows improving the understanding of the field’s performance and production network, fluid flow behavior and optimization at any stage and level during the life of the field through reservoir modeling processes.

This work forms an in depth study of the production data from the K5-F field in the Dutch sector of the Southern North Sea in which the field is analyzed through integrated production modeling to remove the uncertainties coupled with this field. Due to the absence of individual flow meters for the three wells producing from the K5F field, a first step was the determination of a production split per well. This production split is then used to quantifying the water gas ratio which forms the input data for material balance modeling. The effect of a changed production history per well on analysis and parameter estimation is also studied.

The well test analysis results and corrected production history incorporated in the material balance software allowed the estimation of other unknown reservoir parameters such as volumes, saturation, relative permeabilities and compartmentalization per well. Using material balance modelling as a tool for history matching, and taking into account the local geology the K5-F reservoir showed that the K5-F1 is a segmented reservoir behaving as separate compartments. Through interference testing it was found that is communication between K5-F1 and K5-F3 through a shared aquifer that is giving additional pressure support to the K5-F1 field. K5-F2 is not in communication with a different reservoir. For both K5-F1 and K5-F2 a reservoir pressure and water saturation match within a 2% range is found

Even though the K5-F field is one that has many production difficulties, unknowns and uncertainties, the workflow used and presented in this thesis allowed for the successful development of an integrated production model based on the most recent ideas and developments. The designed and simulated reservoir model resulted in cumulative production match around 3% and good reservoir pressure, wellhead pressure and gas rate match for K5-F1. K5-F2 found a cumulative production match of 4,8% which is above the acceptable 3%. With the assumptions and optimizations made throughout this study it was possible to create a reservoir model capable of forecasting the K5-F1 and K5-F2 well performance.

This research has shown that the amount and quality of production history available for a field and/or wells can have a huge impact on the analysis on reservoir parameters and model estimations. Besides the quality of the production data being used, the amount of production history plays a large role in well test analysis. Small amounts of production history for instance can influence in the late stage of the pressure build up derivative which can lead to an underestimation of the skin. Even something as simple as a new production split has led to a 16,76% lower cumulative production for K5-F1 and a 13,21% higher cumulative produced volume for K5-F2. Therefore it can be stated that the quality of a reservoir model and history match of a field has a direct correlation with the quality of the production and field data.