Most of oil and gas companies are building simulation models for its assets to planning reservoir development. However, even in those cases when the models are reliable and well calibrated to the production history, they do not always reflect the interaction between the different parts of a single system "reservoir-well-gathering system-processing facilities". In other cases when hydrodynamic models are the parts of an integrated model (IM), the models become too complex and require a long time of simulation, what mostly is not very convenient.

This article provides an example of the IM building for the two formations of one of the largest oil-gas-condensate field in the world. Two large gas-condensate reservoirs are in the pilot stage. Full-field development of these reservoirs will increase hydrocarbon production by 5 times (Figure 1). To develop and optimize production plans and the development of the asset, it was decided to use the integrated model.
Figure 1

Planned production profiles for gas. Formations Ach3–4 and Ach52–3

Figure 1

Planned production profiles for gas. Formations Ach3–4 and Ach52–3

There were considered different methodologies for constructing the unified model, which combines the reservoir models, models for wells and gathering systems and for processing facilities. Finally the best approach for this project has been selected. The initial compositional hydrodynamic models, which was matched to the production history, have been successfully converted to the Black-Oil models, while giving identical forecasts for gas and condensate and significantly reducing the simulation time. Well models were calibrated to historical data. The formation fluid in the gas gathering network was modelled using a simplified description, while in the models of processing facilities the fluid was modelling with the detailed composition. Despite of the differences in the approaches to the description of PVT properties of gas condensate in different simulators (Eclipse, Gap, Hysys), the developed Integrated Model has demonstrated consistency in the description of fluid PVT-properties. A significant reduction in time of simulation was obtained during the forecast calculations. The results of the Integrated Model were very important for the field development plan optimization, the development of which was previously limited to disparate models of reservoirs and ground infrastructure.

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