The main purpose of this paper is to present the integrated approach to production prediction and reserves evaluation from the North Adriatic fields, taking into account the impact of transportation system's complexity on the gas production process. Production from the North Adriatic began in 1999 with the Ivana field, followed by the fields IKA and IDA in March 2006. After compression at the Ivana-K platform, Italian production share is transported through the 16" pipeline to the Garibaldi-K platform, while Croatian share is transported through the 18" pipeline towards the Pula terminal. Future development plans include several fields with expected production start-up in 2009. With respect to complexity of the production system, which includes 13 platforms and their mutual connection by system facilities, 56 production strings depleting 92 reservoirs, compression conditions on the Ivana-K, a scope to build an integrated model was not only production monitoring, but also searching for best export facility solution for the new development fields. Integrated model consists of three separate models:

  1. Reservoir model - based on material balance calculation matched to historical production

  2. Well productivity model - based on well and completion design and welltest results

  3. Pipeline model - based on existing facility design and matched to production conditions at Ivana-K The integrated model comprises producing elements that are connected via common manifolds and pipelines to a fixed pressure system, which sets boundary conditions for solving mass and pressure balance equations at each node.

Result is pressure and flow distribution in the network for the fixed pressure in system. Full model was run at different points in time during the history at which point consistency of the model was confirmed. As a result of Integrated model and its comprising models, separately matched with production and pressure history, reliable production forecast was obtained as a function of criteria and constraints set by reservoir performance as well as by transportation system. Preparation of such a unique model of all the gas fields in the North Adriatic enables quantification of the impact of changes on production rates, pressures and temperatures at any point in the system throughout the entire production life, better optimization and planning of gas quantities available for the Italian and Croatian market. Its benefit in terms of maximizing production and cost saving has proved to be significant while comparing different gas export facility options for projects in development phase

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