Integrating Asset Modelling for Strategic Gas Field Development Planning and Short-Term Optimization
Authors: Mulkamanov A. , Dorofeev A. , Vorobyev V. , Bolshakova A. , Chupeev A. , Sauve R. , Tonkin T. , Vernus J-C. 
Published: October 2015

Abstract
Severneftegazprom OJSC is the operator of the strategic Yuzhno-Russkoye field, ensuring the gas supply to the Nord Stream pipeline. Fulfillment of contractual obligations and achievement of economically sound hydrocarbon recovery with consideration of operating limitations due to seasonal production fluctuations and natural reservoir depletion, require an efficient field management strategy. Solving these problems is impossible without a unified field model to account for the interaction of all production system elements, from the reservoir to the process facility system.
Taking into account the complexity of production planning, with respect to multi-level limitations, the license holder (mineral developer) decided to test the integrated modeling technology, which is becoming a standard of the oil and gas industry. The document describes the work carried out to create an integrated model of gas Cenomanian deposits of the Yuzhno-Russkoye oil-gas-condensate field. The resultant integrated model (IM) combines a hydrodynamical reservoir model (HDM), well models, a gas gathering system (GGS) and a compressor station (BCS – booster compressor station). Such unified field model, in contrast to stand-alone model calculations, allows calculating pressure losses and phasing transitions accurately during the fluid flow from the reservoir into the main gas pipeline. To minimize the risk when making decisions based on prediction calculations, much attention is paid to improving the quality of historical production data matching, both on a full-scale IM and its individual components. On the basis of IM, long-term predictions are made for 20 years, reproducing the plan of changes in the BCS parameters, taking into account seasonal gas demand and production rates distribution across the specified regions; an analysis is carried out to study the sensitivity of the target seasonal production rates and cumulative recovery to limitations, such as BCS stage commissioning dates, maximum allowable drawdown pressure, water-gas ratio. Based on the calculation results for various scenarios, percentages of deviation from the specified production rates were analyzed. The integrated model allowed adjusting the target seasonal production rates. Most loaded manifolds in the gathering network with gas velocities above 15 m/s were identified. Manifolds where a risk of liquid hold up may exist during production decline stage have also been identified.
As part of the work, a workflow was tested for well and GGS technical regimes optimization, taking into account these limitations, both at the field level (uneven development of reserves), and the level of wells and manifolds (reservoir drawdown, minimum and maximum gas velocities). The results achieved will allow the experts of Severneftegazprom OJSC to use the IM of the field as a tool for making decisions to minimum risks and accomplish long-term tactical and short-term operational objectives.