Today, strategic planning of field development is based on full-field static and flow simulation models which are regularly updated as part of field surveillance programs and by integrating the actual results of drilling and testing of new production and exploration wells and integrated interpretation of seismic surveys and reservoir core and fluid laboratory analyses. One of the key factors for the success of investment projects is how quick and flexible the decision-making process is. Therefore, in modern conditions, prompt integration of new data into full-field flow simulation models followed by their processing, analysis, and decision-making on adjusting the strategic goals is of particular relevance for oil and gas production companies. For unique multi-reservoir fields containing dozens of reservoirs, hundreds of accumulations and wells, it is hardly possible to promptly update full-field static and flow simulation models within less than 6-12 months, therefore, the decisions are made in the absence of up-to-date models, which may lead to poor quality of production forecasts. The purpose of the study was to develop an approach to the modeling of unique fields, which would allow prompt integration of new data in a full-field flow simulation model while keeping the level of detail without significant time input.

The problem of liquid loading in well bores for a great number of gas wells is considered. This problem is observed in the framework of production calculations using the simulation model. It is determined that groundless assignment of wells decommissioning criteria leads to significant errors in the assessment of cumulative gas production and well stop flowing time. Using the results of data after water breakthrough and wells stop flowing, the liquid unloading criteria in the gas wells were formed. The stationary unloading criteria depend on elevator equipment construction and critical production rates. They were evaluated, based on agreement procedure of calculated and actual liquid unloading parameters, by means of hydraulic well models. At the same time, applicability conditions for this technique were determined. In this paper, simple and sufficiently reliable methods and algorithms are proposed. They are used for accounting stationary liquid unloading criteria which are needed for right well decommission time. Moreover, the criteria make it possible to improve the predictive potential of the integrated field models and to arrange the operations for prolongation of well life. For instance, technological regime optimization and running additional tubings of smaller diameter made from coiled tubing (velocity strings) can be proposed.

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