One of the main aspects that is worth paying attention to when planning the development of gas-condensate (GC) fields is accounting for and reproducing gas-liquid phase transitions that affect the flow of hydrocarbons (HC) in the reservoir as well as gas and condensate production indicators during the entire life cycle of the field. Undoubtedly, this effect will be more significant for cases with a complex gas component composition, high condensate content, as well as under conditions of low reservoir formation permeability and a high degree of areal and vertical heterogeneity. Compositional hydrodynamic modeling is a comprehensive tool for assessing hydrocarbon production capabilities, taking into account the phase behavior for GC field. The purpose of this work is to compare the various methods of improving the accuracy of numerical simulations and the reliability of the hydrodynamic modeling results for this type of reservoirs.
Using a high-resolution hydrodynamic simulator and a high-performance cluster system, multivariate simulations were performed to evaluate the effect of various parameters and options on the results of numerical simulations. The simulations were carried out using a compositional model, which is an analogue of a gas-condensate fields in Western Siberia within Yamalo-Nenetsky Autonomous Okrug (YNAO), based on geology, PVT and core, production history and well test data for vertical and subhorizontal wells, accounting for the presence of hydraulic fracturing. The work started with a detailed study of the challenge while the GC systems modeling on local sectors with further transition to a larger scale models using the results obtained on the previous step, taking into account their cross-validation.
Based on the results of the work, several important decisions (observations) were made, allowing determining the potential limits and the technical capability of modeling the GC systems with the required accuracy of phase transitions. In addition, the degree of influence if the numerical grid resolution and detalization of the PVT model (up to 50 components inclusive) on the gas and oil production and the pressure behavior was estimated. The simulation run time with various numerical schemes were also considered as factors affecting the simulation results on the sector and full-scale models. The analysis carried out and the results obtained can be further used by engineers dealing with GC field development as a guideline for choosing the modeling method depending on the complexity of the task and available computational resources.