Procedure for justifying process conditions of gas and gas condensate wells using integrated models
The wells of gas and gas condensate fields are operated in accordance with the assigned operation conditions which are set on the basis of information obtained during the exploration, completion, and development of hydrocarbon reservoirs. The operation conditions of wells should ensure uniform recovery of gas over the area, as well as maintain the parameters for stable and safe operation, taking into account all the subsurface and engineering limitations, including the maximum allowable drawdown and the absence of erosion of casing walls and hydrate formation. In case of significant water cuts in wells, it is also necessary to take into account the limitations on the throughput of a gas treatment unit and an industrial waste injection site. The strong mutual influence of individual field elements requires a systematic approach to designing. An aquifer, a reservoir, wells, gas collection networks, gas treatment facilities and a booster complex should be regarded as a single thermo-hydrodynamic system in which all subsystems are interconnected. The optimal conditions for the joint operation of wells and field facilities that ensure gas recovery in accordance with the business plan at the maximum inlet pressure of a compressor station or a gas treatment plant, as well as the maximum possible condensate production must be justified. This approach is implemented through the use of integrated geological and technological models which include all elements of a gas production and treatment system and provide a flow-through calculation from a reservoir to a trunk gas pipeline. The field is divided into two subsystems, i. e. a reservoir - wells - a gas buster station and a booster compressor station - a gas treatment unit; the functions of gas pressure vs recoveries at the junction of these subsystems at a gas buster station outlet before a booster compressor station are built, which determine the field working area. The field operation conditions are selected within this area, while maintaining the planned gas recoveries and ensuring the maximum economic performance of the field, which, as a rule, corresponds to the maximum pressure at a compressor station inlet which ensures lower compression ratios and fuel gas consumption. A case study of Pyreiny gas condensate field is described with the estimated operation conditions of wells using the developed method. The estimates are in good agreement with the actual operation conditions as of September 2019. The developed method for justifying the operation conditions of gas and gas condensate wells makes it possible to optimize the operation schedule of the entire field to achieve its maximum performance and safety.