EVALUATION OF THE GAS FLOW VELOCITY, PROVIDING REMOVAL OF LIQUID ACCUMULATIONS FROM THE GAS GATHERING NETWORK

Relevance At the final stage of oil and gas condensate field operation there are problems of gas outflow and mass flow rate reduction, decrease of temperature of transported gas and increase of well water cut, which, in its turn, promotes liquid accumulation in pipelines and plumes. The complex action of all the above factors causes a sharp formation of ice plugs in the frost season, which disrupts the normal operation of the entire field. To prevent reduction of pipeline throughput capacity it is necessary to promptly remove the accumulated liquid. The optimal option is to carry the water out by the flow of the transported gas itself. For this purpose, the gas flow velocity should be not less than some critical velocity, the value of which depends on many parameters, in particular, the pipeline diameter, the angle of inclination of its upstream section, the densities of gas and liquid accumulation in the downstream section, viscosity and volume of liquid accumulation. Aim of research The main aim of the research is to improve the efficiency of the automatic control system for the removal of accumulated water in the gas gathering network and to obtain a model linking the parameters, by which it is possible to calculate in real time the pressure drop between the cluster of gas wells and the building of switching equipment, providing a critical rate of gas flow. Research methods Using a mathematical model describing the dynamics of water accumulation removal in the process of gas transportation to determine the critical velocity of gas flow, and investigate the limits of its suitability for different plumes. Determine for what diameters of plumes it is reasonable to use the removal of liquid accumulations from plumes by gas flow. Results Cleaning of plumes from liquid accumulations is an effective way to improve well performance. The results show that by maintaining the required flow rate, the natural gas flow can effectively remove accumulated water from the gas gathering network. Each plume has its own value, which depends on a variety of factors such as pipeline diameter, upstream inclination angle, liquid accumulation volume, gas and liquid density in the downstream section and other variables. As a result of the research, it was revealed that the most effective cleaning is carried out at small pipeline diameters (up to 200 mm) — in this case any volumes of liquid accumulation in the downstream sections are removed. With increasing diameters and volumes, the liquid removal becomes more difficult and under certain conditions impossible. To create the required velocity, it is necessary to provide a certain pressure drop between the plume and the inlet building of the switching equipment. One of the possible solutions is to install an additional compressor of low capacity at the inlet of the booster station to speed up the calculation of the required pressure drop.