FEATURES OF GAS-COLLECTION SYSTEM OPERATION UNDER LIQUID ACCUMULATION

Abstract

Any gas condensate field has an extensive gas gathering system (GGS), through which gas is delivered from the wells to the complex gas treatment plant. The movement of the gas is due to reservoir’ own energy. At the final stage of the field development the operating conditions of the GGS change due, firstly, to a decrease in the temperature of the transported gas, and secondly, to an increase in the water content of well products. Simultaneous action of these factors, especially in winter, leads to the ice and hydrate plugs emergence that violate the normal operation of the GGS. In order for the flowlines to operate in the mode of fluid removal, the gas flow velocity must exceed the so-called critical velocity. Its value is determined by the diameter of the pipeline, the ratio of gas and liquid densities, thermobaric conditions, the slope of the plume and other factors. It’s often not possible to ensure this speed at the final stage of operation, so the complete removal of the liquid is difficult and the danger of ice formation persists. The article proposes an innovative technology, which allows to pre-rotate ice formation in the flowline. The gas-liquid mixture in the GGS receives additional heat from the heat exchanger located inside the GGS. The coiled tubing is used as a heat exchanger. It is filled with constantly circulating coolant liquid, which is heated by passing through the heat exchanger by the discharge heat from the air cooling apparatus (ACA). Water methanol solution is used as coolant liquid. The coolant flow rate changing is carried out by means of variable-frequency drive pump. The control is based on the results of temperature measurement in the loop. The use of the proposed method allows to provide trouble-free operation of the GSS and to dispose of the waste heat from the ACA.