Method and system for recovering light hydrocarbon by oil field associated gas membrane method

Abstract

The invention relates to the field of treatment of oil field associated gas. In a method for recovering light hydrocarbon by an oil field associated gas membrane method, gas phase obtained by low-temperature separation is separated by a membrane and the liquid phase is fed into a deethanizing column for treatment; the treated gas phase is separated by the membrane and the liquid phase is fed into a liquefied gas tower for treatment; two paths of gas are formed after membrane separation; one path of gas is dry gas with barely pressure loss; C<3+> component in the gas is reduced to a certain extent compared with the raw gas, the gas is introduced into a cold box after the pressure and the temperature are reduced and delivered out as the dry gas after heat exchange; the other path of gas has pressure which is slightly higher than that of an inlet of a compressor; and the C<3+> component in the gas is richer than that of the raw gas, is returned to the inlet of the compressor and further compressed and condensed to recover the C<3+> component in the gas. The method and the system realize further recovery of the light hydrocarbon in the dry gas by increasing a small amount of investment and operation cost, so that the economy of the process and the quality of the dry gas are improved, black smoke is prevented during combustion, the environmental pollution is reduced, and the service life of a combustion nozzle is prolonged.

Description

technical field [0001] The invention relates to the field of oilfield associated gas treatment, in particular to a method for further recovering light hydrocarbons still contained in the dry gas after light hydrocarbons are recovered by shallow cooling technology, and the invention also relates to a recovery system thereof. Background technique [0002] At present, there are four methods for recovering light hydrocarbons from oilfield associated gas commonly used at home and abroad, namely: cold oil absorption method, external circulation refrigeration separation method, expansion refrigeration method, and mixed refrigeration separation method. With the continuous development and utilization of new technologies, the cold oil absorption method has been eliminated, while the production method of expansion refrigeration is increasing year by year. The production method of mixed refrigeration is also adopted by many users, especially for the large-capacity low-pressure rich gas,...

AI Technical Summary

Problems solved by technology

[0005] However, at present, the dry gas in this process still contains 6%~10% light hydrocarbons that cannot be recovered. Due to the high content of light hydrocarbons in the dry gas, these components with high value content cannot be effectively recovered, which will cause Huge waste of resources, and in some combustion processes of light hydrocarbons, a large amount of black smoke will be generated, polluting the environment, and it is easy to block the combustion nozzle; at the same time, the dry gas dew point is high, and the pipeline resistance is relatively large during long-distance transportation. Increase the energy consumption of transportation, when the ambient temperature is low, there will be liquid and ice, blockage management, affect the transportation

Images