Method for dynamically controlling separator pressure suppression severe-section slug flow

Abstract

The invention discloses a method for dynamically controlling separator pressure suppression severe-section slug flow. The method is applied to a gathering and transportation-vertical pipeline system adopted in marine oil and gas production, and the gathering and transportation-vertical pipeline system comprises a vertical pipe and a gas-liquid separator arranged at the top of the vertical pipe. An exhaust valve is arranged at the top of the gas-liquid separator at the top of the vertical pipe, and a liquid discharging valve is arranged at the bottom of the gas-liquid separator. The method for dynamically controlling the separator pressure suppression severe-section slug flow comprises the steps of using the opening degree of the liquid discharging valve of the gas-liquid separator as a control variable to keep liquid level stability of the gas-liquid separator through independent single-loop PID operation, using the opening degree of the exhaust valve of the gas-liquid separator as a control variable to stabilize pressure difference of the vertical pipe through cascade-stage PID operation and a main loop and stabilize pressure of the vertical pipe through cascade-stage PID operation and an auxiliary loop, using an output of the main loop as a set value of the auxiliary loop and enabling liquid level and pressure control loops to operate parallelly. The method for dynamically controlling the separator pressure suppression severe-section slug flow inhibits severe-section slug flow and enables the system to be kept stable, the pressure of the separator can be remarkably reduced, and oil and gas yield can be increased.

Description

【Technical field】 [0001] The invention belongs to the technical field of multiphase flow in petroleum engineering, and in particular relates to a control method for suppressing severe slug flow pattern of a gathering-standpipe structure in the process of offshore oil and gas production and transportation. 【Background technique】 [0002] In order to save investment and operating costs of subsea or platform projects in oil and gas fields, make full use of associated natural gas resources and reduce environmental pollution, oil and gas mixed pipelines are usually used in offshore oil and natural gas industries. However, due to the laying of submarine pipelines along complex undulating terrain and the existence of riser structures required to transport crude oil from submarine gathering and transportation pipelines to offshore platforms, multiphase mixed transportation technology brings obvious economic benefits, but also brings urgent needs. The technical problems solved, the m...

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Problems solved by technology

Among them, the method of suppressing severe slug flow by separator back pressure attracted the attention of scholars such as Schmidt (1985) and Taitel (1986) as early as the 1980s. The area where the flow occurs is reduced on the flow diagram, which can effectively suppress the occurrence of severe slug flow without installing additional equipment and modifying pipelines. It is the most economical and practical, but a large increase in the back pressure of the separator will cause a decrease in oil and gas production , may lead to dead well accidents in severe cases

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