Patent RU-2709044-C1 (RU)
Title: Method of automatic control of capacity of installation of low-temperature gas separation in conditions of extreme north
Inventor: ARNO OLEG BORISOVICH
IPC: E21B43/34
Filed: 2019-01-09
Granted: 2019-12-13
Abstract: FIELD: oil and gas industry. 
     SUBSTANCE: invention relates to the field of extraction, collection and preparation of natural gas and gas condensate to long-distance transport, in particular to automatic control of capacity of low-temperature gas separation plants (hereinafter plant). Disclosed is a method of automatic control of capacity of installation of low-temperature gas separation in conditions of Extreme North, including control by means of automated control system of technological processes (APCS) of installation of low-temperature gas separation of following parameters: flow rate of dried gas supplied to main gas line (MGL); consumption of unstable gas condensate (UGC), supplied to main condensate line (MCL); UGC level in buffer tank; gas pressure in MGL and condensate pressure in MCL. At that, task is performed by dispatcher of gas production enterprise by volume of UGC production, supplied to database (DB) APCS, which executes it with the help of PID-regulator of flow rate maintenance UGC in INC. For this, at input SP of said PID-controller APCS sends dispatcher setting signal, and simultaneously to its feedback input PV supplies UGC flowing flow signal to INC. By comparing these signals, the PID-controller generates at its output CV a control signal for setting the capacity of the pump unit, which provides the specified volume of supply of UGC from the buffer tank in MCL. PID regulator itself is implemented based on APCS. Simultaneously APCS UGC level in buffer tank is monitored keeping it within preset limits by means of PID regulator to maintain production level of UGC of plant. For this purpose, at input SP of said PID-controller signal of current flow UGC in MCL, and a feedback signal PV of the same PID-controller is fed with a signal of current flow rate UGC coming from the low-temperature gas separation unit into the buffer tank. By comparing these signals, the PID-controller generates a control signal at its output CV, which is supplied to the regulating valve, which controls the flow of the produced gas-condensate mixture supplied to the low-temperature gas separation unit. At that, PID-regulator of UGC production level maintenance operates in two modes: nominal, if level of UGC in buffer capacity does not exceed limits of upper or lower warning setpoint; with permissible overshoot level, if the level of UGC in the buffer capacity is beyond the upper or lower warning settings. Switching of said PID-controller operation modes is performed by APCS by means of a switch, by supplying to its CS input signal for switching of proportionality factors, which are constantly supplied to inputs of this switching unit. As a result, corresponding to the existing situation, the value of the proportionality coefficient from the output of the switch is supplied to the input Kp of the PID regulator of maintaining the production level of the UGC by the plant. At that, nominal and maximum values of proportionality coefficient are assigned as per results of gas-dynamic tests of wells taking into account the deposit development project. 
     EFFECT: invention provides automatic execution of the task of the dispatcher of the gas producer on the volume of production of UGC and maintenance of its required margin in the buffer tank, which ensures uninterrupted operation of the pump unit, real-time monitoring of pressure and flow rate values of gas and UGC supplied to MGL and MCL respectively, and maintaining stable mode of operation of the plant during transient processes, providing transportation of UGC by MCL in single-phase state, as well as exclusion of "swinging" of operating mode of installation and appearance of gas plugs and their accumulations in condensate line. 
     5 cl, 2 dwg