A Multiphase Separation System

Abstract

The present techniques are directed to a multiphase separation system. The system includes a liquid-liquid separator configured to receive a separated liquid that is further separated into a separated oil and a separated water within the liquid-liquid separator ( 126 ). An oil pump ( 136 ) and a water pump ( 138 ), both with adjustable speeds, are configured to pump the separated oil and the separated water, respectively, from the liquid-liquid separator ( 126 ). An interface level ( 140 ) in the liquid-liquid separator ( 126 ) is regulated by adjusting the speed of the oil pump ( 136 ) and the speed of the water pump ( 138 ).

1 . A multiphase separation system, comprising:
 a liquid-liquid separator configured to receive a separated liquid from a gas-liquid separator;   an oil pump with an adjustable speed configured to pump a separated oil from the liquid-liquid separator;   a water pump with an adjustable speed configured to pump a separated water from the liquid-liquid separator; and   at least one invert action split range controller of the oil pump and the water pump configured to receive signals from at least one interface level detector,   wherein the at least one interface level detector determines the interface level in the liquid-liquid separator and is configured to transmit signals to the at least one invert action split range controller,   wherein the speed of the oil pump is adjusted to operate inversely from the speed of the water pump based on signals transmitted from the at least one invert action split range controller,   wherein the at least one invert action split range controller is tuned to a critically damped or overdamped condition to maintain the interface level in the liquid-liquid separator at a set-point value, the critically damped condition having a damping ratio of one and the overdamped condition having a damping ratio of greater than one.   
     
     
         2 . (canceled) 
     
     
         3 . (canceled) 
     
     
         4 . (canceled) 
     
     
         5 . (canceled) 
     
     
         6 . The multiphase separation system of  claim 1 , further comprising:
 an oil control valve positioned downstream of the liquid-liquid separator and the oil pump in a flow line comprising the separated oil; and   a water control valve positioned downstream of the liquid-liquid separator and the water pump in a flow line comprising the separated water.   
     
     
         7 . The multiphase separation system of  claim 6 , wherein the at least one invert action split range controller adjusts the actuation of the oil control valve inversely from the actuation of the water control valve providing a secondary control feature to regulate the interface level in the liquid-liquid separator. 
     
     
         8 . The multiphase separation system of  claim 1 , further comprising the gas-liquid separator, a liquid level detector for the gas-liquid separator, and a liquid control valve positioned between the gas-liquid separator and the liquid-liquid separator in a flow line comprising the separated liquid, wherein the liquid control valve, the oil control valve, and the water control valve are configured to regulate a liquid level in the gas-liquid separator. 
     
     
         9 . The multiphase separation system of  claim 8 , further comprising at least one controller that is tuned to a critically damped or overdamped condition to maintain a liquid level in the gas-liquid separator at a set-point value. 
     
     
         10 . A method of controlling an interface level in a liquid-liquid separator, comprising:
 receiving a separated liquid into the liquid-liquid separator;   regulating the interface level in the liquid-liquid separator by adjusting a speed of an oil pump with an adjustable speed and a speed of a water pump with an adjustable speed, wherein the oil pump is configured to pump a separated oil from the liquid-liquid separator and wherein the water pump is configured to pump a separated water from the liquid-liquid separator;   determining the interface level using signals from at least one interface level detector, wherein the signals are transmitted by at least one invert action split range controller to the oil pump and to the water pump, the at least one invert action split range controller output for the speed of the oil pump is configured to be the inverse of a controller output for the speed of the water pump; and   tuning the at least one invert action split range controller to a critically damped or overdamped condition to maintain the interface level in the liquid-liquid separator at a set-point value, the critically damped condition having a damping ratio of one and the overdamped condition having a damping ratio of greater than one.   
     
     
         11 . (canceled) 
     
     
         12 . (canceled) 
     
     
         13 . (canceled) 
     
     
         14 . The method of  claim 10 , further comprising recycling a portion of the separated oil from a flow line downstream of the oil pump to a flow line upstream of the oil pump to protect against a minimum flow condition. 
     
     
         15 . The method of  claim 10 , further comprising recycling a portion of the separated water from a flow line downstream of the water pump to a flow line upstream of the water pump to protect against a minimum flow condition. 
     
     
         16 . The method of  claim 10 , wherein the regulating of the interface level in the liquid-liquid separator comprises adjusting actuation of an oil control valve located downstream of the oil pump to operate inversely from actuation of a water control valve located downstream of the water pump during a failure of the adjustable speed on either the oil pump, the water pump, or both. 
     
     
         17 . The method of  claim 16 , further comprising tuning a control system of the oil control valve and the water control valve to a critically damped or overdamped condition to maintain the interface level in the liquid-liquid separator at the set-point value. 
     
     
         18 . A multiphase separation system, comprising:
 a gas-liquid separator;   a liquid control valve positioned between the gas-liquid separator and a liquid-liquid separator in a flow line comprising separated liquid from the gas-liquid separator;   a liquid-liquid separator positioned downstream of the gas-liquid separator and configured to receive the separated liquid from the gas-liquid separator;   an oil pump with an adjustable speed configured to pump a separated oil from the liquid-liquid separator;   a water pump with an adjustable speed configured to pump a separated water from the liquid-liquid separator;   an oil control valve positioned downstream of the liquid-liquid separator and the oil pump in a flow line comprising the separated oil;   a water control valve positioned downstream of the liquid-liquid separator and the water pump in a flow line comprising the separated water; and   at least one invert action split range controller of the oil pump, the oil control valve, the water pump, and the water control valve configured to receive signals from at least one interface level detector,   wherein the at least one interface level detector determines the interface level in the liquid-liquid separator and is configured to transmit signals of a measured value of the interface level in the liquid-liquid separator to the at least one invert action split range controller,   wherein the speed of the oil pump and actuation of the oil control valve are adjusted to operate inversely from the speed of the water pump and actuation of the water control valve based on signals transmitted from the at least one invert action split range controller.   
     
     
         19 . The system of  claim 18 , further comprising at least one liquid level detector to determine a liquid level in the gas-liquid separator, wherein the at least one liquid level detector transmits signals to a first control loop, and wherein the first control loop of a control system is tuned to a critically damped or overdamped condition to maintain the liquid level in the gas-liquid separator at a set-point value, the critically damped condition having a damping ratio of one and the overdamped condition having a damping ratio of greater than one, the first control loop including a gas-liquid separator controller, the liquid control valve, and the at least one liquid level detector of the gas-liquid separator. 
     
     
         20 . The system of  claim 19 , wherein the control system further comprises a second control loop including the interface level detector of the liquid-liquid separator, the at least one invert action split range controller, the oil pump, and the water pump. 
     
     
         21 . The system of  claim 20 , wherein the second control loop further includes the oil control valve and the water control valve. 
     
     
         22 . The system of  claim 21 , wherein the second control loop is tuned to a critically damped or overdamped condition to maintain the interface level in the liquid-liquid separator at a set-point value, the critically damped condition having a damping ratio of one and the overdamped condition having a damping ratio of greater than one. 
     
     
         23 . An inverse operating control system for a liquid-liquid separator, comprising:
 a first pump with an adjustable speed configured to pump a first flow line from the liquid-liquid separator;   a second pump with an adjustable speed configured to pump a second flow line from the liquid-liquid separator; and   at least one invert action split range controller of the first pump and the second pump configured to receive signals from at least one interface level detector,   wherein the at least one interface level detector determines the interface level in the liquid-liquid separator and is configured to transmit signals to the at least one invert action split range controller,   wherein the speed of the first pump is adjusted to operate inversely from the speed of the second pump based on signals transmitted from the at least one invert action split range controller, and   wherein the at least one invert action split range controller is tuned to a critically damped or overdamped condition to maintain the interface level in the liquid-liquid separator at a set-point value, the critically damped condition having a damping ratio of one and the overdamped condition having a damping ratio of greater than one.   
     
     
         24 . A control system for a gas-liquid separator, comprising:
 a liquid control valve positioned between the gas-liquid separator and a liquid-liquid separator in a flow line comprising a separated liquid;   an oil control valve positioned downstream of the liquid-liquid separator and an oil pump in a flow line comprising a separated oil;   a water control valve positioned downstream of the liquid-liquid separator and a water pump in a flow line comprising a separated water; and   a control loop to transmit signals to the liquid control valve, the oil control valve, and the water control valve to regulate a liquid level in the gas-liquid separator, wherein the control loop is tuned to a critically damped or an overdamped condition.   
     
     
         25 . The system of  claim 20 , wherein the first control loop further includes the oil control valve and the water control valve.