|Click to view schematic display A||Click to view schematic display B||Click to view schematic display C||Click to view schematic display D|
|Click to view schematic display E||Click to view schematic display F||Click to view schematic display G||Click to view schematic display H|
The Tank Battery Unit receives gas, hydrocarbon condensates, crude oil and water from three types of production wells and separates the gas, water and hydrocarbon liquids in a Three Phase Separator. Fluids produced by the three wells are combined in a production manifold and routed through the Line Heater to inhibit the formation of hydrates and ice from possible cooling resulting from the depressurization to the Three Phase Separator’s pressure.
Produced gas is taken off the Separator to a gathering pipeline for treatment at a central gas processing plant. The hydrocarbon condensates/crude oil and the produced water streams from the Separator are sent to separate on-site storage tanks to await transport by motor vehicle to off-site treatment facilities.
The Tank Battery Unit is designed to handle a wide variety of produced well fluids ranging from high pressure natural gas wells that are high in methane content to depleted oil wells with low pressure and high water content. There are three types of wells simulated in the Tank Battery Unit: a naturally pressured gas well producing low amounts of hydrocarbon liquids and water, a naturally pressured gas well producing enough hydrocarbon liquids that requires a plunger lift system to regularly clear the well of the accumulating liquids, and an oil well that lacks sufficient natural pressure to force the oil to the surface and uses a sucker rod pump to lift the oil to the surface.
The pressure of the Production Manifold is indicated by PI-004. The temperature of the Production Manifold is indicated by TI-004.
The pressure of the wellhead upstream of choke HV-001 is indicated by PI-001.
The position of the choke is adjusted using HIC-001.
Switch HS-001 is used to activate and reset interlock I-01 for Well #1. Interlock I-01 is also activated when Separator interlock I-05 is activated. When I-01 is activated, surface shutdown valve SDV-001 on the wellhead is closed and the choke hand controller HIC-001 is placed in manual mode with an output of 0% to close the choke HV-001. I-01 will lock these actions until it is reset using HS-001.
The pressure of the wellhead upstream of the Plunger Lift surface equipment is indicated by PI-002A. The pressure at the outlet of the surface equipment is indicated by PI-002B.
The position of the choke HV-002 is adjusted using HIC-002A.
P-002 Plunger Lift
The arrival of the Plunger Lift at the Lubricator SP-002 is indicated by switch XI-002. The position of switch XIC-002 indicates the status of MOV-002 per the Plunger Lift sequencing control logic. Switch HS-002B is used to put the sequencing control logic in the RUN or STOP state. In the RUN state, the sequencer operates as described in the process description for Plunger Lift P-002 above. The output of HIC-002B is used to adjust the time the sequencer waits before closing MOV-002. At 0% output the wait time is 300 seconds; at 100% the time is 1800 seconds. The time is linearly adjusted between these two settings for any other output of HIC-002B. In the STOP state, no sequencing occurs and MOV-002 is opened.
Switch HS-002A is used to activate and reset interlock I-02 for Well #2. Interlock I-02 is also activated when Separator interlock I-05 is activated. When I-02 is activated, surface shutdown valve SDV-002 on the outlet of the Plunger Lift surface equipment is closed, choke hand controller HIC-002A is placed in manual mode with an output of 0% to close the choke HV-002, and the Plunger Lift sequencing logic switch HS-002B is placed in the STOP state. I-02 will lock these actions until it is reset using HS-002A.
The pressure of the wellhead is indicated by PI-003.
The position of the choke HV-003 is adjusted using HIC-003A.
P-003 Sucker Rod Pump
The motor for P-003 is switched on and off using switch HS-003B. The speed of the motor is adjusted using the output of hand controller HIC-003B. At 100% output the motor operates at full speed; at 0% output the motor operates at 50% speed.
Switch HS-003A is used to activate and reset interlock I-03 for Well #3. Interlock I-03 is also activated when Separator interlock I-05 is activated. When I-03 is activated, surface shutdown valve SDV-003 on the outlet of the wellhead is closed, choke hand controller HIC-003A is placed in manual mode with an output of 0% to close the choke HV-003, and the motor of the Sucker Rod Pump is stopped by placing HS-003B in the STOP state. I-03 will lock these actions until it is reset using HS-003A.
The inlet pressure of the production fluid is indicated by PI-201. Its temperature is indicated by TI-201.
The outlet pressure of the production fluid is indicated by PI-202. Its temperature is indicated by TI-202.
The position of the letdown valve HV-201 is adjusted using HIC-201.
The temperature of the glycol solution inside the vessel is controlled by TIC-203. Control valve TV-203 is calibrated so that it is sufficiently open to provide a minimum flow of gas to the burners of the combustor assembly at 0% output of TIC-203 while having a stable flame.
THH-203 is an independent measurement of the glycol solution for the protective interlock I-04. TI-204 is another independent indication of the glycol solution for monitoring purposes.
PI-401 indicates the pressure of the fuel gas supply to the pilot and main fuel pressure regulators. The setpoint of self-regulating pressure control valve PCV-401 is 25.0 PSIG. PI-301 indicates the pressure of the main fuel gas downstream of self-regulating valve PCV-301 whose setpoint is 5.0 PSIG.
BLL-301 indicates the flame status detected in the combustor assembly.
Switch HS-200 is used to activate and reset interlock I-04 for the Line Heater. Interlock I-04 is also activated when Separator interlock I-05 is activated. THH-203 will activate I-04 when the temperature exceeds 200 DEG F. A loss of flame as detected by BLL-301 will also activate I-04.
When I-04 is activated, fuel gas shutdown valve SDV-301 on the fuel gas supply line is closed. The valve remains closed until I-04 is reset.
Interlock I-04 also contains logic to start combustion of fuel gas when the interlock is reset by changing HS-200 to the ON state. In order to do this the trip signal from BSL-301 is bypassed for 15 seconds when HS-200 is switched to the ON state. If BSL-301 does not indicate a flame after 15 seconds, I-04 will activate. A local control board handles lighting of the pilot flame.
Whenever starting the Line Heater care should be made to place TIC-203 into manual with 0% output to avoid large surges of fuel gas when the flame lights off.
The oil level of the Three Phase Separator D-500 is controlled by LIC-500 which regulates the control valve on the line to the Oil/Condensate Storage Tank. The oil flow is indicated on FI-500.
The water/oil interface level of D-500 is controlled by LIC-501. The produced water flow is indicated on FI-501.
The pressure of the gas produced in D-500 is indicated by PHH-500 which serves as a trip to interlock I-05. The produced gas flow from D-500 to the pipeline is indicated on FI-503. Hand controller HIC-501 is used to adjust the opening of HV-501 on the produced gas line. The sales gas pipeline pressure is indicated on PI-502.
PIC-501 is an emergency vent to flare that will open if the pressure of D-500 rises above 250 PSIG. It is designed to open before the pressure safety valve PSV-500 opens (setpoint = 500 PSIG). It can also be used to depressure D-500 at shutdown. If the pipeline pressure operates near or above the setpoint of PIC-501, the setpoint needs to be increased to prevent unnecessary venting of gas to flare. The maximum setpoint should not exceed the trip setting of PHH-500 (see below).
Switch HS-500 is used to activate and reset interlock I-05 for the Three Phase Separator. LHH-500 indicates the top level of liquid over the separation compartment of D-500 and will activate I-05 when the level exceeds 95%. Unlike the other two level control instruments, LHH-500 spans most of the height of D-500. PHH-500 will activate I-05 when it exceeds 350 PSIG.
Interlock I-05 does not directly control any process equipment. Instead, it activates the four other interlocks (I-01 through I-03 for the wells; I-04 for the Line Heater). I-05’s control signal is maintained until it is reset with HS-500. Therefore, the other interlocks will remain activated until I-05 is reset and each interlock is individually reset.
Oil/Condensate Tank T-2000
The level of liquid in T-2000 is indicated on LI-600.
The output of hand controller HIC-600 adjusts the position of gravity unloading valve HV-600. FQI-600 indicates the volume of oil/condensates delivered to the delivery truck. FQI-600 automatically resets to zero indication when it reaches its upper range.
Water Tank T-2001
The level of liquid in T-2001 is indicated on LI-601.
The output of hand controller HIC-601 adjusts the position of gravity unloading valve HV-601. FQI-601 indicates the volume of oil/condensates delivered to the delivery truck. FQI-601 automatically resets to zero indication when it reaches its upper range.