Vapor Recovery Unit (VRU) is a small package of reciprocating compressor that is utilized to recover small amount of flared gas. In VICO Indonesia, very low pressure flared gas is normally burnt at Burn Pit. The almost atmospheric gas (approximately 1-5 psig) will be boosted to the VLP/LP System (40/100 psig) by VRU. The purpose of VRU installation is to reduce Green House Gas (GHG) emission from VICO’s Burn Pits and of course to enhance production rate.
The schematic process diagram of Flared Gas System is shown at the picture above. Flared gas comes from two main sources, Crude Oil & Condensate Stabilization and Oily Water Break Drum. In Oil Processing Plant, Crude Oil & Condensate is stabilized to remove its light components. After Crude Oil is separated from gas & water in production separator, crude oil is transferred to Heater Treater to get further separation process using heat and chemical treatment. Crude Oil at Heater treater still has pressure about 30 psig, so before it is sent to Storage Tank, which pressure is atmospheric, Crude Oil is de-pressurized at Degassing Boot. As the pressure goes down, a small amount of light component in the Crude Oil will be flashed. This flashed gas will normally stream to the Burn Pit.
Oily Water Break Drum is a process separator that handle liquid from Compressor Scrubbers and manual closed drains. Liquids from these sources is separated from its vapor before it goes to further oily water treatment at API Separator. Flashed gas is streamed to the Burn Pit via KO Drum.
Continuous Flashed Gas from Degassing Boot and Oily Water Break drum are flared because its pressure is nearly atmospheric, it can’t go anywhere, so it will burnt. By installing VRU, we could recover some gas. See the process flow diagram above. After VRU is istalled, line to Burn Pit is blocked so flared gas would normally go to VRU suction. VRU Compressor will boost gas into VLP gas (40 psig) or LP Gas (100 psig) and deliver it to the system. Burn Pit is not totally de-activated, it still burns some little amount of pilot and purge gas. If VRU Compressor is shut down, flared gas would automatically flow to Burn Pit.
VRU Installation at Badak Plant
VRU Compressor is a Gas Jack Compressor from Compressco. It is a compressor that is using Ford V-8 type gas engine where four right bank cylinders are used for power driving the crankshaft and the other left bank cylinders are used for gas compression cylinders. The Gas Jack Compressor only available for 50 HP engine. The capacity of this compressor is 0.15 – 0.2 MMSCFD (at 5 psig suction and 175 psig discharge) and liquid capacity is about 50 BPD. The compressor also use low Fuel gas pressure supply (2-5 psig) and low Fuel Gas consumption (8-10 MSCFD). By the design, Gas Jack Compressor is used to save gas at low pressure well that couldn’t flow to the production header.
Burn Pit at Mutiara Plant before VRU is online
Burn Pit at Mutiara Plant after VRU is online
Vico Indonesia has 6 VRU Compressors installed in 5 plants, which are Badak, Nilam, Mutiara, Semberah-14 and Semberah-13. The total compressed gas is about 1.1 MMSCFD. That is equivalent to 2000 tonnes per months of CO2 emission. That is a huge number I think. Since this installation is the first in Indonesia, I could imagine if every PSC in Indonesia could adopt our effort to recover flared gas, how many tonnes of CO2 emission we could reduce.
That’s our effort to make this earth a little bit safer to live in. What about you? It’s time to be greener guys. Like Aa Gym said, “Let start from something little, let start from ourselves and let start from now on”.