Emission reduction in oil and gas production operations is of significant concern.
This presentation is intended to provide operators in the industry with accurate information regarding flare gas recovery to assist them in making sound decisions regarding different methods and technologies.
Over the last few decades, there have been many approaches tried.
In this presentation, we will explore those methods and their pros and cons.
•Pressure in production tanks MUST be held within a 4-5 oz/in². Window.
•Air ingress MUST not be allowed.
•Gathered hydrocarbons must be made sales line ready i.e., pressure and temperature.
•Free liquids must be separated from the gas stream and pumped to a storage tank for further processing.
All of this seems simple until the process conditions are considered.
Typical VRU Process Conditions:
•The typical recovered tank vapor will be saturated at dewpoint.
•The produced gas volume is never at a steady rate as oil is constantly being produced into the tanks and drawn out for sale.
•Typical sales line pressure is around 120 Psig. (But can vary wildly).
•The vast majority of VRUs on the market use the VFD/Bypass Method so let’s explore that.
Assuming a 5 oz/in² operating window.
•The Compressor turns on at a set pressure, usually around 4 oz/in² and off at around 2oz/in² .
•The VFD will increase to maximum speed just as the presently occurring spike peaks and volume drops rapidly.
•Then the compressor will slow to its minimum speed then, a bypass valve begins to open trying to achieve more turn-down at about that time the next spike occurs and maximum the maximum tank pressure.
Causing the system ( Enardos) to vent to atmosphere.
On the next cycle which is now out of sync with the rhythm that the VFD/Bypass can maintain and then the high speed and the low volume of produced gas converge and vacuum breaks allow air into the tanks and subsequently the sales line.
We have designed our systems to handle all the volume spikes with precise control.
We design our flow capacity for the top of the spikes because that is your momentary design point.
We design our systems with a positive shut off at minimum set pressure.
This system utilizes a unique control system that offers many performance benefits:
Watch the flow meter as this VRU perfectly follows the breakout gas as the separators dump. 100% turndown with instantaneous response.