One final environmental issue associated with production is how to deal with natural gas at a well producing primarily oil. This could include gas coming out of the oil while it is stored in a tank as well as gas being produced from the wellhead along with the oil.
In the following video, we’ll consider the environmental issues associated with methane and how the industry can work to resolve them.
Transcript
Methane Leaks – Paul Bommer – The University of Texas Austin
We’ve just spent a great deal of money and effort making sure no methane will leak from our well by cementing the casing strings and installing an appropriate wellhead. What’s the next thing we do?
We purposely vent methane from the well during testing and flowback operations. This gas is burned or flared rather than being allowed to escape to reduce safety risks of explosion.
Really, there are three reasons for the oil and gas industries to flare their gas. They are site safety, economics, and pollution control. Some oil wells in regions in which there is no gas market flare all of the produced gas. There’s no profit in capturing it at this time.
Separators and tanks will also vent gas that must be burned if no market exists for those gases. Even the pneumatic controls of the separators will vent natural gas during operation if nitrogen or air is not used for the gas supply to the controls. Switching the control gas would be one way to eliminate a lot of fugitive emissions.
How much methane is not being burned, but vented at a given site? This can be estimated using EPA formulas for fugitive emissions or determined by careful measurement. There are many researchers undertaking this task.
How much CO2 are we talking about generating when we do flare the gas? Since CO2 hangs around in the atmosphere much longer than methane, this is an important consideration. These numbers can be calculated with a high degree of certainty using flash calculations.
In regions where no market for the natural gas exists or where the tank vapors are not collected and sold, the carbon dioxide emissions could run to several million tons per year. However, much like individual automobiles, the emissions are spread out over thousands of well sites.
All that burning has to be added into the totals when we look at carbon footprints of different fuel options.
The industry should be taking a proactive approach to this. It would be best to start preventing emissions rather than reducing them. Build the required pipeline infrastructure and then capture, separate and compress all of it. Get ahead of the regulations. Find ways to profit from the waste stream.
We don’t have a lot of regulations about these concerns yet, but they will come. It would be best if we were ready when they do.
Images: “Methane Leaks” by Michael Black