How is natural gas stored?
We get a box of diapers each month for our one-year-old son. The diapers are obviously critical items, but we’ve come to really appreciate the diaper boxes themselves too, as they are the perfect size for basically everything. Need to take some items to Goodwill? Diaper box. Wrap a present? Diaper box. Mail something? Diaper box. Wear a crazy hat? Diaper box. Build a fort? Diaper boxes.
It makes you feel good about your consumption of resources when you’re able to get an additional use out of something because killing two birds with one stone nearly always makes sense. The majority of natural gas stored in the US is in depleted natural gas or oil fields. In other words, energy companies have found a great use for their empty diaper boxes.
Taking advantage of depleted fields for storage purposes makes loads of sense. Given that these fields have a proven track record of keeping oil and gas secure, it’s no wonder that 87% of the total jurisdictional storage capacity in the US comes from depleted reservoirs.
If you’re wondering where the other 13% is stored, there are actually two other types of underground storage fields: aquifer storage (10%) and salt cavern storage (3%). Aquifer storage facilities are most common in the Midwestern US and are made by converting depleted natural aquifers into natural gas storage reservoirs. Salt caverns are created in salt formations by drilling a well and then essentially carving out a space for natural gas by injecting water into the well.
Visualizing Three Types of Natural Gas Storage
Source // energyinfrastructure.org
When considering storage options, deliverability rates and capacity are often the chief concerns. Simply put, a deliverability rate is how much gas can be removed from a storage facility on a daily basis. The amount of natural gas in a particular space, along with the pressure within it can affect this rate. The compression capabilities, as well as the functionality of the surface facilities can also change the deliverability rate. Capacity is pretty self-explanatory, but it’s important to note that working gas capacity refers to the total gas storage minus base gas. Base gas must be kept in a storage space on a permanent basis to ensure a certain amount of pressure is maintained. At the end of January 2016, the EIA reported that there were approximately 7,311 billion cubic feet (Bcf) of total natural gas storage capacity in the Lower 48. Of this, 4,361 Bcf, or about 60%, was base gas.
Thanks to the El Niño winter that kept us Dallasites wearing flip flops all winter long, natural gas storage is over 1,000 Bcf higher than it was during this same time period last year. As of April 22, there were 2,557 Bcf of working gas being stored in underground storage. Last year at this time, there were 1,687 Bcf. Clearly, the use of natural gas and related storage levels are highly dependent upon weather patterns and that’s where MLPs like Boardwalk Pipeline Partners (BWP), Niska Gas Storage (NKA), and Plains All American (PAA) come in. With the availability of underground storage, excess gas supply from periods of low demand can easily be reallocated to periods of higher demand.
Hopefully this brief overview has increased your understanding of the way natural gas is stored and shed light on one of the many activities MLPs are involved in. I hope it’s also inspired you to repurpose some of your everyday items into something useful. Click here for a list of great ideas.
2016.05.03 2:32pm CST - Edited post image.