A saltwater disposal (SWD) well is a disposal site for water collected as a byproduct of oil and gas production. Quite often when oil and gas are pumped out of the earth, they aren't pure enough for distribution. The oil and gas go through a separation phase or are treated with chemicals that extract the impurities. After the oil or gas is treated, there is water leftover (referred to as "saltwater") that must be carefully handled.
Companies may choose to recycle the salt water by injecting it back into the well for secondary oil recovery, or dispose of it at a salt water well disposal site. These disposal sites may or may not have filtration in place. As shown in the picture to the right, Coleman Filter Company offers a string wound depth filter that replaces the #2 bags/socks that are often in use at saltwater disposal sites - both commercial SWD operations as well as operator-owned.
These filters are proving useful in dramatically extending the time between change-outs, reducing the cost per barrel to filter and protecting wells, pumps and pipelines as they are superior to bags/socks in the quality of filtration.
Filters most commonly used in saltwater disposal operations include: