Salt water disposal is a large and often overlooked area of the oil and gas industry.
There are approximately 1 million producing oil and gas wells in United States, and altogether they produce 58 million barrels of water each day—twice the amount that flows over Niagara Falls in 24 hours.
This is why the discussion about bringing a well online to produce oil and gas begins with water.
what is Water Management in oil and gas?
There are two primary reasons we talk about water in our industry:
- You need it to crack wells.
Water is an essential part of the completion process. It takes an average of 13 million gallons of water to drill a well. Producers must figure out where to get water, and how to get it to the wellhead.
Some companies use freshwater to do this. They may source it from a pond or river, and pump it through flexible hoses to the well site. Because of the great need, more and more companies are trying to find ways to recycle water.
- You need to do something with it when it comes back up.
As the injected water comes up in the production fluid, commonly referred to as “flowback water” or "oil well water," companies must then figure out what to do with it: dispose of it or recycle it.
water production in Oil wells
Figure 1 below shows the process of oil, gas, and water separation.
Produced water, represented by the brown line, comes out of the wellhead at the top lefthand corner. At this point it mixes together with oil and gas.
It then goes through a separation vessel. In this vessel, water settles at the bottom, oil in the middle, and gas rises to the top. Water is pumped out of the bottom of the tank.
The oil then goes through one or two more stages of separation, often in a heated vessel, which accelerates separation.
At each stage, the water is dumped out of the bottom of the vessel, oil pumped out of the middle, and gas flashed or sent to sales lines.
The water then goes to storage, and producers have two options: dispose of it or treat it and get it ready for re-use.
What is a salt water Disposal well?
A salt water disposal well is a well used to inject the salt water from oil and gas wells back into the formation.
Drive down a road in the Permian Basin, STACK, or any other oil and gas producing area, and you’re sure to spot a disposal well, also referred to as a salt water injection well.
Trucks transport the salt water from a producing well to the unloading facility on these sites, where the water is pumped to a tank battery.
There, what oil remains in the water (referred to as “skim oil”) is separated into a holding tank. The water will settle in saltwater tanks, and eventually be pumped down the disposal well.
The oil will be sold and trucked away from the site, while the water will be injected into the formation. This process is also referred to as SWD in oil and gas.
corrosion in Salt Water injection wells
Salt is a very corrosive element.
You know this if you live near the ocean or in a region where the roads are regularly salted during winter.
While salt itself does not cause metal to rust, it accelerates the rusting process because electrons move more easily in salt water than they do in pure water.
This means the material in your salt water injection valves, vessels and other equipment must be durable.
The Best Valve for Salt Water Disposal
A Weight-Operated Dump Valve* is a weight-operated throttling valve designed to hold liquid level in salt water disposal systems.
The Weight-Operated Dump Valve actuates based on the pressure generated from the column of liquid in the discharge piping from a vessel.
How it Works
A weight and lever hold the seat closed by pushing down on the diaphragm assembly. When the liquid rises above the set level, it overcomes the force of the weight. This lifts the diaphragm assembly against the weight load to open the valve.
As liquid is discharged and the column of liquid lowers, the weight closes the valve.
On a salt water disposal well, the Weight-Operated Dump Valve can regulate the fluid in both the oil tanks and water tanks.
an alternative to Salt water disposal
Some producers have begun to re-use their produced water for completion.
In this process, they will dig storage ponds for the water. The water is treated and processed there and eventually sent back to the well pad to be re-used in the completion process.
To speak with an expert about optimizing your salt water disposal process, contact your local Kimray store or authorized distributor.