Whether it is for sand classification, water treatment or storage, the right tanks must be fit-for-purpose and ready for the long haul.
The United States is now the world’s largest producer of natural gas and oil, thanks in large part to hydraulic fracturing. Water is an indispensible part of the process, because without it there would be no way to produce the sand-loaded slurry that keeps fractures open and allows the formation to release shale oil and gas for pumps to bring to the surface.
From the sand mines to the well to the pipeline, water is the thread that connects it all. Helping ensure water is used and recycled in a way that is responsible and cost effective is the mission of CST Industries.
MINIMAL WATER USE
Sand intended for use in hydraulic fracturing is produced in the following steps:
• Sand is mined;
• Water is mixed with sand;
• Sand is classified by coarseness, fineness and other qualities;
• Silt and clay are removed, forming a slurry that is pumped down the well;
• After pumping, slurry is moved to a clarifier tank, where solids are separated and removed;
• Reclaimed water flows to the process water tank;
• Water is reused for washing and classification of more sand.
A bolted-steel liquid storage tank such as the CST TecTank™ is used for water clarifying and storage as noted in steps 5, 6 and 7. This tank has been supplied to many clients including Process Engineers and Equipment Corporation, manufacturer of systems for sand wash plants that separate the clay and silts from sand and recycle the water. Process Engineers specializes in sand classification and dewatering, fine sand recovery, water clarification, and sludge dewatering systems.
“One of the objectives is to get the job done with minimal water use,” said Rick Howie of Process Engineers. “We think of sand processing as an important part of an environmental assistance program.”
Waste treatment of the slurry requires two tanks: a clarifier tank and a water tank. Clay, silts and water are fed into the clarifier tank where flocculant chemicals are introduced to settle solids to the base of the tank. A rake assembly collects the solids which is pumped out. Clean water is collected at the top of the tank through the launder and discharged into the water tank where it is pumped away to be reused for washing and classification of more sands.
As oil and gas companies identify new oil and gas-bearing shale deposits, frac sand is increasingly sourced closer to the wellsite to improve efficiency and lower costs. As a result, providers of sand processing and recovery systems must be nimble and ready to design, build and launch on demand.
Water is the thread that connects the sand mine to new oil and gas development in today’s growing shale plays.
Traditionally, fracturing processes have used Northern White sand, which is mined in the Midwestern states of Illinois, Indiana, Iowa, Kansas, Kentucky, Minnesota, Michigan, Missouri, Nebraska and Wisconsin.
Northern White is considered superior sand for fracing because of its uniform size, high quartz content and purity. It is typically shipped by rail to fracing sites across the country.
With the recent rapid growth of shale plays in Texas, it is not considered cost effective to continue shipping sand from the Upper Midwest. As a result, operators have turned to Texas Brown sand with greater frequency.
According to an analysis presented at the Annual Frac Sand Industry Update Conference in February, Rystad Energy predicts the share of Northern White used in fracturing will drop from 75 percent in 2014 to an about 34 percent in 2020.
“Most of these sand classification plants operate for about 20 years,” says Howie. “They have to remain active during the entire life of the sand mine. As more types of regional sand are cleared for use, we are seeing plants spring up in many new areas to facilitate local sourcing near the oil or gas well.”
Add to this the fact that demand for frac sand is dynamic. The amount of sand used in each well has increased 15 percent over the last 2-3 years.
“Because the delivery expectations of this market are high, it is important that we work with customers to provide tanks faster,” says Matt Bedell, senior project manager at CST Industries. “The key to success is reaching an agreement on expectations with the customer as soon as possible so we can disseminate the information through our shop.”
Bedell recognizes that compressed timeframes are part of the game, and that sometimes the information does not flow to the factory until all decisions are made. As a result, project timelines can be impacted, he said.
“We make every effort to be transparent with our schedules, so our manufacturing timelines are appropriately integrated with the customer’s project schedule,” Bedell said. “In some instances, project teams will work with our internal departments to improve support to our customers.”
ADAPTABLE AND DURABLE
A typical clarifier tank is 100 feet in diameter by 22 feet tall with a capacity of more than one million gallons. Clarifier tanks are equipped with an effluent launder with adjustable V-notch weir. Typical water tanks are 70 feet in diameter and 20 feet tall, with a capacity of more than 500,000 gallons. Standard sizes are available, and the company often works with customers to fabricate tanks to specific dimensions in order to meet flow rates.
“As a supplier, CST understands the water treatment process and they know our requirements, which means their tanks are extremely adaptable and durable,” Howie said. “We ask a lot of these tanks because under ideal conditions, an operation will process 18,000 gallons a minute for 20 hours a day nonstop. These systems recycle over 90 percent of the water for future use.”
CST manufactures a line of bolted epoxy steel tanks called Trico Bond that uses an OptiBond™ coating process to deliver outstanding performance. This line of steel tanks is considered the industry standard for epoxy durability. Tanks are corrosion resistant and resist UV breakdown and abrasion. They have been used in more than 350,000 applications in 125 countries around the world.
“Coatings are the first line of defense in protecting the integrity an asset,” Bedell said. “The level of knowledge required to properly apply epoxy coatings so they endure in some of the harshest environments is what sets this company apart from others.”
“Working from customer requirements and objectives, we design the right tank to meet their needs,” Bedell noted. “Our approval process ensures our scope of work is understood and agreed by everyone and only then does a project move to fabrication at our Parsons, Kan., plant. When timelines are tight, we can work with customers to deliver tanks faster.”
For sand wash plants, the company assembles tanks onsite from the ground up and build on a base-ring embedded in concrete.
“Most end users of these systems provide the sand used during hydraulic fracturing. These customers need large amounts of water that must be recycled in a safe, clean and efficient facility,” Bedell said. “We can also provide shop-welded clarifiers to customers who process a smaller amount of water.”
Demand for frac sand has increased 15 percent over the last few years, increasing the need for additional sand processing facilities.
By all accounts, oil and gas industry demand for equipment to support the fracing process will continue to grow. Hydraulic fracturing is a proven, cost-effective means of extracting oil and gas resources that were once considered inaccessible. In fact, about 95 percent of all new wells drilled today are hydraulically fractured and new wells are fractured with greater volumes of sand. These wells now account for two-thirds of total U.S. natural gas production and about half of crude oil production.
This observation is substantiated by Howie, of Process Engineers and Equipment. Howie said the amount of sand used in each new frac job has increased 15 percent over the last few years, which will create additional demand for his company’s systems.
As growing demand for frac-grade sand increases the need for additional sand processing and recovery operations, water tanks will be required that are adaptable, durable and right for the job.
Authored by John Novaria