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While a Chevron drilling rig bores down 8,000 feet (2,438 m) below southwestern Pennsylvania to unlock natural gas trapped in dense shale rock, Tim Svarczkopf monitors the mobile water-treatment technology he invented.

"The process takes black, viscous water that flows back after completion, combines it with production brine that is red from iron content, and turns it into crystal-clear water that looks like it comes out of a household tap," he said.

Producing Natural Gas From Shale

Chevron combines two proven technologies—hydraulic fracturing and horizontal drilling—to safely produce natural gas from shale.

Svarczkopf is Chevron's manager of water technology in the region. His work is just one example of how the company is applying new technology to optimize well performance and advance environmental stewardship in its Marcellus Shale operations and in other places where the company extracts natural gas from shale.

Chevron began producing natural gas from shale in southwestern Pennsylvania in early 2011, when it acquired Atlas Energy, Inc. With more than 700,000 acres (283,300 ha) under lease in the Marcellus Shale, Chevron is one of the state's largest leaseholders.

Unlike conventionally sourced crude oil and natural gas, which have migrated toward the earth's surface from an organic-rich source rock into highly permeable reservoir rock, natural gas forms within shale rock, whose low permeability inhibits the gas from moving upward.

The energy industry has long known about huge gas reserves trapped in these deep formations, such as the Marcellus under Pennsylvania and neighboring states, but the complex geology has left this energy source largely beyond reach. However, during the past decade, the combination of two established technologies—horizontal drilling and hydraulic fracturing—has dramatically altered the U.S. energy supply picture. Natural gas from shale is the fastest-growing source of natural gas in the United States and could become a major global energy source.

The operation begins as a drilling rig sinks a vertical well more than a mile (1.6 km) below ground. Then the well extends horizontally 2,000 to 5,000 feet (610–1,524 m) into the shale. For each well in Pennsylvania, the process of hydraulic fracturing injects about 5 million gallons of pressurized water along with sand and additives to selectively crack the rock and provide a pathway for the natural gas to travel to the wellbore. This year, Chevron plans to spend millions of dollars on shale research and on technology that will improve the productivity of shale wells.

"We're working on technologies to improve well performance and find superior ways to handle and treat water, all while minimizing the company's footprint on the ground," said Mike Maneffa, Chevron's shale gas asset-class manager.

To improve the productivity of low-permeability reservoirs, Chevron continues to explore the use of specialized proppants and a new fracturing fluid that uses liquefied petroleum gas instead of water. To pinpoint the most promising drilling sites, the company is using seismic imaging to bounce sound waves off the underground rock. Both 2-D and 3-D seismic and microseismic technologies, along with logging and coring data, provide a road map for how the gas can be extracted in a safe and viable way.

We're working on technologies to improve well performance and find superior ways to handle and treat water, all while minimizing the company's footprint on the ground.
—Mike Maneffa, Chevron manager

"As we understand these formations better, we can make sure we drill only as far as needed. Over the next few years, through technology, we'll be able to selectively fracture with even more precision, which is expected to reduce water needs and the numbers of trucks that haul water," said Mike Power of Chevron Drilling and Completions.

Chevron is applying what it has learned from drilling in the Gulf of Mexico, where its wells have extended more than 30,000 feet (9,144 m) into the earth. Chevron's Real-Time Drilling Optimization Center, pioneered in the Gulf, could help monitor wells drilled on land in Pennsylvania.

"It's an extra set of eyes monitoring operations 24/7," said Power. "This improves the safety of people on location and enhances process safety—everything from rigging up, pumping the frac job and monitoring drilling in real time."

Power said the fractures are more than a mile (1.6 km) below groundwater. To protect groundwater, Chevron's wells in the Marcellus have a combination of as many as eight layers of steel casing and cement that form a seal between the well and the groundwater as drilling telescopes downward. Chevron's technology is coupled with formidable safety ethics from the company's Operational Excellence Management System, a comprehensive, proven means of systematically managing process safety, personal safety and health, the environment, reliability and efficiency.

"Safety is not just a priority, it's part of our culture. First and foremost is the safety of the people on location and process safety—in every task we perform. Environmental protection and operating in a sustainable manner are paramount. It all starts with a robust well design," said Power.

Chevron performs tests over the life of the well to verify its long-term integrity. Before drilling, it also carries out voluntary freshwater monitoring in the areas near its drilling locations that exceeds state requirements. Analyzing that data will help Chevron and others understand the water-quality conditions before, during and after drilling.

In the Marcellus, there has been a concerted effort to reduce the number of additives contained in the fracturing fluids, which make up less than 1 percent of the water and sand mix used during the hydraulic fracturing process. Thanks to Svarczkopf's efforts, Chevron now uses fewer chemicals in its fracturing fluids, reducing the number required by 77 percent.

Chevron is working to capture and reuse 100 percent of the fracturing fluids and water produced with the natural gas.

"The technology enables us to reach this goal, and we're investing in infrastructure that will allow us to do that," said Svarczkopf. "Chevron's emphasis on operational excellence and environmental consciousness made it an easy sell when I asked for funds to advance the technology."

Capture and reuse reduces freshwater consumption as well as the need for water trucking, transfer and disposal. Chevron also has started using water pipelines to lessen the need for tanker trucks to transport water.

"By treating water right on our pad, we can take water from one well to another, reducing truck traffic by half," said Svarczkopf. He also is working to convert pit-based water-treatment systems to deconstructible vertical tanks, which would be in place for 20 weeks and then moved to another site. This system would diminish the drilling-pad footprint and reduce reclamation needs.

Most wells are built and completed within a year. Afterward, Chevron works with the landowner to restore the property's original contours and minimize any other above-ground impacts. Hydroseeding helps to reestablish the indigenous grass more rapidly.

It's a holistic way of managing shale development by constantly searching for better plans, designs and processes, Power said. "We're doing our best to fully use today's technology and develop new technologies for the future."

Natural Gas From Shale

We’re unlocking energy from shale rock.

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