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No Seismic 'Footprints' Left Behind

An Environmental Cliffhanger

In terms of beauty, the area is a geologic wonderland.

It's a wonderland in terms of hydrocarbon potential, too, waiting to be defined by seismic data.

A fragile and beautiful environment that may hold valuable energy resources.

Problem?

Not the way it was handled. Conoco applied an existing technology in a new way to help protect endangered species and the environment while shooting a seismic survey in the steep cliffs in the San Juan natural gas basin of northwestern New Mexico.

The technique, which also trimmed costs by more than 40 percent, utilized shorter cable segments of only one-quarter mile in length and spaced nearly a quarter mile apart for the survey.

"The San Juan is extremely hilly so running long lengths of cable there was not very practical," said Alan R. Huffman, Conoco's manager of seismic imaging technology. "It's complicated by the fact that the road structure in the basin is not very linear."

Along with the physical challenges of shooting seismic in this region, the area also includes a number of archaeological sites and is home to endangered wildlife.

Image Caption

Take only photographs, leave only footprints, was the new imperative for Conoco's seismic crews in the rugged and environmentally sensitive areas of the San Juan basin in northern New Mexico. Photos courtesy of Conoco.

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In terms of beauty, the area is a geologic wonderland.

It's a wonderland in terms of hydrocarbon potential, too, waiting to be defined by seismic data.

A fragile and beautiful environment that may hold valuable energy resources.

Problem?

Not the way it was handled. Conoco applied an existing technology in a new way to help protect endangered species and the environment while shooting a seismic survey in the steep cliffs in the San Juan natural gas basin of northwestern New Mexico.

The technique, which also trimmed costs by more than 40 percent, utilized shorter cable segments of only one-quarter mile in length and spaced nearly a quarter mile apart for the survey.

"The San Juan is extremely hilly so running long lengths of cable there was not very practical," said Alan R. Huffman, Conoco's manager of seismic imaging technology. "It's complicated by the fact that the road structure in the basin is not very linear."

Along with the physical challenges of shooting seismic in this region, the area also includes a number of archaeological sites and is home to endangered wildlife.

But by using this cabling method, virtually no environmental footprint was left after the San Juan seismic project was completed.

Seismic crews worked with professional biologists to avoid disturbing the nests of bald eagles, golden eagles, hawks and other raptors that were hatching and nurturing newborns.

Crews also were able to stay away from the breeding areas of antelope and deer, due to the design of the survey.

The crews discovered 30 previously unknown sites of rare plants including Brack's Cactus and Aztec Gilia in the survey area of San Juan and Rio Arriba counties. In fact, these are the only places in the world where these plants are known to grow.

Company crews avoided the sensitive areas and mapped all the newly discovered sites of endangered plants and archaeological ruins and shared the information with the Bureau of Land Management in Farmington, N.M. The company also worked with the U.S. Fish and Wildlife Service, the Mountain Ute and Southern Ute Indian Nations and the state environmental department.

"We utilized an existing technology with innovative survey design methods," Huffman said, "to implement an intelligent seismic survey that produced minimal imprint on the environment."

Getting Clever

Typically, seismic crews lay cables that run hundreds of miles and can be up to one inch thick.

While these long cables sometimes can be routed away from some small environmentally sensitive areas, it is difficult to place the cables around larger areas.

But the San Juan Survey, which was conducted in 1998, called for a new technique.

"We were in a situation that forced us to get clever," Huffman said. "It was a big survey, 355 square miles."

Quarter mile applications had been used previously but not for these reasons.

Now? "It is now part of our arsenal of survey designs," he said.

This marked the largest seismic survey ever shot in the San Juan basin. "We had 2-D data and several smaller patches of 3-D but never a survey of this size before," Huffman commented.

Conoco wanted to keep its vibrator trucks on the roads so they would not impact the environment.

"That made the survey easier to shoot," he continued, "because off-the-road terrain is so steep you'd need specially designed trucks."

The seismic crews used the roads as their source pattern and went into the terrain. Crews laid out geophones where they could in a systematic pattern.

Using a brick receiver pattern, the crews stored and transmitted seismic data.

"We recorded them on remote units and relayed data back," he said. "That allowed us to minimize the impact."

Because this was a sparsely shot survey, Conoco did not sample the underground geology as often as in a grid survey.

"This is something you do give up when you design a survey like this," Huffman said, "because we didn't want to impact the environment."

Even though costs were trimmed by more than 40 percent, this survey was still expensive since it employed helicopters to get crews into remote areas.

"We very carefully front end-load and design our surveys to get the cost minimal and to get the best quality seismic we can," he said.

This survey method also helped to reduce injuries of crew members. In the past, professional mountain climbers have run the lines through steep, mountainous areas and there were still injuries.

Largely because crews avoided virtually all difficult territory, there were no recordable injuries on this survey.

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