Long time coming

Seismic While Drilling Moves Closer to Reality

For years the oil and gas industry put seismic while drilling (SWD) on its wish list.

This year, that wish is coming true.

The benefits of effective SWD are multiple and meaningful. The ability to see ahead of the drillbit while drilling, in real time, helps the driller avoid hazards, increase drilling efficiency and improve well results.

SWD can assist in confirming or configuring basin and reservoir models, and it can be combined with measurement while drilling data for information-rich downhole profiling.

Successful SWD captures seismic data without interrupting drilling operations, saving money and reducing risk. It also provides the ability to predict pore pressure ahead of the bit.

And it’s happening now.

Shifting Needs

Bob Radtke, president of Technology International Inc. in Houston, has done pioneering work in SWD.

In the 1980s and ‘90s, an early form of SWD used the energy from roller-cone bits as a downhole seismic source, with surface geophones picking up the seismic waves.

But that source disappeared as the industry began phasing out roller-cone technology, Radtke noted.

“In about 2002, Schlumberger said, ‘Ok, we don’t have a downhole source so we’ll use a surface source,’ which is the traditional source for seismic,” Radtke said.

As Schlumberger worked on a viable approach to SWD, a series of workshops promoted SWD concepts to specialists in the industry – first in Dublin, Ireland, and then in League City, Texas, near Houston.

Radtke said a shift in emphasis began to occur as companies viewed SWD primarily as a tool for offshore drilling, with a main benefit of identifying drilling hazards.

“What’s interesting is that the benefits to industry have changed over time,” Radtke observed.

“The future is deepwater,” he said, “and priorities have shifted to avoiding hazards.”

Because day rates for contracting an offshore drilling rig can be so expensive, operators hate to suspend drilling operations and idle a rig for seismic work. SWD captures data while drilling progresses, avoiding downtime.

Plus, offshore operators have become more aware of over-pressured zones in deepwater exploration and other drilling hazards for several reasons. Does the name Macondo sound familiar?

By the time of the Society of Petroleum Engineers-sponsored League City workshop in 2007, it was apparent that Schlumberger and possibly other companies were offering offshore SWD services, Radtke said.

“There it became even more obvious that there were more of these being attempted offshore,” he explained, “and they were successful.”

Making Progress

But SWD still seemed to be a work in progress ­– until May 2013, when SPE and the Society of Exploration Geophysicists (SEG) sponsored another workshop, this one on Galveston Island. At that time, Schlumberger revealed it had already conducted more than 230 SWD jobs worldwide.

Stunner.

“That was new news to many in the industry, that the trend had been so positive,” Radtke said.

Not only was SWD a “thing,” it was a real thing maturing into commercial reality.

And so began the current scramble to develop and offer SWD services, and to enhance SWD capabilities.

“Some of these efforts are still in their infancies, but as I’m told, this has become a high priority,” Radtke said.

What are the service companies saying about SWD? Precious little, other than marketing information. Everyone is looking over their own shoulders.

But companies reportedly are deploying more assets and people to build their SWD capabilities. And for good reason.

“When the requests for quotations are written, especially international, they require seismic while drilling,” Radtke said. “Companies that don’t have seismic while drilling capability will have trouble bidding on those tenders.”

Coming of Age

AAPG award-winning member Bob Hardage was keynote speaker at the Galveston Island SWD workshop. He’s a senior research scientist at the Bureau of Economic Geology at the University of Texas-Austin, former president of SEG and former editor of the EXPLORER’s popular Geophysical Corner column.

Hardage thinks some companies still are hesitant to rely on SWD as a drilling input.

“They see the possibility that it could fail and create a fishing problem they’ll have to deal with,” he said.

With a seismic source at the surface, sensors in the drillstring capture checkshot and interval velocity data for SWD time-depth-velocity detail. The industry has sought a downhole seismic source, both for better resolution and for avoiding some problems with downhole SWD.

“Where we are today is that people are saying, ‘We want to do something like that old rotary bit concept,’” Hardage said. “Ideally, it would not require you to make any alteration in your drilling.”

Radtke’s company has developed a drillstring sparker tool that can generate seismic-friendly, low-frequency waves propagating over a long distance. It’s one solution to the downhole source challenge, and Radtke believes seeing 1,000-3,000 feet ahead of bit is possible with the system.

Currently, SWD is deployed almost exclusively for deepwater or highly deviated/horizontal wells. That might not be the ultimate prize.

SWD holds big potential in unconventional resource development. Researchers already are studying SWD for identification of natural fracture clusters, to help identify sweet spots in resource plays, according to Radtke.

The future is definitely out there, and SWD has started to come of age.

“It’s a positive trend in terms of application right now,” Radtke said.

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Emphasis: Downhole Geology