“Drill, Baby, Drill” Unlikely the Path for European Shales

Microseismic fills the bill by tracking the fracks

It is apparent to most involved in the European shale gas industry that exploration and drilling cannot leave the same heavy footprint that it did in North America, i.e. drilling thousands of holes to find the gas.

That’s why technology suppliers were on hand to speak to delegates at the recent Shale Gas World conference about ways to know more precisely where to drill, resulting in fewer holes.

Peter Duncan, President of MicroSeismic, spoke about some of the enabling technologies supplied by his company.

“It’s important to know where your fracs are going,” insisted Duncan. “What amazes me is how fast things are changing, even for me who’s been in the business for 30 years.”

To depict how fast things were changing, Mr. Duncan showed how production was increasing at different basins. He said, “The Barnett was thought to be the big player, but for reserves it sits there at 50 trillion cubic feet (TCF); this estimate for the Marcellus puts it at 250 TCF.”

“Were not talking about just gas shales,” he said. “The Bakken shale has 3.65 billion barrels of reserves, and since 1995 the reserves in the Bakken have increased 2500%. The rocks aren’t changing, so what is it?”

Duncan noted the technology: the horizontal drilling wells that were sometimes 4,000 meters long. “It’s amazing,” he said.

“There’s also fracking,” he said, showing a picture of a 1946 frack in Kansas. “They threw whatever they could think of down the well to try and prop it.”

Duncan also showed a photograph of what he termed “when the circus comes to town” - seven Christmas trees in the middle of a drill sit. “There’s two complete pumping setups,” he explained. “They’re being monitored with a surface array of geophones. When the trucks go away, it’s really not that big an environmental impact – we can get the gas without killing the environment.”

He said that microseismic technology allowed shale drillers to you to “see the snap, crackles and pops. Not only are shales variable, but frack differently from well to well, and from stage to stage, too.”

Duncan mentioned two clients that monitor 100% of their fracks via microseismic.

He explained that the technology’s growth was out of earthquake location technology – patented in 1973.

Duncan spoke of the methodology, which entails putting a string of microphones down underground to find the event location. “The errors increase as you get further away. Drilling horizontals makes this technique prohibitive.”

He also explained “beamforming” for event location: “The concept of dish microphones is nothing new (like hearing a referee at a football game). “We capture the signals, they are stacked and you can pick them out in a low signal to noise environment.”

“Put in a permanent array,” he continued, “you get away from the noisy surface. It offers you the opportunity to monitor injection, production, using them as nodal receivers, which we can repeat cost effectively.”

Duncan said, “We drill these things into the ground, cement them in. If we’re doing real time we’ll put in a facility to radio back that data in real time.”

Microsize events grow at one location, according to Duncan, who showed a simulation. “First it grew to the right, sanded off and started to move to the left. You’re looking at where it fracked and whether it was confined to the stage you wanted it to. You don’t want to be wasting energy, waking up an aquifer above or below you.”

He said one could drill fewer wells with such information, saving as much as $4 million.

“Most engineers don’t care about how I get the data,” explained Duncan, “but wants to know where’s the oil or where’s the gas. But by moving into reservoir simulation we can address reservoir engineers questions, like ‘at what angle should I be drilling and when should this well be re-fracked?’”

One of his competitors, however, contended that shale exploration could be optimized through a combination of 3D seismic and microseismic.

Senior Vice President and CTO of GlobalGeoPhysical, Chris Usher said, “We are providing insight around reservoirs. We’ve grown dramatically in the last five years - servicing unconventionals in North America and around the world.”

He noted that seismic hardly figured for the first five years in the US, but that now it was an emerging trend.

“These tools are coming together to improve the economics for exploitation,” he said, going on to talk about how to reduce the break even costs of shale drilling.

Usher said that 3D seismic could help drillers find sweet spots, understand structure and thickness, determine stress orientation. “Aquifer identification can help local populations feel comfortable about it,” he explained. “You can understand that your frack fluids are not going into an aquifer.”

“Seismic has been pooh-poohed by engineers, but now were talking about sampling in a full azimuth which allows you to get some of the rock mechanical properties. It enables the engineer to see what’s going on.”

Usher said that in the past there were channel limitations on seismic.

“With this new type of design you’re getting longer offset to be able to compute these properties like brittle and ductile properties, TOC, and porosity – these can start to be used by engineers in their drilling and completion programs.”

“Shales aren’t simple,” he concluded, “so we’re going to see that seismic is embraced earlier in the exploitation cycle; microseismic will expand in its applications and in the tools for regulatory transparency and those tools that will modulate the costs.”