Researchers Are Thinking Small

Is 'Micro' Next Big Thing in Drilling?

By KATHY SHIRLEY
EXPLORER Correspondent

It's all relative. "Micro" technology may make a big impact in downhole operations.

Graphic courtesy of Los Alamos National Laboratory

Memo to the oil industry: Think small.

Smaller techniques and instrumentation already have revolutionized much of our world -- think electronics, computers or the medical field -- so why not the oil industry?

And if a major research initiative by the U.S. Department of Energy is successful, the word downsized could have a whole new meaning for oil and gas operators.

Microhole technology using coiled tubing systems is becoming a real possibility -- and the DOE hopes to jumpstart even more research and development.

The impetus for microhole technology was the constantly shrinking economic viability of testing downhole tools in standard sized wells, according to James Albright with the Los Alamos National Laboratory.

"Back in the 1970s we had all the money in the world to drill holes to test diagnostic tools," Albright said. "We specifically were deploying seismic instrumentation."

Through most of the 1980s oil companies were willing to shut in some wells to gather important information on new tools.

"However, by the 1990s we had less and less access to existing wells," he said, "and it became apparent we were going to be out of business unless we found a way to put instrumentation down hole cheaply."

During that same time frame electronics were getting smaller with the advent of microprocessors and other technology.

"In fact, these advancements allowed us to build instrumentation that actually did not work optimally in larger holes," Albright said. "We realized we needed to look at drilling fit-for-purpose holes."

Los Alamos initially did some white paper studies to determine the potential problems, then tested components and put together a drilling system. Scientists realized they could build on the existing coiled tubing technology that is relatively mature today.

While coiled tubing does not drill from the surface, that application did provide an infrastructure for handling coiled tubing -- so developing a system deployed from the surface was not a completely new scenario, according to Albright.

"This has been an evolutionary versus revolutionary journey," he said. "If we had been forced to start with a revolutionary new drilling system based on new physics with an entirely new infrastructure the idea may have died on the vine. But we have been able to adapt existing technology.

"Our role at Los Alamos has been to prove microholes can be drilled," he added, "and with the lessons learned here others in the industry will find different ways to use the technology to drill faster and cheaper."

Testing the Concept

The drilling system developed at the national laboratory is made up of coiled tubing with a positive displacement motor pushed by water. Ultimately, scientists want to be able to add measurement while drilling tools, logging while drilling tools and directional drilling capabilities to the string.

Tools are not yet being developed for microhole application because the drilling method first had to be proven.

The Los Alamos scientists recently tested the microhole drilling system at the Teapot Dome Naval Petroleum Reserve in Wyoming. The field produces oil and is used for demonstrations and technology development and evaluation.

"We needed to prove we could drill in an oil environment," Albright said. "Plus, we needed a shallow target, and the Shannon Formation at about 500 feet on the Naval Petroleum Reserve was ideal."

The team drilled beneath the Shannon to 497 feet and opened the hole. In earlier tests the biggest challenge, according to Albright, was cementing the small annulus.

Previous test holes around Los Alamos led to "a good deal of difficulty with cementing due to hole stability issues in the soft sediments.

"The well in Wyoming did not have similar problems," Albright said, "so that was encouraging."

There are plans to actually fracture and attempt to produce the microhole, with a second test planned for next spring. Los Alamos scientists have drilled about 2,000 feet of hole using the microhole system and the goal moving forward is to go deeper.

"We want to go to 5,000 feet and we think we can," said Albright, who presented a paper on the subject during the recent Mid-Continent Section meeting in Tulsa.

"With proper preparation we feel we can drill 5,000 feet of hole using this technology today," he said. "Taking the microhole system beyond 5,000 feet will take much more effort because many elements will be stressed to their limits, but as the evolution progresses we will get to even greater depths."

Albright said the DOE now hopes to build on the work done at Los Alamos. In September the DOE Office of Fossil Energy announced a funding initiative for microhole technology development with proposals due Jan. 30. The initiative centers on two areas of interest:

• Field demonstration and technology development of a built-for-purpose microhole coiled tubing rig, a self-contained zero discharge drilling mud system, microhole coiled tubing bottom hole assemblies and microhole completion.
• Production equipment.

DOE anticipates $6 million of available funding, and through competitive bids will likely approve about 15 awards.