There's considerable buzz about the U.S. Department of Energy's microhole technology (MHT) program, which is focused on developing a suite of technologies capable of drilling wells with casing less than 4.5 inches in diameter using coil tubing drilling rigs.
One of the program's goals is to develop shallow (<5,000 feet) gas resources that currently are uneconomic.
However, Geoprober Drilling in Houston is at work on a project that stretches the depth limitations significantly.
The Geoprober project is one of 10 included in the DOE's second round of awards in the MHT program, and it's focusing on the deepwater environment. In fact, the objective is to demonstrate that it's possible to drill simple deepwater, shallow microhole exploration wells for far less cost than current conventional methods.
The Geoprober effort is being funded to the tune of $1 million from DOE and $4.26 million from other sources.
Expectations for deepwater coil tubing MH drilling technology are high.
"The Geoprober project is limited by a total depth of 17,000 to 20,000 feet," said Colin Leach, U.S. director at the company. "So if we're in 7,000 feet of water, then we can go maybe 10,000 feet below the mudline.
"This is significant for exploration, because if you can target wells to about 20,000 feet, this accounts for a lot of wells in deep water," Leach said. "Even though we're limited by water depth of 10,000 feet, there are plenty of wells 6,000 to 8,000 feet below the mudline in the Gulf of Mexico and also in such places as West Africa, Brazil and the Far East."
Time is Money
Conventional drilling in deep water requires a large riser of 21 inches in outside diameter, Leach noted. Adding other bits and pieces brings it up to as much as 50 inches, and it takes a large drilling vessel to accommodate maybe 7,000 feet of that size riser pipe.
This presents an added problem today given that conventional large deepwater drilling rigs are in scarce supply. A microhole "finder well," however, requires a considerably smaller rig.
"Besides the lower cost, we have a means of being able to establish a deepwater well much quicker than with a conventional approach," Leach said. "A well that takes 25 days conventionally, we might drill in 12 days, leading to considerable cost savings of perhaps 59 percent.
"A conventional $14 million well, we could maybe drill for $6 million," he said.
"We're talking about exploration wells," he noted, "and not production wells, which would have to be larger to flow better.
"From a geologist's point of view, we can provide data the same as one would get from a large well but at much less cost," Leach added. "We have the option to use the Halliburton Anaconda (smart pipe/CDT) system, which we think will be able to provide very high baud rate communication to and from the logging tools."
Another advantage of the MH technology is the limited well design, i.e., any hole size is okay for the reservoir as long as it's only 4.75 inches. This translates into few design loops to worry with.
The Geoprober MHT project entails the drilling of three demonstration wells:
- A land well to integrate the drilling and logging tool assemblies.
- A test of the "anchor" portion of the drilling system in shallow water.
- An offshore well that will combine the achievements of the first two wells but stop short of finding hydrocarbons.
The project is currently in the "phase one" land stage, which includes funding from Chevron and Statoil, Leach noted.
The plan is to wrap the three demo wells by September 2006, and Leach envisions spudding the first commercial well sometime in 2007.
He noted it will be a full-blown exploration well on a geologic prospect.
"We think this (MHT) is going to change the whole paradigm in terms of deepwater exploration," Leach said. "All we have to do is show it works — and we're confident it will."