NASA scientists tap the expertise of oil drillers to try to figure out how to construct water wells on the Red Planet.

Some of the coolest conversations begin at conferences. This past March, participants from 17 countries attended a Schlumberger symposium in Rosharon, Texas, titled "Connecting to Your Reservoir." It was your usual technical conference, with case studies and technical papers and PowerPoint presentations.
Then came a pleasant surprise: Some of the well construction experts in attendance were asked whether they could find time to go to NASA's Johnson Space Center outside Houston to discuss a special challenge. So after concluding their conference activities, several drilling and completions gurus met with NASA scientists long into the night, planning Mission Impossible: drilling for water on Mars.
The ultimate wildcat
Imagine drilling and producing a mile-deep well in weather so cold that produced water freezes instantly. Imagine not knowing anything about the rock layers, the temperatures or the pressures you might encounter. Imagine doing this in a near vacuum, requiring power to be supplied by solar or nuclear generators, not gas or diesel engines. And the equipment must be lightweight and compact enough to transport it 40 million miles through space to drill on Mars.
NASA's previous interest in drilling on Mars was limited to obtaining core samples. However, that changed with a startling discovery made by the Mars Global Surveyor about 2 years ago: Water may lie in porous rock layers near the martian surface. Research suggests there is a layer between the basement rock and the martian cryosphere, a region of ice below the planet's surface similar to Earth's permafrost, where substantial amounts of water may exist in liquid form. And such a place is most likely where any microbial martian life forms will be found.
If there is a water source on the surface of Mars, manned missions to the planet become much more feasible. Besides providing something for the astronauts to drink, electricity from solar cells can break water down into hydrogen fuel for the return trip and oxygen to breathe. Upon discovering the possibility of water on Mars, NASA quickly formed the Mars Drilling Project and bumped up the planned launch window from 2020 to 2007. The European Space Agency's Mars Express orbiter is scheduled to arrive at the Red Planet in late 2003 to gather data from ground-penetrating radar, which will supply valuable information about the depth of the cryosphere for the drilling project.
Brainstorming
Conventional drillpipe and collars would be too heavy (about 50 tons) to transport to Mars, but a composite coiled tubing unit might work. NASA people and scientists at Los Alamos National Laboratories have been investigating robotic drilling, casing while drilling and laser drilling as potential alternatives. Water-based drilling mud would be difficult to work with at -85°F
(-65°C), so drilling fluids would need to be heated and kept in pressurized tanks. (They would boil in the 0.1-psi martian atmosphere). One of the hole-cleaning suggestions was to use air, which also could power the drilling motor at the end of the coiled tubing. However, compressors to raise martian air from 0.1 psi up to drilling pressures may be too bulky for transport.
The drilling experts suggested landing the mission near one of the polar caps so chunks of the frozen carbon dioxide could be thawed to create high-pressure gas. NASA scientists immediately rejected this, as astronauts could not survive the -285°F
(-176°C) temperatures.
NASA scientists also would want to save the drill cuttings, as they would contain valuable information about the Red Planet's history. In this case, shale shakers would be like panning for gold. NASA said coring probably would be preferable for capturing and transporting rock samples. The drillers mentioned that although this would take less energy than conventional drilling, it would be much slower because core tubes become stuck, coring bits dull quickly, and extracting the cores would require frequent trips of the drillstring, which is not good for coiled tubing.
The well construction experts described the pros and cons of various lift systems like electric submersible pumps and compressed-gas jet pumps. Several questions were raised:
• Can the liquid or compressed air system that is used in drilling be adapted to produce the well afterward?
• Will the rock be stable, or will the inside of the well tend to collapse during use?
• Will the well need to be supported somehow?
• How corrosive is martian groundwater likely to be to equipment?
• Will the water be clean, or carry sand particles that would erode pumps?
• What is the underground temperature gradient?
• At what depth will the temperature and pressure be high enough for liquid water?
• What water-handling equipment will need to be heated to prevent freezing?
NASA responded that it does not yet know the answers to any of these questions.
Educating NASA
Drew Hembling, a completion engineer for Saudi Aramco who participated in this late-night brainstorming session, said drilling on Mars might be possible by 2007. "They have a lot to do before they spud their first well, but in many other areas, they're almost ready. Take thermal systems, for example. For decades, they've built equipment to resist everything from the deep cold beyond Pluto to the heat of space shuttle re-entries. They have the best people on this planet working these problems."
Hembling added a chief benefit of the discussions was educating NASA about the complexity of drilling and producing. "Members of the Mars Drilling Project now have a much better understanding of the challenges facing this mission," he said.

Editor's note: Much of this content was taken from an article written by Alan Keese for the Saudi Aramco Web site.

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