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DOE-Funded Microhole Drilling Rig Demonstrated Successfully; Technology Could Tap Bypassed Oil and Gas

Los Alamos microhole drilling concept. Click to enlarge. Source: Los Alamos.

A specially designed hybrid microhole coiled tubing rig recently concluded the drilling of 25 test wells to penetrate a particularly intractable natural gas formation called the Niobrara in western Kansas and eastern Colorado. The effort delivered cost savings of 25-35% per well drilled compared with conventional drilling equipment.

As a result, about 1 trillion cubic feet of shallow gas that had been bypassed by conventional drilling has now been made economic. That volume equates to about 5% of America’s annual natural gas consumption. The research project was funded by the US Department of Energy (DOE).

In 1994, Los Alamos National Laboratory advanced a concept for drilling deep, small-diameter holes for sensor deployment to conduct long-term monitoring. The idea quickly expanded to include exploration holes for formation logging, wireline or drill-stem deployed logging, and microdrill-stem production testing. Subsequent to that, microholes began to be considered for production of shallow- and medium-depth gas and shallow oil in special situations.

Some of the specific advantages of microhole drilling are:

  • Equipment is smaller (microdrilling systems could occupy a space roughly 1/20th that of a typical rig) and weighs less (less than one tenth as much) as conventional systems reducing equipment costs (by up to 90 percent) and manpower to operate equipment.

  • Materials required for drilling and well completion are reduced.

  • Coiled tubing saves time and money because it requires fewer trips in and out of the wellbore than conventional drilling techniques.

  • Volumes of drilling fluids and cuttings can be reduced by one-fifth, reducing disposal costs.

  • Drill rigs and associated equipment have smaller footprints, reducing environmental impact and making the system particularly advantageous when operating in environmentally sensitive areas.

Drilling holes as small as 1-inch in diameter is not new. Relatively deep holes with diameters as small as 1.175-inch have been drilled using mining coring rigs for at least 50 years. Small diameter coiled tubing is readily available.

The technological challenge, as DOE describes it, is to develop an entire drilling system. Suitable drill bits and pipes are available today, but subsurface sensors, motors, logging tools, and other borehole instruments small enough to fit into the micro-wellbores and rugged enough to withstand the rigors of underground environment must still be developed.

The commercial Niobrara drilling program—in which 3,000-foot wells were drilled in as little as 19 hours, from rig move-in to move-out —followed a Department of Energy-funded research project undertaken by Gas Technology Institute (GTI), Des Plaines, Ill. In that effort, GTI partnered with two small firms—Advanced Drilling Technology LLC (ADT), Yuma, Colo., and Rosewood Resources Inc., Dallas, Texas—to adapt a conventional coiled tubing rig for drilling exploratory and development wells with ultra-small diameters.

Bore size illustration compares conventional bottom hole well diameters to slimhole and microhole sizes to emphasize the potential for materials and equipment size reduction through the use of microholes. Click to enlarge. Source: Los Alamos

The GTI project received funding from the Energy Department’s Microhole Technology Initiative. Managed by the Office of Fossil Energy’s National Energy Technology Laboratory, the initiative seeks to develop the tools and techniques for drilling ultrasmall boreholes (generally, 1-3/4 to 4-1/2 inches in diameter) and related downhole micro-instrumentation, using coiled tubing drilling rigs that are small and easily transportable.

GTI’s microhole project was meant to pioneer the use of an experimental, purpose-built coiled tubing rig designed to drill exploratory and development wells with ultrasmall diameters in the Lower 48 States. ADT and its predecessor Coiled Tubing Solutions Inc. designed and fabricated the rig specifically for microhole coiled tubing drilling to depths as great as 5,000 feet. Earlier Energy Department research had proven this capability to only a few hundred feet.

GTI and partners field tested this state-of-the-art hybrid coiled tubing rig by drilling a few inexpensive microbore wells to about 1,200-1,400 feet in the Niobrara chalk formation along the Kansas-Colorado border. The results far exceeded expectations, with drilling cost savings averaging 38%.

The project’s initial success and strong commercial follow-up also demonstrated the potential for coiled tubing drilling of exploration and development wells in the Lower 48. For the first time, a Canadian coiled tubing drilling company, Xtreme Coil Drilling Corp., Calgary, AB, Canada, is drilling grassroots wells in the Lower 48 for an American company, Anadarko Petroleum Corp., The Woodlands, Texas. Xtreme Coil is using its newly patented coiled tubing design to drill wells in the aging, marginally economic, shallow oilfields of Colorado’s Denver-Julesburg Basin. By the end of this year, Xtreme Coil also is expected to deploy its coiled tubing drilling at depths as great as 10,000-12,000 feet in deep natural gas fields such as Pinedale and Jonah in Colorado's Green River Basin for another operator, Denver, CO-based EnCana Oil & Gas (USA), Inc.

Microhole coiled tubing drilling technology could be applied to bypassed resources in thousands of oil and natural gas reservoirs across the US, particularly for shallow reservoirs in mature or even apparently depleted fields. The Energy Department estimates the volume of bypassed oil in US oilfields at less than 5,000 feet subsurface at more than 218 billion barrels. Recovering just 10 percent of this targeted untapped resource equates to an amount equal to 10 years of OPEC oil imports at current rates.




This seems a very important development for natural gas production here and drilling technology in general.


If thought about something like this for geothermal in homes. But you realize that we use 20 tcf per year and this is 1 tcf total. So at our present use it would last about 3 weeks. Hate to be a buzz kill folks, but the problem is huge.


A modified version of this might be good for cheap installation of geothermal HVAC in urban areas.


The 1 tcf total referred to in the article might be the amount of bypassed gas in the one field, Niobrara.



That's how I read it, since it also references those reaching those deep fields in the Green River Basin.


So you would have to get 20 such fields to last us a year. There was a recent NG field done in Oklahoma, the guy said yes this is a large field and would last the U.S. about 3 months. We get lots from Canada and now that tar sands are happening will probably get less. I have read the book "High Noon for Natural Gas" and they point out the situation rather clearly. We stand a better chance of gasifiying biomass to SNG with dependable long term output than working on the margins, considering our consumttion. If you want to consume less, use solar thermal heating for homes and businesses.

Rafael Seidl


consuming less to begin with should definitely be the priority, but oil & gas production firms obviously don't see it that way. The new drilling technique could prove useful in extending the useful life of existing fields in the US and other politically attractive places.

It may even prove useful for tapping into the world's vast suboceanic methane hydrate deposits, for which no viable production method exists today. Perhaps just as well, more cheap fossil fuel would take us in the wrong direction wrt global warming.

Note that coiled drilling is exactly the type of tertiary production technology that came about because of Pres. Bush's $7 billion tax giveaway to the oil & gas industry. Would it have come about without this subsidy?



I realize there are climate risks involved. But having a drilling technology that allows us to have access to previously unviable sources of oil and gas domestically has value, also. This is just one piece of a puzzle that includes alternative energy.


This is a good thing. They are proven fields with pipeline access, very good technology. I was just pointing out the size of U.S. consumption as a reference for the magnitudes of the situation.


Any idea on cost of typical drilling . Lets say to 1000 ft. and then from 1000ft to 3000ft. I think it could be applied to geothermal HVAC for offices / houses etc.

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