Almost without exception, today’s shale wells are stimulated using water-based fracturing fluids (slickwater). This technique is popular due to its ability to transport proppant effectively at a relatively inexpensive cost. However, it is a magnet for criticism from environmentalists, who are concerned about the incredible volume of water needed as well as the resulting contaminated wastewater which must be treated and disposed of properly. Water use is often cited as one of the primary reasons that there are more than 435 pending ballot measures seeking a moratorium of fracking in various parts of the US.
An answer may be close to being developed as we speak. Researchers at the Colorado School of Mines claim they have developed a method to unlock hydrocarbons trapped in shale with using any water at all. They are seeking to perfect Cryogenic fracturing, which replaces water with searing cold liquid nitrogen (or carbon dioxide). Used at temperatures below minus 321 Fahrenheit, it is pumped underground at high pressure. Once it comes into contact with the heated, pressurized shale, a reaction occurs which caused the shale to crack open and creates fissures through which the hydrocarbons can gush out. They liken it to pouring hot water onto a frozen car windshield, with the sharp and sudden temperature change causing the glass to crack.
There are several positive results from using this technique. First, the liquid nitrogen will evaporate underground eliminating the need for costly recovery and retreatment. Further, they claim it will form bigger fissures or canals through which hydrocarbons can be extracted, boosting oil and gas production. In theory, the below-freezing liquid should actually be more rather than less effective than water based methods.
Second, it may well solve problems with water-sensitive formations or those with an unwanted amount of clay. Slickwater fracking often causes water saturation around the fracture and clay swelling, hindering the ability to transport hydrocarbons from the fracture to the well bore. Some shale absorbs water very quickly and the entire formation may swell in size and hinder transport through the fissures we have created. Even in a best case scenario, using hydraulic fracturing results in a low recovery factor, caused largely by water trapping.
Technology in fracking in moving incredibly quickly, and methods successful in one play will be mimicked wherever the geology seems similar elsewhere. Cryogenic fracturing has evolved from failed fracturing attempts with gaseous nitrogen first introduced during the ‘70’s and ‘80’s. Critics claim nitrogen does not have a high enough viscosity to carry proppant efficiently, and that the fluid itself may prove to be more costly than producers prefer. Further, it requires special piping and equipment requirements which prove a challenge unto itself.
Obviously the new technology is not yet market ready or completed de-risked. Few technological advancements in this industry are. So much is learned by trial and effort, both success and failure. However, competitors are always paying attention and mimicking the success found by others and the techniques they employ. You best believe the industry has a close eye on what is happening in Colorado, with Pioneer Natural Resources having first crack at the new technology. Stay tuned…..