The US Energy Department reports that mixing the fluids used to fracture a gas formation downhole could be a better technique than mixing them on the surface.
RealTimeZone Inc., Roswell, NM, used the downhole mixing technique for the first time in a 12,300-ft gas well near Carlsbad.
DOE said not only did the company succeed in restoring nearly 300 Mcfd from a well scheduled for plugging, but also it showed that the cost of the fracturing process could be halved. The gas industry spends more than $1 billion/year to fracture wells.
It said RealTime Zone's method of downhole mixing gives the operator more control over the fracturing process. "Changes in stimulation pressures monitored at the surface allow operators to know if the fracture is being created as planned. If necessary, the operators can change the fluid mixture to ensure that a fracture goes in its intended direction."
The test used bauxite mixed with a methanol gel at the surface that was blended with liquid CO2 down the borehole.
DOE explained the bauxite props the fracture open while the CO2 and methanol-gel, which create the fracture, carry it deep into the formation. Because CO2 becomes a gas once the pressure is reduced after the fracture is formed, it comes out of the formation faster than a fluid. This allows the fracture fluid to be recovered at a faster rate, which enables the well to produce gas sooner.
DOE said, "This downhole stimulation method also uses lower treating pressures, which makes the stimulation safer. The operator also saves costs because much less horsepower is used to pump the fracture fluid into the well.
"If RealTimeZone's technology can be used on just 20% of the fracture stimulations carried out by US gas producers, it could save the industry more than $100 million/year."
DOE's National Energy Technology Laboratory began working with RealTimeZone on the hydraulic fracturing project in May 1999. It contribured $922,000 of the $1.3 million project cost. The project will end in June 2002.
