An Energy Department-sponsored project in New Mexico has shown that mixing the fluids used to fracture a natural gas formation at the bottom of the well, rather than on the surface, could lead to a better, safer, and much lower cost way to coax additional gas out of low-producing fields.
RealTimeZone Inc., of Roswell, NM, used the down hole mixing technique for the first time in a 12,300-foot natural gas well in Carlsbad, NM.
Not only did the company succeed in restoring nearly 300,000 cubic feet per day of natural gas production from a well scheduled for plugging, it also showed that the cost of the fracturing process could be cut in half.
The natural gas industry spends more than $1 billion a year to fracture gas-bearing formations as a way to release more gas.
The technique forces fluids from a gas well 300 to 1,000 feet into surrounding rock to create ribbon-thin channels through which the gas can flow back into the well.
Hydraulic fracturing allows a larger portion of the reservoir to be contacted and more gas to be produced.
RealTime Zone's method differs from conventional fracturing techniques in that the fracture fluid is mixed down hole rather than on the surface. This allows the fluid to be changed right at the formation some 12,000 feet into the earth, giving 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 fluid used in the New Mexico test was made of bauxite mixed with a methanol gel at the surface that was blended with liquid carbon dioxide down the borehole.
The bauxite props the fracture open while the liquid carbon dioxide and methanol-gel, which create the fracture, carry it deep into the formation.
Because carbon dioxide 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 removed from the formation at a faster rate, which, in turn, enables the well to produce gas sooner.
This down hole 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 percent of the fracture stimulations carried out by U.S. gas producers, it could save the industry more than $100 million per year – perhaps reducing gas prices and allowing companies to apply additional resources to locate and produce more domestic natural gas.
With the United States expected to increase its use of natural gas by a third or more over the next 15 years, advances that reduce production costs can have a major benefit in keeping affordable gas flowing to customers.
The Energy Department's National Energy Technology Laboratory – the primary field office for the department's Fossil Energy research program – began working with RealTimeZone on the hydraulic fracturing project in May 1999. Valued at $1.3 million with the federal government contributing $922,000, the project is in its last two phases.
Phase 1 was a feasibility study. Phases 2 and 3 involve field testing the down hole mixing technique and real-time monitoring of the fracture as it is created.
Between now and the time the project is scheduled to end in June 2002, operators will focus on measuring fracture height to make sure the fracture does not veer off its planned course.
Source: United States Energy Information Administration.
© 2000 Mena Report (www.menareport.com)