Schlumberger tools may be effective for detecting, monitoring greenhouse gas

BY ROSE RAGSDALE FOR GREENING OF OIL

A carbon sequestration field test in a North Dakota oil field is getting high marks from the U.S. Department of Energy. Researchers at the Plains CO2 Reduction Partnership – one of seven DOE-initiated regional partnerships – injected 440 tons of liquid carbon dioxide into a producing oil well at the Northwest McGregor Oil Field in Williams County, N.D. to test the so-called “huff and puff” enhanced oil recovery method.

The huff-and-puff EOR method occurs in three phases: injection to a depth at which the CO2 is miscible and blends with residual in-place oil (the huff stage); “soaking” for a short period of time (two weeks), and production (the puff stage). Compared to other huff-and-puff operations, the DOE-sponsored test is considered unique because the CO2 was injected to a greater depth, about 8,050 feet, and at among the highest pressures (3,000 pounds per square inch) and temperatures (180 degrees Fahrenheit) of any tests to Oil production from the McGregor well more than doubled over the course of three months, leaping from a baseline rate of 1.5 stock tank barrels per day to 3-7 stb/d. The percentage of oil in the produced fluid, commonly referred to as the “oil cut,” also more than doubled, jumping from less than 3 percent to 6 percent.

Further, the field test determined that two Schlumberger Ltd. technologies – reservoir saturation tools and vertical seismic profiling – may be effective in detecting and monitoring small-volume CO2 plumes in deep carbonate reservoirs to ensure safe and permanent sequestration. DOE created regional carbon sequestration partnerships to help develop technology, infrastructure, and regulations for implementing large-scale CO2 sequestration across the nation. The federal agency said the field test’s outcomes may be applicable to other sites in the Plains partnership region and to similar settings worldwide.