Schlumberger

Industry Article: Hello, Frac

By recording microseismic data in offset wells, operators are steering fracs to where they want them, and stopping fracs before they go awry.

Publication: Oil & Gas International
Volume: March
Issue: 2007
Publication Date: 03/01/2007

It’s not for lack of trying. Today, the vast majority of rigs working in North America are drilling for gas. As conventional gas reservoirs have become exhausted, the industry has directed considerable technological clout toward filling the production gap with gas from tight sandstones, shales and coalbeds. In unconventional reservoirs, the biggest challenge is establishing conduits from the far reaches of the reservoir to the wellbore. By far, the most practical and economical approach to the problem has been to stimulate the formations using hydraulic fracturing. In the past decade, most fracture stimulation has been carried out in sandstone reservoirs treated with only a single hydraulic stage, but results were so encouraging that the technique has been extended to more challenging targets. Following some early successes, hydraulic fracturing has found a home in North America, where some 70% of the world market currently resides. Of this market, nine out of every 10 wells stimulated are gas wells. Maximizing reservoir contact is the name of the game today, and to this end the entire reservoir-development plan has been devoted. Operators have quickly learned that precisely placing multiple fractures in a horizontal wellbore drilled through the heart of the reservoir can expose more than 1,000 times more rock than a vertical wellbore can. Capitalizing on this idea has paid huge dividends. For example, two out of three US land wells serviced by Schlumberger in 2002 were treated with a single-stage hydraulic fracture. Just 3 years later, the number dropped to less than 50%, while 25% received two-stage treatments and 30% were treated with three or more.



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