When policy lags technology, destructive confusion can result. It hasn't happened yet, but the petroleum industry has a new set of drilling techniques that might, in some areas, leave policy choking in a cloud of dust.
Horizontal drilling is catching on around the world. The basic technology isn't new. But it has been refined by improvements in subtechnologies such as measurement while drilling, downhole motors, and slotted liner completions.
Robert Hauptfuhrer, chairman of Oryx Energy Co., recently predicted that in 10 years 30-50% of all onshore wells drilled in the U.S. will be horizontal. His company has completed 12 horizontal wells in the Austin Chalk of South Texas, one of the country's two main horizontal drilling arenas. The other U.S. horizontal drilling hotspot is the Williston basin, where Meridian Oil Inc. leads action targeting thin Mississippian-Devonian Bakken shale in western North Dakota.
A WORLDWIDE SURGE
As a survey in Oil & Gas Journal's Feb. 26 Drilling Technology Report will show, horizontal drilling activity is surging worldwide. One current example is the horizontal hole Norsk Hydro drilled for a 12 month production test of the thin oil zone underlying Troll gas field in the Norwegian North Sea. And Statoil Pres. Harald Norvik this month predicted horizontal drilling will overhaul economics of North Sea oil field development.
There have been failures, of course, and there will be others. Ultimately, they may moderate the current enthusiasm. But successes so far guarantee horizontal technology a growing role in the drilling repertoire.
That should be good news to environmentally conscious governments. A field successfully developed by horizontal drilling will have far fewer total wells than it would have if developed by vertical drilling. That means fewer presumably intrusive drillsites per volume of recovered oil.
But horizontal holes don't drain reservoirs the same way vertical wells do. Their differences are critical to well spacing and location. And there are the new matters of horizontal direction and distance. Authorities who approve drilling and development plans must understand these new dimensions of the horizontal drilling project proposals they increasingly will review.
"The allowable spacing for horizontal wells may be even more important to their success than selecting the optimum well bore length," says Frank J. Schuh of Drilling Technology Inc., Plano, Tex. He told the Interstate Oil Compact Commission last month that vertical well spacing decisions often don't account for directional variations of permeability within single reservoirs. Those variations are crucial to performance of horizontal wells. In general, Schuh pointed out, holes must pass through reservoirs perpendicular to the orientation of maximum horizontal permeability. So surface location patterns differ from those of vertical wells.
DIFFERENCES IMPORTANT
Approval agencies-whether they're reviewing well spacing in the U.S. or whole field development plans somewhere else-must understand these differences. And they must recognize that horizontal projects can't deviate much from the optimum without becoming uneconomic.
Horizontal drilling is an exciting and extremely promising technology. Its success will in large measure be a function of the quality of decisions about where and how the technology is applied. Most governments have a say in that crucial process. They must work with oil companies to learn a different way to look at petroleum exploration and development.
Copyright 1990 Oil & Gas Journal. All Rights Reserved.
