Dr. Henry Williams

Roughly 60 horizontal wells have been drilled in the Pekisko formation, for a 70-80% success rate, while vertical wells have just a 20% success rate, says Henry Williams, a Petro-Canada senior geologist.The problem with drilling horizontal wells in that area, though, is that drillbits grind the rock into fine dust, skewing geologists' findings.

The Rock Creek formation in the Wilson Creek area is only about five metres thick at most, while the layer with porosity is just two metres thick.Petro-Canada wanted to explore the variable porosity using horizontal drilling because it was getting mixed results with its vertical wells.

"We needed to be able to drill a horizontal well and stay within two to three metres, for maybe up to a kilometre," says Williams, poring over logs in a Petro-Canada boardroom.
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The Pekisko was the "guinea pig" because Petro-Canada had drilled there before and it was relatively easy, says Williams.He wanted to open as much porosity as possible but all he had to rely on in previous Pekisko horizontal wells were wellsite geologist interpretations of cuttings and gas response.

Traditionally, real-time drilling information was restricted to gamma ray, survey tools, drilling mud gas readings and rate of penetration."What we needed was a better way of determining whether we were drilling porous rock or not," he says.
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"That was key," says Williams.
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Halliburton's trademarked software system, Insite Anywhere, which displays drilling and formation evaluation data, was also invaluable, especially during some tricky parts, because the wellsite geologist could simply call Williams and ask him to have a look at the log on the Internet, he says.

All the data from the FEWD sensors were transmitted to Calgary, speeding up decision-making between the Calgary office and the drilling rig.Corrections were made sooner than otherwise possible, saving valuable rig time and increasing the percentage of targeted pay drilled.

Having real-time access to the operation is an essential part of logging-while-drilling, says Williams.It meant he could log-in to the project via an Internet site 24 hours a day and see how it was developing.Meanwhile, the wellsite geologist was able to manually insert his observations on the logs.

"If you wake up at 2:30 in the morning and you have nothing else to do, you can say, 'Oh, I'll just go and see what's happening,' and turn on your computer.It makes it a 24-hour operation.That's good or bad, I don't know," he says with a shrug and a grin.
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We could stay in the porous rock," says Williams.

Ultimately, this is a good-news, bad-news story.Both wells were "technical wonders" and did just what Petro-Canada wanted them to, but in terms of production they were disasters, he says.The Pekisko well has been producing 150 thousand cubic feet (mcf) per day and the Rock Creek well has been sputtering along at less than 100 mcf per day, with associated higher-than-expected volumes of oil.

The Rock Creek well appears to be persistently blocking itself off with sand and Williams suspects part of the problem may be that the rock in the wellbore is so poorly cemented (up to 22% log porosity) that it keeps disintegrating.

But Petro-Canada has not given up yet on these wells.It is looking at using coiled tubing on the Rock Creek well this winter, in a process Williams likens to blasting out debris with water through a high-pressure garden hose.

CONTACT FOR MORE INFORMATION

Henry Williams, Petro-Canada, Tel. (403) 296-4168, E-mail: williams@petro-canada.ca

"Geology and hydrocarbon potential of western Newfoundland", by Dr. Henry Williams, Memorial University

Hank WilliamsMemorial University of Newfoundland (ret.)(709) 737-8396hank@sparky2.esd.mun.ca

Mark Cooper,1 John Weissenberger,1 Ian Knight,2 Doug Hostad,3 Derek Gillespie,3 Henry Williams,4 Elliott Burden,4 Janet Porter-Chaudhry,1 Don Rae,5 Elizabeth Clark6
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Henry Williams following his graduation, moved to the University of Oslo, then to Memorial University of Newfoundland, where he obtained a faculty appointment.He has been involved in the selection of global stratotype sections for both the upper and lower boundaries of the Ordovician, was secretary of the International Union of Geological Sciences Subcommission on Ordovician Stratigraphy, and has published over 50 scientific papers on lower Paleozoic stratigraphy, paleontology, and paleogeography.After completing several oil-related consulting projects, Henry left his position at Memorial University last year to begin a new career with Petro-Canada in hydrocarbon exploration and is currently investigating carbonate plays in western Alberta.

Mark Cooper,1 John Weissenberger,1 Ian Knight,2 Doug Hostad,3 Derek Gillespie,3 Henry Williams,4 Elliott Burden,4 Janet Porter-Chaudhry,1 Don Rae,5 Elizabeth Clark6
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Dating of the strata is based on paleontological data from James and Stevens (1986), Botsford (1987), S.H. Williams et al. (1987), S.H. Williams and Stevens (1988), Stenzel et al. (1990), Knight and Cawood (1991), Knight et al. (1991), Stait and Barnes (1991), Cowan and James (1993), and Burden and Williams (1995, 1996).
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The Acadian orogeny created a triangle zone located offshore (Cawood and Williams, 1988; Waldron and Stockmal, 1991, 1994) and caused thick-skinned compressional faulting.
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The stratigraphic relationships in western Newfoundland are complicated by phases of tectonism in the Ordovician (Taconic: H. Williams and Stevens, 1974), Silurian (Salinic: Dunning et al., 1990), and Devonian (Acadian: Cawood and Williams, 1988), that juxtapose coeval, highly diverse strata originally tens of kilometers apart.
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Henry Williams following his graduation, moved to the University of Oslo, then to Memorial University of Newfoundland, where he obtained a faculty appointment.He has been involved in the selection of global stratotype sections for both the upper and lower boundaries of the Ordovician, was secretary of the International Union of Geological Sciences Subcommission on Ordovician Stratigraphy, and has published over 50 scientific papers on lower Paleozoic stratigraphy, paleontology, and paleogeography.After completing several oil-related consulting projects, Henry left his position at Memorial University last year to begin a new career with Petro-Canada in hydrocarbon exploration and is currently investigating carbonate plays in western Alberta.