Will Europe Follow the Decade of Transformation in the US Gas Industry
The Graph Says it All - But Will This Translate to Europe?
Doug Bentley, Manager of Unconventional Resources at Schlumberger’s European division showed his audience at Shale Gas Results in Europe 2011 an annual shale gas production graph which began in 2000, when production looked nearly negligible. By 2011, according to the graph, unconventional gas had reached 4,000 billion cubic feet.
“Not too many of us would have predicted it and in five years it will look totally different,” commented Mr. Bentley.
“What are shale reservoirs?” he asked. “We’re looking at organic rich shale and source rocks. In general these porosities are created through maturation. There’s a lot of things that are going on over time, so we need to know what they went through, and show why the oil and the gas exists.”
“At the end of the day, hydraulic stimulation is required to make it productive,” he said.
According to him, all shale was different and complex.
“You have to look at reservoir quality. If you see the Barnett, the clay volumes are very low; at the Marcellus, the reverse; the Eagle Ford is calcareous. They’re very low permeability so they have to be fractured.”
Technology, he said, was required at all stages of a shale play’s development and involved three steps: evaluating reservoir and completion quality, executing the operational efficiency and environment and achieving flow efficiency and then evaluating it.
He said, “If we look at a gas reservoir, and at a conventional sandstone, you can see the mineral framework. When we start looking at unconventional rock its 100 microns (not 700 as in conventional sandstone). When you get to the next step, you need to blow up the kerogen – there’s no permeability whatsoever.
“It goes back to understanding where the hydrocarbon is actually stored,” added Bentley. “Most are convinced that you need to look at core, to understand what the maturation process is for these rocks.”
Showing a slide entitled “Understanding Anistropic Stress in Shale” he showed well data from two wells, explaining “Reservoir quality was almost identical, but in a year the well on the right was a 3 BCF well, while the other was less than 1 BCF.”
“We redesigned the well placements at a lower stress interval and had a new IP from 2-4 MM/day,” recalled Bentley. “The after tax rate of return on the well doubled and EUR increased by 20%.
Speaking of Reservoir & Completion Quality to find sweet spots, he said it was possible through seismic log and core integration.
“All shale is different,” Bentley said of Understanding Fracture Systems in Shale. “Understanding completion quality allows us to understand how the rock breaks - all planes of weakness need to be clearly mapped.
He showed a contour map of reservoir quality versus completion quality and said: “You can see the area that you want to focus on for improving the chances of success.”
Mr. Bentley noted that while shale play development in the US was more about a “brute force” approach, drilling wells as needed, it would be a technology and adaptation approach in Europe.
“There are lots of things that will work, and that won’t work and you won’t know that until you start integrating your data, so you will know where to focus.