His talk began with a review of the geology and the reality of the definition of the deposits – he quoted Walter Youngquist
"Bankers won’t invest a dime in organic mudstone, but find oil shale an entirely different matter.”And then pointed out why the proper name is the mudstone, but that the MSM and bankers and those seeing their interest have been quite willing to allow the name change. Looking at numbers of around 1.5 trillion barrels of kerogen in the shales of Colorado, about 1.3 trillion in Utah, and 1.3 trillion in Wyoming, gives the United States in those states alone about 4 trillion barrels of oil. None of which, at present is being produced in any significant volume. However he noted that a production rate of 3 mbd is equivalent to a billion barrels a year (i.e. the current world production of around 87 mbd would be around 29 billion barrels a year). And a billion barrels is about the quantity of kerogen that can be found in one square mile of the basin. Normally reserves are only considered if the organic carbon content is about 30% (or roughly 70 gallons/ton).
The only places that are producing oil from the shale are currently in Estonia (with about 8,000 barrels a day); Brazil with about 4,000 barrels a day (bd), and China which is producing about 10,000 bd. However he also noted that China is building about 100 retorts a year to convert the kerogen to oil on the surface, and these retorts are located around China near significant deposits. (Typically the shale must be heated to over 300 degC before the kerogen will turn to oil, and be released from the rock – though the product of this treatment is generally thicker and quite heavy).
The potential for the continued production of liquid fossil fuels is encouraging other countries to take a serious look at developing their own resources. He cited Jordan, which is estimated to have 100 billion barrels, and testing is now going on in Morocco. However he cautioned that production levels would not rise rapidly and this could not be accepted, in the short term, as the answer to the coming shortages. He provided the following predictive plot (which I copied from an earlier talk), showing over a 60 year period the early development of conventional oil in the US against that of the tar sands of Canada, and the oil shales of the US.
The hottest developments however are not in shale oil, but rather in shale gas. The most active search for which appears, at the moment to be in Poland. Conoco Phillips has apparently drilled two wells and is looking at a third, with over 900,000 acres now being leased. Not that the road to success in that county is predicted to be easy.
The talk moved on to describe the technological breakthroughs that have made oil and gas recovery from these shales possible. While part of this has been the ability to drill long horizontal holes, which is of relatively recent origin, the evolution of the multi-stage fracking process to put a multiplicity of cracks out from the well into the reservoir has been the real key. And hydrofracking has been developing and evolving for over 50 years.
It is that hydrofracking that has led to one of the more interesting novel approaches being developed by Exxon Mobil now in Colorado. While officially this is known as the Electro-frac process, almost everyone now is calling it the Giant Toaster.
Moving one step beyond the conventional horizontal drill, and then fracking of the rock, in the oil shale the fractures will be filled with a conductive material, so that, after the pressure is removed and the crack partially closes, the pressure squeezes this proppant , calcined coke and Portland cement, together to form a conductive sheet. By passing current through this (as in your toaster) the surrounding rock can slowly be brought up to temperature and then cooked slowly to transform the kerogen to oil.
Exxon Mobil are encouraged in this by the results that Shell have reported for their in-situ retorting (which I described in my series on oil shale – which are listed on the right hand side at the top of the BTE site). As I noted on the future of oil shale when Shell carried out their slow heating of the oil shale in-situ they were able to draw off a clear, golden oil which could easily be separated into gasoline, jet fuel and diesel.
The updates on the Exxon Mobil process show that they have been able to load the conductive material into the fractures as planned, and have been able to then run current through the material and heat the rock. They have not yet done the sustained higher temperature heating that will be required for full transition of the kerogen.
The Exxon-Mobil process has the benefit of being able to move the fractures further apart to some 125 ft spacing, over the 25 ft planned for the field tests of the Shell process.