Novel heating technology provides CO₂-free heavy oil production

Conventional heavy oil production scenarios require sizable upfront energy investments, often with mixed and environmentally damaging results. A new technology from PyroPhase promises to change this by converting heavy oil deposits into flowable production using renewable energy, without generating CO₂.

The patented PyroPhase process, which is based on technology originally developed by Jack Bridges and Dick Snow at the Illinois Institute of Technology Research Institute in Chicago in the 1970s, was created as a way to heat unconventional hydrocarbons such as tar sands and oil shales in situ, converting them into recoverable oil and gas products.

"Our process was envisioned to have two major energy-generation components," said Bridges, chief inventor and cofounder of PyroPhase. "First, we wanted to develop a way to allow for considerable electricity from wind or solar power such that CO₂ emissions were reduced. Secondly, we wanted to develop a system that could take excess electricity and store it in underground tar-sand or heavy-oil deposits in the form of heat."

The process is designed to take any excess power generated from renewable sources—such as during particularly windy or sunny days—out of the power grid and transfer it to the site of an unconventional oil deposit. "Once there, we change the frequency of the 60-Hz power to something in the middle of the short-wave band using standard radio-frequency [RF] electrodes," said Bridges.

Schematic of the PyroPhase RF heaters arranged in a grid.

A grid is created in the process, consisting of many RF electrodes drilled into the formation. These electrodes incorporate the principle of dielectric heating to heat up the unconventional oil deposits in a volumetric fashion. "Our electrodes do not just heat the area immediately around the electrodes, but also the space in between them," said Snow, chief scientist and cofounder of PyroPhase. "The slow transfer of energy into the formation heats it up to high temperatures, on the order of 650°F. This temperature is sufficient to generate a pyrolysis process in the kerogen, breaking down the heavy oils or shales into lower-viscosity products that can more easily flow and be produced."

The production and processing of this pyrolyzed hydrocarbon proceeds in a conventional manner. "At the surface, we have a gas/liquid cleanup prior to putting the oil into a transmission line," added Bridges. "In addition, if a combined-cycle generator is used at the site, the off-gas is of sufficient quality to be directed to regenerate power back into the line."

The RF heating process has a precise level of control, electronically adjusting the heating load to meet fluctuations in the power supply. "We try to keep the downhole storage temperature close to 650°F, so we can adjust the level of heating accordingly," said C. Dino Pappas, PyroPhase's director of development. "During particularly windy periods in which there is too much electricity for the power grid, we can store the excess electricity in the ground as heat. If there is not enough wind blowing, or if the downhole storage temperature is already in the correct range, we can take the RF heaters offline and put all the electricity into the power grid. We have patents on that process."

In addition to the benefit of producing heavy oil and shales without the generation of CO₂, the PyroPhase process is attractive in that there is little disruption to the surface, no water is needed (particularly important for arid western US states), and the existing oil production infrastructure is used.

While Bridges and Snow began work on the PyroPhase process in the 1970s as a method to heat oil shales in situ, the project did not get beyond some preliminary field studies. "This was mainly a consequence of the dramatic collapse in oil prices in the mid 1980s," said Pappas. "However, we've done some further testing—both in the lab and in small field pilot trials—that indicate that this process is worth doing at an oil price of USD 50/bbl."

This testing included proof-of-concept laboratory tests on oil shales that examined how samples absorb energy and gain sufficient fluidity to flow out of a core. Qualitative field trials followed in which 1 m³ volumes in tar sands and other heavy oil reservoirs were heated; results showed that sufficient permeability was developed to produce the oil from these deposits. "In fact, we saw that the tar sands were easier to produce with this method versus shales because you do not have to pyrolyze the sands," said Snow. "You just have to raise the temperature enough to lower the viscosity such that the oil will flow by gravity drainage to a collection pump located beneath the heated zone."

The field tests with tar sands convinced Snow, Bridges, and Pappas to begin larger-scale field tests with tar sands, as good yield is obtained with a lower upfront energy investment. "We estimate that the net energy recovery is higher for tar sands than for oil shale—on the order of 10 bbl of oil produced for each equivalent bbl of oil you would burn in a power plant," confirmed Snow. "For oil shales, this ratio is closer to 3 bbl produced for every bbl burned."

The field trials also demonstrated that the time to production by dielectric heating is substantially shorter than other heating technologies. "It takes roughly one month of applying the RF power to bring the resource up to the desired temperature, and then several months for drainage to occur to the production well—in total, about a one-year process," said Bridges. "Other technologies may take as long as 5 years to reach the desired level of heating."

The company is working to secure funding from the US Department of Energy (DOE) and other investors to begin the tar sands work, which will be a staged development from initial pilot work that would produce 5–10 B/D, to a 300-B/D commercial module, and finally, to a commercial plant producing 10,000 B/D. "In fact, we have commissioned a large engineering firm to develop a plan for a 100,000-B/D plant for oil shale production," said Snow.

Oil shale is the long-term target for the company, which plans to apply the experience first gained in using the PyroPhase process on tar sands. "According to the US DOE, there are more than 1.6 trillion bbls of oil tied up in oil shale in Colorado, Utah, and Wyoming alone, a 200-yr supply by current usage rates," said Pappas. "I am convinced that this method of producing unconventional hydrocarbons from renewable energy with no generation of CO₂ is beneficial for several reasons: it helps make wind power practical on a massive scale, it makes the vast US supplies of tar sands and shales more economically viable, and it could potentially create thousands of domestic jobs that are so desperately needed today."

To learn more about the PyroPhase process, contact Pappas by email (c.dinopappas@usa.net) or by phone at 847.676.4169.

Ted Moon is the Technology Editor of JPT Online. He brings information on emerging technologies, R&D successes, new field applications, updates from SPE papers about recent innovations, and more. If you have a question or suggestion for future article topics, email Ted at teched@spe.org.