Surface Facilities Solar-to-Steam Technologies

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Saturday 23rd of March 2013 3:27 PM

Solar thermal enhanced oil recovery (abbreviated solar EOR) uses solar arrays to concentrate the sun's energy to heat water and generate steam for steam injection eor processes.

Traditionally, natural gas has been burned in steam boilers to produce steam. Solar EOR, however, is proving to be a viable alternative to gas-fired steam production for the oil industry. Solar EOR can generate the same quality steam as natural gas, reaching temperatures up to 750F (400C) and 1,500 PSI.

It has been standard practice to inject steam at a constant rate into heavy oil reservoirs. Research conducted by leading oil producers shows that variable rate steam injection has no negative impact on production levels. In effect, solar EOR could supply up to 80 percent of a field's annual steam requirements, by injecting solar-generated steam during the sunny hours, and a reduced amount of gas-fired steam at night or in less sunny weather or climates. This method of integrating solar EOR will displace larger amounts of gas consumption without affecting oil output.

According to research analysts at Raymond James, solar EOR can be done more cost effectively than using gas, even at current depressed prices. Steam represents as much as 60 percent of the production cost for heavily oil extraction. In addition to being cost competitive with gas, solar EOR provides a hedge against long-term gas price escalation. Long-term price projections put natural gas at $5.00/Mcf, considerably higher than the 2011 forecast of $3.75/Mcf. When an oil producer invests in a solar EOR system, all costs are upfront and the standard life of the equipment is 30 years. By using solar, instead of gas, to generate steam for EOR, companies can extend their domestic natural gas supplies to higher value uses.

While there are many types of solar-to-steam technologies available, only two are currently deployed for solar EOR: Central Tower and Enclosed Trough.

Central Tower

Originally designed for generating electricity, central tower, or power tower technology, uses a field of large tracking mirrors, called heliostats, to concentrate the sunlight on a boiler filled with water that rests on a central tower. The sun's energy is reflected on the boiler to produce steam, which is used to turn a traditional turbine to create electricity. For EOR, the process ends at steam production.

Enclosed Trough

The enclosed trough architecture encapsulates the solar thermal system within a greenhouse-like glasshouse. The glasshouse creates a protected environment to withstand the elements that can negatively impact reliability and efficiency of the solar thermal system.Lightweight curved solar-reflecting mirrors are suspended from the ceiling of the glasshouse by wires. A single-axis tracking system positions the mirrors to retrieve the optimal amount of sunlight. The mirrors concentrate the sunlight and focus it on a network of stationary steel pipes, also suspended from the glasshouse structure. Regular, oil field-quality water is carried throughout the length of the pipe, which is boiled to generate steam when intense sun radiation is applied.

Sheltering the mirrors from the wind allows them to achieve higher temperature rates and prevents dust from building up as a result from exposure to humidity. Reportedly the technology can produce heat for EOR for about $4 per million BTU, compared to between $10 and $12 for other conventional solar thermal technologies.

Current projects

21Z in McKittrick, California

GlassPoint Solar partnered with Berry Petroleum, California's largest independent oil producer, to deploy the world's first commercial solar EOR project. Commissioned in February 2011, the project is located on a 100-year old McKittrick Oil Field in McKittrick, California. Refered to as the Kern County 21Z Solar Project, the system spans roughly one acre and will produce approximately one million Btus per hour of solar heat, replacing natural gas used for steam generation. The solar EOR project was constructed in less than six weeks and is this is the first installation of GlassPoint's Single Transit Trough technology in an oil field.

Coalinga in Coalinga, California

In October 2011, Chevron Corp. and BrightSource Energy revealed a 29-megawatt solar-to-steam facility at the Coalinga Oil Field in Fresno County, California. The Coalinga solar EOR project spans 100 acres and consists of 3,822 mirror systems, or heliostats, each with two 10-foot (3-meter) by 7-foot mirrors mounted on a 6-foot steel pole focusing light on a 327-foot solar tower.

BrightSource was contracted to provide the technology, engineering and production and construction services, and Chevron Technology Ventures will manage operations of the project. It was reported that Chevron spent more than its $28 million on the contract, and BrightSource lost at least $40 million on the project.


GlassPoint Solar and Petroleum Development Oman (PDO) commissioned a 7MW solar EOR system in December 2012. PDO is a joint venture between the Sultanate of Oman, Shell and Total. The solar EOR facility was designed to cover more than four acres and produce 11 tons of high temperature (312 C), high pressure (1,450 psi) steam per hour, 27 times larger than the system deployed at Berry Petroleum's 21Z oil field.