Coalinga, a small town in California’s Central Valley, is home to the past, present and future of energy. The town was originally called Coaling Station A, and served as a coaling station for the railroads in the late 19th century. The name was later shortened to Coalinga.
Coalinga sits on the aptly named Coalinga Oil Field – one of the largest in California. The oil field was discovered in 1887 and is one of the nation’s oldest producing oil fields. And last month, Coalinga gained another distinction – home to the world’s largest solar-to-steam enhanced oil recovery project.
Most oil in California is considered “heavy.” It is thick and viscous – much like molasses. These attributes make it very difficult to recover using conventional means. That is why steam is injected into the reservoir to heat the oil, reducing its viscosity, and allowing it to be more easily recovered. The steam is generated by burning natural gas.
In October, Chevron launched a new demonstration project that uses the power of the sun to create steam for enhanced oil recovery. Here’s how it works:
The heart of the project is a vast field of mirrors – 7,644 to be exact – covering 65 acres, with another 35 acres devoted to support facilities. The mirrors are 10- by 7-feet and are mounted on a 6-foot steel pole. Throughout the course of the day, the mirrors track the sun and reflect its rays to a receiver positioned on a 327-foot tower.
The solar receiver heats a very pure, pressurized water stream until it becomes high temperature. Then this high temperature, high pressure water is directed to a heat exchange unit near the bottom of the tower. This heat exchange unit is like a kettle, and the heat from high temperature and high pressure water is used to boil another, less pure, water stream recovered during oil production.
The steam produced is then distributed throughout the oil field for enhanced oil recovery. When the steam cools and becomes water, it is directed back to the receiver to repeat the cycle.
This demonstration project will help determine the economic and technical viability of solar-to-steam technology in enhanced oil recovery operations. Based on what is learned from this project, the technology may be implemented into other operations on a commercial scale.
The solar-to-steam project is significant because it could not only help enable energy production, it could also reduce emissions by reducing the need to burn as much natural gas. While we do not expect this technology to eliminate the need for natural gas, it could augment how much is used in areas where natural gas is not readily available or expensive.
While the technology is exciting, it does have limitations. For example, this project, which covers 100 acres, only produces as much steam as one gas powered steam generator, which is the size of a semi-truck.
Another potential challenge is that its operability depends the time of day. Keep in mind, an oil field is producing 24 hours a day, 7 days a week. This technology does not work at night or when it is very cloudy.
There are also geographic limitations. Not every site will be a candidate for this new steam production method. Potential locations must have ample year-round sunlight, extensive acreage, and close proximity to the area where the steam will be employed.
Despite these challenges, we are looking forward to seeing what we can learn from this project. If the technology is proven in Coalinga, it could have potential applications in other parts of the world on a much larger scale.
If successfully applied in other locations, we could improve the cost efficiency of our operations and reduce emissions, as we increase oil production.
Desmond King is the president of Chevron Technology Ventures (CTV) a division of Chevron U.S.A. Inc.that identifies, evaluates and demonstrates emerging technologies. CTV is operating the Coalinga solar-to-steam demonstration project.