Intelligent Energy

Chevron uses solar power to produce more oil

Posting in Energy

Chevron wanted to find a cleaner way to extract more crude from its aging southern California oil field. So, it turned to solar power.

Chevron is using the power of the sun to increase crude production at the one of the oldest oil fields in the United States. If the demonstration project is successful, solar could eventually replace natural gas as the go-to fuel used in enhance oil recovery projects around the world.

The 29-megawatt thermal solar-to-steam facility officially launched Monday at the Chevron's Coalinga Oil Field in the San Joaquin Valley. The field began operations in the 1890s and contains heavy crude oil, which is more difficult to extract than lighter grades. Traditionally, the oil industry will use steam generated by burning natural gas to heat the crude, which reduces its viscosity and makes the oil easier to produce. The traditional process works. It's also extremely energy intensive, which means it's expensive and significantly increases the carbon footprint of an operation.

The project, which was developed by the oil company's subsidiary Chevron Technology Ventures, aims to get around that dirtier method by using more than 7,600 mirrors to reflect the sun's rays to a receiver on top of a solar tower. The concentrated sunlight will be used to produce steam, which will then be sent throughout the oil field to be injected underground.  Solar thermal company BrightSource Energy built the project for Chevron.

Chevron claims its Coalinga solar-enhanced oil recovery project is the largest of its kind in the world.  The project spreads over 100 acres, with mirrors covering 65 of those acres. The 3,822 mirror systems are focused on a 327-foot solar tower.

Why it matters

Oil recovery has become an increasingly important as fields age and access to easy-to-find crude wanes.  SBI Energy estimated the global market for EOR has grown from $3.1 billion in 2005 to $62.5 billion in 2009. Conventional oil recovery methods are only able to extract about 10 percent to 30 percent of the potential oil from any given reservoir. That means up to 90 percent of  the reservoir's oil might be left in the ground. Enhanced oil recovery (or EOR) can boost those rates by an additional 5 percent to 20 percent, according to SBI Energy.

Solar probably won't immediately replace all natural gas used in enhanced oil recovery projects. But it's likely to be adopted where natural gas isn't readily available or cost prohibitive.  The sun-powered oil recovery concept was recently adopted in Oman, where GlassPoint Solar was awarded a contract to build the Middle East's first solar plant generating steam to boost oil production from aging fields.

Here's how it works (numbers in photo correspond with description provided by Chevron below):

  1. The heliostats follow the movement of the sun throughout the day;
  2. The mirrors capture energy, in the form of heat from the sun;
  3. The heat is reflected from the mirrors onto a solar receiver at the top of the tower;
  4. The receiver heats a boiler filled with water. The water is heated until it becomes what's called "process steam;"
  5. The process steam is directed to a heat exchanger unit at the bottom of the tower;
  6. Inside the exchanger, the process steam cycle through a closed loop system of pipes that are intermingled with a different set of pipes that hold water produced during oil production. The process steam heat the produced water until it becomes steam. This is called saturated steam.

7a. Saturated steam moves through a distribution system that delivers it to the oilfield, where it's injected underground.
7b. Process steam cools and becomes water, where it's sent back to the boiler unit at the top of the tower.

Photos: Chevron

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Kirsten Korosec

Contributing Editor

Kirsten Korosec has written for Technology Review, Marketing News, The Hill, BNET and Bloomberg News. She holds a degree from Northwestern University's Medill School of Journalism. She is based in Tucson, Arizona. Follow her on Twitter. Disclosure