Carbon storage technology ramps up oil production, reduces carbon

Efforts to cope with climate change are often at odds with the practices used to stimulate economic growth. But a new technology being used in an oil field in northeast China may offer the dual benefits of more efficient oil extraction and the reduction of greenhouse gases. Top Chinese energy producer PetroChina operates the Jilin Oil Field in the city of Songyuan in northeast China's Jilin province. The field is dotted with bright silver towers standing above its oil wells, connected to each other by a web of pipes that transports carbon dioxide to be injected into the ground. Zhang Hui, chief geologist at the Jilin Oil Field Prospecting Institute, said the injected carbon dioxide can dissolve the crude oil and subsequently expand the oil volume, making it easier to retrieve greater quantities of oil. The injection technique and oil retrieval process, referred to collectively as "Carbon Capture and Storage plus Enhanced Oil Recovery" (CCS-EOR), increases oil recovery efficiency rates by as much as 10 percent, compared to the older technique of using water to displace oil, Zhang said. The field's annual oil production is about 5.6 million barrels and would decrease by 12 percent every year without the CCS-EOR technology, Zhang said, adding that the technology has allowed the field to stabilize its output. The carbon dioxide used in the process is taken from the Changling Gas Field not far from the oil field. The field boasts natural gas reserves of 70.6 billion cubic meters, and its reserves contain a large amount of carbon dioxide. "We found that over one-seventh of the total gas reserves were carbon dioxide. Figuring out how to extract clean gas without increasing emissions was a real headache for us," Zhang said. However, the CCS-EOR technology can help sequester the greenhouses gases that would otherwise be discharged into the atmosphere. A total of 147 additional injection wells will be built in the oil field by 2015, boosting its annual carbon storage quantity to 700,000 metric tons, Zhang said, adding that this amount is equivalent to the coal consumption of a small power plant. "By that time, all the carbon dioxide captured in the gas field will be utilized to ramp up oil production," Zhang said. Zheng Chuguang, a professor at the Huazhong University of Science and Technology, is a top researcher of carbon storage and utilization. He originally proposed building the pilot CCS-EOR project in Songyuan. Although carbon capture storage technology is effective at mitigating the effects of carbon emissions on global warming, capturing and storing the carbon dioxide consumes additional energy, reducing its efficiency. "But the EOR makes the CCS technology more appealing," Zheng said. "It allows us to extract oil even in depleted oil fields." According to Zhang, industrial-scale CSS-EOR projects are under way in Canada's Weyburn Operations and the U.S.'s Salt Creek and Sharon Ridge, but applying the technology in China is more challenging. Wang Feng, the engineer-in-chief of Jilin Oil Field, said oil fields in China are mainly continental fields, meaning that underground oil reserves are more unevenly deposited than in marine reservoirs in North America. "Introducing oil displacement in continental oil fields is a technological breakthrough," Wang said.