A pilot project in China to obtain oil from complex geological structures has been successful, the country's largest oil and gas producer says.

Data showed the oil-recovery rate using a technique known as polymer flooding in conglomerate layers, a form of hydraulic fracturing also known as fracking, was improved by 10.3 percent and would be further lifted by up to 12.1 percent, the China National Petroleum Corp. said.

The pilot project was conducted in the Xinjiang Uygur autonomous region of northwestern China, where a major oil and gas reservoir is estimated to contain 8.6 billion tons of crude oil reserves and 2.1 trillion cubic meters of gas reserves, China's state-run Xinhua News Agency reported.

The energy-rich region, known as the Dzungarian Basin, is believed to account for more than one-quarter of China's total onshore reserves, experts said.

With the completion of the pilot project, the CNPC said it would expand the test zone and strengthen efforts to develop the basin, Xinhua reported.