BEIJING -- A pilot project on obtaining oil from complex geological structures achieved satisfactory results in northwestern China's Xinjiang Uygur autonomous region, China National Petroleum Corporation said Tuesday.

Data showed that the oil-recovery rate in the testing block was raised by 10.3 percent and would be further lifted by up to 12.1 percent, according to the country's largest oil and gas producer.

This marks a breakthrough in the application of polymer flooding in conglomerate layers, a key technique that will bolster oil production, said a spokesman for CNPC.

Following the project, the oil giant will expand the test zone and strengthen efforts to develop Dzungarian Basin, China's major oil and gas reservoir with an estimated 8.6 billion tons of crude oil reserves and 2.1 trillion cubic meters of gas reserves.

The pilot project, initiated in 2005, aimed at solving technical problems occurring in drilling and production, and researchers have patented four technical inventions so far in the experiments, according to the CNPC.

Xinjiang is CNPC's major focus for oil and gas exploitation, as the energy-rich region accounts for over one-quarter of China's total onshore reserves.