| On December 27, 2011, Changqing Oilfield's annual production reached 40.59 million tons of oil equivalent (Mtoe), making another miracle in developing low-permeability, low-pressure and low-abundance reservoirs. Changqing's high-efficiency production in low-permeability reservoirs was made possible thanks to continuous innovation in technology and management. It took 33 years for Changqing's annual output to achieve 10 Mtoe and another four years to reach 20 Mtoe. However, it took only two years respectively to hit new highs of 30 Mtoe and 40 Mtoe. |
The history of exploration and development
Located in the Ordos Basin, Changqing Oilfield has an exploration area of 370,000 square kilometers. The exploration activities starting in 1970s led to discoveries of more than 30 oil and gas fields including Ansai, Jing'an, Jingbian, Xifeng, Jiyuan and Sulige etc.
The deposits in the loess plateau and desert are typically subject to low pressure, low permeability and low abundance. In fact, the reservoirs with a permeability of merely 1 millidarcy (mD) take up more than 70% of the proven oil reserves. In particular, the effective permeability of the Ansai field is only 0.49 mD. With an average formation pressure coefficient of 0.71, a natural reservoir drive is impossible in Changqing.
In the new millennium, Changqing Oilfield has seen an ongoing increase in oil and gas reserves leading China's oil sector for 11 successive years. The newly-added proven, probable and possible reserves identified on a yearly basis have been above 1500 Mtoe since 2008. In particular, more than 2 billion tons of oil reserves and 200 billion cubic meters of gas reserves were proven respectively each year. By now, there are four 1-billion-ton reserve areas, i.e. Shanbei, Huaqing, Jiyuan and Xifeng, with proven gas reserves amounting to approximately 4.2 trillion cubic meters. Meanwhile, Sulige has become the first natural gas field in China with a proven reserve above one trillion cubic meters.
In 2011, the new proven oil and gas reserves of Changqing Oilfield reached 310 million tons and 300 billion cubic meters respectively. Combined with the exploration findings in the previous three years, Changqing Oilfield's cumulative proven oil and gas reserves have exceeded 1 billion tons and 1 trillion cubic meters respectively within four years, ushering in an unprecedented peak of reserve growth. | | Technological strength
At Changqing Oilfield, a series of extraction and recovery techniques have been developed for low-permeability, low-pressure and low-abundance reservoirs. The formation theory of reservoirs in the central part of lake-basin opened a door to the once constrained area of oil exploration and led to the discovery of the Huaqing field; the new multi-stratum theory contributed to the breakthrough finding in the Jiyuan field; the new formation theory of tight gas reservoirs enabled the discovery of the 3-trillion-cubic-meter gas deposits in the Sulige field. By employing proprietary EOR techniques such as water injection and fracturing to increase extraction in stranded, low-yield and unstable wells, a great number of ultralow-permeability reservoirs were developed efficiently. These techniques not only play an important role in developing the low-permeability, low-pressure and low-abundance reservoirs of Changqing Oilfield but also serve as secrete weapons to tackle tight reservoirs.
Among others, the 12 extraction and recovery techniques used in the Sulige gas field initiated commercial development of tight gas in China. The state-of-the-art techniques enabled the effective development and enhanced recovery of the gas field, while ensuring the long-term yield.
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Records in 2011
Changqing's annual production exceeded 40 Mtoe, increasing by 5 Mtoe. Changqing Oilfield's proven oil and gas reserves reached 310 million tons and 300 billion cubic meters respectively, with newly-identified proven, probable and possible reserves above 1500 Mtoe. Changqing Oilfield's daily output exceeded 0.12 Mtoe with an annual capacity up to 45 Mtoe. Changqing Oilfield produced 20.02 million tons of oil and 25.82 billion cubic meters of natural gas in 2011. Changqing Oilfield succeeded in extracting more than one million cubic meters of natural gas on a daily basis from each of the 15 wells in tight reservoirs. In particular, two wells produced more than 2 million cubic meters on the testing day. |
| Highlights of Changqing Oilfield |
 | | A cornucopia of oil and gas resources
Changqing Oilfield is located in the 370,000km2 Ordos Basin, the second largest sedimentary basin in China. The Ordos Basin extends into five provinces, i.e. Shaanxi, Gansu, Ningxia, Inner Mongolia and Jiangxi. These regions are abundant in mineral resources including oil and gas reserves up to 12.85 billion tons and 15 trillion cubic meters respectively. |
 | | A frontrunner in reserve growth
Changqing Oilfield's cumulative proven oil and gas reserves are 2.7 billion tons and 4.2 trillion cubic meters respectively. In the new millennium, Changqing Oilfield has seen an ongoing increase in oil and gas reserves leading China's oil sector for 11 successive years. |
 | | The largest onshore gas field and the natural gas pipeline network hub in China
Changqing Oilfield supplies natural gas to more than 40 cities, e.g. Beijing, Tianjin and Xi'an. With nine domestic long-distance pipelines intersecting here, including the West-East Gas Pipeline and the No.1–3 Shaanxi-Beijing Pipelines, it's the hub of onshore natural gas pipelines. |
 | | One-tenth of China's crude production and one-fourth of China's natural gas production
In 2011, Changqing Oilfield produced 20 million tons of crude oil, representing one-fifth of CNPC's annual production and one-tenth of China's total annual crude output; meanwhile, it produced 25.8 billion cubic meters of natural gas, representing one-fourth of China's total annual natural gas output. |
 | | Advancing towards the goal of 50 Mtoe
It took 33 years for Changqing Oilfield's annual yield to achieve 10 Mtoe and another 4 years to reach 20 Mtoe. However, it took only 2 years respectively to hit new highs of 30 Mtoe and 40 Mtoe. The annual production of Changqing Oilfield is expected to reach 50 Mtoe in 2013. |
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