Changqin oilfield is located in Erdors basin, which is a basin put into exploration earliest in China. Its operation covers primarily Erdors basin and its peripheral areas adjacent to Luliangshan in east, Liupanshan in west, Qinling in south and Langshan and Daqingshan in north across five provinces, including Shaanxi, Ganshu, Ningxia, Inner Mongolia and Shanxi.

Oil and gas exploration in Changqing oilfield initialed in 1903. Yanchang mine was discovered through the commercial oil flow found in well Yanchang-1 (the first onshore well in china) on Sept.10,1907. Changqing oilfield was revealed on Jun.27,1971 by commercial oil flow from well Malingling-9 located in Maling, Changqin of Longdong area, Ganshu province. And in 1988, the high yield gas flowing from well Shanchan 1 led to the discovery of a giant gas field – Shanganning.

At present, its exploration is concentrated in Shanganning basin, covering an area of about 37×104 km2. The oil and gas exploration and development begun in 1970. By the end of 1997, there were 37 oilfields such as Yanchang, Ansai, Qingan and Maling, one large gas field and three small gas fields discovered with an accumulative proven OOIP of 642.1 ×106 t and OGIP of 2926 ×108m3. Now, Changqing is a major gas production zone in China and an important base for gas supply to Beijing.