On June 27, 1971, a high-yield oil flow blew out from well Ling-9 in Longdong region of the Ordos Basin, marking the discovery of Maling Oilfield and kicking off the mass exploration and development of Changqing Oil and Gas Province. The oil and gas province features multiple types of reservoirs, including structural, lithologic and tight sandstone reservoirs. Ansai and Jing'an oilfields, with reserve grade of 200 million tons and 300 million tons respectively, are China's earliest and largest low-permeability oilfields
In 2008 ,as China's third-largest onshore oil and gas field, Changqing maintained its rapid growth, achieving an oil and gas output of more than 25 million metric tons of oil equivalent.
In 2009, Changing produced 15.72 million metric tons of crude, an increase of 1.93 million metric tons over last year, and has kept a year-on-year production growth of 1 million metric tons for six consecutive years. Being the most rapid growing oil/gas field in terms of production, Changqing is capable of producing 30 million metric tons of oil equivalent a year, making it the second largest oil/gas field in China.
In 2010, Changqing’s oil and gas production exceeded 35 million metric tons of oil equivalent, of which 4 million metric tons were contributed by ultra low-permeability reservoirs. Moreover, Changqing produced 21.1 billion cubic meters of natural gas, and became the largest gas province of the company.
In 2011, Changqing Oilfield produced 40.6 million tons of oil equivalent. In fact, the field has seen an annual production increase of more than 5Mtoe for four consecutive years, the fastest among all oil and gas fields in China.
In 2002, Xifeng Oilfield was discovered in the southern part of the Longdong area in the Ordos Basin. From 2003 to 2005, new oil enrichment regions were found on both sides of the main belt and eastern Heshui region in Xifeng Oilfield, further expanding the oil-bearing area of Xifeng Oilfield. By 2006, Xifeng Oilfield was estimated to have 3P reserves of 620 million tons.
The tight oil formations in Xifeng Oilfield, described as "grindstone" by geologists, have brought great difficulties to exploitation. CNPC launched pilot tests in the early development stage, and tackled a series of technical challenges in the efficient development of reservoirs with permeability of 10md, 1md and 0.5md. In 2006, significant progress was made in the development of ultra-low permeability (below 0.3md) reservoirs. Daily output per individual test well reached four tons after fracturing stimulation. And for wells stimulated by hydraulic-jet staged fracturing, the daily output per well was 33 tons. In 2007, Xifeng Oilfield achieved an annual output of over one million tons.
Sulige Gas Field
On August 26, 2000, well Su-6, situated in Suligemiao area of the western Ordos Basin, produced 1.2 million cubic meters of industrial gas, marking the discovery of Sulige Gas Field.
Sulige Gas Field is situated in Maowusu Desert of the Ordos Basin, with more than 1 trillion cubic meters of proven gas in place. The gas field is characterized by extreme heterogeneity with low permeability, low pressure and low abundance, and thus is difficult to develop in an economic and effective way.
By applying adaptable technologies, including fast drilling, downhole choke, and separate pressure production, Sulige Gas Field witnessed large-scale and effective development in 2006, when it achieved an annual production capacity of 1 billion cubic meters and officially began to supply gas to the market.
In 2007, an annual production capacity of 3 billion cubic meters was reached, and there are currently 838 running wells in the gas field, with each of these reaching a daily average output of 13,000 cubic meters of gas. On July 1, 2008, Sulige's daily output exceeded 15 million cubic meters.
In 2008, the Second and Third Gas Processing Plant in Sulige became operational, providing strong support for the rapid growth of gas output in Changqing.
In 2009, Sulige gas field newly built 3.23 billion cubic meters of production capacity, bringing its daily output up to 30 million cubic meters. In total, Sulige has accumulated an annual capacity of 10 billion cubic meters, which has turned Changqing into the largest domestic gas producer that capable of delivering 20 billion cubic meters of natural gas per annum.
By the end of 2010, 3,520 gas wells, 85 gas gathering stations and four gas processing plants had been established at Sulige gas field. The annual gas production capacity had reached 13.5 billion cubic meters, and the annual gathering, transmission and processing capacity had reached 18 billion cubic meters. The field produced 37 million cubic meters of natural gas per day, more than 10 billion cubic meters throughout the year.
In 2011, Sulige produced 46 million cubic meters of natural gas per day, i.e. 13.7 billion cubic meters throughout the year. Following a mode of integrated exploration and development, Sulige Gas Field has been able to build production capacity in a planned and standard-compliant manner. Since its massive and efficient development in 2006, the gas field had built a 17bcm/a gas production capacity, the highest in China, by the end of 2011.