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Changqing Becomes the Second Largest Oil/Gas Field in China

Changqing Field, located in the Erdos Basin, is discovered in 1970. It enjoys the fastest-growing rate for oil and gas production in China in the past decade.

In 2009, Changqing's oil and gas production exceeded 30 million metric tons of oil equivalent, making the field China's second largest. 3-D exploration stimulated the rapid development of Changqing featuring the fast growth in both reserves and production. It took the oilfield 33 years to raise its annual output to 10 million metric tons, four years to reach 20 million metric tons, and only two years to achieve 30 million metric tons.

Changqing experienced more efficient development and increased production thanks to the promotion of an efficient development model for ultra-low-permeability oil reservoirs and Sulige gas field. In 2009, Changqing Oilfield drilled 4,487 wells to develop ultra-low permeability reservoirs, producing more than 2.3 million metric tons of crude, and with a drilling footage of 9.169 million meters. The composite cost per individual well dropped significantly compared with the previous year.

After many years of research and hard work, Changqing has overcome technical difficulties in taping oil effectively from reservoirs with the permeability of 1 millidarcy and 0.5 millidarcy, and achieved significant progress in the research and development of exploitation technologies for reservoirs with the permeability of 0.3 millidarcy. At the same time, 17 technologies in five series were honed, such as quick reservoir evaluation, advanced mild waterflood, multi-stage fracturing, surface process optimization and simplication, and low-cost drilling and extraction, resulting in better-than- expected yield per individual well. Ansai is one of Changqing's main pay zones with the permeability as low as 0.49 millidarcy. Since being developed in 1983, Ansai has maintained the first-grade reservoir development level for 10 consecutive years. It produced 2 million metric tons of crude in 2009.

An integrated technical solution for the effective development of low abundance, low permeability and low output reservoirs has been worked out in Changqing to facilitate the rapid development of natural gas. In 2009, Changqing produced 18.95 billion cubic meters of gas, achieving an average year-on-year growth rate of 20.5% in the past five consecutive years. 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. Moreover, the percentage of cluster well groups risen from 20% to above 60%, saving considrable acreage of land for development engineering. The trial output of horizontal wells reached more than 800,000 cubic meters a day, three to five times that of vertical wells.

In addition, standardized design and modular construction have improved the speed and quality of construction of Changqing Oilfield. Originally, it took one full year to build a couple of stations, but now it only takes one month or so to build a gas gathering station, three months for a union station, and about half a year for a large-scale gas processing plant. In 2009, 144 stations were built and ready for operation in Changqing — 119 for oilfields and 25 for gas fields.