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Changqing Oil & Gas Province

As one of China’s four largest gas provinces, Changqing Oil and Gas Province is located in the Ordos Basin, characterized by complex geological structures, highly dispersed and tight reservoirs, and great challenges in development. The province holds multiple types of reservoirs, mainly structural, lithologic and tight sandstone reservoirs.

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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. Since the 1970s, Changqing has built upon low-permeability lithologic reservoirs and emphasized on new carbonate exploration areas. Multi-strata series composite reservoir-forming theory and large tight lithologic gas reservoir theory were put forward and the carbonate reservoir-forming theory was improved, boosting the hydrocarbon reserves in Jiyuan and Sulige.

Most of the new reserves are contained in low permeability, ultra-low-permeability, and super-low-permeability reservoirs in Changqing. Aiming at increasing output per individual well, it has developed 19 unique technologies in 6 series, namely quick reservoir evaluation, optimization of effective displacement systems, staged fracturing stimulation of horizontal wells, surface process optimization and streamlining, low-cost drilling and production package, and horizontal well development. These have enabled Changqing to effectively tap ultra-low-permeability reservoirs.

In 2016, Changqing Oilfield continued to improve the technology for low-permeability reservoir development, accelerated the commissioning of new wells, took measures to treat stripper wells and renovated long shut-down wells, achieving an annual output of 23.92 million tons of crude oil and 36.5 billion cubic meters of natural gas, and registering an output of over 50 million tons of oil equivalent for the fourth consecutive year.

Xifeng Oilfield

Xifeng Oilfield was discovered in 2002. 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.

CNPC tackled a series of technical challenges in the efficient development of reservoirs with permeability of 10md, 1md and even 0.5md. 18 target-oriented technologies have been innovatively integrated and widely used in reservoir stimulation, advanced water injection, and well pattern optimization, etc. 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.

Sulige Gas Field

Sulige Gas Field is situated in Maowusu Desert of the Ordos Basin, Characterized by extreme heterogeneity with low permeability, low pressure and low abundance, the gas field is difficult to develop in an economic and effective way.

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.

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 March 2013, Sulige was chosen as one of the three finalists for the "Excellence in Project Integration" Award by the 6th International Petroleum Technology Conference (IPTC). In 2014, Sulige became the largest gas field in China, with additional capacity of 3.11 billion cubic meters per year, and produced 23.65 billion cubic meters of natural gas.

As the number of low-output and marginal wells increase along with development, a series of measures such as optimizing the production profile of belching wells, water discharge gas production and fine management were applied in an effort to increase the recovery of low-yield wells and maintain stable production of the field. In 2016, Sulige produced 22.7 billion cubic meters of natural gas and its cumulative production totaled 146.8 billion cubic meters.

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