Yumen Oil Province, known as the cradle of China's petroleum industry, is the first petroleum base in China and was put into operation as early as 1939.
In order to increase the ultimate oil recovery, through fine reservoir description and better understanding of residual oil distribution, CNPC puts this mature oilfield into redevelopment. Well patterns were rearranged in blocks including Laojunmian, Yaerxia and Baiyanghe to build new development patterns with vertical injectors and horizontal producers. Meanwhile, horizontal, directional, cluster and underbalanced wells were drilled to achieve maximum output and recovery. After the first phase implementation of the redevelopment, the output of these old blocks can be increased from the original 300,000 metric tons to 500,000 metric tons, enhancing the recoverable reserves to 8.15 million metric tons and the waterflood recovery factor by 8.3%.
Laojunmiao Oilfield, the earliest oilfield discovered in China, lies in Jiuquan Basin in Gansu Province.
In 1954, pilot waterflood was conducted in Laojunmiao Oilfield in Yumen. This is an important milestone in China's oilfield development history, and provides valuable experience for the long-term high and stable production of giant oilfields discovered subsequently, such as Daqing.
Laojunmiao Oilfield has been developed for nearly 70 years, with low output at many of its oil wells. Complex underground water/oil dynamics and faulty well patterns made the reserves difficult to tap. In 2008, CNPC launched a pilot redevelopment test at the M Block to rearrange the well patterns based on dynamic analysis. In addition, monitoring of the distribution law of residual oil, horizontal drilling, directional drilling, and underbalanced drilling were employed. The rate of production decline at the block was brought under control and the daily oil output increased from 105 metric tons to 136 metric tons.