China's first independently designed ultra-deep large-displacement well, the Enping 21-4 oilfield A1H, recently commenced production in the Pearl River Mouth Basin with a test daily output of over 700 tons of crude oil.
With a drilling depth of 9,508 meters and a horizontal displacement of 8,689 meters, the well has become China's first deep-sea well, setting a national record for drilling horizontal length. This marks a successful breakthrough in the technical bottleneck of 10,000-meter-class large-displacement wells, placing China’s ultra-deep and ultra-long drilling technology at the forefront of the world.
The Enping 21-4 oilfield is located approximately 200 kilometers southwest of Shenzhen, with an average water depth of about 86 meters. It is a small sandstone marginal oilfield. Traditional exploitation methods would require the construction of new offshore production platforms or subsea wellheads, which is costly and time-consuming. By utilizing the unmanned platform Enping 20-5, China National Offshore Oil Corporation (CNOOC) efficiently exploits the oil and gas resources of marginal oilfields through ultra-deep displacement wells.
By relying on existing platform facilities and using extended-reach drilling technology, CNOOC has precisely drilled underground oil reserves several kilometers away, breaking through the barriers to developing marginal offshore oilfields and promoting the development of the Enping 21-4 oilfield.
CNOOC has independently developed environmentally friendly oil-based drilling fluids, continuous circulation systems, and other advanced technologies. During construction, leading techniques such as intelligent downhole steering, real-time collection of downhole parameters, and rotating casing floating were employed, with operational capabilities reaching world-class levels.
Large-displacement wells are vital for efficiently exploring and developing oil and gas resources in complex areas such as oceans and mountains. The ultra-deep large-displacement well in the Enping 21-4 oilfield has set four national records and generated 13 technological achievements, with a domestication rate of materials and equipment reaching 95 percent. In the future, CNOOC will rely on this technology to exploit oil and gas resources within a 10,000-meter range of production platforms, significantly enhancing the efficiency of oilfield development.
(Executive editor: Zhu Zeya)
