Recently, the research team of Changqing Oilfield achieved a major breakthrough in nano smart oil displacement technology. Seven pilot well groups have cumulatively increased oil output by more than 1,488 tons, successfully solving the long-standing challenges of “injection difficulty, limited flow, and poor displacement efficiency” in the block.

“At first glance, the reservoir appears intact, but it is actually filled with microchannels thinner than a strand of hair,” explained technician Gao Hui. In such formations, traditional water flooding proves ineffective — the injected water either “hits a wall” and cannot enter or “wanders aimlessly” through the micro-pores, failing to effectively displace crude oil.

Over 70% of the reservoirs developed by Changqing Oilfield in the Ordos Basin are world-class ultra-low permeability formations, with pore diameters less than one-thirtieth that of a human hair. Without fracturing, wells yield no oil; without water injection, there is no production capacity. To slow the natural decline rate and extend the field’s economic life, efficient water flooding is essential to replenish formation energy, maintain pressure, and improve recovery rates.

To overcome these challenges, Changqing Oilfield launched the “Ultra-Low Permeability Reservoir Nano-Emulsion Flooding Research and Pilot Project” in 2023, assembling a dedicated technical team and selecting pilot test areas to accelerate technological breakthroughs.

The key lies in process innovation. Through molecular dynamics simulation and optimization, the team designed amphiphilic topological molecules and successfully developed nano-sized smart oil displacement agents with particle sizes below 30 nanometers. “These tiny ‘elves’ are both hydrophilic and lipophilic and can automatically adjust their structure according to pore geometry,” explained He Zhiwu, a senior engineer at the Oil and Gas Process Research Institute. Moreover, by introducing dendritic block functional monomers, the team endowed the agents with “navigation” capabilities. The octopus-like molecular branches with polar end groups adhere firmly to rock surfaces, converting oil-wet reservoirs into water-wet environments. This innovation established a comprehensive “nano-scale injection – anti-adsorption – deep displacement” integrated technology system.

Field trials delivered encouraging results. After injection, wellhead pressure dropped by 0.66 MPa, enhancing injectivity and efficiency. More impressively, the average monthly water cut decreased, indicating that the wells not only halted production decline but achieved output growth.

To enable large-scale application, the research team developed a “Changqing-style innovation” — a low-cost, modular, skid-mounted, standardized, and intelligent injection system. At the site, journalists saw the skid-mounted device nicknamed the “smart oil agent vending machine.” Technician Liu Baozhe demonstrated the automated system: “This setup integrates regulation, displacement, and cleaning processes into one continuous operation. Raw materials go in, and nano-emulsion comes out—fully automated. Compared to conventional setups, construction costs are reduced by 40%, and the system occupies an area smaller than half a basketball court.”

It is estimated that this technology can enhance the recovery rate of ultra-low permeability reservoirs by 8–10%. Based on a geological reserve of 5 million tons in the Baima Central Block, this equates to recovering an additional 400,000 tons of oil—essentially the output of a new medium-sized oilfield.

Next, Changqing Oilfield plans to expand application of this technology to similar blocks across the Ordos Basin, expecting to boost annual oil output by more than 100,000 tons, adding another “golden key” to improved oil recovery.