Amidst the cold wind and heavy snow, equipment at the Juzhong 313 Transfer Station in the Ninth Operation Area of the No.1 Oil Production Plant operates rhythmically. Pump units at the Xixi-1 Injection Station maintain a steady hum as staff meticulously adjust injection parameters and monitor well pressure and temperature. This ensures a uniform and stable injection of polymer solution into the formation, continuously "washing" crude oil from the rock pores. In 2025, the annual output from tertiary recovery at the Daqing Oilfield reached 10.87 million tons, marking the 24th consecutive year of production exceeding 10 million tons.

Through dedicated efforts spanning generations, the tertiary oil recovery technology at Daqing Oilfield has evolved from non-existence to catching up and finally leading the way. It now maintains a world-leading position and has become the dominant development technology supporting the high-quality growth of the oilfield. In 2025, the oilfield development system focused on the goal of increasing recovery rates by an additional 1 percentage point throughout the entire process. It overcame adverse factors such as deteriorating development targets, insufficient production capacity scale, a significant reduction in reserves ready for injection, and extended production construction cycles. By tackling challenges head-on and emphasizing precise whole-life-cycle regulation, the system fully promoted the quality and efficiency enhancement of tertiary recovery.

Continuous technological iteration and upgrades persistently challenge the limits of recovery rates. For new block development, the system promoted high-quality agent injection. Adopting an integrated project team management model and using "seven criteria" as a baseline, it emphasized control over key links. Gantt charts were developed for each block to schedule pre-injection activities, including production adjustment, water flooding shut-off, and surface construction. Post-injection, plans were strictly followed to enhance injection quality. As a result, the water-cut ratio in seven new blocks was reduced by 1.9 percentage points, achieving early agent injection, rapid results, and increased oil production.

For blocks currently under injection, precision control was deepened. Technicians, understanding the patterns and timeliness of different development stages in each block, strengthened all-element benchmarking and adjustment. Monthly effectiveness evaluations were conducted to identify shortcomings comprehensively and guide improvements. Special emphasis was placed on the contracted management of 25 blocks in their water-cut decline and stabilization phases, with responsibilities clarified at every level for full-coverage control. For instance, the No.1 Oil Production Plant established three injection schemes for Class II and III reservoirs, optimized design methods, and created tailored adjustment strategies for development conflicts at different stages. This built a supporting technical management model involving injection allocation management, multi-engineering joint analysis, and integrated measure implementation, ensuring all recovery rate enhancement targets were met. In 2025, the oilfield implemented 26,000 well interventions for adjustment and potential tapping, raising the block excellence rate to 90.6%, providing strong support for the 24 consecutive years of tertiary recovery output exceeding 10 million tons.

For subsequent water-flooding blocks, refined management was intensified. The development system adhered to balancing "three drives," with a core focus on "precise potential tapping and scale maintenance." It promoted the application of a development potential evaluation system, deepened analysis of remaining oil potential, and emphasized precise injection-production adjustment and production management. Following the principles of "stop, control, increase, manage, and tap," the No.3 Oil Production Plant optimized the cessation of polymer injection in high water-cut areas during late injection stages, controlled injection intensity in layers with inefficient or ineffective circulation, increased injection intensity in low-pressure, low water-cut layers, enhanced management of long-shut wells in areas with incomplete injection-production patterns, and tapped oil increase potential in low water-cut, thin, and poor layers, continuously improving development efficiency. In 2025, the oilfield implemented 2,582 well measures to control decline rates, limiting the production decline to 5.1%.

Currently, the oil displacement system for tertiary recovery at the oilfield has transitioned from conventional models to salt-resistant polymer flooding, lipopeptide compound flooding, and alkali-free composite flooding, achieving large-scale application of low-cost, high-efficiency displacement systems. Data shows that the recovery rate in blocks using this system is 1 to 2 percentage points higher than with conventional systems, with chemical agent usage reduced by over 10%.