In the pilot test of polymer flooding in Class III oil reservoirs of China's Daqing Oilfield, the oil recovery factor increased by 12.69 percentage points

Recently, the up-return test of polymer flooding in Class III oil reservoirs in the Xingnan Development Area of Daqing Oilfield has achieved a major breakthrough. The block’s stage oil recovery factor increased by 12.69 percentage points, realizing a leapfrog improvement in the producing performance of thin and poor reservoirs. This successful test has overcome several technical bottlenecks encountered in the middle and late stages of old oilfield development, creating a replicable and scalable mature practical paradigm for large-scale and efficient tertiary oil recovery.

The Xingnan Development Area has now fully entered the middle to late stage of high water cut and high recovery. After long-term, high-intensity continuous extraction, the region's high-quality producible reserves have been continuously declining. The main battlefield of oilfield development has gradually shifted to Class III reservoirs, which have large reserves but suffer from disadvantages such as thin reservoir thickness, low permeability, and prominent heterogeneity. This type of reservoir has small effective thickness and weak injection-production response capacity, making it difficult to achieve efficient production with traditional development methods. It has thus become a core problem restricting stable production, quality improvement, efficiency enhancement, and output growth of old oilfields.

To break the development bottleneck of old oilfields and fully revitalize the idle stock resources of Class III reservoirs, Daqing Oilfield officially launched the up return test of polymer flooding in Class III reservoirs in the Xingnan Development Area in 2018. The test precisely targeted the difficulties and pain points in developing thin and poor reservoirs and heterogeneous reservoirs, focusing on building a standardized and systematic polymer flooding technology system for Class III reservoirs. It strived to solve the problem of inefficient development, help similar blocks improve quality and efficiency, and effectively prolong the overall stable production period of the oilfield.

During the test implementation, in response to core technical issues such as scattered remaining oil distribution at the late stage of polymer injection, uneven production of thin and poor layers, and significant interlayer interference, the technical team of the No.5 Oil Production Plant innovatively established a refined development and management model. Technical personnel regularly carried out comprehensive dynamic monitoring of the reservoir formation, accurately identified subsurface fluid migration patterns, interlayer production difference characteristics, and the enrichment and distribution of remaining oil, thereby providing solid data support for targeted potential tapping and precise parameter control in the block.

Relying on accurate dynamic monitoring and scientific evaluation, the technical team worked in both vertical and horizontal directions to finely optimize the injection production structure, improving reservoir producing efficiency in an all round and multi level manner.

A series of precise measures have been implemented and achieved results, significantly improving the development quality and efficiency of the block: the proportion of layers taking fluid in thin and poor reservoirs increased by 14.29 percentage points, the proportion of thickness taking fluid increased by 17.00 percentage points, and the comprehensive water cut of responsive wells decreased by 0.48 percentage points year on year. The overall development situation of the block continues to improve, and the potential of stock resources has been fully released.

"At present, the test area has entered the critical stage of late polymer injection. The remaining oil distribution in the reservoir is becoming increasingly scattered, and precisely tapping hidden remaining oil is the core focus of our next stage," said Bai Yuguo, Director of the Technical Management Office of the Seventh Operation Area of the No.5 Oil Production Plant. He added that for weak areas where remaining oil is enriched, such as fault margins and sand body control blind zones, the team will implement a differentiated governance model of "one well, one strategy, precise measures". At the same time, they will systematically sort out and summarize practical techniques and mature experience for efficiently tapping remaining oil in thin and poor layers and heterogeneous reservoirs, thus laying a solid technical foundation for the long term stable production, quality improvement, and efficiency enhancement of the oilfield.

The extraction of oil and natural gas cannot be achieved without separation equipment.

Shanghai SAGA Offshore Engineering Co., Ltd., established in Shanghai in 2016, is a modern technology enterprise integrating R&D, design, production, and service. We are dedicated to developing separation and filtration equipment for the oil, gas, and petrochemical industries. Our high-efficiency product portfolio includes de-oiling/dewatering hydrocyclones, desanders for micron-sized particles, and compact flotation units. We provide complete skid-mounted solutions and also offer third-party equipment retrofitting and after-sales services. Holding multiple proprietary patents and operating under a DNV-GL certified ISO-9001, ISO-14001, and ISO-45001 management system, we deliver optimized process solutions, precise product design, strict adherence to engineering specifications, and ongoing operational support.

Our high-efficiency cyclone desanders, renowned for their exceptional 98% separation rate, have earned recognition from international energy leaders. Constructed with advanced wear-resistant ceramics, these units achieve 98% removal of particles as fine as 0.5 microns in gas streams. This capability enables the reinjection of produced gas for miscible flooding in low-permeability reservoirs, a key solution for enhancing oil recovery in challenging formations. Alternatively, they can treat produced water, removing 98% of particles larger than 2 microns for direct reinjection, thereby boosting water-flood efficiency while minimizing environmental impact.

Our new product—The High Efficiency Ultra-Fine Particle Desander is a liquid-solid separation device that utilizes an efficient centrifugal principle to separate suspended impurities—such as solids in produced water, seawater, condensate, fine particles in high-viscosity liquids, and catalyst powder in reactors—from fluids (liquids, gases, or gas-liquid mixtures). It effectively removes solid particles with sizes down to 2 microns (at 98% efficiency) or smaller.

The High Efficiency Ultra-Fine Particle Desanderdelivers high sand removal efficiency, capable of removing solid particles down to 2 microns. The equipment features a compact footprint, requires no external power or chemical additives, and has a service life of approximately 20 years. It offers online sand discharge capability without the need for production shutdown.

Proven in major global fields operated by CNOOC, CNPC, Petronas, and others across Southeast Asia, SAGA desanders are deployed on wellhead and production platforms. They provide reliable solids removal from gas, well fluids, and condensate, and are critical for seawater purification, production stream protection, and water injection/flooding programs.

Beyond desanders, SAGA offers a portfolio of acclaimed separation technologies. Our product line includes membrane systems for natural gas CO₂ removal, deoiling hydrocyclones, high-performance compact flotation units (CFUs), shale gas desanding, Cyclonic dewatering package with produced water treatment, and multi-chamber hydrocyclones, delivering comprehensive solutions for the industry's toughest challenges.