Tuhai Oilfield explores new approaches to improve recovery efficiency

As of May 17, after applying CCUS-EOR (carbon dioxide capture, utilization and storage-enhanced oil recovery) technology in the Niuquanhu East area of Santanghu Oilfield, Tuha Oilfield has achieved cumulative oil production increase exceeding 20,000 tons in the pilot block, with a recovery factor improved by 1.4%, effectively doubling production in the test area.
Tuha Oilfield features diverse and complex reservoir types. As development progresses, conventional reservoirs in mature areas exhibit high water content, while new areas primarily rely on unconventional production, leading to rapid production decline. There is an urgent need to explore effective methods for enhancing recovery. After years of research and breakthroughs, Tuha has successively overcome multiple technical challenges, including early water injection in "three-lows" sandstone reservoirs, oxygen-reduced air foam flooding in deep heavy oil reservoirs, natural gas gravity miscible displacement in medium-to-high permeability light oil reservoirs, and CCUS-EOR in low-permeability, low-viscosity reservoirs.
To effectively develop the low-pressure, ultra-low-permeability reserves in the Xishanyao formation of the Niuquanhu block, Tuha Oilfield developed and refined an advanced water-injection development model. After full-scale implementation across the region and continuous optimization, a series of technologies—including gentle water injection, chemical profile control, and repeated fracturing—have been established, enabling the natural decline rate of sandstone reservoirs to be gradually controlled within 10%.
The Lukqin heavy oil reservoirs are deeply buried and highly heterogeneous, characterized by "four highs and one moderate"—high density, high viscosity, high pour point, high non-hydrocarbon content, and moderate wax content. The technical team focused on displacement mechanisms and ultimately developed a "oxygen-reduced air flooding + cyclic steam stimulation" technology system. Application of this technology has more than doubled the recovery factor in the pilot block, surpassing 30%.
In revitalizing mature fields, facing the challenges of high recovery rates and high water cut at Pubei Oilfield, the team deepened geological understanding and continuously optimized the natural gas gravity miscible displacement scheme, successfully expanding sweep volume and improving displacement efficiency.