As of September 10th, Dagang Oilfield has carried out differentiated water injection management in 40 key blocks, achieving a reduction in natural decline and an increase in oil production of over 30,000 tons during the stage. The natural decline rate has decreased by 1.7 percentage points compared to the same period last year, with significant results in tapping the remaining oil.
Currently, Dagang Oilfield is in the ultra-high water cut stage. Long-term water injection has led to increasingly complex reservoir seepage patterns, with highly dispersed remaining oil, making precise characterization more difficult. To address this, researchers have relied on detailed reservoir description results to continuously enhance their understanding of reservoir potential, deeply analyze the injection-production contradictions in different types of reservoirs, and formulate differentiated management strategies.
For medium and high-permeability reservoirs in the later stage of water flooding development, where the well pattern and layer system are poorly adapted and ineffective water circulation is prominent, researchers have established a rapid identification method for single-well dominant seepage channels at risk, improved the layer system and well pattern, implemented precise layer-by-layer water injection within the layer system, strengthened profile control and enhanced water flooding, and improved the control degree of water flooding and the utilization degree of oil layers. For low-permeability reservoirs with the problem of "inability to inject and inability to drive", researchers have continuously worked on the pressure-assisted water flooding energy enhancement technology for low-permeability reservoirs, and promoted the effective displacement model of "pressure - flooding - seepage" on a large scale, improving the development effect of low-permeability reservoirs.
Since the implementation of classified reservoir management in Dagang Oilfield, 497 wells have benefited in the 40 key blocks during the stage, with 175 wells showing positive results. Water flooding controlled reserves have increased by 8.02 million tons, and the control degree of water flooding and the injection-production correspondence rate have increased by 2.3 and 2.9 percentage points respectively compared to the same period last year, laying a solid foundation for stable production in the old area.