Research and Application of Enhancing Net-pressure Fracturing Technology for Tight Oil Reservoirs in Changqing Oilfield
Tight oil reservoirs such as Huaqing,Jiyuan,and Huanjiang in the Ordos Basin generally exhibit poor reservoir physical properties,significant heterogeneity,and substantial differences in horizontal stress in two directions.Traditional fracturing stimulation exhibits limited reservoir utilization and is not conducive to production.Long-term production is expected to be characterized by a low oil recovery rate and degree of recovery.In order to achieve efficient utilization of this type of reservoir,the technical concept of"enhancing net-pressure fracturing technology"was innovatively proposed.This involves multiple rounds of intermittent fracturing,inter-stage blowout injection cycles,cascade increase in displacement,discontinuous sand addition,and temporary fracturing throughout the process.By blocking the steering,the stress"loading-unloading-loading"cycle significantly increases the net pressure in rock fractures,widens the main fractures,opens lateral micro-fractures,enhances connectivity of matrix pores and throats,ultimately leading to an effective increase in three-dimensional fracture volume and fracture volume.The study aims to investigate the network complexity index and in-slit conductivity.Through numerical simulation and physical experimentation,this paper utilizes a large-scale visual fracture network proppant migration simulation device to compare the impact of conventional fracturing with that of"enhancing net-pressure fracturing technology"on fracture morphology and support degree.The field test validated the feasibility of this technology and conducted a comprehensive analysis of the pressure response,inter-stage pressure drop,and water hammer characteristics throughout the entire process of"enhancing net-pressure fracturing technology".The daily oil production of the test well increased significantly from 0.5 tons before implementation to 2.5 tons,reaching the first level.This represents a more than threefold increase in transformation and production rate,with the oil production rate rising from 0.2%to 1.0%.This technology explores an effective technical approach for significantly enhancing production of challenging reserves in tight oil reservoirs.
tight oil reservoirenhancing net-pressure fracturing technologydifficult to exploit reservesfracturing to increase production
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