This study focuses on the hydrated ion bridge(HIB)effect at the oil-rock interface in low-to ultra-low-permeability oil reservoirs.It systematically summarizes the research methodologies,formation mechanisms,interacti...This study focuses on the hydrated ion bridge(HIB)effect at the oil-rock interface in low-to ultra-low-permeability oil reservoirs.It systematically summarizes the research methodologies,formation mechanisms,interaction strength,and disruption mechanisms of HIB,and discusses the influencing mechanisms of HIB on the occurrence state and mobility of crude oil.On this basis,the key challenges inherent in the current HIB research are analyzed,and prospective directions for future development are proposed.Currently,research in this field primarily relies on experimental characterization techniques and molecular simulation methods.The microscopic interactions involved in HIB formation mainly include electrostatic interactions,hydrogen bonds and van der Waals forces.Notably,the hydrogen bonds between polar molecules in crude oil and hydrated ions serve as the primary sites for disrupting the HIB effect.The interaction strength of HIB is collectively modulated by ion type and concentration,reservoir solution environment,mineral type of reservoir rocks,and polar components in crude oil,which subsequently influence the occurrence state and mobility of crude oil.Systematic challenges persist in HIB-related research across three dimensions:research methodologies,scale integration and geological complexity.Specifically,the dynamic evolution mechanism of HIB remains inadequately elucidated;a discontinuity exists in the connection of spatiotemporal cross-scale modeling and prediction;and the reproducibility of actual geological environments in experimental settings is insufficient.Future research may pursue breakthroughs in the following three aspects:(1)developing in-situ dynamic experimental characterization techniques and machine learning-augmented simulation strategies;(2)establishing a framework for cross-scale model fusion and upscaling prediction;and(3)conducting in-depth studies on HIB under the coupled effects of complex mineral systems and multi-physical fields.展开更多
Based on development practices of Gulong shale oil and a series of experiments on interactions between CO_(2) and the rocks and fluids of shale oil reservoirs, the application and adaptability of CO_(2) pre-fracturing...Based on development practices of Gulong shale oil and a series of experiments on interactions between CO_(2) and the rocks and fluids of shale oil reservoirs, the application and adaptability of CO_(2) pre-fracturing to the Gulong shale oil reservoirs are systematically evaluated. The pilot tests indicate that compared to wells with conventional fracturing, the wells with CO_(2) pre-fracturing demonstrate four significant characteristics: high but rapidly declined initial production, low cumulative production, high and unstable gas-oil ratio, and non-competitive liquid production. These characteristics are attributed to two facts. First, pre-fracturing with CO_(2) inhibits the cross-layer extension of the main fractures in the Gulong shale oil reservoirs, reduces the stimulated reservoir volume, weakens the fracture conductivity, and decreases the matrix permeability and porosity, ultimately impeding the engineering performance. Second, due to the confinement effect, pre-fracturing with CO_(2) increases the saturation pressure difference between the fracture-macropore system and the matrix micropore system, leading to continuous gas production and light hydrocarbon evaporation in the fracture-macropore system, and difficult extraction of crude oil in the matrix-micropore system, which affects the stable production. Under the superposition of various characteristics of Gulong shale oil reservoirs, pre-fracturing with CO_(2) has some negative impacts on reservoir stimulation (fracture extension and fracture conductivity), matrix seepage, and fluid phase and production, which restrict the application performance of CO_(2) pre-fracturing in the Gulong shale oil reservoirs.展开更多
基金Supported by the National Key Research and Development Program,China(2019YFA0708700)National Natural Science Foundation of China(52542310).
文摘This study focuses on the hydrated ion bridge(HIB)effect at the oil-rock interface in low-to ultra-low-permeability oil reservoirs.It systematically summarizes the research methodologies,formation mechanisms,interaction strength,and disruption mechanisms of HIB,and discusses the influencing mechanisms of HIB on the occurrence state and mobility of crude oil.On this basis,the key challenges inherent in the current HIB research are analyzed,and prospective directions for future development are proposed.Currently,research in this field primarily relies on experimental characterization techniques and molecular simulation methods.The microscopic interactions involved in HIB formation mainly include electrostatic interactions,hydrogen bonds and van der Waals forces.Notably,the hydrogen bonds between polar molecules in crude oil and hydrated ions serve as the primary sites for disrupting the HIB effect.The interaction strength of HIB is collectively modulated by ion type and concentration,reservoir solution environment,mineral type of reservoir rocks,and polar components in crude oil,which subsequently influence the occurrence state and mobility of crude oil.Systematic challenges persist in HIB-related research across three dimensions:research methodologies,scale integration and geological complexity.Specifically,the dynamic evolution mechanism of HIB remains inadequately elucidated;a discontinuity exists in the connection of spatiotemporal cross-scale modeling and prediction;and the reproducibility of actual geological environments in experimental settings is insufficient.Future research may pursue breakthroughs in the following three aspects:(1)developing in-situ dynamic experimental characterization techniques and machine learning-augmented simulation strategies;(2)establishing a framework for cross-scale model fusion and upscaling prediction;and(3)conducting in-depth studies on HIB under the coupled effects of complex mineral systems and multi-physical fields.
基金Supported by the National Natural Science Foundation of China(U22B2075)。
文摘Based on development practices of Gulong shale oil and a series of experiments on interactions between CO_(2) and the rocks and fluids of shale oil reservoirs, the application and adaptability of CO_(2) pre-fracturing to the Gulong shale oil reservoirs are systematically evaluated. The pilot tests indicate that compared to wells with conventional fracturing, the wells with CO_(2) pre-fracturing demonstrate four significant characteristics: high but rapidly declined initial production, low cumulative production, high and unstable gas-oil ratio, and non-competitive liquid production. These characteristics are attributed to two facts. First, pre-fracturing with CO_(2) inhibits the cross-layer extension of the main fractures in the Gulong shale oil reservoirs, reduces the stimulated reservoir volume, weakens the fracture conductivity, and decreases the matrix permeability and porosity, ultimately impeding the engineering performance. Second, due to the confinement effect, pre-fracturing with CO_(2) increases the saturation pressure difference between the fracture-macropore system and the matrix micropore system, leading to continuous gas production and light hydrocarbon evaporation in the fracture-macropore system, and difficult extraction of crude oil in the matrix-micropore system, which affects the stable production. Under the superposition of various characteristics of Gulong shale oil reservoirs, pre-fracturing with CO_(2) has some negative impacts on reservoir stimulation (fracture extension and fracture conductivity), matrix seepage, and fluid phase and production, which restrict the application performance of CO_(2) pre-fracturing in the Gulong shale oil reservoirs.
