Tight oil reservoir development is faced with the key technical problem that"water cannot be injected and oil cannot be produced"yet.With the diphenyl ethers water-soluble(gemini)surfactants as water phase s...Tight oil reservoir development is faced with the key technical problem that"water cannot be injected and oil cannot be produced"yet.With the diphenyl ethers water-soluble(gemini)surfactants as water phase shell and C10–C14 straight-chain hydrocarbon compounds as oil phase kernel,a nanofluids permeation flooding system was prepared by microemulsion technology,and its characteristics and EOR mechanisms were evaluated through experiments.The system has the following five characteristics:(1)"Small-size liquid":the average particle size of the system is less than 30 nm,which can greatly reduce the starting pressure gradient of water injection,and effectively enter and expand the sweep volume of micro-nano matrix;(2)"Small-size oil":the system can break the crude oil into"small-size oil"under the flow condition,which can greatly improve the percolation ability and displacement efficiency of the crude oil in the micro-nano matrix;(3)Dual-phase wetting:the system has contact angles with the water-wet and oil-wet interfaces of(46±1)°and(68±1)°respectively,and makes it possible for capillarity to work fully under complex wetting conditions of the reservoir;(4)High surface activity:the interfacial tension between the system and crude oil from a tight oil reservoir in Xinjiang is 10-3–10-2 mN/m,indicating the system can effectively improve the displacement efficiency of oil in fine pore throats;(5)Demulsification and viscosity reduction:the system has a demulsification and viscosity reduction rate of more than 80%to inversely emulsified crude oil from a tight oil reservoir in Xinjiang,so it can improve the mobility of crude oil in the reservoir and wellbore.The system can be used to increase oil production by fracturing in tight reservoirs,replenish formation energy by reducing injection pressure and increasing injection rate,and enhance oil recovery by displacement and cyclic injection,providing key technical support for effective production and efficient development and recovery enhancement of tight reservoirs.展开更多
The oil oxidation characteristics of the whole temperature regions from 30 ℃ to 600 ℃ during oil reservoir air injection were revealed by experiments. The whole oil oxidation temperature regions were divided into fo...The oil oxidation characteristics of the whole temperature regions from 30 ℃ to 600 ℃ during oil reservoir air injection were revealed by experiments. The whole oil oxidation temperature regions were divided into four different parts: dissolving and inflation region, low temperature oxidation region, medium temperature oxidation region and high temperature oxidation region. The reaction mechanisms of different regions were explained. Based on the oil oxidation characteristics and filed tests results, light oil reservoirs air injection development methods were divided into two types: oxygen-reducing air flooding and air flooding;heavy oil reservoirs air injection in-situ combustion development methods were divided into two types: medium temperature in-situ combustion and high temperature in-situ combustion. When the reservoir temperature is lower than 120 ℃, oxygen-reducing air flooding should be used for light oil reservoir development. When the reservoir temperature is higher than 120 ℃, air flooding method should be used for light oil reservoir development. For a normal heavy oil reservoir, when the combustion front temperature is lower than 400 ℃, the development method is medium temperature in-situ combustion. For a heavy oil reservoir with high oil resin and asphalting contents, when the combustion front temperature is higher than 450 ℃, the development method at this condition is high temperature in-situ combustion. Ten years field tests of air injection carried out by PetroChina proved that air has advantages in technical, economical and gas source aspects compared with other gas agents for oilfield gas injection development. Air injection development can be used in low/super-low permeability light oil reservoirs, medium and high permeability light oil reservoirs and heavy oil reservoirs. Air is a very promising gas flooding agent.展开更多
基金Supported by the CNPC Science and Technology Major Project(2019E-2607)RIPED Discipline Construction Project(yjxk2019-12)
文摘Tight oil reservoir development is faced with the key technical problem that"water cannot be injected and oil cannot be produced"yet.With the diphenyl ethers water-soluble(gemini)surfactants as water phase shell and C10–C14 straight-chain hydrocarbon compounds as oil phase kernel,a nanofluids permeation flooding system was prepared by microemulsion technology,and its characteristics and EOR mechanisms were evaluated through experiments.The system has the following five characteristics:(1)"Small-size liquid":the average particle size of the system is less than 30 nm,which can greatly reduce the starting pressure gradient of water injection,and effectively enter and expand the sweep volume of micro-nano matrix;(2)"Small-size oil":the system can break the crude oil into"small-size oil"under the flow condition,which can greatly improve the percolation ability and displacement efficiency of the crude oil in the micro-nano matrix;(3)Dual-phase wetting:the system has contact angles with the water-wet and oil-wet interfaces of(46±1)°and(68±1)°respectively,and makes it possible for capillarity to work fully under complex wetting conditions of the reservoir;(4)High surface activity:the interfacial tension between the system and crude oil from a tight oil reservoir in Xinjiang is 10-3–10-2 mN/m,indicating the system can effectively improve the displacement efficiency of oil in fine pore throats;(5)Demulsification and viscosity reduction:the system has a demulsification and viscosity reduction rate of more than 80%to inversely emulsified crude oil from a tight oil reservoir in Xinjiang,so it can improve the mobility of crude oil in the reservoir and wellbore.The system can be used to increase oil production by fracturing in tight reservoirs,replenish formation energy by reducing injection pressure and increasing injection rate,and enhance oil recovery by displacement and cyclic injection,providing key technical support for effective production and efficient development and recovery enhancement of tight reservoirs.
文摘The oil oxidation characteristics of the whole temperature regions from 30 ℃ to 600 ℃ during oil reservoir air injection were revealed by experiments. The whole oil oxidation temperature regions were divided into four different parts: dissolving and inflation region, low temperature oxidation region, medium temperature oxidation region and high temperature oxidation region. The reaction mechanisms of different regions were explained. Based on the oil oxidation characteristics and filed tests results, light oil reservoirs air injection development methods were divided into two types: oxygen-reducing air flooding and air flooding;heavy oil reservoirs air injection in-situ combustion development methods were divided into two types: medium temperature in-situ combustion and high temperature in-situ combustion. When the reservoir temperature is lower than 120 ℃, oxygen-reducing air flooding should be used for light oil reservoir development. When the reservoir temperature is higher than 120 ℃, air flooding method should be used for light oil reservoir development. For a normal heavy oil reservoir, when the combustion front temperature is lower than 400 ℃, the development method is medium temperature in-situ combustion. For a heavy oil reservoir with high oil resin and asphalting contents, when the combustion front temperature is higher than 450 ℃, the development method at this condition is high temperature in-situ combustion. Ten years field tests of air injection carried out by PetroChina proved that air has advantages in technical, economical and gas source aspects compared with other gas agents for oilfield gas injection development. Air injection development can be used in low/super-low permeability light oil reservoirs, medium and high permeability light oil reservoirs and heavy oil reservoirs. Air is a very promising gas flooding agent.
