Physical modeling,numerical simulation and field case analysis were carried out to find out the subsurface thermal oxidation state,thermal oxidation front characteristics and production dynamic characteristics of high...Physical modeling,numerical simulation and field case analysis were carried out to find out the subsurface thermal oxidation state,thermal oxidation front characteristics and production dynamic characteristics of high pressure air injection thermal oxidation miscible flooding technology.The lighter the composition and the lower the viscosity of the crude oil,the lower the fuel consumption and the combustion temperature are.The thermal oxidation front of light oil and volatile oil can advance stably,and a medium-temperature thermal oxidation stable displacement state can be formed in the light oil reservoir under high pressure conditions.With strong thermal gasification and distillation,light oil and volatile oil are likely to form a single phase zone of gasification and distillation with thermal flue gas at the high-temperature and high-pressure heat front,finally,an air-injection thermal miscible front.In light oil reservoirs,the development process of high-pressure air-injection thermal miscible flooding can be divided into three stages:boosting pressure stage,low gas-oil ratio and high-efficiency stable production stage and high gas-oil ratio production stage.Approximately 70%of crude oil is produced during the boosting pressure stage and low gas-oil ratio high-efficiency and stable production stage.展开更多
For low permeability sandstone reservoirs,CO_(2)flooding has been proved to be an effective method to enhance oil recovery.Reservoir A is a typical conglomerate reservoir in Xinjiang oilfield.The reservoir has strong ...For low permeability sandstone reservoirs,CO_(2)flooding has been proved to be an effective method to enhance oil recovery.Reservoir A is a typical conglomerate reservoir in Xinjiang oilfield.The reservoir has strong water sensitivity,and the injection pressure continues to rise.Furthermore the oil well pressure continues to drop.According to the screening conditions of CO_(2)flooding,the reservoir A can easily achieve CO_(2)miscible flooding with moderate temperature.And the reservoir has the advantage of being close to the gas source.Firstly,the relationship curve between CO_(2)oil displacement efficiency and oil displacement pressure was obtained by changing the oil displacement pressure using the fine-tube experimental model,and the minimum miscible pressure of CO_(2)oil displacement was determined.The minimum miscible pressure of reservoir A was 24.1 MPa.The change of oil phase state after CO_(2)injection was further studied by CO_(2)gas expansion experiment.The results show that the saturation pressure of formation oil increases significantly after CO_(2)injection,and the more CO_(2)injection,the higher the saturation pressure of formation oil.When the CO_(2)content in the injected crude oil is 55.29 mol%,the saturation pressure of the CO_(2)formation crude oil system reaches 31.60 MPa.Then,in order to better simulate the real reservoir conditions of conglomerate reservoir,the 2D visualization model of the outcrop was processed to analyze the microscopic oil displacement mechanism of CO_(2).The experimental results show that the remaining oil after water flooding mainly exists in the form of cluster,film,column and blind end,and the remaining oil after gas flooding exists in the form of island,cluster and film,and there is an obvious gravity overlay phenomenon.CO_(2)flooding after water flooding significantly improved sweep efficiency and enhanced recovery.Finally,through the analysis of CO_(2)field injection effect in reservoir A,it is shown that CO_(2)absorption capacity of single well is significantly higher than water absorption capacity.The equilibrium degree of production profile in gas injection stage is better than that in water flooding stage.Injecting carbon dioxide quickly restores formation pressure.The oil recovery effect after gas injection in the trial production stage is obviously improved compared with that in the water flooding stage.The research results of this paper provide a reference for the field application of CO_(2)flooding enhanced oil recovery technology in Xinjiang conglomerate reservoir.展开更多
The miscibility of flue gas and different types of light oils is investigated through slender-tube miscible displacement experiment at high temperature and high pressure.Under the conditions of high temperature and hi...The miscibility of flue gas and different types of light oils is investigated through slender-tube miscible displacement experiment at high temperature and high pressure.Under the conditions of high temperature and high pressure,the miscible displacement of flue gas and light oil is possible.At the same temperature,there is a linear relationship between oil displacement efficiency and pressure.At the same pressure,the oil displacement efficiency increases gently and then rapidly to more than 90% to achieve miscible displacement with the increase of temperature.The rapid increase of oil displacement efficiency is closely related to the process that the light components of oil transit in phase state due to distillation with the rise of temperature.Moreover,at the same pressure,the lighter the oil,the lower the minimum miscibility temperature between flue gas and oil,which allows easier miscibility and ultimately better performance of thermal miscible flooding by air injection.The miscibility between flue gas and light oil at high temperature and high pressure is more typically characterized by phase transition at high temperature in supercritical state,and it is different from the contact extraction miscibility of CO_(2) under conventional high pressure conditions.展开更多
基金Supported by the Science and Technology Project of PetroChina Exploration and Production Company.
文摘Physical modeling,numerical simulation and field case analysis were carried out to find out the subsurface thermal oxidation state,thermal oxidation front characteristics and production dynamic characteristics of high pressure air injection thermal oxidation miscible flooding technology.The lighter the composition and the lower the viscosity of the crude oil,the lower the fuel consumption and the combustion temperature are.The thermal oxidation front of light oil and volatile oil can advance stably,and a medium-temperature thermal oxidation stable displacement state can be formed in the light oil reservoir under high pressure conditions.With strong thermal gasification and distillation,light oil and volatile oil are likely to form a single phase zone of gasification and distillation with thermal flue gas at the high-temperature and high-pressure heat front,finally,an air-injection thermal miscible front.In light oil reservoirs,the development process of high-pressure air-injection thermal miscible flooding can be divided into three stages:boosting pressure stage,low gas-oil ratio and high-efficiency stable production stage and high gas-oil ratio production stage.Approximately 70%of crude oil is produced during the boosting pressure stage and low gas-oil ratio high-efficiency and stable production stage.
文摘For low permeability sandstone reservoirs,CO_(2)flooding has been proved to be an effective method to enhance oil recovery.Reservoir A is a typical conglomerate reservoir in Xinjiang oilfield.The reservoir has strong water sensitivity,and the injection pressure continues to rise.Furthermore the oil well pressure continues to drop.According to the screening conditions of CO_(2)flooding,the reservoir A can easily achieve CO_(2)miscible flooding with moderate temperature.And the reservoir has the advantage of being close to the gas source.Firstly,the relationship curve between CO_(2)oil displacement efficiency and oil displacement pressure was obtained by changing the oil displacement pressure using the fine-tube experimental model,and the minimum miscible pressure of CO_(2)oil displacement was determined.The minimum miscible pressure of reservoir A was 24.1 MPa.The change of oil phase state after CO_(2)injection was further studied by CO_(2)gas expansion experiment.The results show that the saturation pressure of formation oil increases significantly after CO_(2)injection,and the more CO_(2)injection,the higher the saturation pressure of formation oil.When the CO_(2)content in the injected crude oil is 55.29 mol%,the saturation pressure of the CO_(2)formation crude oil system reaches 31.60 MPa.Then,in order to better simulate the real reservoir conditions of conglomerate reservoir,the 2D visualization model of the outcrop was processed to analyze the microscopic oil displacement mechanism of CO_(2).The experimental results show that the remaining oil after water flooding mainly exists in the form of cluster,film,column and blind end,and the remaining oil after gas flooding exists in the form of island,cluster and film,and there is an obvious gravity overlay phenomenon.CO_(2)flooding after water flooding significantly improved sweep efficiency and enhanced recovery.Finally,through the analysis of CO_(2)field injection effect in reservoir A,it is shown that CO_(2)absorption capacity of single well is significantly higher than water absorption capacity.The equilibrium degree of production profile in gas injection stage is better than that in water flooding stage.Injecting carbon dioxide quickly restores formation pressure.The oil recovery effect after gas injection in the trial production stage is obviously improved compared with that in the water flooding stage.The research results of this paper provide a reference for the field application of CO_(2)flooding enhanced oil recovery technology in Xinjiang conglomerate reservoir.
基金Supported by the PetroChina Science and Technology Project(2023ZG18).
文摘The miscibility of flue gas and different types of light oils is investigated through slender-tube miscible displacement experiment at high temperature and high pressure.Under the conditions of high temperature and high pressure,the miscible displacement of flue gas and light oil is possible.At the same temperature,there is a linear relationship between oil displacement efficiency and pressure.At the same pressure,the oil displacement efficiency increases gently and then rapidly to more than 90% to achieve miscible displacement with the increase of temperature.The rapid increase of oil displacement efficiency is closely related to the process that the light components of oil transit in phase state due to distillation with the rise of temperature.Moreover,at the same pressure,the lighter the oil,the lower the minimum miscibility temperature between flue gas and oil,which allows easier miscibility and ultimately better performance of thermal miscible flooding by air injection.The miscibility between flue gas and light oil at high temperature and high pressure is more typically characterized by phase transition at high temperature in supercritical state,and it is different from the contact extraction miscibility of CO_(2) under conventional high pressure conditions.
