Study On Low Temperature Oxidation Mechanism Of Air With Reduced Oxygen Flooding In Light Oil Reservoir

Gas injection flooding is one of the current EOR methods.Among them,air injection drive has the characteristics of low cost,easy access,suitable for low permeability,ultralow permeability light reservoirs and so on.It plays an irreplaceable role in the field of enhanced oil recovery.The process of air flooding not only has the functions of gas flooding,reducing the viscosity of formation oil and supplementation of formation energy,but also can produce a series of unique low-temperature oxidation reactions with formation oil,producing flue gases such as CO2 and CO,and initiating flue gas flooding.According to different oil displacement mechanisms,the effects on EOR are different.In this paper,light oil reservoirs in BZ34 block are taken as the research object.Through the experimental study of low-temperature oxidation kinetic parameters,it is shown that the crude oil has strong volatilization effect in the range of 25 ? 90?.Oxidation of crude oil are divided into three intervals: low temperature oxidation(25 ? 415 ?),fuel deposition(415 ? 481 ?),high temperature oxidation(481 ? 573 ?),with increasing reaction temperature oxidation is more and more intense,light oil sample in low temperature oxidation phase heat loss of more than 80%,heavy oil heat loss of only 40%,rate of light oil sample static tendency of 0.049 ? 0.003(ml · h),and between the dynamic oxygen consumption rate is less than 5.47 tendency(ml · h)and 8.32(ml · h).(2)Study on the influence of phase properties of air-crude oil system with different oxygen concentrations and oil displacement effect.Compared with air and oxygen reducing air,the two crude oils have poor expansibility under saturation pressure,and their dissolution into crude oil can reduce viscosity and increase density.The displacement efficiency of air(16%O2,10%O2 and 5%O2)was 56.88%,53.1% and 51.03%,respectively.The displacement efficiency of nitrogen was 50.75%,which decreased with the decrease of oxygen concentration.(3)Research on the prevention and control of gas channelling in lowpermeability reservoirs.The blocking rate of compound coagulant foam profile control agent can reach 98%.Compared with continuous gas injection,the recovery rate can be improved by about 15% in the two-dimensional model.