| Air injection development technology is a new technology after water flooding.Most blocks in Huabei Oilfield are in the late stage of water flooding development,with low cost of air injection and wide reservoir adaptability.They can be used as water flooding replacement technology.In this paper,the thermal effect(exothermic characteristics)produced by formation after air injection will be taken as the starting point,and the target blocks will be screened,and the mechanism of medium-low temperature oxidation displacement oil for typical low permeability and high temperature reservoirs will be studied.The thermal analysis instrument TGA/PDSC was used to analyze the oil properties and evaluate the basic exothermic characteristics and oxidation exothermic characteristics of the oil.It was found that the reaction weightlessness of crude oil was mainly concentrated in the low temperature oxidation stage,and the reaction interval at atmospheric pressure was also mainly concentrated in the low temperature oxidation stage,and the exothermic characteristics of crude oil tended to light oil.With the increase of pressure and heating rate,the exothermic capacity of crude oil increases,but the range is not large.There is no severe oxidation phenomenon like that of conventional light oil under the condition of rising pressure,but a slow change.The exothermic stability is good.It shows that the pressure and heating rate have no obvious effect on the exothermic promotion of low temperature oxidation stage.Finally,a low-temperature oxidation kinetics model of crude oil was established.The kinetic parameters were obtained according to the experimental results.The activation energies of Yan 63-164 X,Yan 63 Ping 10 and Xiliu 10 crude oils in the target blocks of Huabei Oilfield were 123.59 k J/mol,123.86 k J/mol and 125.78 k J/mol,respectively.The activation energies of Yan 63-164 X,Yan 63 Ping 10 and Xiliu 10 were higher than those of Yumen crude oil and lower than those of Du66 crude oil,the results accord with the recognition of activation energy of lighe/heavy oil.Through one-dimensional physical simulation experiment of long core pipe,nitrogen drive can increase oil displacement efficiency by 10%,while air drive can increase oil displacement efficiency by 11.5%-12%.Laboratory tests show that even if the oxidation ability is weaker,the effect of air flooding is better than that of nitrogen flooding,but considering field safety factors,nitrogen flooding is recommended for crude oil with weak oxidation ability. |
