Ignition Technology Of Heavy Oil Reservoir In Low Permeability

In-situ combustion is one of the thermal recovery methods to improve oil recovery,compared with other thermal recovery methods,it applies to a wider range of reservoir conditions,provides higher recovery,and can improve the quality of oil and reduce viscosity.Ignition is the key technology to the success offire flooding.If the ignition fails,the whole fire drive fails,and the secondary ignition effect is difficult to guarantee.In the case of single reservoir conditions and single oil properties,the ignition process is simple,while Liaohe fire flooding reservoir conditions are complex and oil properties are diverse,which puts forward higher requirements for ignition.At present,the reservoir conditions and oil properties of fire flooding in other oilfields are relatively simple,the requirements for ignition and supporting technology are low,and related research is less.especially in the lack of complex reservoir ignition process design methods related to experimental simulation.The theoretical research of peroxide combustion is carried out at home and abroad,but it is mainly based on the heat conduction of the direct contact core model of the heater(electric rod),which is completely different from the heat transfer mode of the electric ignite heating air to heat the oil layer by thermal radiation.It is difficult to guide the design of the electric ignition process parameters.This paper is based on the main problems existing in the ignition process of fire drive block in Liaohe Oilfield,Using the oil samples and core parameters of the target block,revealing the process mechanism of high temperature ignition in complex heavy oil reservoir by oxidation experiment,oxidation kinetics analysis experiment and one-dimensional physical simulation experiment of high temperature ignition,mainly studies the influence of ignition parameters on ignition effect.On this basis,one-dimensional numerical simulation is carried out.Combined with the fire flooding development parameters of heavy oil reservoirs,Optimizing ignition parameters of low permeability reservoir,forming efficient ignition process design.The following research results and understandings have been obtained:(1)With the increase of temperature,the ignition intensity of crude oil increases sharply,and increasing the heating temperature can reduce the ignition temperature.When the heating temperature is 260 °C,the increase of pressure increases the oxygen content in the confined space,which promotes the rapid increase of low temperature oxidation reaction rate.The calculated activation energy of Miao 5 crude oil at low temperature oxidation stage is19.09 KJ / mol.(2)The fraction content of Miao 5 crude oil below 350 °C is 38.66 %,and the ignition temperature decreases with the increase of low fraction content.The activation energy of Miao 5 crude oil at high temperature oxidation stage is 85.4KJ / mol.DSC results show that with the increase of permeability,the exothermic rate increases and the exothermic peak increases.With the increase of pressure,the heat flow in low temperature oxidation stage increases and the peak moves forward,which is helpful for distillation and carrying light components,and shortens the ignition time.(3)One-dimensional dynamic ignition experiment shows that,under high water cut condition,core temperature rises slowly due to low enthalpy of air,and core is transformed into high temperature hot air after low temperature oxidation,which can improve reservoir connectivity and make combustion temperature peak higher than that without low temperature hot air.At the same time,the combustion effect of combustion chamber can be improved by improving reservoir porosity and permeability.Increasing the intensity of gas injection can quickly ignite and establish combustion chamber,but to injection-production well connected,with drainage exhaust passage;In deep ignition,nano-scale microemulsion system can be used to enrich the remaining oil in reservoir,improve the reaction rate,reduce the ignition temperature and assist ignition.(4)The effect of different parameters on ignition time was obtained by one-dimensional fire driving state experiment.With the increase of hot air temperature,pressure,oil saturation,porosity and permeability,the ignition time of crude oil shortened.The CMG one-dimensional experimental simulation model was built,and the ignition time error was 2.23% by fitting the experimental data.Twenty groups of numerical simulations were carried out.The ignition time model was built based on the simulation results,and the prediction error was 3.07%(compared with the simulation results).Based on the field parameters,the ignition time model is established.The research results will provide theoretical basis for fire flooding in Liaohe oilfield.