| In-situ combustion is an important technology for heavy oil thermal recovery.It is necessary to continuously inject air during the process of in-situ combustion,but the complex situation and underground conditions often interrupt the gas injection process.And then,how to judge whether underground combustion is extinguished or not and how to realize the resurgence after extinguished are the two problems need to be solved.Du 66 Block which located in Liaohe Oifield is an earlier in-situ combustion pilot test block.However,due to the complicated situation of the field,the interruption of gas injection and the fire extinguishing often happened.Aiming at the problem of fire suppression caused by interruption of gas injection,the extinguishing conditions and the main influencing factors on second ignition were studied from two aspects of numerical simulation and physical experiments.The high temperature oxidation characteristics of crude oil were studied by thermal analysis test.And based on thermal analysis test,the movement characteristics of temperature peak were observed through numerical simulation results after air injection interrupted.And the relationship between the per meter thickness cumulative volume of injected air and the extinguishing time is given.At last,the in-situ combustion characteristic parameters of Du 66 crude oil is determined by combustion tube experiment,and the suitable volume of injected fuel were determined.The results show that,with the reduce of injected fuel oil,the air breakthrough more serious,the oxygen utilization rate decreases gradually,the combustion front moves slowly,the combustion state becomes worse.And the main influencing factor of in-situ combustion second ignition are the volume of underground air chamber(cumulative volume of injected air),the temperature of the front,the properties of fuel oil,the volume of injected fuel oil and et.al..And under current experimental conditions,1/4 volume of burned zone fuel oil is the optimum value. |
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