Thick oil reservoir fire flooding oil extraction combustion-supporting ignition method

Abstract

The invention belongs to the technical field of fire flooding oil extraction and in particular relates to a thick oil reservoir fire flooding oil extraction combustion-supporting ignition method. The method is implemented by the following steps of: (1) building an injection well on the conventional well network and a plurality of production wells at the periphery of the conventional well network according to oil layer geological information to form an area well network or a row-line type well network, wherein in the row-line type well network, one well row is the injection well and the adjacent well rows are the production wells; (2) injecting high-temperature steam with equivalent weight of 250 to 300 cubic meters of water into the injection well in the step (1) and preheating a ground layer to 210 to 250 DEG C; and (3) at the later stage of injecting the steam, mixing a combustion improver and crude oil according to the weight ratio of the combustion improver to the crude oil of 8.5 to 11.6 percent, injecting the mixture into the ground layer together with the high-temperature steam, and then continuously injecting sufficient air. By the method, the threshold temperature of high-temperature oxidation of the crude oil is greatly reduced and oil is easy to ignite; ignition is easy to implement; the ignition time is shortened; the ignition success rate is high; and construction is performed conveniently.

Description

technical field [0001] The invention belongs to the technical field of oil recovery by fire drive, and in particular relates to a combustion-supporting ignition method for oil recovery by fire drive in heavy oil reservoirs. Background technique [0002] Fire flooding is a method of oil displacement in the process of oilfield development. In the process of oilfield exploitation, the distribution of oil wells has certain regularity, such as triangular well pattern system and square well pattern system. Oil recovery by fire flooding is to establish an area well pattern consisting of an injection well and multiple production wells around it or a determinant well pattern in which one well row is the injection well and the adjacent well row is the production well on the existing well network. The air injected into the injection well ignites the crude oil in the oil reservoir to displace the crude oil and reduce the viscosity of the crude oil. There are preheating method, electro...

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Problems solved by technology

Among them, the heater method uses a cable to send the heater into the oil well to heat the injected air. This method has the disadvantage that the injected air cannot fully contact the heater, often resulting in uneven heat absorption by the air, and sometimes causing the heater to burn out due to excessive temperature. The phenomenon of the heater; although the thermal flooding of the oil layer by the chemical method is successful, the ignition success rate is very low for heavy oil reservoirs; the steam injection ignition method is to inject a large amount of steam above 350°C through the oil well, but due to the formation The pressure and depth are different. Generally, the ignition temperature of crude oil in heavy oil reservoir formations is above 420°C, and the heat loss from steam injection from the wellhead to the formation reaches 60%. The disadvantage is that it takes a long time to reach the threshold temperature and consumes huge energy and funds