Oil extraction method adopting cold and heat pulse alternate water injection

Abstract

The invention provides an oil extraction method adopting cold and heat pulse alternate water injection. The oil extraction method comprises the following steps that the temperature sensitivity of an oil reservoir is analyzed, if the temperature sensitivity of the oil reservoir is medium to strong or strong, hot water is injected into the oil reservoir through an injection well of an oil field, thewellhead oil pressure of the injection well is recorded every four hours, and when the wellhead oil pressure begins to rise continuously, the hot water injection is stopped; the injection well is opened, and cold water is injected into the oil reservoir to enable the oil reservoir to be cooled; the water injection pressure of the injection well is increased, and under the flushing action of the water injection pressure, a plurality of fracturing cracks can be formed in the oil reservoir in the minimum stress direction of a stratum stress field near a shaft of the injection well; the apparentwater injectivity index of the oil reservoir is calculated, and according to the apparent water injectivity index, whether the effective fracturing cracks are formed in the oil reservoir or not is judged; and the water injection effective rate is calculated, and according to the water injection effective rate, whether the injected water forms effective displacement in the reservoir or not is judged.

Description

technical field [0001] The invention relates to the technical field of petroleum exploitation, in particular to an oil recovery method with alternate cold and hot pulse water injection. Background technique [0002] At present, the commonly used oil recovery methods mainly include water injection displacement development, steam injection displacement development, compound injection displacement development, etc. For conventional sandstone reservoirs, the above oil recovery methods can often effectively delay production decline and improve oil recovery. However, for tight and low-permeability oil reservoirs, the conventional oil recovery methods commonly used at present cannot achieve obvious effects, and it is often necessary to reform the reservoir by means of fracturing, and the cost of fracturing is huge, resulting in many tight and low-permeability oil reservoirs Zang gave up development because he could not recover the cost. Contents of the invention [0003] In view...

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Problems solved by technology

However, for tight and low-permeability oil reservoirs, the conventional oil recovery methods commonly used at present cannot achieve obvious effects, and it is often necessary to reform the reservoir by means of fracturing, and the cost of fracturing is huge, resulting in many tight and low-permeability oil reservoirs Zang abandoned development due to unrecoverable costs

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