The invention belongs to the technical field of oilfield
chemistry, and particularly relates to an oil extraction method and a CO<2> injection amount determination method and device used for assistinghuff-puff oil increase. The oil extraction method comprises the following steps that firstly, pore volume, oil saturation,
crude oil density, gas-oil ratio, gas-water ratio and
crude oil compressioncoefficient are acquired, and substituting the pore volume, the oil saturation, the
crude oil density, the gas-oil ratio, the gas-water ratio and the crude oil compression coefficient into a
carbon dioxide injection amount model is carried out to obtain
carbon dioxide injection amount; the
carbon dioxide injection amount model is constructed according to the relationship between the carbon dioxideinjection amount and the pore volume, the oil saturation, the crude oil density, the gas-oil ratio, the gas-water ratio and the crude oil compression coefficient; then the carbon dioxide injection speed is determined; and finally, carbon dioxide is injected to assist huff and puff according to the determined carbon dioxide injection amount and injection speed so that oil extraction can be carriedout. According to the model, the physical parameters of an oil layer and the
solubility of the carbon dioxide in oil and water are fully considered, the obtained carbon dioxide injection amount is proper, the oil extraction efficiency is high, and the crude oil yield is high.