Thin tube experiment device with overburden pressure and using method

The invention relates to a thin tube experiment device with overburden pressure. The thin tube experiment device is composed of a high and low temperature test box, an autoclave, a thin tube column, arubber sleeve, a fluid injection system and a fluid extraction system, a spiral groove is carved on the upper surface of the thin tube column, and two end points of the groove are correspondingly connected with the fluid injection system and the fluid extraction system through vertical round holes. The method for determining the miscible pressure of injected gas and crude oil by using the devicecomprises the following steps of filling sand in a thin tubular column groove and a round hole; injecting hydraulic oil into the autoclave, and injecting nitrogen into the sand filled in the thin tubular column groove; displacing nitrogen in the thin tubular column groove by using the prepared stratum crude oil; injecting the gas at a certain speed to displace the crude oil in the fine tubular column groove; and drawing a