Shale gas desorption pressure tester

The invention provides a shale gas desorption pressure tester. The tester mainly comprises a cylinder body, a base, an upper cover, a high-pressure micropump and a pressure sensor, wherein a glass observing window is arranged on the cylinder body; the pressure sensor is installed on the upper cover; a liquid inlet is formed in the central position of the upper cover; the upper cover is connected with the high-pressure micropump. Saturated brine with temperature consistent with the formation temperature is continuously added to the cylinder body in which shale cores are put and the value of pressure in the cylinder body immediately rises, linear bubbles generated in quantity because of desorption escape of adsorbed shale gases adsorbed on the surface of shale and in micropores can be observed from the observing window, when the linear bubbles begin reducing, the corresponding pressure value is the initial shale gas desorption pressure, and when the linear bubbles begin reducing in quantity, the corresponding pressure value is the main shale gas desorption pressure. The shale gas desorption pressure tester has the beneficial effects that adopting the direct measurement mode, compared with the prior art, the tester is more reliable and accurate in data, also has the effect of greatly shortening the experimental determination time and provides powerful guarantees for shortening the project period and ensuring the technology and economical efficiency of exploitation.