The invention relates to a multifunctional dynamic
pollution evaluation device of coalbed
drilling fluid, belonging to the technical field of damage evaluation of
coalbed methane drilling fluid. The multifunctional dynamic
pollution evaluation device comprises a gas
booster pump, a triaxial stress
coal core gripper, a measuring axial-loading pump, a gas
mass flow meter, a computer acquisition board, a mud container, an oven, a precise
advection pump, and the like; wherein the gas
booster pump is arranged at the left side of the oven; a gas
storage tank, the precise
advection pump, the measuring axial-loading pump and the gas
mass flow meter are arranged at the lower part of the oven; and the triaxial stress
coal core gripper and the mud container are arranged in a
working space of the oven. The evaluation device can not only simulate the invasion, the
invasion depth and the invasion degree of the
drilling fluid to a
coal bed under the condition of coalbed true triaxial stress, but also simulates the dynamic
pollution process of mud in positive
differential pressure, negative
differential pressure and balanced drilling process and ensures that the coalbed pollution process is integrated with the
percolation test process. The invention solves the problem that the conventional evaluation device can not load different axial loads on three axial directions and has the advantages of convenient operation and standardized experimental data.