The invention provides a device and a method for real 
simulation of underground environments, completeness maintaining of experiment equipment, and accurate and omnibearing evaluation of completeness of a 
cement sheath. The device mainly comprises an upper end cap, a lower end cap, an outer 
pipe, a middle 
pipe, the 
cement sheath, a sleeve 
pipe, a long source distance sector 
cement bond 
logging instrument (SBT (segmented bond tool)) and a high-temperature and high-pressure kettle. The method comprises the following steps of utilizing the high-temperature and high-pressure kettle to simulate the stratum temperature pressure of the curing and forming of the 
cement sheath; loading and unloading an inner annulus and an 
outer annulus, so as to simulate the actions of change of well shaft pressure and stratum pressure on the 
cement sheath under the actual working condition; utilizing a transmitting probe and a receiving probe of the SBT to continuously transmit and receive 
acoustic wave signals, and performing the omnibearing and high-resolution compensation type attenuation 
rate measurement, so as to obtain the bonding qualities of a first interface and a second interface of the 
cement sheath of the 
well cementing cement sheath under the actual stratum environment, and the amounts, sizes and bearings of cracks and channeling in the cement sheath. The device and the method have the 
advantage that the underground environment can be really simulated in the omnibearing way, so as to accurately and efficiently evaluate the completeness of the 
well cementing cement sheath, provide the new method and basis for indoor 
cement slurry evaluation systems and sites to take the targeted measures, and improve the 
well cementing quality.