Of Experimental Study Of The Acoustic Properties Of Mixed Materials Cement Paste

At present, acoustic cement bond log is one of the methods widely applied for primary cement evaluation. But the relation between acoustic coupling and cement mounting quality is uncertain. "Strong bonding" just shows that acoustic coupling is good and does not purport that zonal isolation quality is good .In fact, the outcome of sonic logging is related to the property of alit.The decay rate of CBL is closely connected with cement weight and the velocity of longitudinal wave and transverse wave through the cement sheath. And acoustic impedance is the product of density and the velocity of sound. So acoustic cement bond log is affected by the acoustic impedance of the media (the thimble-cement sheath, cement sheath-the layer) measured. The acoustic impedance of thimble and layer rock has been perceived now. But because influencing factor is very complicated, as the components of alit are changed and the property of alit is changed with time and temperature, the acoustic impedance of cement sheath is difficultly perceived. Because the acoustic impedance of alit will affect the outcome of cement bond log directly the study about the acoustic characteristic of alit is very important.At present Domestic and international research production about admixture cement is seldom. This paper treats the cement sheath as the major study object and searches sonic velocity characteristic of high density , low density admixture cement and normal density cement and qualitatively analyzes how the compound design of the casing cement(component and strength property) effects cement acoustic characteristic by ultrasonic testing. The experiment shows: the change of the velocity of sound through normal density alit is regular and directly proportional to the strength of alit; Different admixture and additive make the change of the velocity of sound different; the degree of alit's compactness, which is reflected by the low porosity of alit measured, is not high because of the influence of hollow admixture; generally, under conditions of good cement job quality the CBL decay rate of normal density and high density admixture cement is higher than that of low density admixture cement and the head wave amplitude of casing wave is lower. micro-siliconcan improve the strength of light weight cement and make the acoustic impedance and CBL decay rate higher; when making use of acoustic cement bond log evaluate cement job quality, the influence of admixture cannot be neglected.