METHOD OF ESTIMATING QUALITY OF CEMENTING BOREHOLES Russian patent published in 1994 - IPC

FIELD: geoacoustic investigations. SUBSTANCE: method involves the steps of: exciting waves at dominant frequencies f₁ and f₂ determined by the most probable propagation velocities of transverse waves in rock V_s and in cement V_y and from borehole radius R, layer thickness h as well from expressions f₁=aV_s/ΠR and f₂=QV_y/h given in the invention description (where a and Q are dimensionless coefficients). The method is characterized in that waves are emitted at second critic angle respectively for liquid-cement boundary for f₂ and cement-rock boundary for f₁. Reflected waves are received within frequency ranges corresponding to f₁ and f₂. Cementing quality is determined from the relationship between high-frequency wave amplitudes corresponding to cement and low-frequency transverse wave amplitudes corresponding to rock, the decrease of the latter and increase in the high frequency wave amplitude corresponding to cement being representative of the presence of a gap between cement and rock. EFFECT: enhanced accuracy and efficiency. 2 dwg