Calculation And Application Of Cement Bond Logging Response With Sector Local Loss

Cementing engineering is the key link between reservoir exploration and exploitation,and its quality seriously affects the effect of reservoir exploitation.The characteristics of acoustic measurement response in cement bond logging based on different bonding conditions of all kinds of boundary,to establish the evaluation standard of cementing quality.At present,it has become the most effective means of testing and evaluating cementing quality.The results of numerical simulation lay a foundation for well logging measurement to be well applied.Evaluation of the degree of local cement rings missing is a difficult problem in cement bond logging interpretation at present.This paper is based on the theory of multi-interface acoustic field propagation in wells.A cylindrical multilayer model with locally missing asymmetric medium is taken as the research object,to research on Three-Dimensional Stress-Velocity Finite Difference Numerical Simulation Method,to realize acoustic response calculation of cement rings with different angle sector missing,and the corresponding wave trains characteristic map is formed.The calculation results provide guidance for quantitative evaluation of the degree of cement rings local missing.Using the numerical simulation method established in this paper,based on Cement Acoustic Density Variable Instrument in Daqing Oilfield,at intervals of 22.5°,acoustic wave train of cement ring with 19 kinds of angle missing between 0°and 360°is calculated.The relationship between missing angle and cement bonding index is established.The calculation results are applied to cementing quality evaluation of actual wells in oilfields,the actual missing angle of the well is given quantitatively.It provides a basis for correcting the missing cement ring in time and accurately.For low pressure and leaky formation,low density cement is often used for cementing quality detection,but the acoustic coupling ability of low density cement is worse than that of conventional density cement,when cementing quality is continuously evaluated by acoustic variable density logging,the evaluation parameters obtained under the condition of low density cement cementation are often much different from the conventional evaluation criteria.Application of the numerical simulation method established in this paper.For computation of cement bonding response under low density cement conditions,be based on the amplitude of sound wave under the condition of conventional cement density,to establish the calibration chart of acoustic wave amplitude and cementation index of low density cement,the calibration chart is applied in cementing quality evaluation of practical low density wells.It effectively solves the problem of wrong judgment in cementing quality evaluation of low density cement.Currently,the quantitative evaluation criteria for cement bond logging production only use bond index parameters,according to the research idea of combining numerical simulation method with actual evaluation effectively in this paper,further establishment of quantitative evaluation criteria for identifying cement bonding quality by wave train,it will be the furtherresearch direction based on this paper.