Study On Cementing Quality Evaluation Standard Of Sand Casing

In cementing operation,sand with certain strength always adhered to the casing surface,which increasing its surface roughness,in order to improve cementing quality.After being adhered to sand,sand adhesion agent and sand grains were existed between casing and cement ring,interfaces can be divided into casing-sand adhesion agent interface,sand adhesion agent-sand grains and sand grains-cement ring interface,thus these interfaces changing the acoustic transmission way in the casing.The research was based on the analysis of logging acoustic refraction and reflection in drilling fluid-casing interface,casing-cementing agent interface,cementing agent-sand grains interface and sand grains-cement ring interface,established relative amplitude calculation model of adhering sand casing first interface with consideration of acoustic attenuation,set up a new standard evaluation of interface cementing quality for adhering sand casing.Influence on relative amplitude of cementing agent first interface by grains size,grains density,composition and thickness of the cementation agent were analyzed.The research results showed that,with increasing of sand grains size,adhering grains density,acoustic impedance of cementation agent and thickness of cementing agent,relative amplitude of adhering sand casing interface decreases,the cementing quality is gradually getting better,in which the affect on cementing quality by grains density of adhering sand casing well is the most significant.The research was determined that refraction and reflection of acoustic in the adhering sand casing cementing layered medium interface as the key point of the research,established relative calculation model of adhering sand casing first interface with consideration of acoustic attenuation,concluded a new standard evaluation of interface cementing quality for adhering sand casing,which can be used as guidance for the cementing quality evaluation of adhering sand casing well,improved the cementing quality evaluation accuracy of adhering sand casing well.Developed amplitude calculation research with consideration of relative amplitude acoustic attenuation in adhering sand casing well,enriched the field content of cementing quality evaluation,which has important significance.