声波水泥胶结测井中岩性对地层波影响研究及资料应用

针对砂泥岩地层,数值研究了套管井中高密度和低密度水泥完全胶结时短源距声波测井全波波形特性,通过地层孔隙度和泥质含量的变化,分析了水泥特性和地层岩性对地层波幅度的影响。结果表明水泥特性对地层波幅度影响很小,但地层孔隙度和泥质含量对地层波幅度影响很大,并给出了地层波岩性影响的校正图版。根据理论结果结合实际测井记录的波形特点,研究了波形信息提取方法,得到了第一、第二界面胶结指数等参数,用以评价固井质量。这种方法在西北油田固井质量评价中获得了较好的结果。

Effect of rock property on formation body wave and data interpretation for cement bond acoustic logging in cased borehole

Synthetic acoustic full waveforms of CBL (Cement Bond Log)/VDL (Variable Density Log) at the perfect bonding (steel-cement-formation) are calculated for the light and high weight cement in the sandstone-shale cased borehole. Through examining the changes of formation porosity and shale content,the effects of the cement and formation properties on formation body wave amplitude are analyzed. These results demonstrate that the influence of the cement properties on the formation body wave amplitude is very small,but that of the formation properties is rather obvious. Therefore,We have pro-posed a correcting method for the formation body wave amplitude that is impacted by the rock properties with the changes of formation porosity and shale content. According to the result of theoretical research and specialty of waveform recording in oil field,acoustic bonding indexes of the first interface (steel-cement) and second interface (cement-formation) are derived from the casing arrival and formation body wave amplitudes. The application in Xibei oil field shows that this method is effective for evaluation of the cement bonding quality.