套管井不同胶结状况下声波测井响应及其时频特征

利用自制的模型井,在实验室内研究了套管井第一界面不同类型的水泥胶结窜槽的声波测井响应特征,基于Choi Williams内核的Wigner Ville分布,对该声波测井响应进行了时频分析。结果表明,发射和接收探头同时处于胶结良好区域或者发射和接收探头之间存在夹角小于180°的周向窜槽时,时频分布图中具有3个幅度不等的能量峰,能量分布范围比较宽;当发射和接收探头之间存在夹角大于180°的窜槽时,时频分布图中仅有2个能量峰。发射和接收探头之间未胶结区域越不规则,其能量峰越不容易区分。当发射和接收探头同时处于自由套管内时,仅有1个幅度较高的单一能量峰,并且其能量分布范围(对频率)减小。

Response characters and time-frequency distribution of acoustic logging in cased hole under different bond conditions

By using the miniature well model,the responses of acoustic logging in cemented bypass channels on the first interface between casing and cementation were experimented. This response of acoustic logging was analyzed on the Wigner-Ville time-frequency distribution with kernel of Choi-Williams. The analysis results show that when the transmit and receive transducers are in a good cemented area or there are some by pass channels with an angle less than 180 degrees along the circumferential direction, there are three different energy peaks with a wide range of energy distribution on time-frequency distribution figure. When the angle between bypass channels in the un-cemented area between transmit and receive transducers along the circumferential direction is over 180 degrees,there are two energy peaks on the time-frequency distribution figure. For the irregular area between transmit and receive transducers, the energy peaks are difficult to be distinguished. When the transmit and receive transducers are all in a free casing, there is only one energy peak with a high amplitude and a reduced energy distribution range against frequency on the time-frequency distribution figure.