双发双收声系扩径段测井响应特征分析

通过数值模拟计算给出了点声源、无衰减各种理想地层条件下双发双收声系在不同扩径层段新的声速测井响应特征规律.计算结果表明,双发双收声系对扩径影响的补偿不彻底.随着地层时差的不同和扩径量的不同,双发双收声系的补偿能力也不同.给出了特定扩径条件下在泥岩、砂岩和白云岩扩径层段双发双收声系最差补偿效果的对比数据.针对单一泥岩地层模型、单一砂岩地层模型和组合岩性地层模型计算了各种扩径情况下双发双收声系的测井响应特征.发现了扩径厚度特征值.当沿井轴方向的扩径段厚度等于扩径厚度特征值时,补偿效果最差;而大于或者小于扩径厚度特征值时,补偿效果都会变好.在沿井轴方向扩径段厚度一定的前提下,垂直于井轴方向的扩径量越大,双发双收声系的补偿效果越差.所以,在扩径段双发双收声系记录的时差数据有时需要进行扩径校正.

Log Responses to Two Transmitters and Two Receivers Acoustic Sonde at Intervals of Hole Collapse

The new characteristics of borehole compens at ed ability of two transmitters and two receivers acoustic log system were given under a pulse resource and no attenuation ideal beds by numerical simulation. T he affects of slowness changes on hole diameter opposite a receiver could not be compensated completely. The compensated ability varies with the difference of bed slowness and changes of hole diameter. The contrast table of the poorest co mpensated results in shale, sandstone, and dolomite was given. The eigenvalue s of diameters at hole collapse was discovered. When interval of hole collapse is equal to the eigenvalue, difference between measured value and true value is large. But when interval of hole collapse is greater or less than the eigenval ue, the difference is small. and far more from the eigenvalue when interval of hole collapse is smaller. When interval of hole collapse does not change, the bigger change in hole diameter, the more poor the compensated ability. The af fects of slowness changes in serious hole collapse interval are not ignored.