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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。
The point sound source is given through numerical simulation and the new sound velocity logging response characteristics of double-double-double sounding system in different expanded intervals are given under various ideal conditions without attenuation. The calculation results show that the compensating effect of double-spaced double-channel acoustic system on diameter expansion is not complete. With the different strata difference and the amount of expansion of the diameter, dual-ear dual sound system compensation ability is also different. The comparison data of the worst compensation effect of double-transmitting and double-sounding system in the expanded section of mudstone, sandstone and dolomite under a specific expanding-diameter condition are given. The log response characteristics of double-double-double acoustic systems for various diameter expansion cases are calculated for a single mudstone formation model, a single sandstone formation model and a combined lithologic formation model. Expanded diameter thickness characteristic value was found. When the diameter of the extended section along the well axis is equal to the expanded-thickness feature, the compensation effect is the worst; while the larger or smaller expanded-thickness feature value, the compensation effect will be better. Under the condition that the thickness of the expanded section along the well axis is constant, the larger the expanded diameter perpendicular to the well axis, the worse the compensation effect of the dual transmitted double sound system. Therefore, it is sometimes necessary to calibrate the time-difference data recorded in the expanded-band dual-transmit and receive system.