随钻声波纵波时差测井
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摘要
一种新的随钻测井仪——声波纵波时差测井仪,已由斯仑贝谢公司研制成功。其工作原理与现代电缆声波测井仪相同。发射器被激发发声,声波沿泥浆和地层传播,并为接收器阵列检测。利用井下信号处理系统,提取纵波时差△t,经泥浆遥测发送器传送到地面。纵波△t和孔隙度的测井数据,可用作识别岩性和确定过压的输入数据。△t数据还可用来形成合成地震图,将它与实际地震剖面比较,可改善地震图质量。现场试验表明,随钻声波测井的质量,可能比钻后电缆声波测井质量更好。这是因为随钻声波是在地层可能发生蚀变和井眼条件可能变差之前测量的。本文还提供在不同岩性和井眼条件下若干测井实例,并与电缆测井作了比较。
A new logging while-drilling(LWD)tool provides sonic compressional △t measurements in real time and recorded modes. The tool operates on the same general principles as modern wireline sonic tools. As the drilling operation progresses, the transmitter is fired and acoustic waves propagating through the mud and formation are detected by the receiver array. Using a downhole processing algorithm,the compressional △t of the formation is extracted from the wavefoms and transmitted uphole in real time via mud telemetry. The compressional △t and porosity logs are generated,providing an input for lithology identification and overpressure determination. The △t log is also used to generate synthetic seismograms for correlation with the seismic section and to upgrade the seismic map. Field test results show that the quality of the sonic log made while drilling can be better than sonic measurements made after drilling because the tool measures compressional △t before possi- ble formation alteration and hole degradation have ocurred. Log examples with wireline comparisons and applications are presented for a variety of lithologies and downhole conditions.
A new logging while-drilling(LWD)tool provides sonic compressional △t measurements in real time and recorded modes. The tool operates on the same general principles as modern wireline sonic tools. As the drilling operation progresses, the transmitter is fired and acoustic waves propagating through the mud and formation are detected by the receiver array. Using a downhole processing algorithm,the compressional △t of the formation is extracted from the wavefoms and transmitted uphole in real time via mud telemetry. The compressional △t and porosity logs are generated,providing an input for lithology identification and overpressure determination. The △t log is also used to generate synthetic seismograms for correlation with the seismic section and to upgrade the seismic map. Field test results show that the quality of the sonic log made while drilling can be better than sonic measurements made after drilling because the tool measures compressional △t before possi- ble formation alteration and hole degradation have ocurred. Log examples with wireline comparisons and applications are presented for a variety of lithologies and downhole conditions.
引文
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