论文详情
常规的双井微测井近地表地层品质因子调查方法为单井激发、单井接收采集方式,利用相同炮点不同检波点或相同检波点不同炮点初至波的谱比斜率计算地层品质因子,计算过程中无法同时消除炮点和检波点耦合对地层品质因子计算精度的影响。为此,提出了一种双井激发、井间近地表接收的采集方法,地层品质因子计算时选择两个左右对称的激发点和接收点,分别计算各激发点不同检波点的初至谱比斜率,将其相加得到消除炮检点耦合的谱比斜率。该方法采用S变换计算初至波的瞬时谱,根据谱比对数的斜率和地震波传播时间计算地层品质因子;利用相同炮点、不同检波点的谱比斜率消除炮点耦合的影响,采用炮检点对称互换方法消除检波点耦合的影响。实际资料应用结果表明,该方法能有效提高近地表品质因子反演的精度。
The conventional double uphole method to survey for a near-surface formation quality factor involves a single explosive uphole and a single receiver uphole.The formation quality factor is then calculated by the first-break spectral ratio of different sources in one receiver or different receivers in one source;however,the method cannot eliminate the influence of source and receiver coupling on the accuracy of the formation quality factor.A survey method with double explosive upholes and near-surface receivers between the two upholes is proposed.Two source points symmetric to two receiver points at the same depth are used in the calculation.The first-break spectral ratio of the two receivers in each source is calculated and then summed to obtain the average spectral ratio with no influence from the coupling of sources and receivers.An instantaneous spectrum is then calculated by S transform method,and the actual formation quality factor is calculated via spectral ratio and seismic wave propagating time.The influence of shot point coupling is eliminated by using the spectral ratio of the same shot points with different receiver points,and the influence of receiver point coupling is eliminated by symmetrically exchanging source and receiver points.Application results show that the proposed method improves the accuracy of the near-surface formation quality factor.
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