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本文介绍一种能在地震阴影带之下获得较好图像的新方法。这些阴影带是由浅层低速带引起的,它对南里海地区的解释产生不良影响。我们将精细的子波处理与炮检距域振幅补偿及叠前层析成像反演相结合,与常规处理相比,显著改善了成像效果。用粘滞声学模拟成功地调查了地震阴影带中的地震衰减效应。对具有不同Q值的正演模拟结果进行了比较,对确定的地震数据进行了最佳拟合。最终获得的结果表明,地震阴影带的Q值较低,为30,异常区外为120,预测更深部的Q值为175。此外,还成功地应用由层析成像反演导出的精确层速度模型,精确预测了孔隙压力和裂缝压力。这些预测压力经过井信息标定后,被用来设计泥浆比重和泥浆循环警告指示器。这些信息能为更好地设计钻井方案提供帮助,从而降低钻井成本和增强安全性。对孔隙压力和岩石裂缝压力差异的了解有利于设计套管深度,有利于选定钻井过程不同阶段所用的泥浆比重。本项研究还预测了中等超压区域可能引起钻井事故的孔隙压力。
This article presents a new way to get better images under seismic shadow bands. These shadow bands are caused by shallow low-velocity bands, which have an adverse effect on the interpretation of the South Caspian Sea. Combining fine wavelet processing with offset amplitude correction at the offset and prestack tomography inversion, we significantly improved the imaging performance compared to conventional processing. The viscoelastic simulation has successfully investigated the seismic attenuation effect in the seismic shadow zone. The results of forward modeling with different Q values are compared and the best fit of the identified seismic data is obtained. The results obtained finally show that the seismic shadow band has a low Q value of 30, an anomalous region of 120 and a deeper predicted Q of 175. In addition, the exact layer velocity model derived from tomographic inversion was successfully applied to accurately predict pore pressure and fracture pressure. These well-known predictions, after well information calibration, were used to design mud weight and mud circulation warning indicators. This information can help to better design a drilling program, reducing drilling costs and enhancing safety. Knowledge of the differences in pore pressure and rock fracture pressures facilitates the design of casing depths and facilitates the use of mud weights at different stages of the selected drilling process. This study also predicts the pore pressure that could cause a drilling accident in a moderately overpressured area.