黄河远古故道，流砂层厚达530米。我队曾在此施工一孔，设计孔深800米，使用细分散泥浆，石灰钙处理泥浆。由于无法保持井壁完好，形成的“大肚子”使钻杆经常在孔内折断而找不到事故头。后来在一次孔内事故的处理过程中，由于处理时间较长井壁严重垮塌，使事故越来越严重，十几米长的立根断入井 The ancient course of the Yellow River, sand layer thickness of 530 meters. My team had a hole in this construction, the design depth of 800 meters, the use of finely dispersed mud, lime calcium treatment of mud. Due to the inability to keep the well intact, the formed “big belly” made the drill pipe often break in the hole and could not find the accident head. Later in a hole accident handling process, due to a long processing time serious collapse of the well wall, so that the accident is more serious, more than ten meters long stand off wells