下套管护孔早已被人们所熟悉。可是往往下入套管后，因无有效的防护措施，经常发生断、脱、跑事故，起拔时又很困难，搞不好造成套管报废。鉴此，有些同志遇到复杂钻孔，理应采用套管护孔的，也不敢下套管，从而造成处理时间过长，浪费了大量的人力和物力，以致报废钻孔。几年来，我们吸取过去的教训，学习外地的先进经验，并在实践中不断地摸索改进，初步解决了套管跑、断、脱事故和起拔困难等技术关键。下面介绍河南许昌铁矿区，是怎样采用套管护孔并解决上述技术难关的。许昌铁矿区，在含铁矿岩性 Under casing casing has long been known. However, often into the casing, because there is no effective protective measures, often occur off, off, running accident, pulling up very difficult, not doing well to cause casing scrapped. In view of this, some comrades encountered complex drilling, should use casing retaining holes, but also not under casing, resulting in processing time is too long, wasting a lot of manpower and material resources, resulting in scrapped drilling. Over the past few years, we learn the lessons of the past, learn advanced experience in the field, and constantly explore and improve in practice, the initial solution to the casing run, break, take off and pull the key technical difficulties. The following describes the iron ore district in Xuchang, Henan, how to use casing protection hole and solve the above technical difficulties. Xuchang iron ore district, iron ore in the lithology