摘要
According to the drilling in complex formations and based on the principle of wire-line drilling,the study on new methods for casing drilling for geological exploration are made by using coring drilling with retractable bit without lifting,including casing coring tools,casing replacing wire-line coring tube,wall protection and casing drilling processing.Good technical and economic effects are achieved in the field production test,and further improving suggestions are put forward according to the existing problems.