Lost wells can be divided into three categories: fractures, cavernous lost wells and permeable lost wells. Different leaks should take different construction measures during drilling and cementing construction. According to the leakage situation, the leakage layer should be treated before cementing, and the balanced pressure cementing design should be carried out after the treatment. For leakage-prone layers and slumping layers, conventional cementing leakage prevention measures include increasing the lower-density pre-fluid, controlling the length of the cement sealing section, and using a low-density cement slurry system. The casing outer packer can also be used to seal the above interval in layers, so as to solve the problems of oil, gas and water channeling and pressure leakage formation in the above well interval, resulting in insufficient return height.

In some special formations, because the oil and gas layers are sensitive to cement slurry, the traditional cementing method of using cement slurry to seal the casing can no longer meet the production requirements. The normal mining of the well effectively solves the problem of cement slurry contamination of the stratum.