Inner tube method well cementation process

The invention relates to an inner tube method well cementation process and belongs to the technical field of well completion and well cementation of oil and mine drilling engineering. Aiming at eliminating the risk that an inner tube is easy to cement in the prior art and reducing the well cementation cost of the inner tube method well cementation process, the invention provides the inner tube method well cementation process. An annular space between a well wall and a casing is sealed by upper delayed coagulation cement slurry, wherein the annular space is formed above half of a well. An annular space between the well wall and the casing is sealed by accelerated coagulation cement slurry, wherein the annular space is formed below half of the well and is 20-50m above the bottom of the well. An annular space between the well wall and the casing is sealed by lower delayed coagulation cement slurry, wherein the annular space is 20-50m above the bottom of the well. The risk that the lower end of the inner tube is cemented can be effectively eliminated, the well cementation cost is obviously reduced, the process is applicable to the inner tube method well cementation of various large-diameter casings, and the success rate of the inner tube method well cementation can be effectively improved.