Application Research Of Expandable Tube Technology In Repeated Fracturing

As a kind of mechanical isolation,the Expandable Liner is applied to the separation of the old production layer and the original perforation in the repeated fracturing.It is one of the new technologies developed in the development of foreign shale gas in recent years.Compared with the traditional re-fracturing operation,the Expandable Liner re-fracturing technology has the advantages of sealing the old production layer more thoroughly,saving valuable well bore space,easy control of fracturing fluid flow direction,and easy monitoring of crack extension direction.At present,this technology has been applied in many shale gas fields in North America,and the yield increase effect is obvious compared with the traditional repeated fracturing technology.This paper introduces the emerging technology,analyzes the technical advantages,collects and collates relevant data,and compiles the construction process and precautions of the Expandable Liner re-fracturing technology,and points out that the technical difficulty is how to analyze and calculate collapse strength,internal strength and burst strength after the expansion of the liner.Aiming at the internal compressive strength,the paper uses the thick-walled circular tube model to analyze the failure process of the Expandable Liner under internal pressure,and divides the two critical states of the inner wall yield point and the outer wall plastic deformation point for analysis and deduces the concrete.The calculation method is verified by experiments.In view of the collapse strength,based on the ideal circular tube model,the factors of shape unevenness,residual stress,Bauschinger effect and other factors affecting the resistance of the liner after expansion are considered,and the specific calculation is derived.The method is verified by experiments.Finally,this paper combines the casewell data to demonstrate the specific use of the internal pressure strength and the collapse strength calculation method deduced in the previous part of the paper.