Key Technology of Drilling Liner Hanger and Tieback Device in Staged Fracturing

In order to solve the problems of high cost,poor conditions,and frac interference,in tight oil and gas and shale gas,a new technique for controlling the liner tieback string for staged fracturing was studied and developed.Based on the analysis and research on the contradiction between cementing leakage and high fracturing pressure of the reservoir,the rapid full-size fracturing was proposed after liner cementing.Through the study on the optimized combination mode of cementing and completing technologies,this paper put forward one segmental fracturing reservoir reconstruction technique which identified zones of preferential enrichment (sweet spots) with fixed-point perforation after the liner cementing in horizontal wells.By means of optimizing the design of the liner cementing and the tie back fracturing tools,the integrated sealing anchor of the cementing and completing tools was realized.The test results proved that the sealing ability of the liner hanger and tie back stinger was up to 90 MPa,and the tensile strength between the tie back stinger and the liner hanger was 1 800 kN,and the tie back stinger was released successfully.In addition,this technology was applied in more than 27 wells,including the Daniudi Gas Field,Dongsheng Gas Field and Longdong Block of the Changqing Oilfield.Although the operation pressures in these applications were high,all fracturing operations were finished successfully,with good application effects being achieved.Research results showed that the new technology of liner tieback string for staged fracturing could solve the problems of the high pressure and jacking force required for fracturing operations,and it could provide a high pressure,large drift diameter,retrievable and anchored wellbore for a segmented fracturing technique after tie back cementing,thus having the effect of protecting the reservoir drive.