Study on the Wellbore Reconstruction Refracturing Technology Based on Expandable Tubular

Abstract

Abstract Refracturing is a promising means to improve the output and estimated ultimate recovery of shale oil and gas resources, which is an efficient method to recover the productivity of low permeability old wells. Refracturing has achieved good results in the development of shale gas wells in North America, and has increased output and decreased the extraction cost significantly of shale gas resources. The disadvantage of unable to control the fracturing fluid accurately of the conventional temporary plugging diverting refracturing technologies like chemical particulates has been exposed in the applications. Wellbore reconstruction technology based on the solid expandable tubular (SET) was studied in this paper, which is a permanent plugging diverting refracturing technology with a high sealing effect and simple operation. Technical principles, tool structures and construction processes were analyzed and relative laboratory tests were conducted to verify the feasibility of this technology. Meanwhile, comparisons between expandable tubular technology and other refracturing technologies were developed to analyze the application prospect in shale oil and gas resources. The indoor tests indicated that wellbore reconstruction technology based on expandable tubular can plug the perforation on the casing effectively with certain sealing pressure, which showed that this technology can realize the wellbore reconstruction to create the wellbore conditions for the next fracturing work. Compared with other temporary plugging refracturing technologies, the expandable tubular technology can achieve accurate control of fracturing fluid and has a better effect of refracturing work. At the same time, it has the advantages of simple operation and big internal diameter compared to other wellbore reconstruction methods like casing plugging technology, which means that bigger displacement can be used and better effect can be achieved in the refracturing work. The conclusions obtained in this paper can promote the development of wellbore reconstruction technology based on expandable tubular, which provides a theoretical reference for the design of the refracturing work in shale oil and gas resources.