This paper chronicles the progression of liner refracs on mature wells in the South Texas Eagle Ford Shale. Operational issues, strategies to mitigate the risk, and well results will be reviewed.
Liner refracs involve running and cementing smaller casing as a liner inside previously stimulated 5 ½-in. cased hole lateral completions. This method of isolating existing perforations has been successfully applied to allow subsequent refrac plug and perf operations. The operational steps to execute these deployments impose more risk than completing new wells and significant failures have occurred. Fit for purpose equipment, best practices, and a steep learning curve have been employed to mitigate the risk and improve the overall economic benefits of the program. An account of the failures and efforts to prevent these issues is provided.
From the summer of 2018 through 2019, 15 liner refracs have been executed in high temperature wells in Dewitt County, Texas. Three of the wells with operational issues are presented along with the approach to prevent reoccurrence. One well was eventually lost when the production casing was inadvertently damaged while attempting to mechanically cut the installed liner. This prompted an alternative deployment method, and the development of an anchor system which has now been used on six wells. The smaller geometry and tools required in liner refracs impose additional challenges. This study outlines this operator's approach to minimize the risk and reduce failure frequency. Dramatic increases in pressure and production have been observed on the liner refracs. The wells that have been executed successfully, have exceeded return on investment expectations.
Liner refracs provide a tool to capture production and reserves from existing wells and enhance field development. Lessons learned and alternative methods to execute liner refracs are considered in this field study.