Advanced Modeling Techniques for Predicting String Connection Performance in Refracturing Operations

Abstract Restimulation treatments like hydraulic refracturing and recompletions are commonly used to extend the life of existing wells and access new zones in legacy wells. However, introducing new liners with tight clearances complicates achieving adequate cement coverage. This inconsistent cement coverage leads to complex loading conditions on the liner due to localized thermal contraction and stimulation pressure ballooning. The objective of this study is to evaluate these complex loading conditions and establish a precise connection selection criterion for liners in restimulation operations. Advanced modeling techniques and finite element analysis (FEA) were employed to simulate various load cases encountered during fracturing operations. The modeling considered factors such as fracture fluid temperature, stimulation pressure ballooning, and inconsistent cement distribution. Four connection designs were evaluated under these conditions: conventional flush joint, wedge custom flush, conventional shoulder upset, and wedge semi-flush connections. The modeling revealed that under certain downhole conditions, tension loads on the liner can increase significantly, potentially leading to connection yielding. This increase in tension is highly dependent on the interaction of fracture fluid temperature, stimulation pressure ballooning, and inconsistent cement coverage. The evaluation provided insights into the performance of the four connection types, identifying which designs are more resilient to the complex loading scenarios during restimulation. Through this analysis, a refined and more precise connection selection criterion was developed, allowing for better prediction of connection performance and integrity in the demanding environments of restimulation treatments. This load case model addresses the specific challenges encountered in recompletion operations, offering a more reliable method for mitigating risks associated with high tension loads and connection yielding.