Improving Diversion Efficiency in Re-Fracturing by Using Engineered Solid Particulate Diverters

Abstract

Currently, solid particulate diverters are frequently used for fluid stimulations, including fracturing, refracturing and acidizing. To ensure the success of a diversion operation, the most common strategy is to increase the amount of solid particles used in each stage to achieve diversion; however, this could lead to the excessive job costs, longer clean-up times and even, in extreme cases wellbore blockage. The success of these diversion treatments is truly dictated by the mechanical characteristics and wellbore displacement of the pumped solid diverters. A full understanding of the underlying mechanism of jamming and plugging can aid in the design and pumping of the particulate diverters efficiently. In this study, an integrated analysis is performed prior to a planned re-frac treatment to assess and improve the diverter application design.

Using the experimental data, an integrated analysis was conducted to quantify the influence of solid particle design on the jamming and plugging process and hence the diversion efficiency. Both a CFDDEM model and a 3D fracture simulator were used to model particle transport and the diversion process prior to a re-fracturing operation. The overall conductive reservoir volume and associated production was predicted to compare and contrast the fluid diversion efficiency between different design plans, as engineered vs. non-engineered solid particulate diverters.

From our analysis, engineered solid particulate diverters can seal the openings and build-up enough pressure to redirect fracturing fluid, as suggested from both the experiments and the numerical simulations. Non-engineered solid particles could fail in blocking the opening or cannot build sufficient pressure required for effective diversion. In this case study, by using the fit-for-purpose particle design, including size, ratio and concentration, the engineered solid particle diverter can effectively plug the active perforations and redistribute the fracturing fluid into non-active perforations to create additional fractures to boost production.

According to our case study, the particle design can be engineered properly to enhance the diversion efficiency and also optimize the usage of diverters. The presented design workflow and analysis will better enable us to design and customize solid particles for efficient fluid diversion.