Abstract
Ball-drop or ball-activated completion systems for multistage hydraulic fracturing are designed to reduce stimulation time and improve efficiency by being pumped in one continuous operation. Actuation balls are used in these systems to activate sliding sleeves and internally isolate the production liner into individually isolated stages. While this technology is traditionally associated with single point entry stimulation (one ball per sleeve), advancements in ball-drop technology have led to the development of a system that uses one ball to activate multiple sleeves, combining the efficiency of ball-drop completions with the placement accuracy of limited entry stimulation in cemented liner completions.
Limited entry ball-activated completion technology has evolved over time. Each iteration has been designed with fewer components to further improve the operational efficiency of having one ball activate multiple sleeves in a treatment zone. The latest advancement in this technology has seen a 40% reduction in the number of components, which in turn reduces operational risk. While limited entry ball-drop completion systems have been run for over a decade in openhole applications, the newest version was specially designed to run in a cemented liner application.
The latest version of limited entry ball-activated completion systems is designed to stimulate a high number of entry points in one treatment more effectively, reduce overdisplacement, reduce completion time, remove risk of wireline and coiled tubing runs, eliminate the need to millout the system prior to flowback, and solve entry point erosion concerns. Each port or sleeve is designed to have its own back pressure or limited entry effect (equivalent perforation pressure), which is customizable for each application. By using a non-erodible material in each sleeve the limited entry effect is designed to be consistent throughout the entire stimulation. This is a significant improvement over existing limited entry tools and plug-and-perf completion designs and will lead to more effective distribution throughout the entire stimulation.
In each field trial to date using the new limited entry ball-drop completion technology, all the sleeves have opened and stimulation treatments have been delivered as designed. In the cemented liner applications, the limited entry ball-activated sleeve system allowed stage to stage transitions without shutting down pumping operations.
Limited entry ball-drop completion systems provide instant time and operational improvements to traditional cemented liner completion methods. These time and cost improvements can significantly reduce total well costs, which is especially important for operators in low price commodity environments.
