Newly Designed High Expansion Through-Tubing Bridge Plug Service to Reduce Operational Costs and Increase Reliability

Abstract

Through-tubing bridge plug (TTBP) service is a common e-line well intervention service for isolating lower non-productive zones for improved production or plug and abandonment. Traditionally, this service was only run on e-line, as it requires a unique electro-mechanical extended stroke setting tool, to set these types of barriers. This paper discusses the challenges of developing a new design of the TTBP, deployed on Digital Slickline (DSL) to help optimize service costs. System-level analysis was adopted to analyze the current e-line TTBP service and identify challenges to DSL deployment. In general, these plugs have extremely high-expansion ratios (2x to 4x) compared to other wireline set barriers as they have to pass through tight downhole restrictions in the completion before passing into the casing. As a result, these plugs have an exceptionally long setting stroke, requiring a specific setting tool with high power demands. The high expansion ratio of the TTBP limits pressure rating and this type of barrier demands a cement cap on the plug to complete the intervention. DSL cannot send power from the surface; therefore, it has electrical power budget limitations. The right balance needs to be found between the stroke length and the available power to achieve a successful plug. The elastomer stack and the backup petal assembly were significantly redesigned to achieve an acceptable expansion ratio while minimizing stroke length. This feature allowed for the development of a battery-powered setting tool with a shorter stroke length. Running the service on DSL lets the operator confirm depth correlation before setting the plug and real-time feedback from downhole sensors to ensure an in-situ quality plug set. Moreover, digital slickline provides accurate bottom-hole temperature, which is critical in achieving a suitable cement plug. The paper will present results from field trials showing the cost savings of running these plugs on DSL compared to e-line.