Abstract
Tubular restrictions from scale buildup can significantly reduce hydrocarbon production, and buildup must be removed to restore the production capacity of a well. Although scale buildup is a global problem, the material composition and characteristics of scales can vary drastically, even within the same field, making most tools on location insufficient for scale removal. A customized jet cleaning tool has recently been developed to address the problems associated with tubular cleaning operations.
Traditional jet cleaning tools are insufficient for removing scale buildup because they do not reliably control jet dwell time. Jet dwell time is the relationship between the difficulty of tubular cleaning and the time required for scale removal. Jet dwell time increases with an increase in the hardness of the buildup material. Ability to control dwell time is a measure of cleaning efficiency. A new, slow-rotating jet cleaning tool can help optimize jet dwell time for cleaning operations without repetitive cyclic effects on a coiled tubing (CT) workstring.
The slow-rotating jet cleaning tool can also be used for cutting tubulars. Previously, tubulars were cut by mechanical, explosive, or chemical methods, and CT was used to deploy positive-displacement motors (PDM's) and pressure-activated firing devices (used for rotating the mechanical cutters and initiating the firing sequence in explosive or chemical cutters, respectively). For many through-tubing applications, traditional cutting methods created significant safety risks and obstacles such as long bottomhole assemblies, increasing service costs. With its capability to control jet dwell time and pump abrasive fluids, the new jet cleaning tool can reduce the safety risks and the costs associated with traditional cutting methods.
This paper discusses the design and application of the slow-rotating jet cutting tool, and provides case histories of the tool's use in removing scale and production buildup on tubing walls. The paper also discusses application of the tool for performing through-tubing cuts.
